Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

Abstract

In this Update period, there were no important developments for AAS, whereas, for OES, options such as alternative excitation sources and miniaturisation were investigated. The multielement capabilities and low detection limits of ICP-MS continued to attract the attention of most users and this was also the technique of choice for developments in pharmaceutical and dietary supplement analysis. Sustained interest was observed for spICP-MS and scICP-MS applications, focussing on sample preparation and introduction, calibration strategies and approaches to interference removal. The ability of LIBS to measure molecular species was exploited to develop an isotope dilution analysis method for the detection of Ca in tap water and milk powder and to tackle bacterial detection in urine. Numerous examples of EDXRF applications were reported including a systematic evaluation of the next generation of portable monochromatic excitation EDXRF systems for the analysis of food, plant and biological CRMs. Both XRF and LA-ICP-MS play a key role to identify element spatial distribution in cancer tissues. Several papers addressed correction and quality control approaches for tissue imaging. Beside instrumental improvements, a substantial number of publications reported digestion, extraction and preconcentration procedures, mostly applied to food. Vapour generation procedures and AFS were employed by several researchers to obtain better detection limits for both elements and their species in various biological matrices. Measurements of nanoparticles, as well as their application for extraction or preconcentration of chemical elements, are now widespread and the relevant developments are dealt with in the analytical technique or application sections, rather than in a separate section. Following the trend seen in previous years, the application of atomic spectrometry to the indirect measurement of complex molecules continued and expanded from research in the clinical area to the detection of pathogens in food. An approach, based on reaction cell chemistry, enabled the determination of volatile organic compounds by ICP-MS. Multielement applications to clinical samples with improved detection limits were reported. A few studies revisited the use of more accessible specimens, such as dried blood spots and samples from the respiratory tract or from biobanks. Element speciation in food, beverages and clinical samples was investigated by several researchers. Beside As, Hg and Se, which appear regularly in this series of Updates, new approaches to the speciation of Cu in serum in relation to Wilson's disease and Alzheimer's disease were reported. Following the trend seen in the last few years, the number of papers focusing on chemometrics to identify origin and authenticity of foods and traditional medicines has significantly increased. Both LIBS and EDXRFS are frequently used for this purpose, but the focus of the work is often the processing of the obtained analytical data. A new section describes applications to “novel food ingredients”, particularly plant-based food and alternative protein sources, in which consumers' interest is growing. To support the quality of analytical measurements, the satisfactory analyses of CRMs is highlighted and publications reporting innovative calibration strategies, novel interlaboratory comparisons and new or revisited CRMs are addressed.