Paul E. Grimmett* and Jean W. Munch
U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 26 W. Martin Luther King Dr Cincinnati, OH 45268, USA. E-mail: grimmett.paul@epa.gov
First published on 9th October 2012
The United States Environmental Protection Agency's (EPA) Office of Ground Water and Drinking Water (OGWDW) collects nationwide occurrence data on contaminants in drinking water using the Unregulated Contaminant Monitoring Regulations (UCMRs). The unregulated contaminants, which are potential candidates for future regulation, may be selected from the Drinking Water Contaminant Candidate List (CCL), or may be emerging contaminants, with the potential for inclusion on future CCLs. In October 2009, OGWDW published the third Drinking Water CCL (CCL 3). Not all of the chemicals on CCL 3 are included in existing analytical methods with sufficient sensitivity and specificity for UCMR monitoring. Some of the chemicals that require method development research fall into the category known as semi-volatile organic chemicals (SVOCs). Currently, EPA Method 525.2 is used to measure SVOCs for both drinking water compliance and UCMR monitoring. The method utilizes C-18 solid-phase extraction (SPE) for contaminant isolation and concentration, followed by full scan gas chromatography-mass spectrometry (GC-MS) detection. A group of 27 contaminants from CCL 3, a list of chemicals from EPA's National Homeland Security Research Center (NHSRC), as well as other emerging compounds of interest, were evaluated for inclusion into a new revision of the method, EPA Method 525.3. Method improvements include: (1) utilizing a polymeric-based SPE sorbent for greater retention across sample pH range, (2) enhanced method sensitivity using GC-MS with selected ion monitoring (SIM), (3) safer and more user-friendly sample preservatives, and (4) sample preparation techniques that help overcome matrix-induced chromatographic response enhancement. To be used for nationwide monitoring, the new method must be rugged across a range of drinking water sources, sensitive and highly specific to minimize false positives. It must also be cost effective and simple enough for commercial lab settings. Accuracy and precision data using full scan GC-MS mode are presented for 125 contaminants. Multi-laboratory data obtained in selected ion mode (SIM) are presented for a subset of priority analytes. Lowest Concentration Minimum Reporting Limits (LCMRLs) of priority analytes obtained from four separate laboratories ranged from 0.0006 to 0.28 μg L−1, with an average LCMRL of 0.035 μg L−1 and median LCMRL of 0.011 μg L−1, under SIM conditions.
Alachlor | Atrazine |
Bis(2-ethylhexyl)phthalate | Endrin |
Hexachlorobenzene | Heptachlor |
Hexachlorocyclopentadiene | Heptachlor epoxide |
Pentachlorophenol | Methoxychlor |
Chlordane | Simazine |
Toxaphene | Benzo[a]pyrene |
Lindane | Bis(2-ethylhexyl)adipate |
PCBs |
a Currently in EPA Method 525.2.b Removed from consideration during early investigation due to poor chromatographic response.c Removed from consideration due to incompatibility with preservation technique.d Removed from consideration after the multi-laboratory study, due to sporadic low recoveries. | |
---|---|
Chemicals listed on CCL 3 | NHSRC chemicals |
Acephateb | Chlorfenvinphos |
Acetochlora | Chlorpyrifosa |
α-HCHa | Dichlorvos |
BHAd | DIMP (diisopropyl methylphosphonate) |
Captand | Methyl parathion |
Dicrotophosb | Mevinphos |
Dimethipin | Parathion |
Disulfotona | Phorate |
Ethion | Phosphamidon |
Ethopropa | |
Fenamiphosd | |
Metolachlora | Other compounds of emerging interest |
Molinatea | BHT (butylated hydroxytoluene) |
Nitrofen | DEET (N,N-diethyl-m-toluamide) |
o-Toluidinec | |
Oxyfluorfen | |
Permethrina | |
Profenofos | |
Quinolinec | |
Tebuconazole | |
Tribufos | |
Vinclozolin |
In addition to expanding the analyte list, one of the goals in updating Method 525.2 was to modify the sample preservation scheme. Tap water samples to be analyzed by Method 525.2 are dechlorinated with sodium sulfite and subsequently acidified with hydrochloric acid. The acidification serves as a microbial inhibitor and to inhibit hydrolysis of some pesticides.2 This scheme is problematic for several reasons. First, the two-step scheme prevents bottles from being sent to the collection site with preservatives inside. Second, the hydrochloric acid, a strong corrosive, presents safety issues during shipping and for sample collection personnel. Finally, the low pH prevents the efficient recovery of triazine-based SVOCs, such as cyanazine.8–10
Another issue to be evaluated was the replacement of C-18 bonded silica sorbents with newer polymeric sorbents. Silica-based sorbents can cause undesirable silanol interactions.11,12 Also, an extremely low pH (∼2) is required to retain pentachlorophenol.13 Finally, C-18 sorbents are not water wettable, and must be carefully conditioned prior to use, and kept wet at all times during sample processing, which could affect data reproducibility. Thus, a number of polymeric sorbents, based on the divinylbenzene (DVB) monomer and the DVB N-vinylpyrrolidone copolymer, were investigated. There has been reported success using DVB-based polymer sorbents to extract and quantitate a wide range of SVOCs, including organochlorinated and phosphorous-containing pesticides, triazines, phenols, as well as the non-polar polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs).14–19
Sensitivity issues with some Method 525.2 components were also addressed by NERL, because several regulated analytes have low EPA regulatory limits. Compounds such as benzo[a]pyrene, heptachlor epoxide, and heptachlor have Maximum Contaminant Levels (MCLs) of 0.2 μg L−1, 0.2 μg L−1, and 0.4 μg L−1, respectively. Also, several CCL 3 compounds, such as disulfoton, profenofos, ethoprop, alpha-hexachlorocyclohexane (α-HCH), and oxyfluorfen, have health reference levels (HRLs) of less than 1 μg L−1.20 While full scan measurements at sub-microgram per liter levels are certainly within modern MS capabilities, it would be easier to reliably meet the sensitivity requirements in selected ion mode (SIM). SIM will also yield lower Lowest Concentration Minimum Reporting Limits (LCMRLs), a statistical estimate of the lowest level at which a single laboratory can meet the specified data quality objectives, for regulated compounds that have an MCL goal (MCLG) of zero. This provides EPA an opportunity to consider lowering the MCL for those compounds. Therefore, the option of performing analyses in SIM for compounds requiring extra sensitivity was investigated.
Finally, NERL has investigated solutions to high quantitative bias for some method analytes that exhibit matrix-induced chromatographic response enhancement (MICRE). This is a phenomenon in which improvements in analyte peak quality are observed in sample extracts when compared to solvent based standards, due to the presence of co-extracted matrix material which binds to thermally active sites in the GC.21 Often, MICRE is a problem associated with food analysis, but it has also been documented in water analysis.22–25 Organophosphorous pesticides are one of the classes of compounds susceptible to MICRE. Several of these pesticides are candidates for inclusion in Method 525.3. The analytes of concern were typically phosphorus-containing compounds, such as mevinphos, dichlorvos, and fenamiphos, as well as pentachlorophenol. In food analysis, additives to sample extracts known as “analyte protectants” are added to samples and calibration standards prior to GC injection. These protectants bind to active sites in the GC injector and column, preventing those sites from affecting sensitive analytes and eliciting a response that is comparable in both standards and matrix-containing extracts. NERL investigated various forms of analyte protection, such as polyethylene glycol (PEG), ethylglycerol, gulonolactone, and D-sorbitol during method development.
Chemical standards, including those carried over from EPA Method 525.2, were obtained in solution and in neat form from Accustandard, Inc. (New Haven, CT), Ultra Scientific (N. Kingstown, RI) and Absolute Standards (Hamden, CT), except for diisopropyl methylphosphonate (DIMP), which was obtained from Cerilliant Corporation (Round Rock, TX), and 13C-penatchlorophenol, which was purchased neat from CDN Isotopes, Inc. (Pointe-Claire, Quebec, Canada). A full list of Method 525.3 analytes, surrogates, and internal standards are provided in Table 3.
RT (min) | Internal standards, analytes and surrogates | IS ref. # | QI (m/z) | Confirmation ion(s) (m/z) |
---|---|---|---|---|
a Confirmation ions may be at or below 30% relative abundance depending upon instrument tune compounds without values do not have qualifier ions of significant relative abundance. | ||||
13.21 | Acenaphthene-d10 (IS 1) | 162 | 164 | |
16.35 | 13C-Pentachlorophenol (IS 4) | 276 | — | |
16.73 | Phenanthrene-d10 (IS 2) | 188 | 160a | |
24.29 | Chrysene-d12 (IS 3) | 240 | 236a | |
7.24 | DIMP | 1 | 97 | 123 |
8.20 | Isophorone | 1 | 82 | 138a |
9.13 | 1,3-Dimethyl-2-nitrobenzene (SUR) | 1 | 77 | 134 |
9.97 | Dichlorvos | 1 | 109 | 185a |
11.21 | HCCPD | 1 | 237 | 235, 239 |
11.53 | EPTC | 1 | 128 | 86 |
12.44 | Mevinphos | 1 | 127 | 109a, 192a |
12.48 | Butylate | 1 | 57 | 146, 156 |
12.71 | Vernolate | 1 | 128 | 86 |
12.74 | Dimethylphthalate | 1 | 163 | 77a |
12.77 | Etridiazole | 1 | 211 | 183 |
12.84 | 2,6-Dinitrotoluene | 1 | 165 | 63, 89 |
12.87 | Acenaphthylene | 1 | 152 | — |
12.88 | Pebulate | 1 | 128 | 57, 72 |
13.43 | 2-Chlorobiphenyl | 1 | 188 | 152 |
13.45 | BHT | 1 | 205 | 220 |
13.47 | Chloroneb | 1 | 193 | 191 |
13.69 | Tebuthiuron | 1 | 156 | 171 |
13.79 | 2,4-Dinitrotoluene | 1 | 165 | 63, 89 |
13.92 | Molinate | 1 | 126 | 55 |
14.31 | DEET | 1 | 119 | 91, 190 |
14.44 | Diethylphthalate | 1 | 149 | 177a |
14.46 | 4-Chlorobiphenyl | 1 | 188 | 152 |
14.53 | Fluorene | 1 | 165 | 166 |
14.68 | Propachlor | 1 | 120 | 77, 176 |
15.00 | Ethoprop | 1 | 97 | 126, 139, 158 |
15.03 | Cycloate | 1 | 83 | 55, 154 |
15.27 | Chlorpropham | 1 | 213 | 127 |
15.34 | Trifluralin | 1 | 264 | 306 |
15.66 | Phorate | 1 | 75 | 121 |
15.75 | α-HCH | 1 | 181 | 109, 183, 219 |
15.81 | 2,4′-Dichlorobiphenyl | 1 | 222 | 152, 224 |
15.83 | Hexachlorobenzene | 1 | 284 | 142, 249 |
16.08 | Atraton | 2 | 196 | 169, 211 |
16.20 | Simazine | 2 | 201 | 173, 186 |
16.21 | Prometon | 2 | 225 | 168, 210 |
16.28 | Dimethipin | 2 | 54 | 53 |
16.29 | Atrazine | 2 | 200 | 215 |
16.30 | β-HCH | 2 | 181 | 109, 183, 219 |
16.35 | Pentachlorophenol | 4 | 266 | 264, 268 |
16.36 | Propazine | 2 | 214 | 58, 229 |
16.46 | γ-HCH (lindane) | 2 | 183 | 109, 181, 219 |
16.66 | Pronamide | 2 | 173 | 145 |
16.69 | 2,2′,5-Trichlorobiphenyl | 2 | 256 | 186 |
16.79 | Phenanthrene | 2 | 178 | 152a |
16.81 | Chlorothalonil | 2 | 266 | 264, 268 |
16.91 | Disulfoton | 2 | 88 | 61a, 97a |
16.91 | Anthracene | 2 | 178 | — |
17.01 | Terbacil | 2 | 117 | 161 |
17.06 | δ-HCH | 2 | 181 | 109, 183, 219 |
17.53 | Phosphamidon | 2 | 127 | 72, 264 |
17.68 | Acetochlor | 2 | 146 | 59, 162, 223 |
17.71 | Metribuzin | 2 | 198 | — |
17.73 | 2,4,4′-Trichlorobiphenyl | 2 | 186 | 256 |
17.79 | Vinclozolin | 2 | 212 | 124, 285 |
17.84 | Methyl parathion | 2 | 109 | 125, 263 |
17.87 | Alachlor | 2 | 188 | 160 |
17.96 | Simetryn | 2 | 213 | 155, 170 |
18.04 | Ametryn | 2 | 227 | 212 |
18.05 | Heptachlor | 2 | 100 | 272, 274 |
18.10 | Prometryn | 2 | 241 | 184, 226 |
18.39 | Terbutryn | 2 | 226 | 170, 185, 241 |
18.47 | 2,2′,5,5′-Tetrachlorobiphenyl | 2 | 220 | 290, 292 |
18.53 | Dibutyl phthalate | 2 | 149 | — |
18.56 | Bromacil | 2 | 205, 207 | 207, 205 |
18.72 | Metolachlor | 2 | 162 | 238 |
18.76 | Chlorpyrifos | 2 | 97 | 197, 199 |
18.84 | Aldrin | 2 | 66 | 79, 263 |
18.87 | Cyanazine | 2 | 225 | 68, 172, 198 |
18.87 | Dacthal (DCPA) | 2 | 301 | 332 |
18.91 | 2,2′,3,5′-Tetrachlorobiphenyl | 2 | 220 | 255, 292 |
18.92 | Ethyl parathion | 2 | 109 | 97, 291 |
19.01 | Triadimefon | 2 | 208 | 57 |
19.27 | Diphenamid | 2 | 72 | 167, 239a |
19.30 | MGK 264(a) | 2 | 164 | 66, 111 |
19.59 | MGK 264(b) | 2 | 164 | 66, 111 |
19.72 | Heptachlor epoxide | 2 | 353 | 81, 355 |
19.74 | Chlorfenvinphos | 2 | 267 | 269, 323 |
19.85 | 2,3′,4′,5-Tetrachlorobiphenyl | 2 | 220 | 110, 292 |
20.27 | trans-Chlordane | 2 | 375 | 237, 272 |
20.38 | Tetrachlorvinphos | 2 | 109 | 329, 331 |
20.46 | Butachlor | 2 | 176 | 57, 160 |
20.54 | Pyrene | 2 | 202 | — |
20.58 | cis-Chlordane | 2 | 375 | 373, 377 |
20.59 | Endosulfan I | 2 | 241 | 195, 207 |
20.65 | trans-Nonachlor | 2 | 409 | 407, 411 |
20.76 | Napropamide | 2 | 72 | 100, 128 |
21.00 | Profenofos | 2 | 339 | 97, 139, 208 |
21.12 | 4,4′-DDE | 2 | 246 | 176, 318 |
21.17 | Tribufos (+merphos) | 2 | 57 | 169 |
21.23 | Dieldrin | 2 | 79 | 81 |
21.25 | Oxyfluorfen | 2 | 252 | 63, 361 |
21.26 | 2,3,3′,4′,6-Pentachlorobiphenyl | 2 | 326 | 184, 254 |
21.69 | Nitrofen | 2 | 283 | 139, 202 |
21.72 | Endrin | 2 | 263 | 81, 281 |
21.81 | 2,2′,3,4′,5′,6-Hexachlorobiphenyl | 2 | 360 | 218, 290 |
21.90 | Chlorobenzilate | 2 | 251 | 111, 139 |
21.91 | 2,3′,4,4′,5-Pentachlorobiphenyl | 2 | 326 | 184, 254 |
21.99 | Endosulfan II | 2 | 195 | 207, 241 |
22.11 | 4,4′-DDD | 2 | 235 | 165 |
22.11 | Ethion | 2 | 231 | 97, 153 |
22.40 | 2,2′,4,4′,5,5′-Hexachlorobiphenyl | 2 | 360 | 218, 290 |
22.82 | Norflurazon | 2 | 145 | 102, 303 |
22.91 | Butylbenzylphthalate | 2 | 149 | 91, 206 |
22.91 | Endosulfan sulfate | 2 | 272 | 237, 387 |
23.03 | 4,4′-DDT | 2 | 235 | 165 |
23.06 | 2,2′,3,4,4′,5′-Hexachlorobiphenyl | 2 | 360 | 218, 290 |
23.17 | Hexazinone | 2 | 171 | 83a |
23.38 | Di(2-ethylhexyl)adipate | 3 | 129 | 57, 70 |
23.39 | Tebuconazole | 3 | 125 | 83, 250 |
23.48 | Triphenyl phosphate (SUR) | 3 | 77 | 169, 326 |
24.26 | Benzo[a]anthracene | 3 | 228 | 226a |
24.37 | Chrysene | 3 | 228 | 226a |
24.40 | Methoxychlor | 3 | 227 | — |
24.67 | 2,2′,3,4,4′,5,5′-Heptachlorobiphenyl | 3 | 394 | 252, 324 |
24.93 | Di(2-ethylhexyl)phthalate | 3 | 149 | 167 |
25.79 | Fenarimol | 3 | 107 | 139, 219 |
26.64 | cis-Permethrin | 3 | 183 | 163a |
26.82 | trans-Permethrin | 3 | 183 | 163a |
27.49 | Benzo[b]fluoranthene | 3 | 252 | 126a |
27.54 | Benzo[k]fluoranthene | 3 | 252 | 126a |
28.22 | Benzo[a]pyrene-d12 (SUR) | 3 | 264 | 132a |
28.28 | Benzo[a]pyrene | 3 | 252 | 126a |
28.50 | Fluridone | 3 | 328 | 329 |
30.72 | Indeno[1,2,3-c,d]pyrene | 3 | 276 | 138a |
30.80 | Dibenzo[a,h]anthracene | 3 | 278 | 139a |
31.20 | Benzo[g,h,i]perylene | 3 | 276 | 138a |
(b) SPE disk extraction − Experiments using a 47 mm disk (3M SDB-XC, Catalog # 2240) were performed with a 6-place filter manifold apparatus and a suitable collection tube (40 mL collection vial) inserted to contain the extract. Sample preparation, sorbent conditioning, sample loading, drying time, and elution solvents and volumes were the same as described in the cartridge extraction section, but with an extra final rinse of the filtration reservoir with 5 mL of 1:
1 EtOAc
:
DCM transferred to the collection vial. Sodium sulfate drying and nitrogen evaporation were performed in the same manner described in Section 2.2 (a) SPE cartridge extraction.
(c) Baker Speedisk disk extraction − Experiments using JT Baker (Phillipsburg, NJ) Speedisk Hydrophobic DVB extraction disks, Catalog # 8068-06 (regular) and Catalog # 8068-07 (high capacity), were performed with a six-port Expanded Extraction Station (JT Baker Catalog # 8095-06). Sample preparation, sorbent conditioning, sample loading, and elution solvents and volumes were the same as described in the cartridge extraction section, but with only 3 min of vacuum drying after sample loading, and an extra bottle rinse and elution of the Speedisk with 2 mL of acetone transferred to the collection vial (40 mL vials) prior to standard cartridge elution. Sodium sulfate drying and nitrogen evaporation were performed in the same manner described in Section 2.2 (a) SPE cartridge extraction.
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Fig. 1 Recoveries from fortified reagent water (4 μg L−1 each analyte, 20 μg L−1 tebuconazole) replicates (n = 4) extracted from SPE cartridges with various sorbents (a–d). Control limit bars set at 70% and 130%. |
The analytes from EPA Method 525.2 and the remaining CCL 3 compounds, along with a small group of compounds requested for evaluation by EPA's National Homeland Security Research Center (NHSRC), were evaluated together for extraction performance using polymeric-based sorbents, with optimum performance achieved on divinylbenzene sorbents, such as Baker DVB H2O-phobic cartridges, Baker Speedisk DVB disks, Baker High Capacity (HC) Speedisk DVB disks, Waters Oasis HLB cartridges, as well as 3M Empore SDB-XC 47 mm disks. Some compounds were removed for performance reasons. For example, CCL 3 compound dicrotophos exhibited bad chromatographic peak shapes as well as poor recovery from SPE media and thus, was eliminated. Method 525.2 compounds tricyclazole and methyl paraoxon were eliminated due to poor peak shapes and sensitivity. Endrin aldehyde could not be successfully extracted from water samples using the preservation scheme and the SPE media selected for the method and therefore, was eliminated. Fig. 2 shows recovery data from the entire Method 525.3 analyte list (after eliminating problem compounds) in LRW and multiple sources of tap water. Compounds were extracted using Baker HC DVB Speedisk, but similar results were attained for the other aforementioned sorbents. The lone exception was dimethipin, which only met DQOs using Oasis HLB and the Baker HC Speedisk.
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Fig. 2 Extraction efficiencies of all Method 525.3 compounds fortified at 2 μg L−1a into 1 L sample replicates (n = 4) of LRW, surface water-source drinking water, surface water-source drinking water with high TOCb, and groundwater-source drinking water with high hardness levelsc. Control limit bars set at 70% and 130%. |
A comparison study of 1 μg mL−1 of analyte mix in EtOAc, and 1 μg mL−1 of analyte mix in an analyte protectant mix (ethylglycerol, gulonolactone, and D-sorbitol) in acetone, was carried out. However, ethylglycerol was immediately excluded from consideration due to mass spectral masking of the front portion of the chromatogram, resulting in the inability to reliably detect several early eluting compounds, such as dichlorvos and hexachlorocyclopentadiene (HCCPD). Also, gulonolactone and D-sorbitol eluted from the GC column as large “blobs” in the middle of the chromatogram, causing mass spectral match failures for some compounds and rendering quantitation difficult (Fig. 3). Concentrations of protectant material were lowered in an attempt to reduce the interferences, but reduced interferences were matched with diminished protective properties. Some compounds exhibited improved peak performance with only a single protectant, but suffered when protectants were combined. For instance, dichlorvos peaks were sharper with gulonolactone added, compared to the addition of all three protectants together. Because many of the analytes of concern benefitted from different protectants, and the aforementioned chromatographic and spectral interferences caused by other compounds, ethylglycerol, gulonolactone, and D-sorbitol were removed from consideration.
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Fig. 3 Total ion current (TIC) chromatograms of a blank containing 1 mg mL−1 gulonolactone, a blank containing 1 mg mL−1D-sorbitol, a 1 μg mL−1 standard mix with gulonolactone and D-sorbitol at 1 mg mL−1, and a 1 μg mL−1 standard mix. |
The polyether PEG, which has been referenced in various articles as an effective analyte protectant,24,25,31,32 was also used in trial extractions. However, results yielded little improvement in peak shape of susceptible compounds. Also, PEG has been cited to cause rapid deterioration of column performance, which cannot be corrected by simple column trimming.29 Therefore, PEG was also eliminated from consideration.
A commonly used approach to adjust for MICRE in the food chemistry field is the use of matrix-matched calibration standards, which involves the preparation of standards from blank food extracts.33 However, the application to drinking water analysis is a challenge due to different finished drinking water having a wide variation of total organic carbon (TOC) and hardness concentrations. Therefore, the option to prepare standards in solvents from the extraction of LRW was investigated. A set of 1 L LRW samples were preserved and extracted in the standard manner, with all SUR, IS, and standards added immediately before bringing to a final volume of 1 mL. The final product is a set of standards in a matrix extract that mimics actual drinking water extracts, termed “matrix-matched” standards. Initial comparisons of matrix-matched standards and solvent (EtOAc) standards were performed, with an entire calibration curve (0.1–5.0 μg mL−1) of each set analyzed. Results indicated an improved peak shape for several problem compounds, such as dichlorvos, DIMP (an NHSRC compound), s-ethyl dipropylthiocarbamate (EPTC), and fenamiphos (Fig. 4). Peaks from matrix-matched standards exhibited less tailing, peak splitting and fronting than did peaks of solvent-based standards. This phenomenon was particularly true of problem compounds at mid- to low-range concentrations (2 μg mL−1 or less), the range in which peak shape can be critical for maintaining consistent quantitation. For example, dichlorvos, mevinphos, fenamiphos, and oxyfluorfen, when fortified in tapwater at 1 to 2 μg L−1, were recovered at concentrations of 123%, 136%, 137%, and 134%, respectively, when quantitated with calibration standards prepared in EtOAc. However, recoveries of 82%, 84%, 98%, and 109%, respectively, were noted when analytes were quantitated from matrix-matched standards. The latter values coincide with recovery data from analytes normally unaffected from MICRE, and are well within DQOs.
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Fig. 4 Comparison of extracted quantitation ion currents of select problem analytes at 2 μg mL−1 in (a) EtOAc and (b) matrix-matched solvent. |
Trials were performed using matrix-matched standards to quantitate fortified replicates (n = 4) of 1 L LRW samples, drinking water from a surface water source, drinking water from a groundwater source high in mineral content, and drinking water from a surface water source high in total organic carbon (TOC). Fig. 2 contains recovery and precision data of all Method 525.2, CCL 3, and NHSRC compounds considered for inclusion into Method 525.3. Extractions were performed using the Baker H2O-phobic HC DVB Speedisk, but comparable data were obtained for all sorbents listed in the Material and Methods section. The mean recovery of each analyte meets the previously stated DQOs of the research project.
Analyte | EPA HRL (H) or MCL (M) (μg L−1) | NERLa | Lab Ab | Lab Bc | Lab Cd | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Reagent water (n = 4) | Tap water (n = 4) | LCMRL (μg L−1) | Reagent water (n = 6) | Tap water (n = 7) | LCMRL (μg L−1) | Reagent water (n = 4) | Tap water (n = 4) | LCMRL (μg L−1) | Reagent water (n = 4) | Tap water (n = 4) | LCMRL (μg L−1) | ||||||||||
% Recovery | % RSD | % Recovery | % RSD | % Recovery | % RSD | % Recovery | % RSD | % Recovery | % RSD | % Recovery | %RSD | % Recovery | % RSD | % Recovery | % RSD | ||||||
a Samples fortified at 0.1 μg L−1 for most analytes, except PCP (4×) and tebuconazole (5×). Oasis HLB manual SPE, Thermo DSQ GC/MS.b Samples fortified at 0.2 μg L−1 for most analytes, except PCP (4×) and tebuconazole (5×). Baker High Capacity H2O Phobic Speedisk automated SPE, Agilent 5975C GC/MS.c Samples fortified at 0.2 μg L−1 for most analytes, except PCP (4×) and tebuconazole (5×). Oasis HLB automated SPE, Agilent 5975C GC/MS.d Samples fortified at 0.1 μg L−1 for most analytes, except PCP (4×) and tebuconazole (5×). Oasis HLB manual SPE, Agilent 5975C GC/MS.e NC = not calculated. The LCMRL value could not be determined.f Regulated as chlordane.g Cancer HRL.h Non-cancer HRL. | |||||||||||||||||||||
Alachlor | 2 (M) | 112 | 1.1 | 112 | 3.6 | 0.016 | 93.4 | 10 | 96.6 | 7.4 | 0.006 | 102 | 1.1 | 105 | 2.1 | 0.0014 | 104 | 2.1 | 108 | 0.9 | 0.0056 |
Atrazine | 3(M) | 118 | 3.6 | 101 | 0.45 | 0.023 | 88.1 | 28 | 110 | 13 | NCe | 101 | 1.1 | 103 | 1.4 | 0.0014 | 104 | 1.4 | 106 | 1.5 | 0.0049 |
Benzo[a]pyrene | 0.2 (M) | 103 | 2.2 | 104 | 7.6 | 0.036 | 99.4 | 11 | 101 | 6.1 | 0.011 | 81.4 | 2.2 | 81.2 | 1.8 | 0.23 | 94.9 | 2.6 | 95 | 1.8 | 0.003 |
Chlordane, cis | 2 (M)f | 102 | 2.9 | 97.9 | 3.9 | 0.0073 | 100 | 9.6 | 103 | 6.4 | 0.0091 | 90.0 | 1.7 | 91.5 | 1.7 | 0.05 | 98.3 | 2.7 | 98.6 | 0.9 | 0.00078 |
Chlordane, trans | 2 (M)f | 99.4 | 5.3 | 102 | 3.7 | 0.0097 | 95.6 | 10 | 99.1 | 6.3 | 0.0078 | 87.6 | 1.7 | 89.4 | 1.8 | 0.094 | 96.7 | 2.6 | 97.2 | 2.1 | 0.00068 |
Dimethipin | 153 (H) | 108 | 7.4 | 103 | 18 | 0.022 | 102 | 10 | 108 | 5.9 | 0.043 | 96.5 | 0.6 | 96.4 | 2.1 | 0.023 | 93.2 | 18 | 105 | 2.1 | 0.0067 |
Endrin | 2 (M) | 105 | 3.7 | 107 | 3.3 | 0.014 | 99.0 | 13 | 107 | 8.6 | 0.033 | 105 | 2.5 | 113 | 3.0 | 0.0072 | 104 | 2.2 | 113 | 3.9 | 0.01 |
Ethoprop | 1.25 (H)g, 0.7 (H)h | 109 | 3.2 | 102 | 3.6 | 0.036 | 103 | 11 | 105 | 5.4 | 0.06 | 105 | 0.9 | 108 | 2.1 | 0.0023 | 102 | 2.9 | 108 | 1.5 | 0.0079 |
HCCPD | 50 (M) | 108 | 1.2 | 82.8 | 7.3 | 0.014 | 101 | 7.8 | 103 | 3.3 | 0.0061 | 80.5 | 2.4 | 84.2 | 1.1 | 0.21 | 90.4 | 3.7 | 99.6 | 2.0 | 0.00085 |
HCH, α | 0.006 (H)g, 56 (H)h | 114 | 3.3 | 84.5 | 7.2 | 0.021 | 94.3 | 9.7 | 95.5 | 4.6 | 0.0059 | 100 | 1.0 | 102 | 1.9 | 0.0021 | 99.0 | 3.0 | 98.6 | 2.0 | 0.0036 |
HCH, γ (lindane) | 0.2 (M) | 110 | 2.0 | 108 | 4.6 | 0.031 | 106 | 8.4 | 110 | 8.5 | 0.014 | 100 | 1.0 | 101 | 1.8 | 0.0022 | 97.9 | 2.3 | 100 | 0.8 | 0.0081 |
Heptachlor | 0.4 (M) | 99.9 | 3.4 | 85.3 | 5.8 | 0.01 | 94.6 | 9.6 | 96.4 | 4.6 | 0.012 | 95.2 | 2.7 | 99.1 | 3.3 | 0.088 | 95.9 | 2.6 | 102 | 1.4 | 0.0057 |
Heptachlor epoxide | 0.2 (M) | 103 | 4.6 | 103 | 1.4 | 0.017 | 100 | 9.3 | 104 | 6.1 | 0.0076 | 97.6 | 1.0 | 100 | 1.5 | 0.0014 | 97.7 | 4.2 | 99.2 | 2.2 | 0.0014 |
Hexachlorobenzene | 1 (M) | 95.3 | 2.1 | 83.8 | 3.3 | 0.014 | 94.3 | 9.6 | 95.4 | 4.0 | 0.005 | 82.0 | 2.0 | 84.2 | 1.1 | 0.16 | 92.5 | 4.0 | 90.5 | 2.3 | 0.0029 |
Methoxychlor | 40 (M) | 116 | 2.8 | 128 | 1.3 | 0.021 | 104 | 11 | 109 | 5.4 | 0.015 | 110 | 2.8 | 116 | 2.6 | 0.014 | 99.9 | 2.6 | 111 | 0.8 | 0.0035 |
Oxyfluorfen | 0.478 (H)g, 21 (H)h | 115 | 5.2 | 123 | 4.6 | 0.035 | 106 | 9.9 | 113 | 4.7 | 0.0083 | 108 | 6.3 | 116 | 6.8 | 0.048 | 106 | 2.5 | 116 | 3.4 | 0.0065 |
Pentachlorophenol | 1 (M) | 96.3 | 6.7 | 94.9 | 0.88 | 0.068 | 102 | 8.8 | 102 | 4.6 | 0.11 | 94.6 | 2.3 | 96.2 | 1.7 | 0.03 | 97.8 | 2.4 | 103 | 1.4 | 0.024 |
Permethrin, cis | 3.65 (H)g, 1.750 (H)h | 113 | 3.2 | 102 | 5.1 | 0.012 | 96.4 | 9.7 | 100 | 5.8 | 0.011 | 86.6 | 2.3 | 86.4 | 1.8 | 0.043 | 97.8 | 2.8 | 102 | 1.7 | 0.0018 |
Permethrin, trans | 3.65 (H)g 1.750 (H)h | 104 | 2.0 | 108 | 3.0 | 0.02 | 95.8 | 11 | 99.4 | 5.4 | 0.015 | 83.5 | 2.2 | 83.1 | 1.5 | 0.14 | 96.3 | 2.0 | 102 | 2.0 | 0.0028 |
Profenofos | 0.35 (H) | 92.0 | 2.3 | 110 | 6.8 | 0.029 | 113 | 11 | 116 | 6.6 | 0.011 | 108 | 1.8 | 112 | 3.1 | 0.016 | 104 | 2.9 | 110 | 2.0 | 0.0049 |
Simazine | 4 (M) | 101 | 13.0 | 105 | 3.0 | 0.048 | 90.3 | 30 | 121 | 13 | NC | 101 | 1.3 | 102 | 1.1 | 0.0019 | 103 | 1.4 | 105 | 1.7 | 0.0051 |
Tebuconazole | 210 (H) | 116 | 1.9 | 99.9 | 4.5 | 0.2 | 113 | 11 | 115 | 6.6 | 0.01 | 113 | 1.5 | 118 | 2.4 | 0.041 | 105 | 2.4 | 109 | 1.1 | 0.044 |
Tribufos | 7 (H) | 101 | 3.5 | 110 | 3.5 | 0.023 | 106 | 9.6 | 107 | 6.5 | 0.027 | 91.0 | 5.2 | 96.4 | 6.7 | 0.12 | 103 | 1.3 | 110 | 1.3 | 0.011 |
Vinclozolin | 21 (H) | 110 | 2.0 | 104 | 4.2 | 0.0098 | 106 | 8.0 | 106 | 5.5 | 0.0061 | 100 | 1.0 | 102 | 2.0 | 0.0014 | 100 | 2.4 | 102 | 0.8 | 0.0029 |
PCB congeners (by IUPAC#) | 0.5 total (M) | ||||||||||||||||||||
2-Chlorobiphenyl (1) | — | 106 | 1.1 | 95.8 | 4.5 | 0.008 | 98.3 | 8.7 | 99.4 | 4.9 | 0.0013 | 87.1 | 1.8 | 89.6 | 1.1 | 0.097 | 95.2 | 4.1 | 92.8 | 2.4 | 0.0015 |
4-Chlorobiphenyl (3) | — | 105 | 1.0 | 96.5 | 3.5 | 0.0073 | 99.0 | 9.1 | 100 | 4.1 | 0.0038 | 86.5 | 1.8 | 88.7 | 1.2 | 0.11 | 94.8 | 3.9 | 92.0 | 2.5 | 0.0021 |
2,4′-Dichlorobiphenyl (8) | — | 110 | 7.1 | 90.0 | 4.9 | 0.023 | 89.0 | 10 | 90.3 | 5.0 | 0.0078 | 86.9 | 2.0 | 89.1 | 1.1 | 0.1 | 94.9 | 3.6 | 92.6 | 2.1 | 0.00076 |
2,2′,5-Trichlorobiphenyl (18) | — | 106 | 3.0 | 92.7 | 3.2 | 0.013 | 98.4 | 9.2 | 102 | 5.4 | 0.0049 | 87.2 | 1.6 | 88.9 | 1.7 | 0.087 | 94.5 | 3.2 | 93.0 | 2.1 | 0.002 |
2,4,4′-Trichlorobiphenyl (28) | — | 105 | 1.7 | 91.4 | 2.1 | 0.014 | 97.8 | 10 | 102 | 5.4 | 0.02 | 82.2 | 1.9 | 82.4 | 1.0 | 0.17 | 94.6 | 3.0 | 92.8 | 1.7 | 0.0027 |
2,2′,3,5′-Tetrachlorobiphenyl (44) | — | 108 | 5.7 | 81.6 | 5.2 | 0.025 | 103 | 8.8 | 107 | 6.9 | 0.0031 | 84.8 | 1.4 | 85.0 | 1.6 | 0.13 | 95.6 | 3.4 | 93.8 | 1.8 | 0.00061 |
2,2′,5,5′-Tetrachlorobiphenyl (52) | — | 105 | 1.3 | 95.3 | 5.0 | 0.0078 | 96.9 | 9.1 | 101 | 6.5 | 0.022 | 84.7 | 1.5 | 84.9 | 1.5 | 0.14 | 93.0 | 3.2 | 90.9 | 2.5 | 0.0029 |
2,3′,4′,5-Tetrachlorobiphenyl (70) | — | 103 | 6.5 | 98.8 | 0.85 | 0.036 | 88.4 | 9.3 | 90.2 | 4.4 | 0.024 | 80.7 | 1.7 | 80.7 | 1.6 | 0.18 | 97.7 | 4.2 | 95.2 | 2.0 | 0.00068 |
2,3,3′,4′,6-Pentachlorobiphenyl (110) | — | 99.9 | 4.9 | 97.5 | 3.0 | 0.0092 | 99.8 | 11 | 105 | 6.1 | 0.0088 | 80.3 | 1.5 | 80.1 | 1.0 | 0.21 | 95.7 | 2.4 | 95.6 | 2.0 | 0.00065 |
2,3′,4,4′,5-Pentachlorobiphenyl (118) | — | 96.5 | 3.7 | 92.3 | 3.0 | 0.013 | 100 | 9.8 | 104 | 5.4 | 0.00065 | 77.1 | 1.7 | 77.1 | 2.1 | 0.28 | 95.6 | 2.9 | 94.9 | 2.0 | 0.00071 |
2,2′,3,4,4′,5′-Hexachlorobiphenyl (138) | — | 96.1 | 4.4 | 96.9 | 3.5 | 0.016 | 102 | 9.6 | 105 | 6.7 | 0.0041 | 79.4 | 1.6 | 79.9 | 2.1 | 0.2 | 93.5 | 3.1 | 93.6 | 2.1 | 0.00058 |
2,2′,3, 4′,5′,6-Hexachlorobiphenyl (149) | — | 97.4 | 3.1 | 96.6 | 1.5 | 0.012 | 102 | 11 | 106 | 6.2 | 0.00055 | 79.8 | 1.4 | 80.0 | 2.3 | 0.19 | 94.7 | 3.2 | 94.4 | 2.1 | 0.00056 |
2,2′,4,4′,5,5′-Hexachlorobiphenyl (153) | — | 98.7 | 0.79 | 94.5 | 0.86 | 0.013 | 100 | 10 | 103 | 5.5 | 0.0044 | 80.1 | 1.7 | 81.1 | 1.5 | 0.23 | 93.2 | 3.6 | 93.3 | 1.8 | 0.0011 |
2,2′,3,4,4′,5,5′-Heptachlorobiphenyl (180) | — | 97.6 | 4.3 | 92.6 | 2.1 | 0.015 | 98.3 | 10 | 100 | 6.5 | 0.0046 | 84.1 | 1.1 | 85.5 | 1.3 | 0.14 | 93.5 | 3.1 | 89.7 | 2.0 | 0.0007 |
Footnote |
† Electronic supplementary information (ESI) available. See DOI: 10.1039/c2ay25880c |
This journal is © The Royal Society of Chemistry 2013 |