Atomic spectrometry update. Clinical and biological materials, foods and beverages
Andrew Taylor*a, Simon Branchb, David Hallsc, Marina Patriarcad and Mark Whitee
aSupra-Regional Assay Service, Trace Element Laboratory, Centre for Clinical Science and Measurement, School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey, UK GU2 7XH. E-mail: A.Taylor@surrey.ac.uk
bThe Lord Rank Centre, R. H. M. Technology, Lincoln Road, High Wycombe, Buckinghamshire, UK HP12 3QR
cTrace Element and Micronutrient Unit, Department of Clinical Biochemistry, Glasgow Royal Infirmary University NHS Trust, Castle Street, Glasgow, UK G4 0SF
dLaboratoria di Biochimica Clinica, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Roma, Italy
eHealth and Safety Laboratory, Health and Safety Executive, Broad Lane, Sheffield, UK S3 7HQ
First published on 14th March 2002
Abstract
This ASU reviews publications that appeared in the twelve months up to the end of October 2001. Analytically, there were few new developments. Indeed, some of the innovations that we have highlighted in the last couple of Updates, such as capillary electrophoresis and movable reduction bed hydride generation, were less evident during this period. In contrast, work to validate the use of XRF for measuring lead in bone in vivo is moving forward although it is only a few centres that have the capability to carry out this very specialised application. In addition, a non-invasive XRF method of determining skin Fe concentrations to assess liver Fe concentrations in haemochromatosis and β-thalassaemia was presented. Interesting developments in low-cost techniques for dissolution of samples and preconcentration using flow injection are again evident. It appears that, perhaps as more laboratories replace AAS by ICP-MS, the latter technique is being used for work where just one or two analytes were reported. A number of examples were seen of problems in the clinical trace element field relating to the use of newer materials, and techniques in medicine and surgery appeared. Materials for prostheses were highlighted along with the use of relatively high concentrations of some unusual compounds for body organ imaging techniques and radiation therapy. Further applications of techniques for As speciation are featured within the clinical and foods/beverages sections. The most important development was the demonstration of methylated species containing AsIII, the significance of which is likely to become apparent in the near future. For the first time reports were seen of investigations involving organically produced foods and it will be of interest to see whether this continues. The writing team was strengthened with the inclusion of an experienced Italian colleague, Dr. Marina Patriarca, who helped with the preparation of the section on clinical and biological materials.
1 Analysis of clinical and biological materials
Our previous annual review on atomic spectrometry in the analysis of clinical and biological materials, foods and beverages was published in April 2001.1 This Update reviews publications appearing up to October 2001. Table 1 summarises details of the publications while the text describes the more important developments.1.1 General reviews and articles
Tsalev2 has argued that both vapour-generation AAS and ETAAS should be part of the analyst's repertoire of techniques and they should not be viewed simply as alternatives. In his review, the scope, merits, limitations and sample preparation requirements are discussed for the two approaches and how they can interact with each other in recent trapping of hydrides and vapours in ETAAS is described. Examples of his recent research on environmental and biological samples are outlined.Speciation of metals and metalloids by hyphenated techniques was reviewed by Szpunar.3 Separation techniques covered include size-exclusion, anion- and cation-exchange, reversed-phase HPLC and flatbed and capillary electrophoresis. Detection by element using AAS, ICP-AES and ICP-MS were compared with detection by molecule using electrospray MS/MS.
1.2 Sampling and sample preparation
For on-line sample preconcentration, a column is generally used for collecting the element of interest followed by elution at a different pH or with a different solvent. Almeida et al.9 used this approach for the determination of Cu in urine by FAAS. The Cu from 5 ml of digested urine was concentrated on a polyamine chelating ion-exchange column and then eluted allowing determination down to an LOD of 1 µg l−1. In the method of Benkhedda et al.,10 Co was preconcentrated from biological samples by a factor of 15 using ion-pair adsorption on the walls of a PTFE knotted reactor. The ion-pair was formed by the reaction between the negatively charged Co-nitroso R salt complex and the counter ion tetrabutylammonium. The knotted reactor was also used by Liu et al.11 for the collection of Cd, Cu, Fe and Pb trapped by coprecipitation with NiDDC. The precipitate was dissolved in IBMK for determination by FAAS. Enhancement factors of 65, 60, 59 and 58 were obtained for Cd, Cu, Fe and Pb, respectively.
Wang and Hansen12,13 have adopted a different approach to on-line preconcentration by using a renewable column of a defined volume of ion-exchange beads. The resin beads and 30 µl of 1∶16 v/v HNO3 were transported by air-segmentation into the graphite tube of an ET-AA spectrometer for quantitation. While the furnace programme was run, new material was aspirated into the column and the preconcentration of the next sample begun. In this way, Bi could be determined in urine13 down to an LOD of 27 ng l−1 with an enrichment factor of 33.4 and Ni down to 9 ng l−1 with an enrichment factor of 72.1.12
1.3 Developments in and applications of multi-element techniques
To study the binding pattern of elements in human milk, Bocca et al.17 coupled size-exclusion HPLC to an ICP-AE spectrometer with a USN nebulizer. Milk samples from 60 lactating mothers were studied. Calcium and Mg were associated with low Mr mass compounds. Copper and Fe were spread across all the five organic fractions seen, whereas Mn concentrated in the first (caseins) and the fifth (low Mr). Zinc was found in highest percentage in the fourth (alpha-lactalbumin).
A screening method for the determination of Pb in microsamples of blood was described by Van der Wilp and Karanassios.18 The blood was diluted with a diluent containing Triton X-100 and 0.5% v/v HNO3 and 5 µl of this were deposited on a rhenium cup which was dried and ashed close to the torch before final introduction to vaporise the Pb. Precision was 10–15% RSD.
In an evaluation of the potential of ICP-AES for the determination of trace elements in digested serum, Rahil-Khazen et al.19 concluded that it could be used for normal levels of B, Ba, Cu, Fe, Li, Se, Sr and Zn and elevated levels of Al, Be, Co, Cr, Ni and Pb. Their method was applied to the determination of reference values for B, Ba, Cd, Cu, Fe, Mn, Li, Se, Sr and Zn in 141 healthy Norwegians.20 Serum B, Ba and Sr were found to increase with age.
1.3.2.1 Reviews. Inductively-coupled plasma mass spectrometry and its application in the determination of trace elements in clinical samples was reviewed by Stastna et al.21 Problems encountered in the analysis of body fluids and tissues were discussed with possible solutions.
1.3.2.2 Multielement determination by ICP-MS. Reference ranges for 25 trace elements in urine samples from a US population were established by Komaromy-Hiller et al.22 using ICP-MS; Cr concentrations, however, were determined by ETAAS. High outliers were assumed to be the result of exposure to the element and were excluded. Results were expressed as a ratio to creatinine. Using sector-field ICP-MS, Alimonti et al.23 determined Cr, Ni and V concentrations in the urine of schoolchildren aged 6–10 years. Ranges established were 0.07–0.76, 0.20–1.23 and 0.02–0.22 µg g−1 creatinine for Cr, Ni and V, respectively. Forrer et al.24 reported reference ranges for Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr and Zn in human serum determined simultaneously by ICP-MS. Thirty-two elements in human liver and kidney and 20 elements in bone were determined by Benes et al.25 on samples from 70 autopsied individuals. In the liver, the concentrations of Al, As, Cd, Rb and V were higher in men than in women whereas Bi, Cr, Hg and Zn concentrations were lower. Differences between the sexes were also found for concentrations in the kidney and bone.
Reports on applications of collision cells or reaction cells in quadrupole ICP-MS in the clinical field are still small in number. Marchante-Gayon et al.26 showed that a collision cell with He and H2 was effective in reducing interference from polyatomic Ar interferences in the determination of the Se isotopes, 78Se and 80Se. This, when coupled to an HPLC system through a hydraulic high-pressure nebuliser, gave low LODs (30–80 ng l−1) suitable for the speciation of Se in urine. In their study on eight subjects, trimethylselonium was found in the urine of only three subjects, both before and after supplementation, but the main Se-containing constituent was not identified.
Concentration changes of elements in plasma and dialysis fluids of seven patients on haemodialysis were followed by Krachler et al.27 by ICP-MS. In the patients' plasma, concentrations of Cu and Zn continuously increased during dialysis. Concentrations of Ba, Ca, Mg and Sr were above the normal reference range. Plasma Mg concentrations fell during dialysis but at the end were still 50% above the top of the reference range. A further paper28 looked at the changes in Cd, Co, Cs, Cu, La, Mg, Mo, Rb, Sr, Tl and Zn over 6 months. Concentrations of Cd, Co, Cu, Pb and Zn rose over this period while Cs, Mg, Mo and Rb decreased. Speciation of Cu, Fe and Zn in serum of patients on haemodialysis was achieved by Muniz et al.29 The samples were separated on an anion-exchange column and the eluant was mixed with a solution containing the enriched isotopes 57Fe, 65Cu and 67Zn to allow measurement by isotope dilution with a sector-field ICP-mass spectrometer set at medium resolution. This resolution allowed the main Cu, Fe and Zn isotopes to be separated from polyatomic species. The speciation of patient samples differed from healthy controls, especially in Fe distribution.
To examine the effect of percutaneous transluminal coronary angioplasty on blood and plasma concentrations of trace elements in patients with heart disease, Krachler et al.30 measured concentrations by ICP-MS on samples taken 4–12 h prior to and 24–30 h after the operation. Concentrations of Co, Cs, Fe and Rb decreased in both whole blood and plasma. No significant changes were seen in the other elements measured (Ca, Cu, Mg, Pb, Sr and Zn).
Krachler and co-workers31,32 have also measured concentrations of 17 elements in osteoarthritic knee-joint effusions and related them to measurements in the patients' sera. Generally, the knee-joint effusions had lower concentrations than their corresponding sera, with strong correlations between the two concentrations. They reported that the concentrations of Cu and Zn in serum were at or below the reference range for healthy adults.
In infection, plasma concentrations of trace elements change markedly, but Funseth et al.33 wished to establish whether these were reflected in the target tissues. In their study, they measured, by ICP-MS, concentrations of 12 trace elements in the myocardium of mice infected with coxsackievirus B3 and in controls. Concentrations of Ca, Cu, Se and Zn increased but Mg decreased.
Menegario et al.34 developed a method to determine concentrations of Ba, Cd, Cu, Pb and Zn in human saliva by ID-ICP-MS using a DIN. Samples were prepared by taking 0.4 ml of saliva, 0.1 ml of concentrated HNO3 and diluting to 2 ml with H2O. This was spiked with a solution containing 135Ba, 112Cd, 65Cu, 206Pb and 66Zn. Results obtained by ID were in agreement with those obtained by external calibration on digested samples.
In a study on the relationship between trace elements and the risk of preeclampsia in pregnancy, Mahomed et al.35 measured, by ICP-MS, leucocyte Cu, Se and Zn in 171 mothers with proteinuric pregnancy-induced hypertension and 184 normotensive controls. Concentrations of Se and Zn were significantly higher in the patient group with evidence of an increasing risk of preeclampsia with increasing concentrations of Se and Zn.
As a marker of environmental pollution in Poland, Appleton et al.36 measured concentration of Cd, Cu, Pb, Sr and Zn in the teeth of bank voles by ICP-MS. The premise was that heavy metals are incorporated into hydroxyapatite in teeth during its formation and thus provide a permanent record of exposure during the development of the teeth. Higher concentrations of heavy metals in teeth were indeed found to be related to the more polluted areas.
1.3.2.3 Laser ablation ICP-MS. It has been found that Ga inhibits osteoclastic resorption in vitro. Ghazi et al.,37 therefore, wished to find whether Ga could diffuse through dentine in teeth to prevent external root resorption by osteoclasts. Measurements by laser ablation ICP-MS showed that when the root space was filled with 1.0 M Ga(NO3)3, the concentration reached in the peripheral root dentine exceeded the 10−4 M concentration necessary to inhibit osteoclastic activity.
1.3.2.4 Determination of isotopes by mass spectrometry. Gwiazda and Smith38 have discussed the value of measurement of Pb isotopes by sector field ICP-MS as an economical method for assessing the source of household lead exposure. By measuring 207Pb∶206Pb and 206Pb∶204Pb ratios, it was possible to identify the main sources of lead exposure to a child, discard unlikely sources and point to sources of Pb in dust. Case studies were used to illustrate this.
Sector field ICP-MS was used by Latkoczy et al.39 to measure 87Sr∶86Sr ratios in archaelogical samples of soils and bones. Because 87Rb overlapped the 87Sr peak, a prior separation by on-line anion-exchange HPLC was necessary. The sensitivity of the method was increased by using a shielded torch system and USN.
1.3.2.5 Accelerator mass spectrometry. Iron status affects absorption of aluminium, according to a study by Winklhofer et al.40 To three groups of rats, iron-deficient, normal and iron-overloaded, a dose of 26Al was given and they were sacrificed 24 h later. Using AMS, the 26Al was measured in the plasma, urine, femur, liver and spleen. The iron-deficient rats had the highest intestinal Al uptake and the highest concentrations in the spleen, liver and plasma whereas the iron-overloaded rats showed decreased Al uptake and lower tissue concentrations. Transfer of Al from pregnant rats to their fetuses through the placenta and transfer to suckling rats through maternal milk was shown in a study by Yumoto et al.41 Again using injection of 26Al and measurements by AMS, high 26Al concentrations were found in the brain and liver of fetuses or the brain, liver, kidneys and blood of suckling rats.
1.3.3.1 Elemental mapping. Microbeam imaging of Fe in a single neuron of patients with Parkinson's disease using SRXRF allowed Ektassabi et al.42 to demonstrate that Fe accumulated in the neuromelanin aggregates co-precipitating with Ca, Cu, S and Zn. The Fe intensity inside the melanin pigment granules of a patient sample was about an order of magnitude greater than in controls. Using an SRXRF microprobe of 100 µm resolution, Carvalho et al.43 measured profiles of Br, Cu, Fe, Pb, Sr and Zn in teeth from populations living on the isolated Portuguese Islands of the Azores. Concentrations of Sr were highest in the external enamel, while concentrations of Br, Fe, Pb and Zn were higher in the inner part of the teeth. Copper and Mn, both present at low concentrations, varied little from region to region.
1.3.3.2 Fundamental developments in in vivo XRF determination of lead in bone. Bateman et al.44 showed that two new digital spectroscopy systems allowed improvements in LOD in the determination of Pb in bone by 109Cd-based XRF. A conventional analogue amplifier system gave an LOD of 6–10 µg g bone mineral−1 but with a Canberra DSA-2000 or an ORTEC DSPECPLUS system the LOD was reduced to 1.2–2.5 and 0.5–1.0 µg g bone mineral−1, respectively. The feasibility of combining the K- and L-XRF methods for the determination of Pb in bone was investigated by Lee et al.45 Their system used a 109Cd source and Ge and Si(Li) detectors for the K and L X-rays, respectively. Monte Carlo simulated results indicated an improved LOD over a conventional single detector system.
Calibration of in vivo XRF determination of Pb in bone is normally with phantoms of material (often plaster of Paris) containing known amounts of Pb. Then a coherent conversion factor (CCF) is applied which converts between the response in the standards and that in human bone. Todd46 looked critically at the the effect on the CCF of various factors. He concluded that impurities in plaster or bone matrices, coherent scatter from non-bone tissue and the individual subject's measurement geometry were all minor or negligible effects and also that a synthetic apatite matrix was more representative of bone than plaster of Paris. In a further paper,47 he addressed the treatment of the calibration-line intercept and proposed refinements to the accepted method of subtracting the phantom calibration line from the in vivo measurements to calculate the in vivo concentrations. Spitz et al.48 developed a new type of phantom which reproduced the anatomy of the human leg and had components (polyurethane and CaCO3) that exhibited the same density, energy transmission and Ca content as cortical bone, bone marrow and muscle.
The effect of measurement location was studied by Todd et al.49 On bare bone, the measured XRF intensity and its uncertainty increased towards the proximal and distal ends of the tibia but in an intact leg, there was no effect of proximal–distal location but the uncertainty was increased towards the ends. In their study on two young male cadavers, Hoppin et al.50 showed considerable differences in mean bone Pb concentrations in the left and right legs of the same individual (mean mid-point bone Pb 0.8 and 2.0 µg g bone mineral−1 in a 17-year old and 3.6 and 6.0 µg g bone mineral−1 in a 20-year old).
1.3.3.3. Applications of in vivo XRF determination of lead in bone. It has been apparent in recent years that the development of in vivo XRF methods has rekindled a large interest in studies on environmental and occupational lead exposure. This measurement is important as bone is the main storage tissue for Pb and its Pb concentration reflects Pb accumulated over the subject's lifetime. It would appear to be a reliable index of exposure although, as is evident in the previous section, there is room for improvement in the methodology and in the understanding of the biological variability in the measurement.
Changes in bone Pb concentrations of workers in a lead smelter were studied by Brito and co-workers.51,52 Following improvements in industrial hygiene, tibia Pb concentrations in 51 subjects had fallen to a mean of 33 µg g bone mineral−1 from a mean of 39 µg g bone mineral−1 in a previous study five years earlier. However, surprisingly, calcaneous Pb had not fallen significantly from a level of 64 µg g bone mineral−1. In a more extensive study on 327 individuals,52 the findings were confirmed and by looking at subgroups of subjects, it was found that workers aged under 40 had a shorter half-life for release of Pb from the tibia than their older colleagues. In addition, those with a lifetime average blood lead less than or equal to 25 µg per 100 ml (1.21 µmol l−1) had a shorter tibia half-life than those with a higher blood lead. High tibia Pb concentrations were found in lead workers in Taiwan by Todd et al.53 using in vivo XRF. In 43 workers, the mean and maximum tibia Pb concentrations were 54 µg g bone mineral−1 and 193 µg g bone mineral−1, respectively, corresponding to blood Pb concentrations of 44 µg 100 ml−1 (2.12 µmol l−1) and 92 µg 100 ml−1 (4.64 µmol l−1), respectively.
As part of an extensive study (The Normative Ageing Study), Cheng et al.54 studied the relationship between environmental Pb exposure as measured by blood and bone Pb concentrations and the development of hypertension in 833 participants. A positive association was found between the baseline bone Pb level and the incidence of hypertension but no association was found with blood Pb level. In a study of 156 boys aged between 11 and 14 years, Campbell et al.55 found that those children in the highest bone lead quartile had decreased performance in the most difficult language processing tasks. There was no difference in the easier tasks, however. Tibial Pb concentrations were measured by in vivo XRF.
1.3.3.4 Determination of other elements by in vivo XRF. In order to establish whether skin Fe levels measured by in vivo XRF could be used to monitor iron overload, Farquharson et al.56 injected rats with iron-dextran and then treated them with an iron chelator. Non-haem Fe concentrations in the liver, heart and spleen were measured colorimetrically. The skin Fe concentration correlated strongly with the concentration of Fe in the inner organs and they foresaw that this technique had great potential in the diagnosis and treatment of hereditary haemochromatosis and β-thalassaemia.
Kadhim et al.57 developed a method for measuring Pt concentrations in the kidneys of patients receiving Pt-based chemotherapy drugs. The optimal conditions included an operating voltage of 220 kV, a 0.25 nm Sn filter and a polarizer made of Cu and Si. With a measurement time of 2000 s, the LOD was 16 µg g−1. To support the development of a system for in vivo determination of Cd in kidney using 133Xe as an excitation source, Al-Ghorabie58 used Monte Carlo simulation to show that, for distances between the skin and kidney surface of 30–60 mm, Cd concentrations of 15–60 µg g−1 could be detected.
1.3.3.5 Other applications of X-ray techniques. In a comparison of Fe concentrations in the liver of 50 Greenlandic Inuit and 72 Danes by XRF, Milman et al.59 reported no significant overall difference between the two groups or between genders. However, in the age group less than 50, the Inuit had a significantly lower Fe content than the Danes and for age greater than 50 the Inuit had higher liver Fe than the Danes.
A range of elements in white and grey matter of the brain were measured by Boruchowska et al.60 using particle-induced X-ray emission. The elements Ca, Cu, Fe, K, Mn, S and Zn were found in higher concentrations in grey matter. Zinc concentrations in the white matter were found to increase with age. A study by Akanle et al.61 on maternal breast milk in Nigeria showed that breast milk for preterm infants had higher concentrations of Cl, Cu, Fe, K, Mg, Mn, Na and Zn and lower concentrations of Br and P than milk from term mothers. Concentrations of Al, Ca, I and Rb were not significantly different. Measurements were by INAA and PIXE.
A sensitive method for the determination of Au and Pd in urine using total reflection X-ray fluorescence was developed by Messerschmidt et al.62 The elements were separated by reductive co-precipitation with Hg, followed by evaporation of the Hg. Concentrations in occupationally exposed and non-exposed individuals could be measured down to LODs of 2.0 µg l−1 for As and 2.5 ng l−1 for Pd.
Normal values for As and Se in human lung tissue were determined by Kraus et al.64 using HGAAS. Samples taken from 50 persons at autopsy gave As results from <1 to 74 ng g−1 dry wt and Se concentrations from <3 to 574 ng g−1 dry wt. Smoking habits, age and lung disease did not appear to affect the concentrations.
Release of trace metals from metal prostheses is a topical subject. Brodner et al.65 measured serum Co and Cr in patients post-operation by ETAAS. They found that patients with chronic renal failure had maximum serum Co values 100-fold higher than the median values for patients with the same prosthesis but no known renal disease. They concluded that metal-on-metal bearings should not be inserted into patients with chronic renal failure. Schaffer et al.66 reported increased Co and Cr levels in the blood and urine of patients with hip replacement operations. They measured concentrations by ETAAS in 76 patients and 26 controls. Significant correlations were found between blood and urine concentrations for both elements and between Co and Cr concentrations. Release of Cr and Ni from fixed orthodontic appliances into saliva was studied by Kocadereli et al.67 Saliva samples were taken before insertion and 1 week, 1 month and 2 months after insertion. Measurements by ETAAS showed no significant difference between the results and those in a control group with no appliances, leading to the conclusion that there was no significant release of Cr and Ni in the first two months.
A study from six medical centres in Taiwan68 investigated the prevalence of abnormal Al, Cd, Cu, Hg, Pb and Zn concentrations in the blood of patients on haemodialysis. Measurements by AAS showed that 78% of the patients had low plasma Zn, 31% had high plasma Al and 73% had high blood Cd levels. The majority had normal plasma Cu, blood Pb and blood Hg concentrations.
Factors that influence the concentration of trace elements in human milk were investigated by Silvestre et al.69 Copper, Fe and Zn were determined by FAAS. Iron concentrations were higher in hind-milk samples and at the night-time feeding and depended on which breast the sample was taken from. Copper and Zn concentrations showed no such differences. The Zn concentration in transitional milk was lower than in colostrum but no significant differences were seen in Cu and Fe concentrations. They concluded that a standardised sampling protocol procedure was important to obtain comparable results. They applied this to a longitudinal study70 to follow changes at 5 stages up to a time of 3 months. Zinc concentrations fell from 7.99 mg l−1 to 1.05 mg l−1, whereas Fe concentrations varied little (from 0.56 to 0.40 mg l−1). Overall, the Cu concentration fell from 0.38 mg l−1 to 0.19 mg l−1, but these workers identified two distinct patterns of increase or decrease on transition from colostrum to transitional milk. Concentrations of Cu, Fe, Mn and Zn in milk from Kuwaiti mothers were measured by Al-Awadi and Srikumar71 by AAS and compared with concentrations in milk from non-Kuwaiti mothers. The Kuwaiti mothers had significantly higher Cu, Fe, Mn, Zn and total protein concentrations in their milk than the non-Kuwaiti mothers. Turan et al.72 reported concentrations of Cu, Cd, Cr, Mn, Pb and Ni in colostrum samples which were determined after wet ashing by ETAAS with a modifier of W, Pd and citric acid. Iron and Zn concentrations were additionally determined by FAAS. An in vitro method to predict the availability of Ca, Fe and Zn in infant formulae and human milk was developed by Bosscher et al.73 Continuous-phase dialysis against a simulated intraluminal gastric juice appropriate for infants less than 6 months modelled availability and the dialysates were analysed by AAS. Human milk showed higher availability of Fe and Zn than all forms of formula but the availability of Ca was similar.
Methods for the determination of trace elements in blood fractions were developed by Prohaska et al.74 using ETAAS with Zeeman-effect background correction. Samples of erythrocytes, plasma and lymphocytes were diluted with a solution containing HNO3 and Triton X-100 and an appropriate modifier added to allow separate determination of Cd, Cr, Cu, Mn and Se.
In a study of trace elements in the spinal cord of horses with equine motor neuron disease, Polack etal.75 found that Cu concentrations were significantly higher than in control horses. No significant difference was found in the other elements measured (Al, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Se and Zn) using the techniques of ICP-AES, ETAAS, CVAAS and fluorimetry. They concluded that Cu was possibly involved in the pathogenesis of this disease. Interestingly, Pamphlett etal.76 carried out a study on human sporadic motor neuron disease by ICP-MS and ETAAS. Of the elements they measured in blood, plasma and red cells (Cd, Cu, Hg, Pb and Se), only plasma Cd was found to be significantly different from controls; Cu concentrations did not differ.
Human tooth enamel was analysed by Reitznerova et al.77 for Cu, Fe, Mg, Mn, Pb and Se by FAAS, ETAAS, ICP-AES and ICP-MS. Successive layers of 50 µm thickness were etched off with 3 M HClO4 up to a depth of 200 µm. The Cu, Fe, Mn, Pb and Zn concentrations decreased with successive layers whereas the Mg and Sr concentrations increased.
Savarino et al.78 may have found the secret of a healthy long life. They measured serum Se and Zn concentrations by ETAAS and FAAS, respectively, in two groups of “healthy” elderly people. The first group aged between 91 and 110 (90 subjects) had significantly higher Se and Zn concentrations than a second group aged between 60 and 90 (62 subjects). Moreover, 84.4% of these nonagenarians/centenarians had both Se and Zn concentrations equal to or greater than the lowest values of the elderly group.
1.4 Developments in single element techniques
Tungsten-filament atomisers for determination of blood lead by ETAAS have featured in previous reviews. Zhou et al.79 completed a comparison of three types—short and long wire filaments based on Osram W-filaments and a third etched filament produced by lithographic imaging and photoetching. Whole blood was diluted 1 + 4 with a modifier containing phosphate, Triton X-100 and HNO3. The long wire filament proved the best with an LOD of 0.05–0.10 µmol l−1 and a lifetime of 60–70 firings. Within-run precision was better than 10% RSD.Cathode materials for electrolytic hydride generation were investigated by Denkhaus et al.80 Glassy carbon was suitable for hydride generation with AsIII, SbIII, SeIV and SnIV. However, Hg–Ag could generate stibine from both SbIII and SbV and arsine from AsIII and AsV with efficiencies greater than 90%. The method was applied to the determination of As and Se by HGAAS in CRMs and tissue from cancer patients. Machado et al.81 used electrochemical hydride generation in an FI system coupled to a flame-heated T-tube in an AA spectrometer for the determination of Se. The electrolytic cell consisted of two reservoirs each with a Pt electrode and separated by a Nafion membrane. One cell contained the sample and the other an electrolytic solution. Optimised conditions allowed an LOD of 10 µg l−1 to be reached and a throughput of 30 determinations h−1. Accuracy was established by analysing food and animal CRMs.
1.5 Reference materials
Parr et al.82 reported improved values for Cs, I, Sr, Th and U in NIST Diet, Bone Meal and Bovine Muscle SRMs. Seven laboratories in five countries took part in this study using ICP-MS and instrumental and radiochemical NAA.1.6 Hair and nail analysis
Using sector-field ICP-MS, Rodushkin and Axelsson83 determined reference values for 71 elements in hair and fingernail samples for an urban population living in the north-east of Sweden. A strong correlation between hair and nail concentrations for the elements Bi, Cd, Hg, Pb and Sb was seen as evidence for reliable assessment for exposure to these elements. Reference values for 13 essential elements and 6 toxic elements in hair from urban schoolchildren aged between 3 and 15 years were established by Senofonte et al.84 using ICP-AES. Certain elements showed significant differences according to age and sex. For example, the mean Ca concentration was 336 µg g−1 in boys and 537 µg g−1 in girls. A study by Sakai et al.85 on growing children showed higher Cu and Mn concentrations in the hair of boys than in girls. They found that Cu, Mn and Zn concentrations decreased from 6 months to 14 years for boys and 6 months to 12 years in girls then increasing up to 20 years for both sexes. Measurements were made with ETAAS and ICP-AES. Selenium concentrations in hair samples from mothers and their children were determined by Barrera et al.86 using ETAAS after digestion with HNO3–H2O2. Concentrations in the child (mean 0.77 ± 0.25 µg g−1) were higher than in the mother's hair (mean 0.54 ± 0.34 µg g−1).Toribara87 has described the results of the analysis of a single hair sample from a chemistry professor five months after exposure to dimethylmercury in a laboratory incident. Analysis by XRF along the length of the hair showed a large peak corresponding to the date when exposure occurred. A later peak corresponded to release of Hg on chelation therapy. The professor died five months later.
Rahman et al.88 developed a continuous-flow vapour-generation system coupled to an atomic-fluorescence detector for determination of As, Bi, Hg, Sb and Se in hair after microwave digestion. For Hg, a two-stage digestion with HNO3–H2O2 was used whereas for the others a common digestion with HCl–H2O2 was preferred. The LODs were 0.2 ng g−1 for Hg and between 2 and 10 ng g−1 for the others. Accuracy was demonstrated by the agreement of the results obtained on analysis of a CRM with the certified values. Application of AFS to the determination of Hg in hair for a population survey was described by Pellizzari et al.89 Using 5 mg samples, Hg could be determined down to an LOD of 12 ng g−1 with a duplicate sample precision of 12.5% RSD and allowed measurable values in 95% of the population surveyed. The mean Hg concentration was 287 ng g−1.
Differences between major and trace elements in black and grey hairs from the same individual were found in a study by Tsai et al.90 Grey hairs had lower concentrations of Ca, Cu, Fe, K, Mn, Na, K and Zn than black hairs but differences in Fe, K and Zn failed to reach statistical significance. They concluded that reduction in hair mineral and trace element concentrations could be one of the factors associated with greying of hair.
MacPherson and Bacso91 reported the results of an extensive study to examine further their earlier findings of an inverse relationship between hair calcium and coronary heart disease ( CHD). Hair samples were collected from 4393 males in 40 different health districts in the UK and analysed by XRF. Standardised mortality ratios for CHD for each region showed significant relationships to hair calcium, water hardness and sunshine hours. Scotland with the highest mortality from CHD showed the lowest hair calcium, the softest water and the least sunshine hours, whereas South-East England had the lowest mortality from CHD, the highest hair Ca, the hardest water and the most sunshine hours. This is an important study but does not clarify whether hair calcium is directly related to CHD or simply related to the hardness of the water. It will be interesting to see how this work develops.
Confirmation that hair Pb is not a reliable guide to an individual's exposure to Pb was produced in a study by Campbell and Toribara.92 Children being screened for lead exposure by a standard blood lead measurement also provided hair samples. Measurement of Pb at the root of the hair by XRF failed to distinguish between children with low and high blood lead concentrations.
1.7 Drugs and pharmaceuticals
Interest in the determination of trace element contamination in pharmaceuticals has always been very limited. The “heavy metals test” prescribed by the US, European and British Pharmacopeia involves a crude colorimetric test. Wang et al.93 developed an alternative method using ICP-MS which was fast and sensitive and allowed all the elements possible by this technique to be surveyed. Lead concentrations in calcium supplements were measured by Scelfo and Flegal94 using sector-field ICP-MS. Two-thirds of the calcium supplements exceeded the 1999 California limit for an acceptable Pb level (1.5 µg per daily dose of supplement).Concentrations of potentially toxic elements in traditional Chinese medicines were determined by Chuang et al.95 using AAS. Concentrations of As, Cd, Co, Mn and Pb were higher in medicines of mineral origin than in those derived from plants and animals. Copper concentrations were higher in products of animal origin. The concentrations of heavy metals in many medicines exceeded those allowed by health agencies in several countries. Speciation of the As in the Chinese medicines, realgar and orpiment, was made by He et al.96 using ion-chromatography and HG-ETAAS. Concentrations of AsIII, AsV and dimethylarsinic acid (DMA) could be quantified.
An on-line FI method was developed by Sweileh97 to determine Cu, Fe and Zn in nutritional supplements. The powdered multi-vitamin tablet was inserted into a special chamber and carried by the digestion solution to a heated coil. The analytes were retained as their chloro-complexes on an anion-exchange mini-column. After a brief column wash, the elements were eluted with dilute HNO3 for determination by AAS. Two different derivatization approaches were compared by Pelaez et al.98 for the determination of selenomethionine in nutritional supplements by GC-ICP-MS. The preferred method involved esterification of the carboxylic acid group of the seleno-amino acid with propan-2-ol and then acylation of the amino group with trifluoroacetic acid anhydride. Concentrations of V contamination in infusion solutions were measured by Heinemann and Vogt99 using ETAAS. Albumin solutions showed V concentrations greater than 600 µg l−1. In a multi-trace element solution used in total parenteral nutrition, 14.8 µg l−1 V was found.
1.8 Marine and freshwater biology
Arsenic species in oyster tissue were extracted with methanol–H2O with 40 W microwave power for 5 min in a method developed by Vilano and Rubio.100 Subsequent measurements were made with LC–UV irradiation–HG-AFS. Three species were detected, arsenobetaine (AB) (87%), an arsenosugar (4.9%) and DMA (4.7%). A similar method described by Suner et al.101 was used for speciation of AB, arsenocholine (AC), trimethylarsine oxide (TMAO) and tetramethylarsonium ion (TMI) in fish CRMs.1.9 Progress for individual elements
Two groups reported the findings of studies to investigate the impact of Al on the immune system. Graske et al.105 determined Al in urine of volunteers, administered daily doses of Al(OH)3 antacid, using ICP-MS. Blood samples were taken to measure circulating concentrations of immunoglobulins, interleukins and lymphocyte sub-populations. During a 6 week period of three daily doses of 590 mg Al(OH)3, urine Al levels rose to values 10–20 fold higher than in controls but no major differences were found between the groups in the measured immunological parameters. Kosch et al.106 compared intracellular concentrations of Al in lymphocytes from haemodialysis patients and healthy controls. Intracellular Al levels were determined using AAS. In B-lymphocytes intracellular Al was significantly increased from dialysis patients (2.9 µg g−1 protein) compared with controls (1.4 µg g−1 protein). Levels of Al in dialysis fluids are still a cause for concern. Martin and Cannata107 presented the findings of a multi-centre study of Al concentrations in dialysis solutions from all Spanish dialysis centres. The authors reported that over 80% of centres had dialysate Al concentrations below 2 µg l−1 compared with only 45% in 1990. However, they highlighted that there was still a proportion of centres (4%) with dialysate fluids having high concentrations (>10 µg l−1) of Al.
Riihimaki et al.108 investigated the relationship between body burden of Al and central nervous system (CNS) function in a group of Al welders. Workers were divided into three exposure groups based on aggregated estimates of Al body burden. Both serum and urine Al concentrations were determined using ETAAS with Zeeman effect background correction. Median levels of serum Al were 0.08 µmol l−1, 0.14 µmol l−1 and 0.46 µmol l−1 for controls, low exposure and high exposure groups, respectively. Corresponding urine Al levels were 0.4 µmol l−1, 1.8 µmol l−1 and 7.1 µmol l−1, respectively. The authors reported that both objective and subjective measures of CNS function showed dose dependent changes associated with increased Al body burden. They established that urine Al levels of 4.6 µmol l−1 and serum Al levels of 0.25–0.35 µmol l−1 were threshold values for adverse effects on CNS function.
Nakazato and colleagues113 reported a sensitive method for the determination of eight inorganic and organic As species in biological matrices using a combination of LC-ICP-MS and LC-HG-ICP-MS. Good chromatographic separation of the As species was achieved with a carboxylated methacrylate resin ion-exchange column and Na2SO4 mobile phase. With nebulisation injection of the LC eluent, reported LODs for the species ranged from 0.067 to 0.34 µg l−1. With HG–ICP-MS LODs for AsIII, AsV, DMA, MMA and TMAO were improved to 0.016–0.075 µg l−1, but AB, AC and TMI-salt were not detected. The method was validated by analysis of urine and tuna CRMs
Methylated As species containing AsIII have been recognised as potent enzyme inhibitors and cytotoxins and thus formation of methylarsenicIII species may be considered to be an activation of As toxicity rather than detoxification. Two groups reported the findings of studies to determine methylated AsIII species in biological samples. Gregus et al.114 used HPLC coupled with HG-AFS to determine biliary and urinary As species in rats exposed to AsIII and AsV. They identified MMAIII in bile but not in urine and hypothesised that acid MMAIII was subsequently oxidised to MMAV and excreted in urine. Del Razo et al.115 developed a method for differential determination of methylated AsIII and AsV species. The method was based on the pH dependent differences in generation of hydrides from As species containing either AsIII or AsV. Only hydrides from AsIII species were generated at pH 6, whereas at pH 2 hydrides were generated from both species. Hydrides were trapped on a liquid N2 GC cold trap which was subsequently gradually heated to separate the hydrides according to their boiling point for analysis by AAS. The authors used the method to determine As species in water, urine and cultured cells. They identified methylarsenicIII species in the urine of individuals who had consumed water contaminated with inorganic As.
Duckett et al.117 used SIMS to localise Be in histological sections of pulmonary tissue from rats with Be-induced granulomatous pneumonitis. They observed that Be passed through the vascular wall into pulmonary tissue where it was phagocytosed by macrophages.
Phillips et al.120 examined the safety aspects of colloidal bismuth subcitrate (CBS) quadruple therapy for heliobacter pylori. They used ICP-MS to determine blood Bi levels in 34 patients receiving CBS quadruple therapy. Whole blood Bi levels were determined before and 24 h after treatment. Three patients had levels within the “alarm level” for blood Bi of 50–100 µg l−1. The authors advised that caution should be exercised in prescribing CBS with gastric suppression and that alternative Bi preparations should be investigated.
Pavanetto and colleagues122 studied the efficacy of different stablilized liposomes for the delivery of boronophenylalanine to hepatic metastases in rats. Conventional liposomes were composed of phosphatidylcholine-cholesterol (1∶1v/v) whilst “stealth” liposomes also contained polyethyleneglycol (PEG), in which the drug was encapsulated as a complex with fructose. Following administration of the liposomes, tissue concentrations of B were determined by ICP-MS and histological analysis with α-spectroscopy was used to visualise the distribution of B in the liver. The PEG liposomes accumulated B in metastatic tissue at therapeutic concentrations (>30 µg g−1) and the authors considered that PEG liposomes should be further explored for enhanced drug delivery to tumour sites.
Crews et al.124 described studies in which the stable106Cd isotope was used to examine dietary Cd uptake. Porridge was prepared from wheat intrinsically labelled with 106Cd and eaten by adult and child volunteers. Faecal collections from volunteers were analysed for Cd species using ICP-MS, to determine the unabsorbed fraction. The results indicated that dietary absorption of Cd could be greater than the 5% figure generally quoted. Van Cauwenbergh et al.125 investigated daily dietary Cd intake in the Belgian population using a duplicate portion sampling strategy. Diet samples were microwave digested and the Cd content determined by AAS. A mean daily intake of 23.1 µg was estimated, which was similar to values reported for other countries. The Japanese group of Watanabe and co-workers126–129 presented the findings of a series of long term studies examining exposures to Cd and Pb in urban populations of Japan and South-East Asia. They reported the findings of a survey on changes in the intensity of exposure to Cd by comparing the recent situation with that of over 15 years ago. Over the period 1991–1997, they determined Cd concentrations in duplicate diet samples, blood and urine samples from over 500 non-smoking women using ICP-MS. Mean values for dietary Cd intake, blood Cd and urine Cd were 25.5 µg per day, 1.9 µg l−1 and 4.39 µg g−1 creatinine, respectively, which represented a 32% reduction in dietary intake and 450% reduction in blood Cd levels compared with the situation 15 years previously. Nevertheless, these values were still considered high compared with levels in European populations. The authors established that Cd intake was almost entirely through the dietary route and that 40% came from rice. The group examined the relationship between blood Cd and urine Cd in women from South-East Asia. A significant correlation was observed between blood Cd and urine Cd when blood Cd levels were greater than 1 µg l−1. They also investigated whether current levels of Cd exposure in the Japanese population were associated with kidney dysfunction, again measuring Cd in dietary samples, blood and urine using ICP-MS after acid digestion of samples. Urine samples were also analysed for a number of low Mr proteins indicative of renal tubular damage. The authors established a borderline significance for evidence of kidney damage, which suggested that the margin of safety for the Japanese population is small.
Tateyama et al.132 determined Ca in artery, vein, cartilage and bone autopsy samples using MIP-ICP-AES. They noted that as Ca accumulation increased in the aorta it also increased in the femoral artery, intervertebral disk and cruciate ligament but did not increase in veins. Freeman and colleagues133 investigated skeletal Ca metabolism by administration of 41Ca and 45Ca tracers to volunteers and determination of the tracers in urine using AMS. They reported excellent diurnal stability and considered the method to be suitable for assessment of anti-resorptive osteoporosis treatment and clinical monitoring. Nagano et al.134 used AAS to determine Ca concentrations in testes of mice treated with i.v. injections of rare earth elements. No significant biochemical changes or changes in testicular weight were noted following injection, but testicular Ca concentrations were significantly increased. The authors considered that the Ca accumulation may be significant in the toxic action of rare earth metals.
Alimonti et al.23 established reference concentration ranges for urine Cr, Ni and V in a population of healthy children living in urban areas of Rome. Urine element concentrations were quantitatively determined by sector field ICP-MS with minimal sample pre-treatment to avoid potential contamination sources. Log transformed data were normally distributed for all three elements. The calculated reference ranges were 0.07–0.76 µg g−1 creatinine for Cr, 0.2–1.23 µg g−1 creatinine for Ni and 0.02–0.22 µg g−1 creatinine for V.
Ford138 examined the relationship between serum Cu and coronary heart disease in US adults using data obtained from the National Health and Nutrition Survey (1976–1992). Serum Cu was determined by AAS. Age adjusted serum Cu levels were determined to be about 5% higher in subjects who had died from heart disease than those who had not, which was in agreement with other prospective studies that had identified elevated serum Cu to be associated with cardiovascular disease. Mansoor and colleagues139 examined the relationship between plasma Cu and homocysteine in peripheral vascular disease. Plasma concentrations of Cu and other trace elements were determined using TXRF. Plasma homocysteine was determined by HPLC. A positive correlation between plasma Cu and homocysteine was observed for patients with peripheral vascular disease but not in healthy control subjects. Hatano et al.140 investigated the relationship between Cu and hepatic damage caused by hepatitis C infection. Levels of Cu and other trace elements were determined in needle biopsy samples of liver from patients with hepatic fibroses using PIXE. Serum Cu levels were determined using ETAAS. The results showed that liver Cu levels increased with progression of fibrosis, whereas Fe and Zn showed no correlation with progression of disease. The authors hypothesised that Cu may contribute to hepatic injury through oxidative stress caused by an excess of the metal. Yilmaz et al.141 used AAS to determine concentrations of serum Cu and Zn in individuals from Southern Turkey with chronic renal failure undergoing haemodialysis. Both Cu and Zn were significantly lower in the haemodialysis patients compared with healthy controls, although serum Cu levels in dialysis patients were still within the normal reference range. The authors recommended that chronic renal failure patients undergoing dialysis should receive Zn supplementation.
Milman et al.59 used XRF to determine liver Fe concentrations in autopsy samples from urbanised Greenland Inuit and urban Danes. The median liver Fe content in Inuit was 17.23 mmol kg−1 and 16.51 mmol kg−1 in urban Danes. The authors observed significant correlations between age and liver Fe in both populations. They found that young and middle aged Inuit had smaller Fe stores than Danes, whilst elderly Inuit had larger Fe stores than their Danish counterparts.
The relationship between Pb levels in biological fluids and hypertension was investigated by several groups. Kosch et al.152 determined intracellular Pb concentrations in lymphocytes of patients with essential hypertension using ETAAS. They noted that one sub-group of hypertensive patients had markedly increased levels of intracellular Pb, which they hypothesised may play a pathogenic role. Cheng et al.54 determined bone Pb using K-shell XRF and blood Pb using AAS in a group of over 800 volunteers in order to examine the relationships between bone and blood Pb levels and hypertension. In subjects with no history of hypertension, a positive relationship between bone Pb and systolic blood pressure was identified. In another study of former organolead workers, Schwartz et al.153 found that blood Pb was a predictor of systolic and diastolic blood pressure and hypertension status in men aged over 58.
Two groups reported very interesting studies on the influence of aminolevulinic acid dehydratase (ALAD) polymorphism on levels of Pb in blood and bone. Hu et al.154 determined blood Pb using ETAAS and bone Pb by XRF in over 700 non-occupationally exposed men. They observed that individuals with the ALAD-1 allele had cortical bone Pb levels approximately 2.55 µg g−1 higher than those with the ALAD-2 variant allele. They also observed that the ALAD-2 variant allele was also associated with higher blood Pb levels when trabecular bone Pb levels exceeded 60 µg g−1. They hypothesised that the variant allele modified Pb kinetics by increasing mobilisation of Pb from trabecular bone. Schwartz et al.155 examined the relationship between bone Pb, blood Pb and ALAD polymorphism in a large group of lead workers and a non-exposed population. They also established that individuals with the variant allele had higher blood Pb levels but found no difference in tibia Pb levels. Like Hu and colleagues, they concluded that the variant ALAD gene modifies Pb toxicokinetics. The same group also established that the variant allele of the vitamin D receptor also modified Pb kinetics.156
Todd and colleagues presented a comprehensive series of papers on factors influencing the accuracy and reproducibility of in vivo bone Pb measurements by XRF.157,158 They established that the bone Pb value and its uncertainty increased towards the ends of the tibia which they considered to be associated with the more trabecular composition of the tibia ends.49 The group addressed the problem of contamination of phantom calibration sources used for the determination of bone Pb and proposed a refinement to the current calibration methods to eliminate underestimation of bone Pb levels.47 They also established that a synthetic apatite matrix was a more representative calibration phantom than plaster of Paris for bone Pb measurements.46
Brown and colleagues159 examined environmental factors contributing to blood and bone Pb of women from Mexico City who had recently given birth. They established that age, cumulative use of lead-glazed pottery and the period spent in the city were the major predictors of high bone Pb. Mean blood Pb and tibia Pb concentrations were 9.5 µg dl−1 and 10.2 µg g−1, respectively, which were significantly higher than values for women in the United States. They considered that bone Pb stores may pose a threat to women of reproductive age long after Pb exposure had declined. In a related study, Hernandez-Avila et al.160 investigated the impact of menopause on bone Pb mobilisation in women from Mexico City. They found an inverted U-shaped relationship between age and blood Pb with highest blood Pb levels in women aged between 48 and 57 years. They concluded that bone Pb was re-mobilised at menopause and could constitute an important exposure source.
Two groups reported the findings of population studies on Mn levels in biological fluids and tissues. Diaz et al.170 used ETAAS to determine serum Mn concentrations in a representative sample (368 individuals) of Canary Islanders. A reference range of 0.19–3.33 µg l−1 was determined. Mean serum Mn levels were higher in individuals from Fuerteventura, which the authors attributed to differences in both environmental levels of Mn and dietary habits compared with the rest of the Islands. The authors also noted that serum Mn levels tended to decrease with increasing alcohol consumption and that sportsmen had higher Mn levels than other groups. The findings of a study by Fortoul et al.,171 which determined concentrations of Mn in lung autopsy samples from Mexico city residents, led the authors to conclude that Mn exposure via air did not pose a health hazard to residents of Mexico City
Chen and Chou174 developed a modified T-piece device to overcome an identified problem of insufficient reaction time in a commercial HG system used for the determination of Hg in biological samples. The introduction of the T-piece, which combined sample and reductant streams, increased the reaction time between sample and reagent to achieve complete release of Hg vapour for determination by AAS. The modified system gave accurate results for a variety of biological CRMs.
Jeffry and Barry175 compared different sample digestion mixtures for the determination of Hg in biological samples using closed vessel microwave digestion with FI-CVAAS. They observed that digestion of reference materials, having a low Hg content (<0.05 µg g−1), with HNO3–HCl–H2O2 gave markedly elevated values compared with the certified value. They hypothesised that the high results were due to interference from NOx species absorbing close to the Hg absorption wavelength. Addition of sulfamic acid to the digest prior to FI-CVAAS overcame the interference and gave results in agreement with certified values. Tu et al.176 described a rapid simple method for the determination of methylmercury in biological samples using GC-MIP-AES and GC-ICP-MS. Samples were leached with acid and then derivatised and extracted in situ with NaEt4B and nonane. The nonane phase was injected into a gas chromatograph coupled to either MIP-AES or ICP-MS for determination of Hg. Recoveries of Hg in the nonane phase were greater than 90% and reported LODs were 4.4 ng g−1 with MIP-AES and 2.6 ng g−1 with ICP-MS. Two groups described methods for the determination of Hg in biological matrices by XRF. O'Meara et al.177 optimised polarisation, filtration and X-ray tube voltage parameters for the in vivo determination of Hg in kidney using polarised XRF. Toribara87 reported a study on the determination of Hg in single hair strands using linear scanning XRF. The technique was used to establish the circumstances surrounding a fatal exposure to dimethyl Hg.
Vahter et al.178 presented the findings of a longitudinal study of exposure to inorganic and organic mercury in pregnant and lactating women. Inorganic and organic Hg were determined in maternal and cord blood using alkaline reduction and CVAAS. Total Hg in urine was determined using ICP-MS. The authors noted that blood methylmercury decreased during pregnancy due to a reduced intake of fish. Cord blood methylmercury levels were almost twice maternal blood levels, which the authors considered to reflect earlier maternal exposure before pregnancy. Maternal blood Hg (median level = 0.37 µg l−1) and urine Hg (median level = 1.6 µg l−1) were highly correlated and were both associated with the number of amalgam fillings. Warfvinge179 examined the distribution of Hg in brains of neonatal and adult squirrel monkeys following exposure to Hg vapour. Brain Hg concentrations were determined using CVAAS and Hg distribution in brain sections examined by autometallographic silver enhancement. Accumulation of Hg in the cerebellum after exposure to Hg vapour was similar to the distribution pattern following exposure to methylmercury.
Oliveira et al.181 determined urine Ni levels using ETAAS to assess workers' exposure to NiSO4 in a Brazilian galvanising plant. Urine samples were taken before and after workshifts on five successive days. On each day levels of Ni in workplace air were also monitored by personal sampling. Low to moderate exposure to Ni was identified in all work areas investigated. Air Ni levels ranged from 2.8 to 116.7 µg m−3 and corresponding urine Ni levels ranged from 3.5 to 43.2 µg g−1 creatinine. Significant differences between pre- and post-shift urine Ni levels were observed on each of the workdays. A good correlation (r = 0.96) between urine Ni and air Ni levels was reported, which further supports the well established case for urine Ni measurements being a reliable indicator of internal dose following occupational exposure to soluble Ni compounds.
Morrison et al.185 used sector field ICP-MS to determine Pt in plasma ultrafiltrate, plasma and whole blood from patients administered the novel anti-cancer drug oxaliplatin. A standard nebuliser was used for analysis of blood and plasma whilst ultrafiltrate was analysed using a USN. A second group, Massari et al.,186 used ETAAS to determine Pt in the same biological matrices for pharmacokinetic studies of oxaliplatin. They identified that oxaliplatin was rapidly and extensively bound to erythrocytes (40%) and plasma proteins (33%). Vouillamoz-Lorenz et al.187 developed a method for the determination of Pt in biological fluids using ETAAS. Urine samples were diluted with 10% HCl whilst plasma samples required the addition of 5% Triton-X100, as a chemical modifier, to the furnace platform prior to injection of the plasma sample. Reported LOQs were 50 ng ml−1, 10 ng ml−1 and 5 ng ml−1 for urine, plasma and ultrafiltrate, respectively. The method was used to determine levels of Pt in samples from patients administered the oral Pt drug JM216.
Two groups described methods for the determination of platinum in biological matrices using XRF. Greaves et al.188 used XRF to determine Pt in both serum and urine from paediatric patients treated with Pt drugs. Kadhim et al.57 developed a method for in vivo quantitative determination of Pt in kidneys of patients receiving Pt drugs. A polarised X-ray beam from a radiotherapy unit was used to produce emission of characteristic X-rays from Pt in the kidneys, which was derived from carboplatin and its analogues.
Kubota et al.191 studied the “in vitro” cytotoxicity of Gd in rat and mouse alveolar macrophages. Intracellular concentrations of Gd were determined using ICP-MS. The results showed a marked species difference in cytotoxicity of colloidal Gd to alveolar macrophages. Rat macrophage viability was compromised by Gd concentrations above 3 µM whereas mouse cells were resistant to Gd exposures up to 1000 µM. Lu et al.192 examined the speciation of La in rat liver, using ultrafiltration and gel exclusion chromatography with quantitative determination of La by ICP-MS. Liver La was associated with a soluble protein fraction having a Mr > 60000 and six elution peaks containing La were resolved by chromatography. Normann and colleagues193 developed a method for quantitative determination of Gd in serum, faeces and peritoneal dialysate by ICP-OES in order to study the pharmacokinetics of the contrast medium gadodiamide. They reported that LOQs for Gd in serum, dialysate and faeces were 6.5 nmol l−1, 1.6 nmol l−1 and 11 nmol g−1, respectively, and the method was sufficiently sensitive to determine faecal Gd levels less than 0.1% of a clinical dose of the contrast medium.
Several groups described methods for speciation of selenium using ICP-MS. Pelaez et al.98 compared two derivatisation procedures for the determination of selenomethionine (SeMet) in nutritional supplements using GC-ICP-MS. Esterification and acylation were either carried out simultaneously with ethylchloroformate–ethanol or sequentially using propan-2-ol esterification and acylation with trifluoracetic acid anhydride. Derivatives were extracted into CHCl3 and injected into the gas chromatograph. The authors selected the two-stage method for the determination of SeMet in parenteral solutions. Gammelgaard et al.196 determined Se species in urine using cation exchange chromatography coupled with ICP-MS and CE-ICP-MS. Urine samples were extracted with a crown ether to remove Na and K ions. With oxalic acid or ammonium formate eluents, five Se containing species were separated. Two of the species were identified as SeMet and trimethylselenonium ion (TMSI), but the remaining three remained unidentified. Marchante-Gayon et al.26 evaluated the analytical performance of ICP-MS with a hexapole reaction cell for the determination of Se species in human urine. Selenium species were separated using reverse-phase and ion-pair HPLC. Following administration of a Se nutritional supplement to 8 volunteers, TMSI was determined in the urine of 3 subjects as a major component, but in all cases the main urinary Se species was not identified. Cao et al.197 also used reverse-phase HPLC to separate Se species from a urine sample prior to determination using ICP-MS and characterisation by ES tandem MS-MS. Six distinct Se species were separated and the first two fractions identified as SeMet and selenocystamine.
Li and colleagues198 developed a method for the quantitative determination of total selenium in serum using FI-HG-AAS. Serum samples were digested by microwave heating and selenate was reduced to selenite. The reported LOD was 0.3 µg l−1 and the results of analysis of serum CRMs were in good agreement with the certified values. The authors used the method to determine dietary Se status in Austrian and Slovenian populations and, in particular, Se status in Slovenian mothers and newborn infants.199 The mean serum Se concentration of mothers at the time of birth was 62 µg l−1, whilst the umbilical cord serum concentration was 34 µg l−1 (55% of the maternal value). A significant correlation was determined between maternal serum Se and umbilical cord Se levels but no correlation between maternal serum Se and colostrum Se levels was observed. The authors concluded that the dietary Se status for pregnant women in Slovenia was borderline. Several other groups have presented the results of studies on Se status of selected populations. Trzcinka-Ochocka et al.200 examined Se status in children and adults from a non-polluted and a contaminated region of Poland. Whole blood Se concentrations were determined using ETAAS with a copper acetate–Mg(NO3)2 chemical modifier. Mean blood Se concentrations in adults and children from the unpolluted region were 54.8 µg l−1 and 43.8 µg l−1, respectively, and these levels were not significantly different from levels determined in the individuals from the contaminated region. Romero et al.201 determined serum Se concentrations in 395 individuals from the Canary Islands using HG-AAS. The mean serum Se concentration was 74.7 µg l−1 and 22 adults (7%) had serum levels below 45 µg l−1, a level at which an increased risk of cardiovascular disease and cancer has been reported. Children below 14 years of age had serum Se levels significantly lower than the remainder of the group. Al-Awadi and Srikumar202 investigated the relationship between plasma Se levels and human milk Se levels in lactating Kuwaiti mothers. Milk and plasma Se was determined using AAS. They identified SeMet as the major chemical form of Se in milk. Barrera et al.86 determined Se levels in hair of mothers and infants using ETAAS. Hair samples were digested with HNO3–H2O2 and diluted with H2O. A Pd chemical modifier was injected with the sample to achieve complete pyrolysis of the sample at 1200 °C.
Boulyga et al.203 developed a sensitive method for the determination of Se in biological matrices using ICP-MS after acid digestion of the samples. The sensitivity for Se was significantly improved by using a sample introduction system, which combined pneumatic nebulisation with HG in a mini-cyclonic spray chamber. Analytical performance of the method and Se losses during sample preparation were monitored by spiking samples with enriched 78Se prior to digestion. Machado et al.81 described a novel method for the determination of Se in biological matrices using FI-AAS with electrochemical hydride generation. The electrolytic cell was composed of two reservoirs, one containing sample and the other electrolytic solution, separated by a Nafion membrane. The generated hydride was transported, in an Ar stream, to a quartz tube in an air–propane flame for determination of Se. The authors reported the optimum conditions for analysis and the accuracy of the method was assessed by analysis of biological CRMs.
There is continued interest in assessing the health risks associated with silicone implants, where silicone may be released into body tissues from ruptures of the implant or gradual diffusion through the implant envelope. Lugowski et al.206 determined both total Si and organic solvent extractable Si (silicone) in body fluids from patients with breast implants and a matched control group, using ETAAS. The mean whole blood Si level in implant patients was 38.8 µg kg−1 compared with a mean of 24.2 µg kg−1 in controls. Mean levels of Si in breast milk from implant patients was 58.7 µg kg−1 compared with 51.1 µg kg−1 in control subjects.
Vanadocenes (cyclopentadienyl complexes of V) have been identified as a potential new class of contraceptive agent due to their potent inhibitory effect on sperm motility. D'Cruz and Uckun215 investigated the intravaginal toxicity of gel-micro-emulsion formulations of two vanadocenes (VDACAC and VDDTC) in rabbits, using AAS to quantitatively determine V levels in selected body fluids and organs following repeated administration of the vanadocenes over 10 consecutive days. No vaginal irritation or inflammation was observed in animals administered a 0.1% concentration of the formulations and only mild irritation was observed at a concentration of 0.25%. For both dose groups, no changes in clinical chemistry profiles were observed, neither was V incorporated into body fluids or tissues at levels above 1 µg g−1. The authors concluded that repeated administration of VDACAC and VDDTC at levels up to 2000 times greater than their spermicidal EC50 value did not cause marked vaginal irritation or systemic absorption of V in the rabbit model.
Kwiatek et al.216 compared PIXE and AAS methods for the quantitative determination of V in blood and tissue samples from rats administered a V supplemented diet. For both analytical methods, samples were mineralised and V extracted with APDC. No statistically significant differences were observed between tissue levels of V determined by the two techniques.
Griffin and colleagues221 developed a six compartment pharmacokinetic model for Zn metabolism in children using data obtained from stable isotope determinations of Zn in biological fluids and excreta. Seven healthy female volunteers were given an oral dose of 67Zn enriched tracer. Blood, urine and faeces samples were collected for 6 days following administration and Zn isotopes determined using TIMS. Using the model, the authors noted that body weight corrected Zn compartments were significantly greater in children than in adults.
2 Analysis of foods and beverages
This section draws attention to papers that describe novel developments for the measurement of major and trace elements in individual foods and beverages and in whole diets. We also summarise reports that document typical concentrations in selected food types. Table 1 presents the essential points of these and other papers.Little by way of formal review articles has been seen. The comprehensive 2001 Atomic Spectrometry Update cited almost 200 papers published in 1999–20001 while properties and applications, toxicity, measurement and daily dietary intake of Be were reviewed.222
Problems associated with contamination were highlighted in one paper223 where release of 15 elements from six devices for milling and grinding wheat was measured. None of those investigated was completely contaminant-free.
Two papers were seen where differences between organic and non-organic foods were investgated. Kidney Cd concentrations were significantly higher in pigs fed with organic feed compared with those conventionally fed; 91.6 and 84.0 µg kg−1, respectively.224 This was despite the feed having lower levels of Cd. The authors noted, however, that the vitamin–mineral supplements given to the organic pigs contained much greater amounts of Cd and that Cd in the manure was also greater, indicating larger total ingestion of the metal. Rasmussen et al. reported that I was lower in organic than in non-organic milk.225
2.1 Sampling and sample preconcentration
It is well known that Cd is not evenly distributed throughout the kidney. In a study involving microwave digestion and ETAAS, it was shown that variations are less dramatic in porcine compared with bovine kidney and that freezing the sample caused some redistribution of the Cd.226 The authors confirmed that a well designed sampling method is necessary.In an elaborate investigation, Bermejo-Barrera et al.6 sought to determine optimum conditions of acid concentration and volume, sample size, microwave power and exposure time for the preparation of seafood products for many elements. Appropriate procedures for measuring different elements by AAS were recommended and applied to CRMs, with good accuracy.
An unusual application involved the measurement of As in sugar by ETAAS with in situ digestion. An 8% m/v solution in 0.2% v/v HNO3 was sampled and the high C content was removed by introducing air during a 40 s pyrolysis step at 600 °C.237
Sweileh constructed a novel FI system, which accepted powdered multi-vitamin tablets into an acid solution, which was passed through a heating coil to an anion exchange column where Cu and Zn were retained. After a column wash the analytes were eluted with dilute HNO3 for determination by AAS. Accurate and precise results were claimed.97 Digestion solutions typically contain HNO3, HClO4, H2SO4 and H2O2 in various combinations but more vigorous oxidising agents, V2O5 for Al238–240 and HF for Sn241 have been reported.
Alkaline digestion with Na2CO3–NaOH was employed to prepare infant formulas for determination of I−,242 while Se was measured by ETAAS in mussel and wheat samples after TMAH digestion.243
In a comparison of trypsin and pancreatin for the enzymatic digestion of baby foods, good results were obtained for the subsequent speciation of As using trypsin but there was poor separation of DMA and AB with pancreatin treated specimens.244
2.2 Speciation
Examples of separation of inorganic species predominate in this period with publications referring to Al, As, Br, Cr, Fe, Hg, I and Se. Most of the technical details relating to separations were similar to those reported previously although some of the applications were novel. Developments for the speciation of As and Se are described in the sections on individual elements below.Al in drinking water was separated into particulate, exchangeable, non-exchangeable inorganic and non-exchangeable organic species by filtration and ion-exchange. Exchangeable and non-exchangeable inorganic Al were the main forms and changes occurring by boiling the water were reported.252 The anion exchange separation of bromate and bromide in drinking water253,254 also removed polyatomic ions at m/z values of 79 and 81 which eluted before and after the bromate.253 CrVI in infant formula was similarly isolated by ion exchange, for measurement by ETAAS.255 I in milk was speciated by SEC256 and by IC257 and the measurements made by ICP-MS. Chemical isolation by extraction of a complex formed with thiocyanate into IBMK was used to determine FeIII in wines.230
SEC with ICP-AES for detection was employed for the separation of complexes and multi-element analysis of breast milk17 and tea.258 Well established procedures involving ion exchange HPLC and ICP-MS were similarly used to examine samples of water and fish.228,259
2.3 Applications using hydride generation
In over half of the papers reviewed for this section AFS was used for the eventual measurement, to take advantage of the lower detection limits afforded by this technique. A number of food types were investigated, usually for As or Se but other hydride forming elements, including Pb, were also determined. A range of foods available in Ireland were analysed to compare dietary intakes of Se with that of other countries.260 Only one report81 made use of a system for electrochemical HG. A Nafion membrane separated the sample and electrolyte and conditions such as flow rates, applied current, etc., were optimized. An air–liquid petroleum gas (LPG) flame heated the quartz atomization cell. For the determination of Se, the LOD was 10 µg l−1.Exceptional LODs may be achieved by using vapour generation coupled to ETAAS. Matusiewicz and Mikolajczak used HG and CV to determine As, Sb, Se, Sn and Hg in beer.250 The hydrides were formed and transported by gas flow to a Pd-treated graphite furnace where they were retained by adsorption. When trapping was complete the furnace was heated to atomize the analyte. Using a 10 ml sample the LODs were 28, 21, 10, 50 and 90 ng l−1, respectively.
Other reports include work where total analyte concentrations were measured or where species were separated by on-line HPLC (see Table 1).
2.4 Applications using flame atomic absorption and emission spectrometry
Costa et al. reported on the measurement of Cu, Fe, Mn and Zn in Portuguese wines by FI-FAAS.261 Sample volumes were selected to allow determinations in ranges between 0.25 and 15.00 mg l−1. Sweet wines from the Canary Islands, Spain, were classified according to the concentrations of Ca, Cu, Fe, K, Mg and Na measured by FAAS.262 Lower concentrations of Cu263 and of FeIII 230 were determined using on-line separation techniques. On-line preconcentration methods were developed to measure Cd in mussels,248 Pb in seafoods,245 and Cu263 and Pb264 in water, with determination by FAAS. Impressive enhancement factors (up to 340 times) were reported using these rapid procedures.Phosphate in foods was determined by forming the bismuth phosphomolybdate complex, extraction into IBMK and measurement of Bi by FAAS. The LOD was 0.008 µg l−1.265
After a simulated gastro-intestinal digestion, infant foods with added phytate were dialysed and the fraction containing low molecular weight Zn species measured by FAAS to assess bioavailability.232
A methane–air flame was investigated for the measurement of Rb in water by FAES. Flame composition, observation height and spectral bandpass were optimized and an LOD of 2.3 µg l−1 was obtained.266
2.5 Applications using electrothermal atomic absorption spectrometry
A few interesting developments have been seen in this review period. On-line preconcentration10,247 and furnace trapping of hydride species250 were described above. Matrix modification continues to be a fruitful topic for further investigation. A combination of W + Pd + tartaric acid was used by Acar et al. to stabilise Pb for the successful analysis of Turkish cookies.267 Recovery was 99% and the LOD was 1.2 µg l−1. Samples of mussels from coastal areas of Japan were lyophilised and digested using HNO3, HF and HClO4 and the residue dissolved in HNO3. This solution was then analysed for Sn, with Ni added as modifier.241Various “difficult” sample matrices were effectively analysed. An La modifier was used for the measurement of P in vegetable oil, with results in the range of 10–790 mg kg−1.268 Wheat prepared in various ways to produce acidic slurries were taken for measurement of Fe and Zn and a modifier containing Al(SO4)3 improved the signal shape and the stability of the slurry.234 Two reports referred to the analysis of sugar, one for the measurement of seven elements, the second for As. Both employed a Pd modifier with air ashing and one included ascorbate with the Pd.237,269 The volatility of Hg and I makes these elements difficult to measure by ETAAS but three papers appeared in this period. Samples of baby foods and seafoods were prepared as slurries and suspended in 0.1% Triton X-100–3% HNO3–2% KMnO4–4% AgNO3 for determination of Hg.270 Iodine in milk and baby formulae was indirectly measured by forming an ion pair with HgII and 2,2′-dipyridyl, which was extracted into IBMK. A maximum ash temperature of 150 °C was possible with Pd in IBMK as the modifier.231 Analysis of CRMs showed that both procedures gave acceptable results and data from the analysis of real samples were given. In the third paper the I− in infant foods was again indirectly measured, this time by precipitation with Ag, redissolution in a cyanide solution and determination of the Ag by ETAAS.242 Details of the temperature programme and chemical modifiers were given and the LOD was 3.1 µg g−1. Preparation of samples as slurries featured in other work involving Al in typical foods consumed in Spain,238 and Cd in seafoods.271 Supporting media containing 10% C2H5OH–5% H2O2–0.5% HNO3 or 0.1% Triton X-100–5% H2O2–0.5% HNO3 were used to prepare slurries of baby foods for measuring Al and Cr, respectively.272 Aqueous calibration was possible as there was no matrix effect and LODs were 50 and 4 pg for Al and Cr.
2.6 Applications using inductively coupled plasma mass spectrometry
A quick glance at the papers seen in this review indicate that more than half of those using ICP-MS were concerned with measurements of just a single analyte. Furthermore, in two-thirds of the publications ICP-MS was presented merely as the analytical technique for a specific application, with no new instrumental or methodological development. In one innovative piece of work a new miniature cyclonic spray chamber and a concentric glass nebuliser designed for low sample uptake, were used to measure I in foods.273 With the low sampling rate nebulizer wash out was accelerated compared with other systems. Sample digestion using only HNO3 was achieved under pressure within a sealed container at 230 °C. Ethanol in wine is reported to impose a matrix effect when samples are aspirated using a conventional nebuliser, requiring use of an internal standard. A microconcentric nebulizer with a membrane desolvator (MCN 6000) eliminated the interference.274 Specimens with high Ca contents suppress the Pb signal causing erroneously low results or failure to detect the presence of this metal. Sector field ICP-MS however is not subject to this interference and was used to measure Pb in calcium supplements at concentrations down to 0.6 µg g−1 which was suitable to meet the legislative requirements set by safety authorities.94 Work to show that this technique may be employed for multielement analyis of milk fractions275 and tomatoes276 was reported but no obvious advantages in terms of simplicity, freedom from interferences, sensitivity, etc., were claimed.Measurement of a single isotope or of isotopic ratios provides useful information to identify the source, or to follow the fate, of an element. Barbaste et al.277 compared different mass analysers and found that the precision achieved with TOF or sector field MS was far superior when compared with Q-MS for the determination of 206Pb∶207Pb, 208Pb∶206Pb and 206Pb∶204Pb ratios in wine. The Pb isotopic ratios in wine have been thought to be specific for the region of origin but long-term changes in ratios were reported as a consequence of discharges into the atmosphere from industry and petrol additives during the last 50 years.278 An alternative to Pb isotopic ratios for this purpose may be afforded by 87Sr∶86Sr.279 Wine samples were diluted in H2O and submitted to a two-step cation exchange separation, which also removed interference from Rb. Eluted fractions were evaporated, taken into HNO3 and sampled at the mass spectrometer. Precision was better than 0.3% RSD. Intestinal absorption of Cd was investigated in human volunteers following ingestion of porridge containing flour intrinsically labelled with 106Cd.124 It was suggested that absorption may be greater than previously stated.
Using chromatography to eliminate interferences was a feature of several papers including that of Creed and Brockhoff253 who determined bromate in drinking water. Br−, brominated haloacetic acids and ions at m/z 79 and 81 (speculated as possibly being PO3+, H2PO3+, HSO3+) were all removed by IC using a PA-100 column. Bromate was measured with an LOD of 0.3 ng g−1. A similar analytical arrangement was described for measuring several halogen and arsenic ions in drinking water.259 The chromatographic system incorporated an anion micro-membrane suppresser that removed Na+, K+ and other ions, which can cause polyatomic interferences and produce instability within the ICP.
Electrothermal vaporization requires little sample preparation prior to introduction into the plasma and can obviate the need even for dilution, which may introduce contamination. Multielement analysis of honey280 and vegetable oil281 were accomplished by ETV-ICP-MS.
Unusual applications for which ICP-MS was used include measuring the bioaccumulation of 137Cs and 40K in mushrooms282 and Mo in diets prepared for infants with phenyketonuria.180
2.7 Applications using other analytical techniques
Inductively coupled plasma-atomic emission spectrometry is a well established technique and is widely used for multielement analysis of foods and beverages. Several papers were seen in which the technique was employed for measuring trace and major elements, or as a detector following chromatographic separation of complexes (Table 1). However, none of these publications included any novel analytical innovations.A simple, rapid procedure was reported in which methylmercury was extracted from fish by a 5 min leach in acid. Sodium tetraethylborate and nonane at pH 7.0 were then added and after 40 min, assisted by ultrasonication, ethylation and extraction had occurred. More than 90% of the methylmercury was recovered in the nonane phase, which was analysed by GC with MIP-AES or ICP-MS for detection. The LODs for Hg were 4.4 and 2.6 ng g−1, respectively.176
Concentrations of Cs and Se in mushrooms,283 and of 12 elements in rice284 were determined with essentially no sample preparation using XRF. The influence of stages of lactation on trace elements and minerals in human milk of Nigerian women were investigated using PIXE.285
2.8 Developments in individual elements
Drinking water with high As concentrations may be treated with Fe to form precipitates. As this occurs the natural AsIII and AsV distribution alters so that investigation of the original water is impaired. Addition of EDTA to the water maintained As in solution for speciation and measurement by IC and ICP-MS.290 A simple differentiation of AsIII and AsV in beer was described based on treatment with or without KI.291 Recoveries of AsIII and AsV were 95% and 96%, respectively.
Total As was measured in flour by ETAAS following a preconcentration procedure. After digestion the As was precipitated by adding an Ag solution. The Ag3AsO4 was dissolved in a small volume of 6 M NH4OH and taken for analysis with an LOD of 0.3 ng ml−1, a 20 fold improvement.246
Although Pb can be measured with a HG technique this is not usually the method of choice due to limitations of sensitivity. One report, however, noted that HG-AAS gave a wide analytical range with good precision and accuracy.295 Measurement of Pb in a calcium medium and of Pb isotopes, by ICP-MS was reviewed in section 2.6.
Capillary electrophoresis has been developing rapidly in recent years. Separation of six Se species was demonstrated and the technique applied to the analysis of a nutritional supplement.302 Extraction of Se compounds from nutritional formulas proves to be a particular challenge and two studies concentrated on this aspect. For the analysis of yeast-based supplements microwave heating with HCl or enzymatic treatment with proteinase K were equally effective.303 Esterification of seleno-amino acids and acylation with trifluoroacetic acid anhydride, was the approach adopted for GC-ICP-MS.98 For the measurement of SeIV in drinking water sodium tetraethylborate was added to form the ethane-1,1′-selenobis complex which was measured by GC-MS.304
2.9 Single and multielement analysis of foods
A few food types feature in much of the published work (see Table 1). The following sections present some of the items of special interest that relate to particular food items.There is considerable current interest in infant exposure to Hg during pregnancy and from human milk, where the maternal dietary intakes are high. Samples of human milk and other specimen types were analysed for Hg by AAS and significant associations with Hg in the maternal diet were reported.307 Other studies of toxic elements in infant foods included comparison of enzymic extraction prior to As speciation244 and measurement of Al and Cr in slurried samples.272
The European drinking water maximum admissible levels do not apply to mineral waters and an examination of bottled waters provided some startling results. In a study in which 66 elements were measured in 56 different waters from throughout Europe, it was found that only 15 would meet the drinking water regulations.311 In a similar Japanese study 22 elements were determined in 170 samples of bottled water. As in the European study some regionally associated variations were seen. None of the results exceeded the Japanese standards for mineral water but four samples would not have satisfied the maximum drinking water levels in Japan.312
2.10 Dietary intake studies
Several interesting studies were reported during this year. Total dietary intakes for adult reference groups were reporteds for Br and I in the UK,316 Cd and Si in Belgium,125,317 Cd and Pb in south-east Asia and Japan,127,318 I and Sr in Germany,319,320 Mn in India321 and for eight elements measured in foods in Thailand.322 Again using duplicate diet analysis, the intake of Cd by women in Japan was found to have fallen by 32% between 1981 and 1997 although it is still high compared with other countries.129 Rice was seen to be the major source of the Cd. Dietary intakes of Cu by the same individuals showed considerable variation when measured on six different occasions throughout one year323 and it was suggested that short term investigations will give very misleading data. Intakes in infants and children also featured with analyses of breast milk and infant formulas164,306 and total diets.3242.11 Reference materials and collaborative trials
A panel of RMs of relevance to radiological protection, including a Total Diet and a Typical Diet were prepared by NIST and evaluated by seven laboratories. Caesium, I, Sr, Th, and U were measured by various techniques including ICP-MS.82A series of reports were published by the AOAC International, of a collaborative study, in which up to 16 laboratories participated on related projects.325–327 Samples of different food types were sent to each participant for measurement of up to five elements by AAS. The reports examined results achieved after microwave digestion, results after dry ashing and As results after microwave digestion. Agreement between laboratories for each of the analyses was presented as the relative standard deviations.
3.0 Conclusions
It has been apparent in recent Updates that a newer set of problems is emerging in the clinical trace element field relating to the use of newer materials and techniques in medicine and surgery.One important issue is the breakdown of surgically-implanted metal prostheses. It is clear that the use of Co–Cr alloy prostheses results in release of Co and Cr into the surrounding tissue and into the circulation.65,66 Brodner et al.65 recommended that, because of the build-up of these elements in blood serum, they should not be inserted into patients with chronic renal failure. From the study by Kocadereli et al.,67 the release of Cr and Ni from fixed orthodontic appliances into saliva is not significant over the first two months. The search for alloys with improved corrosion resistance involves other metals which also need examining for their potential toxicity. Alloys of Ti–Al–V have been developed for spinal implants and Villarraga et al.212 examined the release of Ti in a canine model. Release of Ag from a silver coating on mechanical heart valve prostheses into blood was studied by de la Riviere et al.207
Medical advances in body organ imaging techniques and radiation therapy have resulted in the use of relatively high concentrations of some unusual compounds. In this review year, the pharmacokinetics of release of Gd from the contrast medium gadodiamide193 and B concentrations in blood and tissues from the neutron capture agent boronophenylalanine121 have been studied.
A third concern of continuing interest is the release of silicones from silicone breast implants. Lugowski et al.206 demonstrated increased mean whole blood and breast milk Si concentrations in patients with breast implants. However, the range of Si concentrations in controls and patients is considerable with significant overlap such that the measurement of an individual's blood Si concentration would not be suitable for the monitoring of implant leakage.
There were two interesting advances reported that may have future potential. The first is the use of Ga to inhibit osteoclastic resorption of roots of teeth which can lead to tooth loss. An interesting study using LA-ICP-MS37 showed that diffusion of Ga(NO3)3 into root dentine was sufficient to get a concentration high enough to be therapeutically useful. Secondly, a non-invasive XRF method of determining skin Fe concentrations56 seems to have potential for assessing liver Fe concentrations in haemochromatosis and β-thalassaemia.
For the first time reports were seen of investigations involving organically produced foods and it will be of interest to see whether this continues.
Further application of techniques for As speciation featured within the clinical and foods/beverages sections. The most important development was the demonstration of methylated species containing AsIII, the significance of which is likely to become apparent in the near future. After much interest in capillary electrophoresis in the last few years few examples were found of the recent use of this technique.
Analytically, there have been no discernible new directions. It is interesting, however, to see further developments in low-cost techniques for dissolution of samples and preconcentration using flow injection. It appears that, perhaps as more laboratories replace AAS by ICP-MS, the latter technique is being used for work where just one or two analytes were reported.
| Element | Matrix | Technique; atomization; presentationa | Sample treatment/comments | Ref. |
|---|---|---|---|---|
| a Hy indicates hydride and S, L, G and Sl signify solid, liquid, gaseous or slurry introduction, respectively. Other abbreviations are listed elsewhere. | ||||
| Al | Serum | AA;ETA;HPLC | Al speciation after the administration of DFO was studied in serum samples obtained from 6 dialysis patients 44 h after the administration of a single dose of DFO. Both HPLC and ultrafiltration techniques were used to separate different Al species | 104 |
| Al | Serum | AA;ETA;L | Low Mr complexes of Al in human serum from 6 CAPD patients were separated by FPLC and identified by ES-MS-MS as Al-phosphate and a mixture of Al-citrate and ternary Al-citrate-phosphate complexes | 103 |
| Al | Serum | MS;ICP;L | Binding of Al and Fe to sites on transferrin was investigated | 328 |
| Al | Bone | MS;ICP;L | Al was determined in 30 bone samples taken from one patient. Results reported by weight of dry bone had the lowest coefficient of variation as compared with results reported by weight of wet bone, weight of bone-ash and Ca content of bone | 329 |
| Al | Foods, beverages | AA;ETA;L | Al was measured in the Spanish diet. Samples were mineralised using HNO3–V2O5 | 238 |
| Al | Baby foods | AA;ETA;Sl | Untreated foods were prepared in 0.1% w/v Triton X-100. Following homogenisation the slurries were taken for ETAAS yielding LODs of 4 pg. See also Cr, ref. 272 | 272 |
| Al | Herbs, spices | AA;ETA;L | The same authors as in ref. 238 used the same method to determine Al in 72 samples of 17 herbs and spices regularly consumed by the Spanish population | 239 |
| Al | Potable water | -;-;L | Field extraction via a variety of chelation columns followed by measurement in the laboratory was used for on-site speciation of: 1) total recoverable; 2) total acid-leachable; 3) total dissolved; 4) dissolved extracted; and 5) dissolved non-extracted Al | 330 |
| Al | Tap water | AA;ETA;L | Al speciation in water boiled in an aluminium kettle was investigated | 252 |
| As | Cells, urine | AA;Hy;L | AsIII species were separated exploiting the effect of pH on the generation of arsine. The LODs were 1.1, 1.2, and 6.5 µg As l−1 for AsIII, MMAIII and DMAIII, respectively. Methylated AsIII species were detected in urine from environmentally exposed subjects and in human cells exposed in vitro to inorganic AsIII | 115 |
| As | Urine | AA;-;IC-HG | Reference values were evaluated for 4 As species (AsIII; AsV; DMA; MMA) in urine from 101 men in northern Germany. The LODs of the analytical method used were: 1.1; 10; 2 and 2 µg l−1, respectively | 331 |
| As | Blood, serum, urine | AA;ETA;L | The determination of the total content of As in blood, serum and urine by ETAAS with Zeeman correction is described. Samples were diluted with 0.1% w/v Triton X-100. A mixture of H2O2 (15% w/v)–HNO3 (0.65% w/v)–Ni (0.5% w/v) was used as a chemical modifier. The LOD was 20 pg (2 ng ml−1) | 332 |
| As | Urine | AF;Hy;ion-pair chromatography | Samples were collected after treatment with dimercapto-1-propane sulfonate. In addition to AsIII, AsV, MMA and DMA and a new species (MMAIII) was identified | 333 |
| As | Urine | MS;ICP;HG | A procedure for the oxidation of AsIII to AsV prior to speciation of As compounds in human urine was investigated, using either Cl2, MnO2, H2O2 or I3−. I3− gave the best results | 334 |
| As | Urine | MS;-;LC MS;ICP;LC | As species in urine of rats chronically exposed to DMA were identified and quantified by both LC-ES-MS and LC-ICP-MS. LODs in LC-ES-MS were 75–200 pg As, about ten times higher than that of LC-ICP-MS. Three of the five As peaks in urine were identified as DMA, TMAO and TMA. The mechanisms underlying the generation of the unidentified compounds were investigated | 335, 336 |
| As | Urine | MS;-;GC | DMA and MMA were determined in urine after a newly developed solid-phase microextraction (SPME). The LODs were 0.12 and 0.29 ng ml−1, for DMA and MMA, respectively | 111 |
| As | Urine | MS;ICP;LC-HG | Using an ion exclusion column with carboxylated methacrylate resin and Na2SO4 mobile phase, good separation of seven As species was achieved. LODs were 0.016–0.075 ng ml−1 | 113 |
| As | Urine | MS;ICP;LC | Features influencing separation of AsIII, AsV, AB, DMA and MMA, such as column temperature, eluent molarity, Cl− and sampling via direct nebulization or by HG, were investigated and optimum conditions were recommended | 112 |
| As | Urine | MS;ICP;HPLC | Different columns were evaluated for separation of As species and removal of the Cl− induced polyatomic interference on AB. A silica based cation exchange column was the most effective and AB was measured in a urine CRM | 337 |
| As | Urine | MS;ICP;HPLC | Eight species were separated by anion exchange chromatography and identified. Urine samples from subjects drinking contaminated water were analysed without any pre-treatment. Questions concerning As metabolism were raised | 338 |
| As | Urine | MS;-;GC | DMA and MMA were determined in human urine samples by GC-MS after derivatisation with thioglycol methylate. The LODs were 0.95 and 0.8 ng ml−1, respectively | 339 |
| As | Lung | AA;Hy;L | Reference ranges were determined for As and Se concentrations in lung and hilus tissue from 50 deceased persons. Wide intra- and inter-individual variations were observed | 64 |
| As | Biological samples | MS;ICP;HPLC MS;ICP;CE | Methods for separation of As, Cd and Se species were reviewed. The most popular technique was SEC-ICP-MS | 340 |
| As | Tissue | MS;ICP;L | The bioavailability of As in gold mine tailings was investigated in mouse pups administered a sample of size-fractionated mine tailings as an aqueous suspension, by oral gavage, providing 4 mg As kg−1 body weight. As was determined by ICP-MS in microwave-digested tissue samples collected 1 h after gavage. The LOD was 2 ng As g−1 dry weight. Tissue As was significantly higher in exposed pup than in control tissues in the following order: liver > blood > skin > brain > carcass | 341 |
| As | Seafood | AA;Hy;HPLC AF;Hy;HPLC | On-line thermo-oxidation and switching between cation and anion columns allowed the separation of 8 As species. The precision of measurement was at worst 12% | 286 |
| As | Seafood | AA;ETA;L | 8 laboratories participated in a collaborative study of the determination of As in seafood using acid microwave oven digestion and ETAAS. The highest (worst) repeatability and reproducibility RSDs were 17.4 and 24%, respectively | 327 |
| As | Seafood, water | AF;Hy;LC | AB, AC, TMAO and TMI were determined using HPLC-thermo- oxidation-HG-AFS. | 101 |
| As | Oyster | AF;Hy;HPLC | As species were extracted using a low power microwave procedure. Quantitative extraction of AB, DMA and arsenosugars was obtained at a power of 40 W, and in 5 min, using the extracting agent CH3OH–H2O (1 + 1) | 100 |
| As | Oyster | MS;ICP;L | HNO3 + H2O2 were used to digest samples in a microwave oven. By varying the applied power it was possible to extract differing quantities of the cationic and ionic species, which were then separated using ion-exchange HPLC and measured by ICP-MS | 287 |
| As | Tuna fish, human urine | MS;ICP;HPLC MS;ICP;HG | A robust ion-exclusion LC method was coupled either directly or via HG to ICP-MS and used to separate AsIII, AsV, MMA, DMA, AB, AC, TMAO and TMI | 113 |
| As | Baby foods | MS;ICP;HPLC | As species—AB, AC, DMA, AsV—were determined following extraction using either trypsin or pancreatin, with the former being of most practical use | 244 |
| As | Carrots | MS;ICP;HPLC | As was extracted using accelerated solvent extraction and 5 species quantified. Recoveries were in the range 80–102% | 289 |
| As | Rice | MS;ICP;L | AsIII, AsV, MMA and DMA were determined following extraction with 2 M trifluoroacetic acid at 100 °C for 6 h. The majority of the As was inorganic, with MMA and DMA accounting for less than 10% of the total | 288 |
| As | Wheat flour | AA;ETA;L | AsV was precipitated using Ag, dissolved in 6 M NH4OH, collected in an ETAA spectrometer cuvette and determined using Pd(NO3)2 as modifier. The LOD was 0.3 ng ml−1 | 246 |
| As | Sugar | AA;ETA;L | 60 µl of sugar solution in 0.2% HNO3 were pipetted directly into a preheated tube held at 70 °C. By using 5 µg of Pd, a first pyrolysis step at 600 °C and air during the 40 s, large C deposits were avoided. The LOD was 0.08 µg l−1 | 237 |
| As | Drinking water | AF;Hy;L | AsIII, total As, SbIII, and total Sb were determined with LODs in the low ppt region | 342 |
| As | Drinking water | MS;ICP;L | EDTA treatment was found to stabilise AsIII and AsV in Fe-rich waters for up to 14 days | 290 |
| As | Beer | AF;Hy;L | The LOD was 39 ng l−1 | 291 |
| Au | Urine | XRF;-;- | Separation and enrichment of Au and Pd from environmental and biological samples was achieved by Au and Pt co-precipitation with Hg, followed by complete evaporation of Hg. The LODs were 2.0 ng l−1 for Au and 2.5 ng l−1 for Pd | 62 |
| Be | Urine | AA;ETA;L | Urine was mixed with 0.2% acetylacetone–2 M ammonium acetate buffer and 0.4% Triton X-100. An LOD of 0.37 µg l−1 was obtained and analysis of a CRM gave excellent results | 343 |
| Be | Urine | MS;ICP;L | Concentrations of 0.12–0.15 µg l−1 were reported following occupational exposure | 116 |
| Be | Drinking water | AA;ETA;L | Samples were chelated, preconcentrated on Sep-Pak columns, then eluted using C2H5OH and a 20 µl portion introduced into the cuvette of an ET-AA spectrometer. The LOD was 2.3 ng l−1 | 229 |
| Bi | Blood, urine | AA;ETA;L | W and Rh were used as chemical modifiers. The platform was coated with a mixture of W and Rh and 100 ng Rh were added with each injection. Urine and blood samples were diluted with a solution containing 1.0% v/v HNO3 + 0.2% Triton X-100. The LODs were 3.3 µg l−1 (urine) and 8.4 µg l−1 (blood) | 118 |
| Bi | Urine, river sediments | AA;ETA;IC | A sequential system for the on-line ion exchange separation and preconcentration of metal ions was developed. Samples were loaded onto SP Sephadex C-25 cation exchange resin, eluted with diluted HNO3 and transported via air segmentation into the graphite tube for quantification | 13 |
| Bi | Urine | AE;ICP;FI-HG | On-line preconcentration at pH 4.5 was achieved using a quinolin-8-ol and Amberlite XAD-7 column. The complex was eluted by HNO3. With 100 ml urine the LOD was 0.02 ng ml−1 | 119 |
| Br | Drinking water | MS;ICP;L | Bromate was separated from interfering ions on a PA-100 column in combination with a 5 mM HNO3 + 25 mM NH4NO3 mobile phase and determined using ID–ICP-MS | 253 |
| Br | Drinking water | MS;ICP;FI | FI with an on-line anion exchange column was used to determine bromate and bromide, with the LOD for the former being 0.13 µg l−1 for a 500 µl injection | 254 |
| Br | Foods, beverages | MS;ICP;L | Br and I were determined in 20 UK food groups, sampled in 1997 | 316 |
| Ca | Urine | AMS;-;- | It was shown that 41Ca may be used to investigate skeletal Ca metabolism in situations such as osteoporosis and during treatment for bone disease | 133 |
| Ca | Infant formula, human milk | AA;-;L | Formula is sometimes thickened to prevent regurgitation. The results of a study of Ca, Fe and Zn in thickened formulas were described. The results showed that thickening with non-digestible fibre, such as locust bean gum, reduced bioavailability | 305 |
| Ca | Human milk, infant formula | AA;-;L | An in vitro method for determining Ca, Fe and Zn bioavailability was claimed to offer results in agreement with those obtained by in vivo studies, but with greater efficiency and lower costs | 73 |
| Ca | Cow's milk | AA;F;L | Samples were digested using HNO3–HClO4, 4 + 1 | 344 |
| Ca | Cheese, dental plaque | AA;F;L | A study, using 16 adult volunteers, suggested that cheese-containing meals increase plaque calcium concentration and thus probably protect against dental caries | 345 |
| Ca | Chinese foods | AA;-;L | Ca and Fe levels were measured over a 6 week post-partum period in special Chinese foods such as “ginger vinegar soup”. This soup was found to contain levels of Fe normally associated with high Fe foods | 346 |
| Cd | Blood | MS;ICP;L | An ID procedure was developed for the certification of RMs. Two digestion methods were evaluated and the method also included anion exchange chromatography to remove interferences from Cl, Mo and Na. The LOD was 0.005 ng g−1 | 347 |
| Cd | Blood, urine, food | MS;ICP;L | Two papers on the results of a comprehensive study of non-occupational exposure to Cd and Pb, conducted between 1991 and 1998, in 11 major South-Eastern Asian cities. The first paper concentrated on urban populations, the second on female intakes | 127, 318 |
| Cd | Blood, urine, food | MS;ICP;L | A study of 607 Japanese women showed blood and urine Cd results could be used as biomarkers of environmental exposure to Cd, but that urine Pb results were not reliable enough to replace blood Pb in assessing environmental exposure | 128 |
| Cd | Blood, urine, food | MS;ICP;L | Cd levels in a survey conducted in Japan over the period 1991–1997 were compared with those found in a similar survey conducted in 1977–1981. Although levels had decreased, they were still high when compared with international values | 129 |
| Cd | Liver | AA;F; IC-HPLC | A method was developed to determine the concentration of metallothionein (MT) isoforms. Critical steps in sample preparation, such as MT extraction, MT saturation with Cd and protein separation, were optimized. The LODs were 2.0 µg g−1 liver for MT-1 and 1.3 µg g−1 liver for MT-2, respectively | 348 |
| Cd | Liver cytosol | AE;ICP;HPLC | MTs in extracts from cirrhotic livers were separated by SEC–anion exchange chromatography. Cu, Cd and Zn were determined to calculate the concentrations of the MTs, highest levels were in primary biliary cirrhosis | 349 |
| Cd | Metallothionein | MS;ICP;HPLC | The analytical performances of FPLC and anion-exchange chromatography for rabbit liver metallothioneins separations and Cd speciation were compared | 350 |
| Cd | Biological samples | MS;ICP;HPLC MS;ICP;CE | See As, ref. 340 | 340 |
| Cd | Kidney | XRF;-;S | Using a Monte Carlo model, 133Xe was investigated as the excitation photon source for an XRF system for the measurement of Cd concentration in kidney. Cd concentrations of 15–60 µg g−1 kidney tissue could be easily detected for distances between the skin and the kidney surface of 30–60 mm | 58 |
| Cd | Foodstuffs | AA;ETA;L | Cd and Pb were determined simultaneously using transverse heating, Zeeman-effect background correction and a 0.5% (w/v) NH4H2PO4–0.03% (w/v) Mg(NO3)2 mixture as chemical modifier. Using these conditions the LODs were 0.38 and 9.3 pg for Cd and Pb, respectively | 294 |
| Cd | Equine meat | AA;ETA;L | Horse meat is a constituent of the diet in parts of Italy and this study showed that this product accounted for approximately 1% of the Cd intake in this population group | 351 |
| Cd | Porcine and bovine kidney | AA;ETA;L AA;F;L | To detect small differences in renal Cd levels between groups, e.g., in the case of biological monitoring of Cd exposure, sampling of the outer cortex was suggested as the optimal method in a detailed study of sub-sampling strategies | 226 |
| Cd | Porcine tissues | AA;ETA;L | In an investigation of organically and conventionally reared pigs, the organic animals' kidneys were found to contain significantly higher levels of Cd; this was thought to be due to differences in feed and bioavailability | 224 |
| Cd | Seafood | AA;ETA;Sl | A method using platform atomisation, NH4H2PO4 modification and Triton X-100 as dispersing agent was reported to give accurate, precise results for a range of samples including tuna and mussels | 271 |
| Cd | Durum and soft wheat | AA;ETA;L AA;F;L | Cd, Cu, Pb and Zn were determined in more than 400 samples of Italian wheat | 314 |
| Cd | Wheat | MS;ICP;L | Hydroponically grown wheat was intrinsically labelled with 106Cd, made into porridge and fed to human volunteers. ICP-MS analysis of the faeces suggested Cd absorption rates may be higher than previously suspected | 124 |
| Cd | Carrot, endive | AA;F;L AA;ETA;L | Samples were collected from 8 gardens in Slovenia at different distances from a power station and Cd, Pb and Zn determined. Although heavy metals were not found in the soil, high levels were found in the edible portions of the vegetables | 352 |
| Cd | Radish, spinach | AA;ETA;L | High Mr Cd-containing proteins were characterised as part of a comprehensive study | 292 |
| Cd | Vegetable oils | MS;ICP;L | ETV–ICP-MS was used to determine Cd, Pb and Zn at LODs of 0.1, 0.2 and 2.0 ng ml−1, respectively. The sample was introduced as an emulsion of 10% v/v oil–2% v/v Triton X-100–2% v/v H2O2–0.4% v/v HNO3 | 281 |
| Co | Urine | AA;ETA;L | 4-(2-Thiazolylazo)resorcinol was added to urine and the Co-complex was retained on a column of Amberlite XAD-16. Elution was achieved with 1 M HNO3 in acetone | 353 |
| Co | Hip joint wear particles | AA;F;L | Protocols to isolate particles employ treatment with aggressive agents or the use of enzymes. Depending on the procedure followed, extraction of Co or Cr from the particle may occur leading to erroneous results when the composition of the particles is determined. Enzymatic extraction caused the least change | 354 |
| Co | Natural waters | AA;ETA;L | An on-line FI–ETAAS method utilising ion-pair sorption on the inner walls of a PTFE knotted reactor was described. An enhancement factor of 15 was obtained for a 60 s loading and the LOD was 5 ng l−1 | 10 |
| Co | Flour fractions | AA;ETA;L | Flour fractions were wet ashed in 0.1 mol l−1 HNO3, and the resulting solution carried by a FI system to a chelation system and then a preconcentration column. The column was flushed using ethanol and the eluent collected in a PTFE autosampler cup. Co was found to be mainly associated with the bran fractions. The milling process did not affect results | 247 |
| Cr | Body fluids | AA;-;- | The literature (1983–March 1999) on Cr speciation in liquid matrices was reviewed | 355 |
| Cr | Blood, urine | AA;ETA;L | Cr in blood or urine was determined after dilution with water and using NH4NO3 as matrix modifier | 356 |
| Cr | Urine | MS;ICP;L | Reference concentration ranges (µg g−1 creatinine) for Cr (0.07–0.76), Ni (0.20–1.23) and V (0.02–0.22) in urine were estimated for children, aged 6–10, from the urban area of Rome | 23 |
| Cr | Hip joint wear particles | AA;F;L | See Co, ref. 354 | 354 |
| Cr | Infant formula | AA;-;LC | CrVI was found to be in the range 10–75 ng g−1 | 255 |
| Cr | Baby foods | AA;ETA;Sl | Samples were treated with 10% v/v C2H5OH–5% v/v H2O2–0.5% v/v HNO3, slurried and analysed using ETAAS which yielded an LOD of 50 pg. See also Al, ref. 272 | 272 |
| Cr | Herbs, spices | AA;ETA;L | Samples were digested using HNO3–V2O5 and Cr determined in 72 samples of 17 herbs and spices. The highest levels found were 1042 µg g−1(dry weight) | 357 |
| Cr | Milk, sugar | AA;ETA;L | A fast, direct method using Zeeman-effect ETAAS was described, yielding LODs of 0.13 ng ml−1 and 0.23 ng ml−1 for cane sugar and milk, respectively | 358 |
| Cr | Water | AA;ETA;L Thermal lens spectrometry;-;L | CrVI was determined directly or on-line following chromatographic separation. Thermal lens spectrometry performed favourably in comparison with ETAAS and offered a lower LOD, 0.1 µg l−1, than ETAAS | 359 |
| Cs | Mushrooms | XRF;-;S | Cs and Se were determined in mushrooms following treatment of the fungi with the 2 elements. Cs was found to accumulate within the mushrooms | 283 |
| Cu | Serum | MS;ICP;L | After separation of proteins by anion exchange chromatography a solution containing stable isotopes was added to permit an ID analysis | 29 |
| Cu | Serum, urine | AA;ETA;L | The method was applied to both urine and diluted (1 + 24) serum samples. Zeeman-effect background correction was used. The LOD was 0.98 µg l−1 | 136 |
| Cu | Urine | AA;F;L | A polyamine ion exchange column was included in an FI system. Cu was retained from a 5 ml sample to give an LOD of 1 µg l−1. However, H2O2 pre-digestion was necessary to achieve accurate results | 9 |
| Cu | Biological materials | AA;F;L | Samples were solubilised using microwave heating. Cu and Zn were concentrated by extraction onto polystyrene–divinylbenzene with imidazoylazo functional groups. Parameters to provide optimal performance were investigated | 137 |
| Cu | Liver cytosol | AE;ICP;HPLC | See Cd, ref. 349 | 349 |
| Cu | Human milk | AA;F;L | 62 women provided samples from the 2–15th day post-partum. Cu, Fe and Zn were determined and the effect of the mother's habits and condition on the results evaluated | 69 |
| Cu | Human milk | AA;F;L | The evolution of Cu, Fe and Zn in 144 milk samples from 39 healthy women was analysed from colostrum to the third month post-partum | 70 |
| Cu | Foods, beverages | MS;ICP;L | The results of a detailed US study using 80 individuals suggested that estimates of the fraction of a population at risk from chronic Cu deficiency or excess Cu intake can be overestimated if based upon short-term measures of intake | 323 |
| Cu | Peanuts | AA;F;L | Samples were digested in H2SO4–30% H2O2 | 360 |
| Cu | Butter | AA;ETA;L | A rapid method involving simply dissolving the sample in solvent and then direct injection was described for Cu and Fe | 361 |
| Cu | Durum and soft wheat | AA;ETA;L AA;F;L | See Cd, ref. 314 | 314 |
| Cu | Vegetable oils | AA;ETA;L | Cu and Fe were extracted using 10% HNO3 and the HNO3 injected directly into the furnace | 362 |
| Cu | Vitamin tablets | AA;-;S | Sample powder was placed in a special chamber, then carried by the digestion solution to a thermally heated PVC coil. The analyte metal as the chloro-complex was retained on a coarse-particle (>0.5 mm) anion exchange resin mini-column, the beads held between two plastic screens which allowed insoluble residue to pass through to waste. After a brief column wash, the analyte was eluted with diluted HNO3 and determined spectrophotometrically or by AAS. Cu, Fe and Zn were determined this way | 97 |
| Fe | Serum | MS∶ICP;L | See Al, ref. 328 | 328 |
| Fe | Serum | MS;ICP;L | See Cu, ref. 29 | 29 |
| Fe | Liver, serum | AA;-;- | The Fe content of serum ferritin was determined in groups of patients with normal or increased Fe stores by using ferritin immunoprecipitation followed by Fe quantitation. Liver Fe concentrations were measured non-invasively by superconducting quantum interference device (SQUID) biomagnetometry. The diagnostic value of the test in iron overload diseases was assessed | 145 |
| Fe | Skin | AA;-;- | A non-invasive procedure, microdialysis, was used to collect sample material, ex vivo. Concentrations of 3.6–7.7 µg l−1 were obtained and it was concluded that the technique is appropriate for in vivo sampling | 146 |
| Fe | Skin | XRF;-;S | To assess the validity of skin Fe as a biomarker to monitor treatment in cases of Fe overload, Fe levels in samples of abdominal skin and non-haem Fe concentrations in liver, heart and spleen were determined in Fe loaded rats | 56 |
| Fe | Brain | XRF;-;S | Microbeam imaging using SRXRF was carried out in single neurons from patients with Parkinson's disease (PD) and a control subject. Fe accumulated in neuromelanin aggregates in and around the nigral neurons, coprecipitating with Ca, Cu, S, Zn. The Fe intensity inside the melanin pigment granules of a PD case was about one order of magnitude higher than that of the control samples | 42 |
| Fe | Human milk | AA;F;L | See Cu, ref. 70 | 70 |
| Fe | Human milk, infant formula | AA;-;L | See Ca, ref. 73 | 73 |
| Fe | Human milk | AA;F;L | See Cu, ref. 69 | 69 |
| Fe | Infant formula, human milk | AA;-;L | See Ca, ref. 305 | 305 |
| Fe | Flour, milk | AA;F;L | Samples were dry ashed at 600 °C. The method was used to assess Fe intake in pre-school children from the Ivory Coast | 363 |
| Fe | Chinese foods | AA;-;L | See Ca, ref. 346 | 346 |
| Fe | Chicken meat | AA;-;- | This investigation involved the slaughter by shotgun of 60 chickens, removal and then frying of the meat. Fe, Pb and Zn were then determined in the cooked meat and compared with levels from chickens that had been slaughtered without the use of shotgun. Pb levels in the shot birds exceeded recommended concentrations and the authors concluded lead should be replaced with Fe or Zn in shotgun pellets | 364 |
| Fe | Cooking utensils, apple sauce, hamburgers | AA;-;- | Preparation of apple sauce in iron cooking utensils reduced consumer acceptability due to discolouration and flavour change. No negative effects were found in hamburger preparation | 365 |
| Fe | Peanuts | AA;F;L | See Cu, ref. 360 | 360 |
| Fe | Butter | AA;ETA;L | See Cu, ref. 361 | 361 |
| Fe | Vegetable oils | AA;ETA;L | See Cu, ref. 362 | 362 |
| Fe | Bulgur wheat | AA;ETA;L | Al2(SO4)3 was found to be necessary as chemical modifier in a comparison of sample preparation procedures for the measurement of Fe and Zn | 234 |
| Fe | Grape juice, wine and other alcoholic beverages | AA;ETA;L | An evaluation of sample preparation procedures concluded that mineralisation using HNO3–H2SO4 yielded the best results | 233 |
| Fe | Vitamin tablets | AA;-;S | See Cu, ref. 97 | 97 |
| Ga | Teeth | MS;ICP;LA | Ga diffusion in human root dentine was investigated by quantitative measurement of Ga in teeth to assess the efficacy of Ga treatment to inhibit osteoclastic activity | 37 |
| Gd | Faeces, peritoneal dialysate, serum | AE;ICP;L | A method was developed for the determination of gadodiamide as Gd in biological samples. The limits of quantification in serum and peritoneal dialysate were 6.5 and 1.6 µM Gd, respectively, and in faeces 11 nmol Gd g−1 dry weight | 193 |
| Hg | Urine | AA;CV;L | Hg excretion after administration of the chelating agent 2,3-dimercaptopropane-1-sulfonate (DMPS) was measured in patients reporting symptoms allegedly caused by exposure to Hg from dental fillings and controls | 366 |
| Hg | Cord blood, blood, urine | AF;CV;L MS;ICP;L | Exposure to methylmercury and Hg vapour was assessed in pregnant women and their newborns in Stockholm | 178 |
| Hg | Hair | AF;-;- | Hg was determined in samples of hair (approximately 5 mg) collected as part of the National Human Exposure Assessment Survey. With LODs ranging from 4 to 22 µg kg−1, Hg levels could be quantified in 95% of the samples. The mean, median and maximum of the annualised Hg levels in hair were 287, 204, and 3505 µg kg−1, respectively | 89 |
| Hg | Hair | XRF;-;S | A scan along a single strand of hair showed peaks that indicated the date at which exposure to dimethylmercury had occurred and the date at which treatment had been administered | 87 |
| Hg | Kidney | XRF;-;S | Instrumental improvements and optimisation of operating conditions were discussed with respect to the in vivo determination of Hg in kidney for occupational monitoring in cases of mild to moderate exposure | 177 |
| Hg | Food, hair, urine (CRMs) | AA;-;- | The assessment of method uncertainty was described | 367 |
| Hg | Environmental samples, biological samples, CRMs | AA;CV;L | A new, rapid technique is described for the determination of total Hg, after the pyrolysis of the sample in a combustion tube at 750 °C under an O2 atmosphere and Hg collection on a gold amalgamator | 368 |
| Hg | Plants, tissues | AA;CV;FI | Three digestion procedures in a closed vessel microwave oven were compared using CRMs | 175 |
| Hg | Biological CRMs | AA;CV;S | Samples, without pre-treatment, were pyrolysed at 750 °C in an O2 atmosphere, collected on a gold trap and analysed using AA with a silicon UV diode detector | 368 |
| Hg | Biological CRMs | AA;CV;HPLC | FI–HPLC–CVAAS yielded absolute LODs of 1.7 and 3.4 pg methyl and inorganic Hg | 369 |
| Hg | Biological CRMs, fish | MS;ICP;GC AE;MIP;GC | In situ ultrasonic assisted derivatisation and extraction using sodium tetraethylborate and nonane, respectively, were used for sample preparation | 176 |
| Hg | Water, biological samples | -;-;HPLC | Methods for Hg speciation using HPLC were reviewed | 172 |
| Hg | Biological materials | -;-;- | Methods for Hg speciation were reviewed | 173 |
| Hg | Babyfood, seafood | AA;ETA;L | Samples were slurried in solutions containing 0.1% Triton X-100–3% v/v HNO3–2% m/v KMnO4–4% m/v AgNO3, yielding LODs of 59 pg | 270 |
| Hg | Fish | AA;CV;L | Hg was determined in fish from a gold mining area in Brazil. The highest reported level was 2250 µg g−1 | 297 |
| Hg | Fish | AA;CV;L | The LODs for inorganic and methylmercury were 125 and 183 ng g−1, respectively | 296 |
| Hg | Mushrooms | AA;CV;L | A study of 13 species of wild edible mushrooms, collected near the Polish town of Augstow was reported. Supposedly an uncontaminated region, but levels up to 2100 ng g−1 dry weight were recorded in stalks | 298 |
| I | Blood, urine | XRF;-;- | A method to determine residual renal function of HD patients and dialysis efficiency was developed using I-based contrast media (iohexol and iodixanol) | 144 |
| I | Human albumin | MS;ICP;L | Optimised conditions were studied for the simultaneous determination of Pt and I in mixtures of diiodo Pt complexes and human albumin to investigate reaction mechanism and kinetics of these potential anticancer drugs | 370 |
| I | Infant formula | AA;ETA;L | I− was determined indirectly. Following alkaline digestion I was precipitated using Ag, then dissolved in cyanide solution prior to measurement of the Ag using ETAAS | 242 |
| I | Infant formula, milk | MS;ICP;L | I species were separated using an SEC column with 30 mM Tris buffer as mobile phase. I speciation in cow, goat, human milk and infant formulae, all from different countries was conducted. The whey was found to contain 95% of the I for all of the samples except infant formulae, in which it accounted for 15–50% | 256 |
| I | Cows' milk | MS;ICP;HPLC | I species in cows' milk from the Thuringian region of Germany, were determined at LODs of <2 µg l−1 | 257 |
| I | Milk, beverages | MS;ICP;L | Large geographical (and seasonal) variations in I concentrations were found in different beverages supplying an appreciable part of the I in the Danish diet. Organic milk was found to have a lower I content than non-organic milk | 225 |
| I | Dairy foods | MS;ICP;L | In a study of 12 women receiving diets rich in dairy foods, no evidence was found to suggest low availability was a factor influencing the continued high incidences of goitre in Germany | 319 |
| I | Foods | MS;ICP;L | See Br, ref. 316 | 316 |
| I | Biological and nutritional SRMs | MS;ICP;L | Samples were digested in HNO3 and I measured using ID–ICP-MS, the instrument was equipped with a mini cyclonic spray chamber | 273 |
| Mg | Plasma | AA;F;L | The distribution of Mg in plasma was investigated by SEC, AAS, ion selective electrodes and 31P-NMR. Ionized Mg accounted for 60% of total Mg, with the rest bound to plasma proteins (27%) and low Mr compounds (13%) | 161 |
| Mg | Plasma | AA;F;L | In 16 hyperthyroid patients plasma Mg was 0.74 ± 0.08 mmol l−1 vs 1.01 ± 0.09 mmol l−1 in 20 controls | 167 |
| Mn | Blood, brain | AA;ETA;L | The correlation between Mn concentration in blood and Mn deposition in brain were investigated using magnetic resonance imaging and measurements of blood and brain Mn in rats which received total parenteral nutrition (TPN) with 10-fold the clinical dose of trace elements for 7 d | 168 |
| Mn | Brain | AA;ETA;L | Mn was determined in mouse brain by ETAAS with D2 background correction and Ca(OH)2 as a chemical modifier. The LOD was 1.04 pg | 371 |
| Mn | Wine | AA;ETA;L | Wine was found to contribute an average of 281 µg d−1 to the Mn intake of the French population | 372 |
| Mo | Infant formula, plasma | AA;F;L MS;ICP;L | Because formula is heavily supplemented with Mo, Mo intake and retention in infants with phenylketonuria was more than 18 times that of breast-fed infants | 180 |
| Ni | Urine | AA;ETA;FI | The FI system included an SP Sephadex C-25 cation exchange column which retained Ni from the sampled solution. A flow of buffer solution then transferred the Sephadex beads with the Ni into the graphite furnace. While the heating programme was in progress, the next sample was trapped on a renewed column. An enrichment factor of 72.1 was reported with an LOD of 9 ng l−1 | 12 |
| Ni | Urine | MS;ICP;L | See Cr, ref. 23 | 23 |
| P | Vaccines | AE;ICP;L | P in haemophilus influenzae type b vaccines was directly related to the concentrations of polysaccharide in the preparations | 373 |
| P | Cow's milk | AA;F;L | See Ca, ref. 344 | 344 |
| P | Vegetable oils | AA;ETA;L | Levels were in the range 10–790 mg kg−1 | 268 |
| P | Foods | AA;F, air–C2H2;L | P was determined indirectly as bismuth phosphomolybdate at the Bi 223.06 nm line, with an LOD of 0.008 µg g−1 | 265 |
| Pb | Blood, urine | AA;ETA;ED | In situ electrodeposition was applied to separate Pb from biological matrices after sample acidification. The method was tested on CRMs. For blood analysis, the LOD was 1.5 µg l−1 and CV 3.0% | 147 |
| Pb | Blood | AA;ETA;L | A method was described for determining blood Pb using continuum-corrected ETAAS | 374 |
| Pb | Blood | AA;ETA;L | Three designs of W-filament atomizers were evaluated for use in a previously described system. Best results were obtained with a long wire style that gave a characteristic mass of 200 pg, an LOD of 1–2 µg dl−1 and acceptable accuracy and precision | 79 |
| Pb | Blood | MS;ICP;L | Samples were diluted 1 + 9 with 0.1% v/v Triton X-100–0.1% v/v HNO3. The LOD was 0.06 µg l−1. The method was applied in a preliminary clinical investigation to assess the potential of blood Pb as a biomarker of bone resorption | 151 |
| Pb | Serum, blood | MS;-;L AA;ETA;L | Serum Pb measured by ID–TIMS was 0.24% of the blood Pb concentration | 149 |
| Pb | Blood | MS;ICP;L | Examples were presented of how measurement of 207Pb∶206Pb and 206Pb∶204Pb may identify likely sources of exposure within homes | 38 |
| Pb | Blood, urine, food | MS;ICP;L | See Cd, ref. 127 | 127, 318 |
| Pb | Blood, urine, food | MS;ICP;L | See Cd, ref. 128 | 128 |
| Pb | Blood | AE;ICP;Re cup in torch | Sample, diluted with H2O and Triton X-100–0.5% HNO3, was placed into a rhenium cup which was introduced into the torch. The Pb vaporised to give the AE signal. CRMs were analysed and accurate results were given | 18 |
| Pb | Biological materials | AA;ETA;Sl | The furnace platform was pre-treated with a W–Rh modifier that was stable for up to 300 measurements. 20 µl slurry containing up 1.5% m/v sample were added to the platform. Furnace lifetime and analytical sensitivity were improved by the modifier | 148 |
| Pb | Biological specimens | MS;ICP;L | Measurement uncertainties for the determination of Pb in RMs by ID were calculated for three instruments; Q-MS, double focusing single collector MS and single focusing double collector MS. Accurate results were given by all three | 150 |
| Pb | Tooth enamel | MS;ICP;L | Pb in tooth enamel was measured by ICP-MS and TIMS, as a marker of environmental lead exposure. In neolithic samples the Pb was only one order of magnitude less than was found in modern teeth | 375 |
| Pb | Bone | XRF;-;S | The performances of two new digital spectroscopy systems were compared with a conventional system for the in vivo measurement of bone Pb. Improved precision and LODs were observed. LODs were 1.5–2.5 and 0.5–1.0 µg Pb g−1 bone mineral for the two new systems, compared with conventional LODs of 6–10 | 44 |
| Pb | Bone | XRF;-;S | A combined K- and L-based XRF in vivo method was proposed with a 109Cd radiation source and Ge and Si(Li) detectors. It was suggested that a lower LOD is possible | 45 |
| Pb | Bone | XRF;-;S | Replicate measurements were made using cadaver legs and, over a prolonged period, on in vivo volunteers. Variation in results were 6–50 µg g−1 and 6–13 µg g−1, respectively | 157 |
| Pb | Bone | XRF;-;S | Repeated measurements were made along the length of the tibia of cadaver legs. Variations of the results and of the measurement uncertainty were obtained depending on the sampling site | 49 |
| Pb | Bone, blood | XRF;-;S | Bone Pb and blood Pb were determined in 43 occupationally exposed subjects. The results were used to assess measurement uncertainty of XRF determinations of bone Pb, with particular attention to spatial orientation, and to address factors influencing bone and blood Pb concentrations | 53, 376 |
| Pb | Bone | XRF;-;S | Uncertainty of measurement was similar with samples from children and adults | 158 |
| Pb | Bone | XRF;-;S | An anthropometric phantom for calibrating in vivo measurements of stable Pb in the human leg was developed, which energy spectrum is indistinguishable from that of the human leg. It provides a realistic calibration standard to be used for intercomparison measurements | 48 |
| Pb | Bone | XRF;-;S | Coherent conversion factors (i.e., factors which convert between the matrix of the calibration standards and those of human bone) for plaster of Paris (the present matrix of calibration standards) and a synthetic apatite matrix were compared. Synthetic apatite matrix was more representative of bone mineral than plaster of Paris | 46 |
| Pb | Bone | XRF;-;S | Sources of measurement and calibration errors were estimated | 47, 377 |
| Pb | Bone | XRF;-;S | The relationships between either bone Pb levels or its variation with time and the cumulative blood Pb index was investigated in a repeated bone Pb survey. Half-lives between 9 and 15 years for the release of Pb from the tibia were estimated by regression models | 51 |
| Pb | Bone | XRF;-;S | The variability of K-XRF bone Pb measurements in young subjects was investigated using tibiae from two male cadavers, aged 17 and 20 years | 50 |
| Pb | Blood, bone, urine | XRF;-;S | The associations between biomarkers of Pb exposure and polymorphisms in the δ-aminolevulinic acid dehydratase and the vitamin D receptor genes were evaluated in former organolead manufacturing workers | 155, 156 |
| Pb | Bone | XRF;-;S | In vivo measurements in lead workers were much lower than on a previous occasion. The authors suggest that contamination may occur when investigating lead workers | 378 |
| Pb | Bone | XRF;-;S | Longitudinal changes in bone Pb concentration were assessed | 52 |
| Pb | Hair roots, blood | XRF;-;S | Pb in the hair root did not correlate with blood Pb concentrations. Analysis of hair roots cannot be used to screen for undue Pb exposure | 92 |
| Pb | Foodstuffs | AA;ETA;L | See Cd, ref. 294 | 294 |
| Pb | Chicken meat | AA;-;- | See Fe, ref. 364 | 364 |
| Pb | Durum and soft wheat | AA;ETA;L AA;F;L | See Cd, ref. 314 | 314 |
| Pb | Cookies | AA;ETA;L | W, Pd, W + Pd and W + Pd + tartaric acid (TA) were tested as chemical modifiers in the determination of Pb. The W + Pd + TA modifier mixture was found to be preferable, yielding an LOD of 1.2 µg l−1 | 267 |
| Pb | Carrot, endive | AA;F;L AA;ETA;L | See Cd, ref. 352 | 352 |
| Pb | Calcium supplements | MS;ICP;L | High resolution ICP-MS was used to determine Pb in 136 brands of supplements. Two thirds of the samples failed to meet the Californian requirements | 94 |
| Pb | Vegetable oils | MS;ICP;L | See Cd, ref. 281 | 281 |
| Pb | Water | AA;F;L | Chelation preconcentration and the slotted quartz furnace yielded LODs of 1 µg l−1 | 264 |
| Pb | Wine | MS;ICP;L | The accuracy of the determination of Pb isotope ratios was evaluated using quadrupole, multicollector magnetic sector and TOF analysers for measurement of a range of European wines. The poor sensitivity of TOF necessitated preconcentration. The quadrupole gave poor isotope precision | 277 |
| Pb | Wine | MS;ICP;L | Pb isotope ratio analysis showed that the ratios in wine reflected environmental inputs | 278 |
| Pd | Urine | MS;ICP;L | Environmental exposure to Pd, Pt and Rh was assessed in 310 children, aged 6–10 years, from Rome (Italy). Urine samples were UV irradiated prior to analysis. The mean concentration values were (ng g−1 creatinine) 7.5 ± 5.4 (Pd), 0.9 ± 1.1 (Pt) and 8.5 ± 8.0 (Rh) | 184 |
| Pd | Urine | XRF;-;S | See Au, ref. 62 | 62 |
| Pt | Plasma | AA;ETA;L | A validated method was described for the monitoring of patients treated with cisplatin in a liposomal formulation | 379 |
| Pt | Biological fluids | AA;ETA;L | Urine was diluted with 10% HCl, and plasma was mixed with 5% Triton X-100. Ultrafiltrates were preconcentrated onto the graphite platform. Heating programmes were optimised for each matrix. Samples were from patients treated with JM216 | 187 |
| Pt | Blood, plasma, urine | MS;ICP;HPLC | The fate of oxaliplatin after its i.v. administration was investigated by HPLC-ICP-MS and ESMS. In plasma, Pt was mainly bound to γ-globulins (40%) and albumin (40%). In urine 1 h after infusion, 50% of the total Pt was oxaliplatin. In red blood cells, Pt was bound to haemoglobin (60%) and to low Mr compounds (40%) | 380 |
| Pt | Blood, plasma, plasma ultrafiltrate | MS;ICP;L | Standard equipment was used for blood and plasma samples (LOD = 0.1 µg ml−1) while a USN (LOD = 0.001 µg ml−1) was required for the ultrafiltrate. Pharmacokinetic studies following administration of oxaliplatin were reported | 185 |
| Pt | Human albumin | MS;ICP;L | See I, ref. 370 | 370 |
| Pt | Urine | MS;ICP;L | See Pd, ref. 184 | 184 |
| Pt | Serum, urine | XRF;-;S | A TXRF procedure was developed for the routine monitoring of plasma and urine Pt levels in paediatric cancer patients undergoing chemotherapy with Pt-containing drugs | 188 |
| Pt | Kidneys | XRF;-;S | An in vivo XRF method was developed to measure Pt concentrations in the kidneys of patients receiving chemotherapy | 57 |
| Rb | Serum | AA;ETA;L | Concentrations in 70 dialysis patients were low compared with 75 control subjects; 304 ± 81 and 350 ± 74 µg l−1, respectively. This may be relevant to neurobehavioural activity of uraemic patients | 194 |
| Rb | Mineral and well waters | AE;F, CH4–air;L | Using the 780 nm line the LOD was 2.3 µg l−1. The effect of interfering group I and II atoms was considered | 266 |
| Rh | Urine | MS;ICP;L | See Pd, ref. 184 | 184 |
| Ru | Blood | AA;-;- | The fate of the antimetastatic Ru complex ImH was investigated by measuring blood and organ Ru contents in mice after acute i.v. treatment | 381 |
| Ru | Tumour cells | AA;ETA;L | Ru uptake by tumour cells was measured as part of a study on the RuIII complex (NAMI-A). The relationship between cell uptake, cell cycle arrest and cytotoxicity was evaluated | 382 |
| Sb | Urine | MS;ICP;HPLC | A PRP-X100 anion exchange column with 20 mM EDTA pH 4.7 as mobile phase was used to separate SbIII from SbV. TMSbCl2 and SbV were separated with an ION-120 column and a mobile phase of 2 mM NH4HCO3–1 mM tartaric acid pH 8.5. LODs were 8 to 20 ng l−1 | 109 |
| Sb | Drinking water | AF;Hy;L | See As, ref. 342 | 342 |
| Se | Serum, foods | AA;Hy;FI | A method was developed for the determination of Se in serum following microwave digestion and reduction of SeVI to SeIV. The LOD was 0.3 µg l−1. The method was applied to the determination of Se in sera of Austrian and Slovenian subjects and for the calculation of dietary intakes | 198 |
| Se | Serum | AA;ETA;L | Serum Se was measured in 169 adults and 210 children from Poland. A Cu–Mg mixture was used as a matrix modifier. Mean values were <60 µg l−1 | 200 |
| Se | Plasma | AA;-;L | Plasma Se and glutathione peroxidase (GSH-Px) activity in blood were estimated in 304 horses. Estimates of Se content from GSH-Px activity values were unsatisfactory when compared with measured values | 383 |
| Se | Urine, serum | AA;ETA;L | Samples were diluted with 0.2% HNO3 and 0.1% Triton X-100 added. The solution was injected into the furnace and a modifier containing Ni2+–Pd–NH4NO3–HNO3 was added. LODs for urine and serum were 4.4 and 21.4 µg l−1, respectively. Evaluation using CRMs was satisfactory | 343 |
| Se | Blood (CRM) | AA;F;FI-HG | A new system is described, based on electrochemical HG, FI and AAS, to determine Se in biological materials. The LOD was 10 µg l−1 | 81 |
| Se | Urine | AA;Hy;LC | SeIV, SeVI, SeMet and selenocysteine were separated using a C18 anion exchange column. Conditions for optimum separation were determined and LODs calculated | 384 |
| Se | Urine | AA;Hy;HPLC | A method was developed for the separation and quantification of SeMet. The LOD was 1.08 µg l−1 | 385 |
| Se | Leucocytes | MS;ICP;L | See Cu, ref. 35 | 35 |
| Se | Serum, water | MS;ICP;ETV | ID was used to improve the performances of a previously described method. The uncertainties for the two methods were calculated according to ISO guidelines | 386 |
| Se | Urine | MS;ICP;IC | K and Na were removed by extraction of samples with benzo-15-crown-5-ether, which led to improved speciation compared with unextracted urine. IC separation provided five species, SeMet, TMSI and three unidentified compounds | 196 |
| Se | Urine | MS;ICP;HPLC | Urine samples from subjects consuming different nutritional supplements were analysed. The work included an evaluation of nebuliser types and of a hexapole collision and reaction cell | 26 |
| Se | Urine | MS;ICP;L | Six species in urine, including SeMet and selenocystamine, were separated by reversed-phase chromatography | 197 |
| Se | Kidneys, liver, serum, urine | MS;ICP;HPLC | The metabolic pathways of different Se species (selenite and selenate) were investigated in rats injected 82Se-enriched selenate or selenite | 195 |
| Se | Biological samples | MS;ICP;HPLC MS;ICP;CE | See As, ref. 340 | 340 |
| Se | Lung | AA;Hy;L | See As, ref. 64 | 64 |
| Se | Hair | AA;ETA;L | Se was determined after digestion with HNO3 and H2O2 using Pd as a chemical modifier. The ashing step was carried out at 1200 °C and atomization at 1900 °C | 86 |
| Se | Environmental samples, biological samples | AF;Hy;L | Interferences arising from matrix components (e.g., Co2+, Cu2+, Ni2+) and digestion medium were investigated. Calibration using matrix matched standards or standard additions was recommended | 387 |
| Se | Brain | XRF;-;S | Se concentrations were measured in rat brain with an LOD of 20 ng g−1 | 388 |
| Se | Mushrooms | XRF;-;S | See Cs, ref. 283 | 283 |
| Se | Human milk, plasma | AA;-;L | The major form of Se in Kuwaiti mothers' milk was found to be SeMet; this species was not found in cows' milk | 202 |
| Se | Cows' milk, infant formula | AA;Hy;L | Over a period of 11 years there was little variation in the Se content of branded cows' milk or infant formula in a Japanese study | 389 |
| Se | Foods | AA;Hy;L | An Irish study found that Se levels in breads were lower than the USA and Canada and only marginally higher than the UK | 260 |
| Se | Rice and dried fish SRMs | AA;F, air–liquid petroleum gas;FI | Electrochemical HG was used to determine Se in biological samples. 30 samples h−1 was the throughput and the LOD was 10 µg l−1 | 81 |
| Se | Mussels, wheat flour SRM | AA;ETA;L AA;Hy;L | TMAH digestion was compared with acid mineralisation. The use of TMAH in speciation studies was also evaluated | 243 |
| Se | Cereals | MS;ICP;HPLC | Laboratory experiments investigated if the addition of selenate to fertilizers could be used to enhance Se content of Austrian cereals. Using enzymatic extraction, which greatly improved recoveries, it was found that the selenate had been incorporated in the plants as SeMet | 300 |
| Se | Mushrooms | AF;-;LC | Se in mushrooms was found mainly in low MR forms | 301 |
| Se | Plant tissues | MS;ICP;HG | HNO3–HF–H2O2 with microwave oven heating were used for sample dissolution. A special solution introduction device combined pneumatic nebulization with HG in the thin liquid film on the walls of the minicyclonic spray chamber. The LOD was 0.03 µg g−1 | 203 |
| Se | Coconut milk, coconut water | AA;ETA;L | Sample treatment involved simple suspension in a mixture (1 + 4 v/v) of tertiary amines. Zeeman-effect ETAAS was used, with Pd as modifier, for measurement. For six samples, the Se concentration in coconut water varied from 6.5 to 21.0 µg l−1 and in coconut milk from 24.2 to 25.1 µg l−1 | 227 |
| Se | Drinking water | MS;GC;L | SeIV was derivatised to ethane 1,1′-selenobis by reaction with sodium tetraethylborate and then extracted using SPME (solid phase microextraction). Measurement was by GC-MS and LODs were in the range 81–166 ng l−1 | 304 |
| Se | Garlic, yeast | MS;ICP;HPLC | Selenised garlic and yeast were speciatied using HPLC–ES–ICP-MS showing the main forms to be γ-glutamyl-Se-methylselenocysteine (73%) and selenomethionine (85%), respectively. In rat feeding studies, supplementation of Se-garlic in the diet caused a lower total tissue Se accumulation when compared with Se-yeast. Se-garlic was significantly more effective in suppressing the development of premalignant lesions and the formation of adenocarcinomas in the mammary gland of carcinogen-treated rats | 299 |
| Se | Yeast-based food supplements | MS;ICP;HPLC | Total Se and selenomethionine were determined in 6 brands of supplements. Total levels conformed to label claims, but species present varied widely, with 1 brand containing all inorganic Se. The paper contained details of method development, with overnight treatment with Proteinase K being particularly effective | 303 |
| Se | Dietary supplements | -;-;CE MS;ICP;HPLC | 6 species were separated in 8 min using CE, with results in good agreement with those obtained using HPLC–ICP-MS | 302 |
| Si | Blood, human milk, tissue | AA;ETA;L | Si levels were measured in patients with silicone implants and controls. Control of Si contamination was achieved using a Class 100 laboratory for sample preparation and washing specimen collection tools and laboratory plasticware | 206 |
| Si | Serum | AA;ETA;L | Reference values were obtained for Belgian children and adults, including pregnant women | 204 |
| Si | Biological specimens | AE;ICP;L | TMAH was added to samples with microwave heating to effect dissolution. An LOD of 2 mg kg−1 was reported | 205 |
| Si | Foodstuffs | AA;-:L | Using the duplicate diet method the normal daily Si intake in Belgian adults was found to be 18.6±8.5 mg d−1 | 317 |
| Sn | Blood, tissue, urine | MS;ICP;- | The distribution of organotin compounds in body fluids and organs were studied in a fatal case victim of poisoning from organotin contaminated food | 210, 390 |
| Sn | Shellfish | AA;ETA;L | Samples, 0.5 g, were digested using HNO3–HClO4–HF, 10 + 5 + 5, evaporated to dryness and the residue redissolved in 3 ml HNO3. 20 µl were injected into the furnace of a Zeeman-effect ETAA spectrometer along with 5 µl of 20 g l−1 Ni as chemical modifier | 241 |
| Sn | Lard | MS;ICP;L MS;-;GC | Tri- and dimethyltin in lard were found to be responsible for a poisoning incident in the Jiangxi region of China. Unfortunately limited details were given of how this contamination arose. Blood, urine and organs from those affected were also analysed | 211 |
| Sr | Bone | AA;F, air–C2H2;L AA;F, N2O–C2H2;L | The effect of common matrix components and ionization interferences were studied. The effectiveness of a “Y” shaped device, connected to the nebulizer for the simultaneous introduction and on-line mixing of standard solutions or samples digests with releasing agents or ionization buffers, to suppress these effects was assessed by comparison with results obtained by ETAAS. The LODs were 0.030 and 0.015 mg l−1, and the precisions were 1.5% and 0.5% RSD, for the air–C2H2 and N2O–C2H2 flames, respectively. The latter flame type was recommended | 208 |
| Sr | Bone, soil | MS;ICP;L | An on-line IC procedure was developed to separate Rb and Sr, thus allowing the removal of the isobaric interference affecting the determination of Sr isotope ratios. The use of the shielded torch system and USN enhanced Sr signal intensity by 100-fold | 39 |
| Sr | Wine | MS;ICP;L | 87Sr∶86Sr showed promise as a method of fingerprinting wine origin | 279 |
| Sr | Foods, beverages | -;-;- | Using the duplicate portion method, Sr intake in 14 towns in Eastern Germany was measured. The average Sr intake was 1.1–4.5 mg d−1 | 320 |
| Th | Urine | MS;ICP;L | Depending on the level of exposure to 232Th the samples were diluted 20- or 100-fold. Measurements were set up for monitoring occupational exposure to Th | 214 |
| Ti | Tissues | AE;ICP;L | Mechanisms contributing to the release of Ti from spinal implants were proposed | 212 |
| Tl | Blood, faeces, tissues | AA;ETA;L | In an experiment to determine if dimercapto-1-propansulfonic acid and Prussian blue may be used to treat thallotoxicosis, tissues of Tl-dosed rats were analysed. Some beneficial effects were seen using Prussian blue | 391 |
| Tl | Brain | AA;-;- | The concentration of Tl was measured in rat brain regions after subchronic administration of sublethal doses of TlI acetate | 209 |
| V | Intravenous solutions | AA;ETA;L | V was determined in solutions for i.v. administration and in 6 salt components of a multitrace element solution. The highest V concentrations were found in albumin solutions | 99 |
| V | Urine | MS;ICP;L | See Cr, ref. 23 | 23 |
| V | Blood, kidney, liver | PIXE;-;- AA;ETA;L | Samples from animals given V-supplemented diets were analysed by two techniques. Similar results were obtained but the advantage of PIXE was the multielement measurements | 216 |
| W | Plasma | AE;ICP;L | The performance of a method for the determination of W in rat and dog plasma was described and compared with the requirements necessary to carry out pharmacokinetic studies. The limit of quantification was 100 ng ml−1 | 213 |
| Zn | Serum | AA;F;L | Concentrations in 152 healthy subjects aged more than 90 years were 11.97 ± 2.00 µmol l−1. Lower levels were seen in those living in institutions | 78 |
| Zn | Serum | AA;F;L | See Cu, ref. 392 | 392 |
| Zn | Serum | MS;ICP;L | See Cu, ref. 29 | 29 |
| Zn | Blood, faeces, urine | MS;-;L | Zn metabolism was investigated in 7 girls using stable Zn isotopes and compartmental modelling techniques with TIMS for measurement | 221 |
| Zn | Urine | AA;F;L | Basal urinary Zn∶creatinine ratio was investigated as an indicator of dietary Zn intake in healthy women | 393 |
| Zn | Liver, serum | AA;ETA;L PIXE;-;S | See Cu, ref. 140 | 140 |
| Zn | Biological materials | AA;F;L | See Cu, ref. 137 | 137 |
| Zn | Liver cytosol | AE;ICP;HPLC | See Cd, ref. 349 | 349 |
| Zn | Proteins | XRF;-;S | The in situ analysis of trace elements by SR XRF was described. The distribution of elements in protein bands separated by electrophoresis from human liver cytosolic samples was analysed along the polyacrylamide gel | 394 |
| Zn | Infant formula, human milk | AA;-;L | See Ca ref. 305 | 305 |
| Zn | Human milk, infant formula | AA;-;L | See Ca, ref. 73 | 73 |
| Zn | Human milk | AA;F;L | See Cu, ref. 69 | 69 |
| Zn | Human milk | AA;F;L | See Cu, ref. 70 | 70 |
| Zn | Infant foods | AA;F;L | An in vitro method was developed to study the effect of phytate∶Zn molar ratio on Zn bioavailability. Availability was lower in soybean-based formula than those based on cows' milk | 232 |
| Zn | Chicken meat | AA;-;- | See Fe, ref. 364 | 364 |
| Zn | Carrot, endive | AA;F;L AA;ETA;L | See Cd, ref. 352 | 352 |
| Zn | Durum and soft wheat | AA;ETA;L AA;F;L | See Cd, ref. 314 | 314 |
| Zn | Bulgur wheat | AA;ETA;L | See Fe, ref. 234 | 234 |
| Zn | Vegetable oils | MS;ICP;L | See Cd, ref. 281 | 281 |
| Zn | Vitamin tablets | AA;-;S | See Cu, ref. 97 | 97 |
| Various | Biological and clinical samples, foods and beverages | -;-;- | The 2001 ASU highlighted a number of recent trends including growth in CE applications and movable reduction bed HG | 1 |
| Various | Food, blood | MS;ICP;L | A study of the nutrient intake of 52 women in Bangkok showed that Ca and Fe intakes were deficient in the majority of cases | 322 |
| Various (4) | Erythrocytes, plasma | AA;-;L | Post operative changes of Cu, Fe, Mg and Zn were observed in plasma but not erythrocytes of 11 patients undergoing neurosurgery | 395 |
| Various (4) | Blood, tissues | AA;F;L AA;ETA;L | Rats subjected to stress by restraint and cold had changes to the concentrations of Mg, Mn and Zn but not of Cu | 396 |
| Various (5) | Blood, cells, plasma | AA;ETA;L | Specimens were diluted with HNO3–Triton X-100. The chemical modifiers and heating programmes were optimized for each sample type and element. Reference ranges for the sample types were presented (Cd, Cr, Cu, Mn, Se) | 74 |
| Various (10) | Serum | AE;ICP;L | Serum reference values in 141 healthy Norwegians were determined by a validated method. The effects of gender, age, smoking and oral contraceptives on serum levels of trace elements were investigated (Ba, B, Cd, Cu, Fe, Mn, Li, Se, Sr, Zn) | 20 |
| Various (16) | Serum | AE;ICP;L | Digested samples were taken with Yt as internal standard and serum based calibration materials. Detection limits and results with a serum CRM were reported. In real samples, the concentrations for eight elements were too low to measure | 19 |
| Various (12) | Serum | MS;ICP;L | Reference values for Al, Cd, Co, Cu, Li, Mn, Mo, Ni, Rb, Sb, Se and Zn in serum of term newborns from Rome (Italy) were reported | 397 |
| Various (12) | Plasma | MS;ICP;L | In coxsackievirus B3 (CB3) infection, the myocardium is a target in both humans and mice. The concentrations of 12 trace elements were determined in the myocardium of sham-inoculated controls and infected A/J mice 4 and 7 d postinoculation | 33 |
| Various (12) | Blood, plasma | MS;ICP;L | The concentrations of electrolytes and trace elements in blood or plasma were determined in samples from patients with coronary heart disease undergoing percutaneous transluminal coronary angioplasty collected before and after the clinical intervention (Ca, Co, Cs, Cu, Fe, K, Mg, Na, Pb, Rb, Sr, Zn) | 30 |
| Various (18) | Serum, synovial fluid | MS;ICP;L | The correlation between trace elements in synovial fluid of osteoarthritic knee joints and blood serum was investigated. The grade of inflammation did not correlate with any elemental concentration determined | 31, 32 |
| Various (12) | Plasma | MS;ICP;L | Plasma concentrations of Cd, Co, Cs, Cu, La, Mg, Mo, Pb, Rb, Sr, Tl and Zn were studied in haemodialysed (HD) patients over a 6 month period. Cs, Mg, Mo and Rb were reduced and Cd, Co and Pb increased in HD patients as compared with controls | 28 |
| Various (7) | Blood | MS;ICP;L AA;ETA;L | Cd, Cu, Hg, Mn, Pb, Se, Zn were determined in samples from patients with motor neuron disease. Cd was higher than in controls | 76 |
| Various (15) | Plasma | MS;ICP;L | REEs were determined in human plasma. The LODs for 15 elements ranged from 0.7 (Eu) to 5.4 (Gd) ng l−1. Three sample preparation methods were compared | 190 |
| Various (12) | Plasma, myocardium | MS;ICP;L | Mice were infected with coxsackievirus to determine if the inflammation promotes changes in trace elements. Various decreases and increases were observed in plasma and heart tissue which may be related to the disease process | 398 |
| Various (17) | Serum | MS;ICP;L | Yet another study to report reference ranges in human serum (n = 110) | 24 |
| Various (4) | Urine | AA;ETA;L | Analyte ions were precipitated from 10 ml urine into 1 ml HNO3. Parameters to affect precipitation were discussed (Cd, Cr, Mn, Pb) | 399 |
| Various (4) | Urine | AA;ETA;L | The determination of Al, Cr, Cu and Mn in urine was performed using a simultaneous AA instrument and Pd as the chemical modifier. Using an Ar–H2 mixture (95∶5) as the purge gas resulted in smaller and more uniformly distributed Pd particles. The LODs were 0.06 (Al), 0.05 (Cr), 0.08 (Cu) and 0.06 (Mn) µg l−1 | 63 |
| Various (25) | Urine | MS;ICP;L AA;ETA;L | Urine specimens from patients residing in the United States were used to determine representative ranges for 25 trace elements | 22 |
| Various (4) | Urine | MS;ICP;FI | Samples were digested and the solutions taken for on-line preconcentration. LODs were from 0.05 (U) to 2.24 pg ml−1 (Te) (Ag, Au, Te, U) | 400 |
| Various (7) | Urine | MS;ICP;FI | The method involved on-line dilution (by a factor of 16.5) and internal standardisation with 103Rh. The LODs were 0.30 (As), 0.12 (Cu), 0.09 (Mo), 0.08 (Ni), 0.09 (Pb), 0.45 (Se) and 0.96 (Zn) µg l−1 | 8 |
| Various (25) | Urine | MS;ICP;L AE;ICP;L | Samples from patients with chronic exposure to As in food and air were analysed. Significant differences from unexposed controls were recorded | 401 |
| Various (4) | Semen | AA;-;- | The concentrations of Cd, Cu, Pb and Zn in bovine semen samples, to be used for artificial insemination, were investigated in relation to semen activity | 402 |
| Various (4) | Semen, plasma | AA;-;- | Low levels of Mg were seen in men with premature ejaculation (Cu, Mg, Se, Zn) | 163 |
| Various (4) | Bile | AA;-;- | The concentrations of Ca, Mg, Pb and Sr in bile were determined in 119 patients with cholelithiasis and 25 controls | 403 |
| Various (13) | CSF | AE;ICP;L | Several elements were determined in CSF from subjects with Alzheimer's disease and controls (Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, S, Zn) | 404 |
| Various (11) | TPN fluids, serum, tissues | MS;ICP;L | Contaminants were identified in different fluids which were then infused to animals to determine the accumulation in tissues and possible pathologies (Al, As, Cd, Cr, Ge, Hg, Mn, Pb, Sn, Sr, V) | 405 |
| Various (5) | Saliva | MS;ICP;DIN | Samples of human saliva were mixed with HNO3, diluted 1∶4 with water and spiked with enriched isotopes for quantification of Ba, Cd, Cu, Pb and Zn by ID. The LODs were 0.11, 0.03, 0.40, 0.05 and 0.59 µg l−1, respectively, and sample throughput was 30 samples h−1 | 34 |
| Various (7) | Dialysis fluid, plasma | MS;ICP;L | Changes in Ba, Ca, Cu, Pb, Mg, Sr and Zn concentrations during haemodialysis were monitored by measuring their concentrations in plasma and dialysis fluids before and after passing the artificial kidney | 27 |
| Various (5) | Pleural fluid, serum | MS;ICP;L | Samples were collected from 13 patients with emphysaema. Results were compared with fluid from other pulmonary conditions and with the corresponding sera (Cu, Mg, Mn, Rb, Zn) | 406 |
| Various (10) | Plasma proteins | XRF;-;- | The distribution of trace elements in plasma proteins from mice treated with cisplatin was determined by SEC-SRXRF (Br, Ca, Cu, Fe, Ni, Pt, S, Se, Sr, Zn) | 407 |
| Various (11) | Blood | PIXE;-;S | Br, Ca, Cd, Cl, Cu, Fe, K, P, Rb, S and Zn were measured in samples from hypertensive Nigerians and their controls. Significant differences for seven elements were reported | 408 |
| Various (14) | Human milk | PIXE;-;S | The content of Al, Br, Ca, Cl, Cu, Fe, I, K, Mg, Mn, Na, P, Rb and Zn in human breast milk from Nigerian mothers was investigated in relation to stages of lactation and term or pre-term delivery | 61, 285 |
| Various | Biological materials | -;-;- | The application of hyphenated techniques to the speciation of elemental forms was comprehensively reviewed | 3 |
| Various (6) | Tissue | AA;-;- | Concentrations of Al, Ca, Mg, Zn, Cu and Fe in stomach, kidneys, bone and liver of mice fed various Al compounds in drinking water were determined to evaluate the risk of long-term gastrointestinal Al exposure | 409 |
| Various (4) | Tissue | AA;Hy;L | Electrolytic HG using different cathode materials was investigated for analytical applications to the determination of As, Sb, Se and Sn. The LODs were in the range of 0.11–0.13 µg l−1 for As and Sb | 80 |
| Various (32) | Tissue | MS;ICP;L | Trace element concentrations were measured in liver and kidney (32 elements) and bone (20 elements) of 70 deceased adults from the Czech Republic. Some sex-related significant differences were reported | 25 |
| Various (10) | Heart tissue | AE;ICP;L | The content of Ca, Cu, Fe, K, Mg, Mn, Na, P, S and Zn in specialised heart tissue was determined to investigate their relationship with fatal cardiac dysfunction of unknown origin | 410 |
| Various (8) | Heart valves, nerves, trachea | AE;ICP;L | In a series of papers the authors examined differences between the named elements in various sample types, and the effects of ageing (Ca, Fe, Mg, Na, P, S, Si, Zn) | 14–16 |
| Various (17) | Spinal cord | AE;ICP;L AA;ETA;L AA;CV;L | The concentrations of trace elements in the spinal cord of horses with equine motor neuron disease were compared with those of controls. Cu concentration was significantly higher in horses with equine motor neuron disease than control horses (Al, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Se, Zn) | 75 |
| Various (11) | Brain, erythrocytes | XRF;-;S | The concentrations and distribution of metals were determined in I-deficient rats treated with I and Se (Br, Ca, Cu, Fe, I, K, Mn, Pb, Rb, Se, Zn) | 411 |
| Various | Brain | PIXE;-;S | Validation of the technique was reported with details of calibration and LODs given | 60 |
| Various | Brain | PIXE;-;S | Normal and Alzheimer's brains were studied. Variations within and between regions of the brain were reported | 412 |
| Various (4) | Breast tissue | XRF;-;S | The content of Ca, Cu, Fe and Zn was evaluated in healthy and pathological breast tissue, as a possible diagnostic technique for breast cancer | 413 |
| Various | Tissue | PIXE;-;S | The release of trace elements from metallic prosthesis to surrounding soft tissues was confirmed and migration paths investigated | 414 |
| Various (6) | Tissues | XRF;-;S | EDXRF was used to investigate the effect of Li administration on trace element profile in control and diabetic rats (Br, Cu, Fe, K, Rb, Zn) | 415 |
| Various (7) | Gallstones | AE;ICP;L | Samples were digested with HNO3 and H2O2 by means of focused microwave. The effect of the Ca content on the determination of Co, Cr, Cu, Fe, Mn, Ni and Zn was studied | 416 |
| Various (7) | Tooth enamel | AA;F;L AA;ETA;L AE;ICP;L MS;ICP;L | The whole enamel and surface layers of extracted non-carious human teeth from population samples and prehistorical remains were analysed using different techniques (Cu, Fe, Mg, Mn, Pb, Sr, Zn) | 77 |
| Various (6) | Tooth enamel | XRF;-;S | Using a SR probe with a resolution of 100 µm, profiles for Br, Cu, Fe, Pb, Sr and Zn through a tooth were determined. Variations between samples from different regions were thought to be caused by the types of diet | 43 |
| Various (8) | Hair | AA;F;L | An assessment of the content of Ca, Cu, Fe, K, Mg, Mn, Na and Zn in the black and gray hairs of the same person in Taiwan revealed significant differences | 90 |
| Various (9) | Hair | AA;F;L | Age-, sex- and ethnic group related differences were investigated (Ca, Cu, Fe, K, Mg, Mn, Na, Sr, Zn) | 417 |
| Various (6) | Hair, nails, teeth | AA;-;- | The relationship between environmental exposure to Cd and Pb and the levels of the essential elements Ca, Cu, Fe and Zn was investigated | 418 |
| Various (6) | Hair | AA; F;L AA;ETA;L | Acid-leaching procedures assisted by ultrasonic energy for the extraction of Ca, Cu, Fe, Mg, Mn and Zn from human hair samples were optimised. Acid concentrations and temperature of the ultrasonic bath were the critical parameters | 5 |
| Various (4) | Hair | AA;ETA;L | Samples were dissolved in TMAH. A mixture of Pd and phosphate was used as modifier for Pb analysis, Pd alone for As and Cd determinations, none for Ni. The LODs were 0.4, 0.009, 0.1 and 0.5 µg g−1, respectively, for As, Cd, Ni and Pb. Results agreed with those obtained by using a conventional acid dissolution | 7 |
| Various (4) | Hair | AA;ETA;L AE;ICP;L | Age and sex related differences were observed for Cu, Fe, Mn and Zn concentrations in head hair from 418 subjects aged between 6 months and 20 years | 85 |
| Various (13) | Hair | AE;ICP;L | The concentrations of Al, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Ti, V and Zn were determined in the hair of fox terrier, schnauzer and mini schnauzer dogs. The effect of five washing solutions (deionized water, acetone, methanol, EDTA and Triton X-100) was investigated | 419 |
| Various (19) | Hair | AE;ICP;L | Reference values were determined in hair samples of children, aged 3–15 (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Pb, Se, Sr, Ti, V, Zn) | 84 |
| Various (13) | Hair | AE;ICP;L | Changes in the concentration of Al, Ba, Ca, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Zn and other trace elements in human hair of subjects with chronic hepatitis were investigated | 420 |
| Various (5) | Hair | AF;Hy;L AF;CV;L | A novel method for the determination of As, Bi, Hg, Sb and Se was developed. Pretreatment included microwave digestion followed by continuous flow vapour generation. Samples were digested in two stages with HNO3 and H2O2 for Hg analysis, whilst for the other elements a common digestion step with HCl and H2O2 was used. The LODs were 0.2 ng g−1 for Hg and between 2 and 10 ng g−1 for the other elements | 88 |
| Various (71) | Hair, nails | MS;ICP;L | Concentration ranges and differences related to age, sex and smoking habit were assessed in a sample of urban population from Sweden not occupationally exposed | 83 |
| Various (10) | Hair | MS;ICP;L AE;ICP;L | Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni and Zn were determined in hair samples collected from participants in the expeditions in Antarctica prior to departure and at the end of the period spent at the bases | 421 |
| Various (4) | Human milk, plasma | AA;-;L | The Cu, Fe, Mn and Zn status of Kuwaiti breast milk was evaluated | 71 |
| Various (60) | Human milk | AE;ICP;L | SEC–USN–ICP-AES was used to speciate Ca, Cu, Fe, Mg, Mn and Zn in human milk from 60 lactating Italian mothers. Different binding patterns were observed, dependant on the protein and low MR fractions yielded by the chromatographic separation | 17 |
| Various | Milk, skimmed milk, whey | MS;ICP;L | Double-focusing ICP-MS was used to determine Al, Ca, Cd, Cr, Cu, Fe, Hg, Mn, Na, Ni, Pb, Se, Sr and Zn in a range of milk and milk-derived samples | 275 |
| Various (8) | Skimmed-milk yoghurts | AA;F;L | Following dry ashing at 460 °C, Ca, Cu, Fe, K, Mg, Mn, Na and Zn were determined. A second paper from the same group estimated dietary intakes from yoghurt | 309, 310 |
| Various | Water | MS;ICP;L | An interesting coupling of IC with a conductivity detector and ICP-MS allowed determination of bromate, bromide, iodine, iodide, AsIII, AsV, Cl−, NO3− and SO42− in drinking water | 259 |
| Various (66) | Mineral water | MS;ICP;L AE;ICP;L | 56 brands of mineral water from throughout Europe were analysed. Only 15 would fulfil the drinking water regulations for all parameters where action levels are defined. Potentially toxic elements such as Pb appeared higher in waters packaged in glass rather than plastic | 311 |
| Various (22) | Bottled water | MS;ICP;L | In a study of 170 samples of bottled water from the Japanese market 4 samples contained elements at more than the maximum levels recommended in the Japanese water quality standard | 312 |
| Various (22) | Orange juice | MS;ICP;L | Multivariate analysis was used to discriminate between Australian and Brazilian juices | 422 |
| Various | Beer | AA;F;L AE;F;L | Samples were digested using HNO3–H2O2 in a microwave oven. The resulting data were analysed using chemometric procedures to classify 25 beer samples | 423 |
| Various (5) | Beer wort | ETA;Hy;L | Hydrides of As, Sb, Se, Sn and Hg vapour, were trapped onto Pd- or Au- (for Hg) pre-treated walls of the graphite cuvette. All LODs were <100 ng l−1 | 250 |
| Various (12) | Sherry brandies | AA;F;L AA;ETA;L AE;ICP;L AA;Hy;L | A survey of 20 brands showed no elevated levels of potentially toxic elements (Al, As, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Pb, Zn) | 424 |
| Various (11) | Spanish brandy | AA;F;L AA;ETA;L | Brandies were classified using multielement data and chemometrics | 425 |
| Various (8) | Tea | AE;ICP;L | Pattern recognition techniques allowed green, black and oolong teas to be differentiated (Al, Ba, Ca, Cu, K, Mg, Mn, Zn) | 426 |
| Various | Tea leaves | MS;ICP;HPLC AE;ICP;HPLC | Numerous element–organic molecule complexes were found when SEC was used to speciate black tea leaves | 258 |
| Various (8) | Beet sugar | AA;ETA;L | Sucrose crystals were dissolved in 0.1% HNO3 and As, Cd, Co, Cr, Cu, Pb, and Sn determined using Pd–ascorbic acid as chemical modifier. Zn was determined without modifier | 269 |
| Various (19) | Honey | MS;ICP;ETV | LODs of 0.1–0.5 ng g−1 were achieved for a wide range of elements of environmental concern | 280 |
| Various (12) | Rice | XRF;-;S | Al, Ca, Cu, Fe, K, Mg, Mn, Na, P, Ti, Si and Zn were determined without any form of pre-treatment | 284 |
| Various (10) | Sardines | AA;-;- | The elemental content of canned sardines from regions of pacific Mexico was determined as part of a larger study of the nutritional profile of the fish content (Ca, Cd, Cr, Cu, Fe, K, Mg, Na, Pb, Zn) | 427 |
| Various | Seafood | AA;F;L AA;ETA;L AA;CV;L | An experimental design process, known as Plackett-Burman 2(7) X 3/32 design, was used to optimise seven factors (HNO3 concentration, HCl concentration, H2O2 concentration, acid solution volume, particle size, microwave power and exposure time to microwave energy) | 6 |
| Various (14) | Seafood | AA;ETA;L AA;CV;AA | The Plackett-Burman method was used to optimise ultrasonic bath-assisted extraction (As, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Pb, Se, Zn) | 428 |
| Various | Fish | AE;ICP;L | HNO3 wet-ashing by Parr bomb digestion, HNO3 wet-ashing by microwave digestion, TMAH–HNO3 wet digestion, and dry-ashing were compared. The microwave oven method gave the best results | 236 |
| Various (22) | Harp seal tissues | MS;ICP;L | Levels of nutrient and harmful elements in young Harp Seal blubber, liver, kidney and muscle were reported | 429 |
| Various (10) | Flour | AE;laser;S | A novel technique, known as laser-induced breakdown spectroscopy was used to directly determine Al, Cd, Cr, Cu, K, Mg, Mn, Pb, Rb and Sr at LODs of <18 µg g−1. All of the RSDs were in the range 2–10% | 430 |
| REE (15) | Wheat | MS;ICP;L | REEs were determined in 60 wheat varieties | 431 |
| Various | Soft wheat, Durum wheat | MS;ICP;L | A study of six different homogenisers showed that all contributed contamination to the analysis of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, V and Zn | 223 |
| Various | Olive oil | AA;F;L AA;ETA;L | Following digestion using HNO3–V2O5 Ca and Mg were determined using FAAS and Cr, Mn, Se and Zn by ETAAS | 240 |
| Various (5) | Foodstuffs, CRMs | AA;F;L MS;ICP;L | A pair of papers describing methods to determine Cd, Cu, Fe, Pb and Zn using microwave digestion and dry ashing respectively. The microwave method was adopted as official first action by AOAC International | 325, 326 |
| Various (4) | Bovine liver and apple leaf SRMs | -;-;L | IR generated by tungsten lamps was proposed as an aid to rapid sample decomposition. Total preparation times were 5 min for dilute acid solutions (Cu, Fe, Mn, Zn) | 4 |
| Various (13) | Food SRMs | AE;ICP;L | 5 digestion procedures were compared including dry ashing at 500 °C, wet digestion with HNO3–HClO4, microwave digestion with HNO3, microwave digestion with HNO3–H2O2, and microwave digestion with HNO3–H2O–THF. The last method gave the best recoveries for Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, P, S, Sr and Zn in 7 food SRMs | 235 |
| Various (5) | SRMs | MS;ICP;L | The results of a study, involving 7 laboratories, to improve reference values for Cs, I, Sr, Th and U were reported | 82 |
| Various (4) | Fish, soil, urine and water SRMs | MS;ICP;HPLC | The stability of As, Sb, Se and Tl species in the named SRMs under different storage regimes and during different extraction procedures was investigated | 228 |
| Various | Biological samples, environmental samples | AA;ETA;L AA;Hy;L AA;CV;L | ETA and vapour generation techniques for AA and their hyphenation were reviewed and compared. Optimal application fields were defined | 2 |
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