The U.S. Environmental Protection Agency's New Methods for Detecting Pesticides in Ground Water WGS-Mail Stop 412 July 26, 1990 OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM NO. 90.12 SUBJECT: The U.S. Environmental Protection Agency's New Methods for Detecting Pesticides in Ground Water: Status of Method Promulgation and Comparison with Current U.S. Geological Survey National Water-Quality Laboratory Methods. The purposes of this memorandum are to: 1. Describe the Environmental Protection Agency's (EPA) new pesticide methods developed initially for the National Pesticide Survey, 2. Describe the status of the EPA-methods promulgation, and 3. Compare the EPA methods to current pesticide analytical methods of the National Water-Quality Laboratory (NWQL) of the U.S. Geological Survey (USGS). The detailed descriptions and comparisons are presented in Attachment 1, which was prepared by Bill Foremen, Methods Research and Development Program, of the NWQL. To support the National Pesticide Survey, the EPA Office of Drinking Water Technical Support Division and the Environmental Monitoring Systems Laboratory (EMSL)-Cincinnati in conjunction with Battelle-Columbus Laboratories developed six new pesticide methods. Five of the methods were designed as multi-residue methods applicable to a number of pesticides and a few major degradation products. The sixth method was developed specifically for ethylene thiourea, a degradation product of a family of fungicides (see below). All six methods were developed for relatively clean water matrices, including drinking water and most ground waters. Summarized descriptions of the analytical procedures for the six EPA methods are provided in Appendix A of Attachment 1. To date, none of these methods have been implemented at the USGS's NWQL. Four of the EPA methods (507, 508, 515.1, and 531.1) are applicable to drinking water regulations as proposed in the May 22, 1989, issue of the Federal Register. The four proposed methods also can be found in the report "Methods for the Determination of Organic Compounds in Drinking Water" (EPA, 1988). These four methods are anticipated to undergo final promulgation in the Federal Register in December 1990, at which time they can be used to fulfill appropriate testing requirements under drinking water regulations. Tables 1-5 of Attachment 1 list the target analytes determined under the five EPA multi-residue methods, along with the analyte estimated detection limit (EDL) for the EPA method. This EDL is defined as either the method detection limit (MDL) or a level of compound in a sample yielding a chromatographic peak in the final extract with a signal-to-noise ratio of approximately 5, whichever value is higher. The MDL is calculated from the standard deviation of replicate measurements, and is defined as the minimum concentration of a substance that can be identified, measured, and reported with 99% confidence that the analyte concentration is greater than zero. These EDL or MDL are intended to provide an indication of the capability of the method. (For more information on the EPA MDL determination see Code of Federal Regulations (1989)). EDL values in Tables 1-5 are based on measurements made in a single laboratory. Also included in Tables 1-5 of Attachment 1 are the laboratory schedules (methods) under which the analytes are determined at the NWQL, where applicable. Summarized descriptions of these NWQL methods are also provided in Appendix A. The NWQL methods make no distinction as to whether the sample matrix is a surface- or ground-water sample. For those NWQL schedule numbers without a footnote in the tables, the analyte is a schedule target compound which is routinely analyzed and reported via the PRIME computer to the Districts for storage in the National Water Information System (NWIS) data base. All analytes which have footnotes given with the NWQL schedule numbers are method add-on compounds that have been included as a request of the National Water-Quality Assessment (NAWQA) Program (noted as a RNAWQA add-onS), or as a specific project request having a high enough sample demand for the NWQL to add the analyte to the schedule (noted as a Rmethod add-onS). These footnotes provide additional information regarding the current availability status of these add-on compounds to all USGS projects. The NWQL analyte reporting limit is also provided in Tables 1-5 for comparison with the EPA method EDL. Each NWQL reporting limit has been set as the lowest measured concentration of a constituent that may be reliably reported using the analytical method. The NWQL reporting limit is a value set somewhat higher than the method detection limit established when the method was originally developed at the NWQL. The NWQL uses these reporting limits because of unpredictable matrix effects on method detection limits. While EPA uses statistical precision as a basis for establishing MDLs and EDLs, the agency does not establish reporting limits. See page 11 for a discussion of the comparability of EPA's MDLs and EDLs to NWQL's reporting limits. David A. Rickert Chief, Office of Water Quality This memorandum does not supersede any previous Office of Water Quality memorandum. Key Words: Methods, National Water-Quality Laboratory, Pesticides WRD Distribution: A, B. S, FO, PO ATTACHMENT 1 The Environmental Protection Agency's New Methods for Detecting Pesticides in Ground Water: Status of Method Promulgation and Comparison with Current U.S. Geological Survey National Water- Quality Laboratory Methods. EPA METHOD 507 -- Determination of Nitrogen- and Phosphorus- Containing Pesticides in Water by Gas Chromatography with a Nitrogen-Phosphorus Detector Table 1. Comparison of EPA Method 507 and NWQL Schedule Target Analytes _________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Level Schedule No. Reporting Limit (5g/L) (5g/L) _________________________________________________________________ Alachlor 0.38 1389 0.1 Ametryn 2 1389 0.1 Atraton 0.6 Atrazine 0.13 1389 0.1 Bromacil 2.5 1389b 0.1 Butachlor 0.38 1389b 0.1 Butylate 0.15 1389b 0.1 Carboxin 0.6 1389b 0.1 Chlorpropham 0.5 Cycloate 0.25 1389b 0.1 Diazinon*a 0.25 1319 0.01 Dichlorvos 2.5 Diphenamid 0.6 1389b 0.1 Disulfoton* 0.3 1319c 0.01 Disulfoton sulfone* 3.8 Disulfoton sulfoxide*a 0.38 EPTC 0.25 Ethoprop 0.19 Fenamiphos 1 Fenarimol 0.38 Fluridone 3.8 Hexazinone 0.76 1389b 0.1 Merphos* 0.25 Methyl paraoxon 2.5 Table 1. Comparison of EPA Method 507 and NWQL Schedule Target Analytes--(continued) __________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Level Schedule No. Reporting Limit (5g/L) (5g/L) __________________________________________________________________ Metolachlor 0.75 1389 0.2 Metribuzin 0.15 1389 0.1 Mevinphos 5 MGK 264 0.5 Molinate 0.15 Napropamide 0.25 Norflurazon 0.5 Pebulate 0.13 Prometon 0.3 1389 0.1 Prometryn 0.19 1389 0.1 Pronamide*a 0.76 Propazine 0.13 1389 0.1 Simazine 0.075 1389 0.1 Simetryn 0.25 1389 0.1 Stirofos 0.76 Tebuthiuron 1.3 Terbacil 4.5 1389b 0.1 Terbufos*a 0.5 Terbutryn 0.25 Triademefon 0.65 Tricyclazole 1 Vernolate 0.13 1389b 0.1 __________________________________________________________________ * These compounds, although identified, are not quantitated in the EPA method because control over precision has not been accomplished. a/The EPA method notes that the compound exhibits aqueous instability. Therefore, quantitative analysis for this compound may not be possible. b/NAWQA add-on compound not reported via the PRIME. This compound is currently available to non-NAWQA projects as a prearranged custom analysis. NOTE: These nine NAWQA add-on compounds to schedule 1389 are currently undergoing further method recovery and precision tests at the NWQL. Upon completion, those add-on compounds shown amenable to the method will be routinely available to all WRD projects and reported through the PRIME. In addition, propachlor is also being evaluated under schedule 1389, and is currently available as a custom analysis. Propachlor is a target analyte of EPA method 508 below. c/A method add-on compound routinely reported via the PRIME to all projects. EPA METHOD 508 --Determination of Chlorinated Pesticides in Water by Gas Chromatography with an Electron Capture Detector Table 2. Comparison of EPA Method 508 and NWQL Schedule Target Analytes _________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Level Schedule No. Reporting Limit (5g/L) (5g/L) _________________________________________________________________ Aldrin 0.075 1324 0.01 Chlordane-alpha 0.0015 Chlordane-gamma 0.0015 Chlorneb 0.5 Chlorobenzilate* 5 Chlorthalonil 0.025 DCPA (Dacthal) 0.025 79b 0.01 4,4'-DDD 0.0025 1324 0.01 4,4'-DDE 0.01 1324 0.01 4,4'-DDT 0.06 1324 0.01 Dieldrin 0.02 1324 0.01 Endosulfan I 0.015 1324 0.01 Endosulfan II 0.024 Endosulfan sulfate 0.015 Endrin 0.015 1324 0.01 Endrin aldehyde 0.025 Etridiazole 0.025 HCH-alpha 0.025 1324c 0.01 HCH-beta 0.01 1324c 0.01 HCH-delta* 0.01 1324c 0.01 HCH-gamma (Lindane) 0.015 1324 0.01 Heptachlor 0.01 1324 0.01 Heptachlor epoxide 0.015 1324 0.01 Hexachlorobenzene 0.0077 1324c 0.01 Methoxychlor 0.05 1324 0.01 cis-Permethrin 0.5 trans-Permethrin 0.5 Propachlor 0.5 1389d 0.1 Trifluralin 0.025 1389 0.1 Table 2. Comparison of EPA Method 508 and NWQL Schedule Target Analytes--(continued) __________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Level Schedule No. Reporting Limit (5g/L) (5g/L) __________________________________________________________________ Aroclor 1016 NAa 1364 0.1 Aroclor 1221 NAa 1364 0.1 Aroclor 1232 NAa 1364 0.1 Aroclor 1242 NAa 1364 0.1 Aroclor 1248 NAa 1364 0.1 Aroclor 1254 NAa 1364 0.1 Aroclor 1260 NAa 1364 0.1 Toxaphene NAa 1324 1.0 Technical Chlordane NAa 1324 0.1 __________________________________________________________________ * These compounds, although identified, are not quantitated in the EPA method because control over precision has not been accomplished. a/NA = Not Available. These complex multicomponent mixtures are included in the list, because the extraction conditions are the same as those used in EPA method 608, which does measure the multicomponent constituents as mixture equivalents in terms of commercial polychlorinated biphenyl (PCB) mixtures (Aroclors), technical toxaphene, and technical chlordane. However, no recovery data were collected for these constituents during development of EPA method 508. NOTE: EPA method 508 does not represent a good method for determining these complex mixtures since liquid chromatography cleanup/fractionation using silica and alumina columns is not included. NWQL schedules 1364 and 1324 (see Appendix A) do include alumina cleanup, and additional class fractionation of PCBs from the major components of chlordane and toxaphene is available upon request for those projects requiring more detailed analysis of these contaminants. b/Method add-on compound not reported via the PRIME. This compound is currently available as a prearranged custom analysis. Schedule 79 also determines the DCPA monoacid and diacid metabolites [see Table 3 footnote (a)] along with DCPA. EPA method 508 does not include these acid metabolites, however, these metabolites are included in EPA method 515.1. c/Method add-on compound not reported via the PRIME. This compound currently is available as a prearranged custom analysis. d/NAWQA add-on compound reported via the PRIME. This compound currently is available to non-NAWQA projects as a prearranged custom analysis. Propachlor also currently is undergoing further method recovery and precision tests at the NWQL under schedule 1389 [see Table 1 footnote (b)]. EPA METHOD 515.1 -- Determination of Chlorinated Acids in Water by Gas Chromatography with an Electron Capture Detector Table 3. Comparison of EPA Method 515.1 and NWQL Schedule Target Analytes __________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Level Schedule No. Reporting Limit (5g/L) (5g/L) __________________________________________________________________ Acifluorfen* 0.096 Bentazon 0.2 Chloramben* 0.093 79b 0.1 2,4-D 0.2 79 0.01 Dalapon* 1.3 2,4-DB 0.8 DCPA and acid metabolitesa 0.02 79b 0.01 Dicamba 0.081 79 0.01 3,5-Dichlorobenzoic acid 0.061 Dichlorprop (2,4-DP) 0.26 79 0.01 Dinoseb 0.19 5-Hydroxydicamba 0.04 4-Nitrophenol* 0.13 Pentachlorophenol (PCP) 0.076 Picloram 0.14 79 0.01 2,4,5-T 0.08 79 0.01 2,4,5-TP (Silvex) 0.075 79 0.01 __________________________________________________________________ *These compounds, although identified, are not quantitated in the EPA method because control over precision has not been accomplished. a/The monoacid and diacid metabolites of DCPA (Dacthal) are included in both EPA method 515.1 and NWQL schedule 79. b/Method add-on compound not reported via the PRIME. This compound currently is available as a prearranged custom analysis. EPA METHOD 531.1 -- Measurement of N-Methylcarbamoyloximes and N- Methylcarbamates in Water by Direct Aqueous Injection High Performance Liquid Chromatography (HPLC) with Post Column Derivatization Table 4. Comparison of EPA Method 531.1 and NWQL Schedule Target Analytes __________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Levela Schedule No Reporting Limit (5g/L) (5g/L) __________________________________________________________________ Aldicarb 1.0 1359b 0.5 Aldicarb sulfone 2.0 Aldicarb sulfoxide 2.0 Baygon (Propoxur) 1.0 1359b 0.5 Carbaryl 2.0 1359 0.5 Carbofuran 1.5 1359b 0.5 3-Hydroxycarbofuran 2.0 Methiocarb 4.0 1359b 0.5 Methomyl 0.5 1359 0.5 Oxamyl 2.0 __________________________________________________________________ a/EDL values approximately 2-4 fold lower can now be achieved due to improved sensivity of the fluorescence detector. Thus, EPA EDL values and NWQL reporting limits are similar. b/NAWQA add-on compound now routinely available to non-NAWQA projects as well, but not reported via the PRIME. DRAFT EPA PESTICIDE METHODS The two other methods developed for use in the EPA National Pesticide Survey are shown below. EPA draft method #4 has undergone interlaboratory validation, and following review the EPA has decided not to propose use of this method because there does not appear to be sufficient interest within the EPA programs for the majority of method target analytes (personal communication from David Munch, EPA EMSL-Cincinnati, May 1990). EPA draft method #6 is presently undergoing interlaboratory validation and review, and EPA still intends to propose use of this method in the Federal Register. EPA DRAFT METHOD #4 -- Determination of Pesticides in Ground Water by High Performance Liquid Chromatography with an Ultraviolet Detector Table 5. Comparison of EPA Draft Method #4 and NWQL Schedule Target Analytes __________________________________________________________________ EPA Estimated Detection NWQL NWQL Target Analyte Level Schedule No. Reporting Limit (5g/L) (5g/L) __________________________________________________________________ Atrazine deethylated 0.25 Barban 0.50 Carbofuran phenol 1.8 Cyanazine 0.58 1389 0.1 Diuron 0.070 Fenamiphos sulfone 5.7 Fenamiphos sulfoxide 1.0 Fluometuron 0.10 3-Ketocarbofuran 0..25 Linuron 0.25 Metribuzin DAa 0.21 Metribuzin DKa 0.10 Metribuzin DADKa 2.5 Neburon 0.15 Pronamide metabolite 0.81 Propanil 0.067 Propham 0.75 1359 0.5 Swep 0.75 __________________________________________________________________ aDA = deamino-metabolite. DK = diketo-metabolite. DADK = deamino, diketo-metabolite. EPA DRAFT METHOD #6 -- Determination of Ethylene Thiourea (ETU) in Ground Water by Gas Chromatography with a Nitrogen-Phosphorus Detector Ethylene thiourea (ETU) is a major degradation product of a family of organometallic fungicides used on crops. All of these organometallic compounds are complexes of transition metals as ethylene-bis-dithiocarbamic acid salts. Examples include Zineb (containing zinc) and Maneb (containing manganese). ETU is of interest because it is highly soluble in water and is a suspected carcinogen and a teratogen. The EPA draft EDL value determined by Battelle-Columbus Laboratories for ETU is 5 5g/L. The NWQL does not analyze for ethylene thiourea. ADDITIONAL PESTICIDE ANALYTES IN THE NWQL SCHEDULES Table 6 lists additional pesticides available under NWQL schedules 1319, 1324, and 1359 that are not target analytes of the six EPA methods above. NWQL schedules 1389 and 79 do not contain any additional target analytes (or add-ons) not determined under EPA methods 507, 508, 515.1 and Draft Method #4. Table 6. Additional NWQL Pesticide Schedule Analytes _____________________________________________________________ Schedule No. Analyte Reporting Limit (5g/L) _____________________________________________________________ 1319a Chlorpyrifos 0.01 1319 DEF (Butifos) 0.01 1319 Ethion 0.01 1319a Fonofos 0.01 1319 Malathion 0.01 1319b Methyl azinphos (Guthion) 0.1 1319 Parathion (-ethyl) 0.01 1319 Parathion-methyl 0.01 1319 Phorate 0.01 1319 Trithion 0.01 1319 Trithion-methyl 0.01 1324 Mirex 0.01 1324 Perthane (Ethylan) 0.01 1359c 1-Naphthold 0.5 _____________________________________________________________ aMethod add-on compound routinely reported to all projects but not via the PRIME. bMethod add-on compound not reported via the PRIME. This compound is currently available as a prearranged custom analysis. cNAWQA add-on compound now routinely available to non-NAWQA projects as well, but not reported via the PRIME. dDegradation product of carbaryl. Although not included in the target analyte list under EPA method 531.1 (Table 4), 1-naphthol can be determined by method 531.1. COMPARISON OF EPA ESTIMATED DETECTION LIMITS AND NWQL REPORTING LIMITS For a number of analytes in Tables 1-3 above, the NWQL reporting limit is either similar to or lower than the EPA EDL by a factor of approximately five or less. In the latter case of lower NWQL values, the differences between the NWQL and EPA values are likely attributable to differences in the NWQL and EPA methods final extract volume from which instrumental analysis is conducted. EPA methods 507, 508, and 515.1 extract 1 liter (L) of water and concentrate the extract to a 5 mL final volume, from which a 2 uL aliquot is used for instrumental analysis. The comparable NWQL methods (schedules 1389, 1319, 1324, 1364, and 79) all extract 1 L of water, but end up at a 1-2 mL final extract volume, from which a 2 uL aliquot is analyzed (see Appendix A for procedural details). This theoretically represents a 2.5- to 5-fold enhancement in analyte mass introduced to the GC for the NWQL methods versus the EPA methods. For a few other analytes, the NWQL reporting limit is nearly an order of magnitude or more lower than the EPA EDL, the reasons for which are not obvious but may be attributable to chromatographic or detector performance. It is interesting to note the differences between the EPA 531.1 EDL and the NWQL 1359 reporting limits given in Table 4. EPA 531.1 requires minimal sample preparation steps and no preconcentration of the water prior to instrumental analysis by HPLC with fluorescence detection. However, the method is limited to N-methylcarbamates and N-methylcarbamoyloximes because of the requirement to form methyl amine in the post-column derivatization step. On the other hand, NWQL 1359 requires time-consuming sample preparation and preconcentration steps prior to analysis by HPLC with photodiode array ultraviolet detection (see Appendix A for procedural details). Considering differences in concentration factors and instrument injection volumes, NWQL 1359 should theoretically introduce 714 times more analyte mass onto the HPLC column than EPA 531.1. Table 4 shows that the NWQL reporting limits are only up to a factor of eight lower than the EPA 531.1 EDL. The lack of a much greater difference in EPA EDL and NWQL reporting limits is due to the much greater sensitivity of the fluorescence detector versus the ultraviolet detector. (Currently, an approximately 2-4 fold increase in sensitivity of method 531.1 compounds can be achieved due to improved sensitivity of the fluorescence detector.) It is important to note that NWQL 1359 is not limited only to N-methylcarbamates and N- methylcarbamoyloximes, and can theoretically be used to analyze for other non-N-methyl carbamates and other analytes, assuming good performance of the sample preparation steps and HPLC separation. However, at present the only non-N-methyl compounds analyzed for under 1359 are propham (Table 5) and 1-naphthol (Table 6), though 1-naphthol also can be determined under EPA method 531.1 [see Table 6 footnote (c)]. In Table 5, the EPA EDL and the NWQL reporting limit for propham are similar. The difference for cyanazine is likely attributable to instrumental differences between EPA draft method #4 (HPLC-UV) and NWQL 1389 (GC-NPD). USE OF SAMPLE PRESERVATIVES EPA methods 507, 508, and 515.1 use field addition of 10 mg/L of the bactericide mercuric chloride (HgCl2), or any other reagent shown to work as well, and 80 mg/L sodium thiosulfate, if residual chlorine is present, to the sample bottles prior to shipment to the field. EPA draft methods #4 and #6 call for addition of HgCl2 only. These methodUs samples are stored and transported in amber glass bottles at 4 deg C. The comparable NWQL methods (schedules 1389, 1319, 1324, 1364, and 79) likewise call for storing and transporting samples in amber glass bottles at 4 deg. C, but do not call for addition of any bactericide or residual chlorine scavenger. While HgCl2 may represent an effective bactericide, its use in samples targeted for organics analysis is not recommended by the Methods Research and Development Program of the NWQL because it requires special treatment of the samples to remove the Hg before disposal. Preservation with HgCl2 introduces a contamination potential for those projects also collecting water samples for Hg analysis, and can interfere with organic instrumental analysis under certain conditions (Foreman and others, 1990). HgCl2 is also highly toxic to humans. It should be noted that in the absence of a biocide, studies may need to be conducted to determine the stabilities of target analyses in water matrices being investigated. EPA method 531.1 requires field addition of 1.8 mL 2.5 M monochloroacetic acid solution to buffer the 60 mL water sample to pH 3. This is done to help preserve the analytes, since oxamyl, 3-hydroxycarbofuran, aldicarb sulfoxide, and carbaryl reportedly all can degrade (hydrolyze) rapidly in neutral or basic waters at room temperature. The pH adjustment also minimizes analyte biodegradation. The comparable NWQL carbamate method (1359) does not incorporate any field pH adjustment to minimize hydrolysis or biodegradation. OTHER COMMENTS ON DIFFERENCES BETWEEN EPA AND NWQL METHODS Some compounds included in the EPA methods are not currently available from NWQL. EPA 507 represents a potential alternative to NWQL 1389, especially if final extract volumes are reduced to 1 mL or less. EPA 507 covers all current 1389 analytes (except propachlor and trifluralin (EPA 508) and cyanazine (EPA Draft Method #4), all three of which should be easily added to EPA 507) plus determines 25 additional analytes not currently available at the NWQL. An even greater enhancement to either EPA 507 or schedule 1389 would be the substitution of GC with mass spectrometric detection (GC-MS operated in the selected ion monitoring mode) for the current GC-NPD instrumental method. The Methods Research and Development Program (MRDP) and the Organics Program of the NWQL will be implementing a new GC-MS method within the next year as an alternative to schedule 1389. EPA 508 probably does not represent an improvement to NWQL 1324 or 1364, since no column cleanup/fractionation steps to separate complex mixture constituents are included in 508. It may be possible to add the eleven analytes in EPA 508 not determined at the NWQL to schedule 1324. Because of procedural similarities (see Appendix A), the nine analytes in EPA 515.1 not presently determined at the NWQL could likely be added to NWQL 79. EPA draft method #4Us target analyte list represents some important compounds that various District projects have identified as a need, but for which the NWQL does not currently have methods. Better method detection limits would be achievable for EPA draft method #4 if the final extract volume was reduced. CONTACTS For additional information regarding the EPA methods or their comparison with NWQL methods, please contact Bill Foreman, Methods Research and Development Program, NWQL, Arvada, Colorado 80002 at FTS-776-9363 or 303-236-9363 or EDOC to WTFOREMAN. Please direct all inquiries regarding custom analyses for the above NWQL Schedules to Doug Manigold, NWQL Organics Program Chief, at FTS-776-5345 or 303-236-5345 or EDOC to DBMANIGOLD. Project chiefs who may require analytical services for analytes not presently offered by the NWQL should make their needs known to their Regional Water-Quality Specialist and/or to Richard O. Hawkinson, Chief, Branch of Analytical Services, NWQL. Appendix A PROCEDURAL DETAILS OF THE EPA AND NWQL METHODS The following summarized descriptions of both the EPA and NWQL methods are provided for individuals interested in the actual procedures. Those requiring greater detail regarding EPA methods 507, 508, 515.1, and 531.1 should consult EPA (1988). The EPA draft methods #4 and #6 have not been officially published. The NWQL schedule procedures described below are from Wershaw and others (1987), and include some updated procedural revisions. EPA SCHEDULES EPA METHOD 507 -- Determination of Nitrogen- and Phosphorus Containing Pesticides in Water by Gas Chromatography with a Nitrogen-Phosphorus Detector An approximate 1 L volume water sample is fortified with a surrogate standard solution, the pH is adjusted to 7 with phosphate buffer, and 100 g of NaCl is added. The sample is extracted three times with 60 mL portions each of dichloromethane by shaking in a separatory funnel and the solvent portions combined. An automated extraction method is also permitted. The extract is dried using anhydrous sodium sulfate, and concentrated using a Kuderna-Danish (K-D) apparatus and solvent exchanged to methyl t-butyl ether to give a final extract volume of 5 mL. An internal injection standard solution is added to the extract if an internal standard calibration procedure is used. The extract is then analyzed by fused silica capillary column gas chromatography (GC) with a nitrogen-phosphorus detector (NPD) by injecting a 2 5L aliquot of the extract onto a GC column. The primary column is a 30 m x 0.25 mm internal diameter (ID) column coated with a 0.25 5m film thickness of 5% phenyl methylpolysiloxane (J & W Scientific DB-5 column or equivalent). The secondary confirmation column is a 14% cyanopropylphenyl methylpolysiloxane (J & W Scientific DB- 1701 column or equivalent). EPA METHOD 508 -- Determination of Chlorinated Pesticides in Water by Gas Chromatography with an Electron Capture Detector This method is identical to Method 507 in all respects, except that the analytes are determined by capillary column GC with an electron capture detector (ECD). EPA METHOD 515.1 -- Determination of Chlorinated Acids in Water by Gas Chromatography with an Electron Capture Detector An approximate 1 L volume water sample is placed in a separatory funnel. The sample is fortified with a surrogate standard solution, 250 g of NaCl is added, and the pH is adjusted to 3 12 with 6 N NaOH to hydrolyze any chlorinated acid esters present. The sample is periodically shaken over a 1 hour period during this hydrolysis step. Extraneous base/neutral organic material is removed by extracting the sample three times with 60 mL portions each of dichloromethane in the separatory funnel and discarding the solvent portions. An automated extraction method is also permitted. The sample is acidified to pH 2 2 using 12 N H2SO4, and the chlorinated acids are extracted three times with 60 mL portions each of diethyl ether by shaking in a separatory funnel and the solvent portions combined. The extract is dried using acidified anhydrous sodium sulfate, poured through acid washed glass wool into a K-D apparatus, and concentrated and solvent exchanged to methyl t-butyl ether to a 5 mL final volume. The chlorinated acids are then converted to their methyl ester derivatives using either a gaseous or solution diazomethane derivatization procedure. A Florisil cleanup procedure can be included at this point to eliminate additional interferents, if encountered. An internal injection standard solution is added to the extract if an internal standard calibration procedure is used. The final extract (now at a 5 or 10 mL final volume depending on whether the Florisil cleanup step is omitted or used, respectively) is analyzed by capillary column GC-ECD using GC columns and conditions identical to Methods 507 and 508. EPA METHOD 531.1 -- Measurement of N-Methylcarbamoyloximes and N-Methylcarbamates in Water by Direct Aqueous Injection High Performance Liquid Chromatography (HPLC) with Post Column Derivatization A 60 mL water sample is collected and buffered to pH 3 in the field using 2.5 M monochloroacetic acid buffer solution. This is done to help preserve the analytes, since oxamyl, 3- hydroxycarbofuran, aldicarb sulfoxide, and carbaryl reportedly all can degrade rapidly in neutral or basic waters at room temperature. A 50 mL portion of the sample is placed into a 50 mL volumetric flask and 5 5L of internal standard solution is added. Then 20 mL of this sample is filtered, with only the last 5 mL of filtrate retained. A 400 5L aliquot of this filtrate is injected into a HPLC where the analytes are separated on a 15 cm x 3.9 mm ID stainless steel column packed with reverse phase octadecylsilyl silica (C-18) stationary phase (Waters NovaPak C18 column or equivalent). Following elution from the HPLC, the analytes are hydrolyzed with 0.05 N NaOH at 95 oC and the methyl amine formed during hydrolysis is reacted with o-phthalaldehyde and 2- mercaptoethanol to form a highly fluorescent derivative which is detected by a fluorescence detector. EPA DRAFT METHOD #4 -- Determination of Pesticides in Ground Water by High Performance Liquid Chromatography with an Ultraviolet Detector An approximate 1 L volume of water sample is fortified with a surrogate standard solution, the pH is adjusted to 7 with phosphate buffer, and 100 g of NaCl is added. The sample is then extracted three times with 60 mL portions each of dichloromethane by shaking in a separatory funnel and the solvent portions combined. An automated extraction method is permitted. The extract is dried using anhydrous sodium sulfate, and concentrated and solvent exchanged to methanol using a K-D apparatus to a final extract volume of 5 mL. An internal injection standard solution is added to the extract and a 10 5L aliquot of the extract is analyzed by HPLC with ultraviolet (UV) detection at a 254 nm wavelength. The primary HPLC column is a 25 cm x 4.6 mm ID stainless steel reverse phase C-18 column (DuPont Zorbax ODS or equivalent) with secondary confirmation accomplished using a 25 cm x 4.6 mm ID silica column (DuPont Zorbax Silica or equivalent), if necessary. EPA DRAFT METHOD #6 -- Determination of Ethylene Thiourea (ETU) in Ground Water by Gas Chromatography with a Nitrogen-Phosphorus Detector The ionic strength and pH of a 50 mL aliquot of the water sample is adjusted by adding 25 g potassium fluoride and 1.5 g ammonium chloride to the aliquot and shaking. The aliquot is fortified with a surrogate standard solution, introduced onto a modified diatomaceous earth column and allowed to stand for 15 minutes. The column is then eluted with 400 mL of dichloromethane in 50-75 mL portions, with the eluant collected into a K-D apparatus containing 5 mL of 1000 5g/mL dithiothreitol (a free radical scavenger) in ethyl acetate. The eluant is concentrated to 5 mL using the Kuderna-Danish apparatus, and down to 1 mL using N2 blowdown. The extract is finally diluted to 5 mL with ethyl acetate and an internal injection standard is added. The extract is analyzed by fused silica capillary column GC-NPD by injecting a 2 5L aliquot of the extract onto each column. The primary column is a 10 m x 0.25 mm ID column coated with polyethylene glycol (J & W Scientific DB-WAX column or equivalent). The secondary confirmation column is a 5 m x 0.25 mm ID 14% cyanopropylphenyl methylpolysiloxane (DB-1701 type) column. Both columns have a 0.25 5m film thickness. NWQL SCHEDULES NWQL SCHEDULE 1389 -- Triazine Herbicides, Total Recoverable (O-3106-83) An approximate 1 L volume water sample is fortified with a surrogate standard solution and transferred to a separatory funnel containing 5 g of NaCl. The sample is adjusted to pH 7-9 with KOH or H2SO4 solution as necessary, and extracted with 75 mL of dichloromethane, and repeated with two 50 mL portions of dichloromethane. The extracts are combined, dried with non-acid anhydrous sodium sulfate, transferred to a K-D apparatus containing 4 mL hexane and concentrated to 3-5 mL. The extract is further concentrated to 1 mL and solvent exchanged to hexane using N2 blowdown, and then analyzed by dual fused silica capillary column GC-NPD using 2 5L injections of the extract per column. An alumina column cleanup step can be included prior to GC analysis to eliminate interferents, if necessary. The two GC columns are 25 m x 0.25 mm ID columns coated with 0.25 5m film thicknesses of either methylpolysiloxane (Hewlett-Packard Ultra 1) or 5% phenyl methylpolysiloxane (Hewlett-Packard Ultra 2 or equivalent). NWQL SCHEDULE 1319 -- Organophosphorus Insecticides, Total Recoverable (O-3104-83) An approximate 1 L volume water sample is fortified with a surrogate standard solution and extracted with three 50 mL portions of hexane. The hexane portions are combined, dried with nonacid anhydrous sodium sulfate, concentrated to 3-5 mL using a K-D apparatus, and further reduced to 1 mL using N2 blowdown. If schedule 1324 is also requested, the 1 mL extract is split in half with 0.5 mL carried though the schedule 1324 procedure outlined below for organochlorine insecticides, and the remaining 0.5 mL analyzed for organophosphorus insecticides by dual fused silica capillary column GC with a flame photometric detector using 2 5L injections of the extract per column. If schedule 1324 is not requested, then the 1 mL extract is analyzed. The two GC columns are 30 m x 0.25 mm ID columns coated with a 0.25 5m film thickness of either 5% phenyl methylpolysiloxane (J & W Scientific DB-5 column or equivalent) or 14% cyanopropylphenyl methylpolysiloxane (J & W Scientific DB-1701 column or equivalent). NWQL SCHEDULE 1324 -- Organochlorine Insecticides with Gross Polychlorinated Biphenyls (PCBs) and Polychlorinated Naphthalenes (PCNs), Total Recoverable (O-3104-83) The 0.5 mL split of the extract generated under the schedule 1319 procedure above (or the entire 1 mL if schedule 1319 is not requested) is cleaned up by introducing the extract onto an 8.5% water deactivated alumina column, and eluting the column with 10 mL hexane. The hexane eluant is concentrated to 0.5 mL using N2 blowdown, and analyzed by dual fused silica capillary column GC- ECD using 2 5L injections of the extract per column. The GC columns used are identical to schedule 1319. NWQL SCHEDULE 1364 -- Polychlorinated Biphenyls as Aroclor Equivalents, Total Recoverable This procedure is identical to schedule 1324, except that following the alumina column, the extract can optionally be further fractionated on a 3 percent water deactivated silica column prior to dual capillary column GC-ECD analysis. The GC columns are those used for schedule 1324. The silica column fractionation is included to separate the PCBs from other complex organochlorine mixtures, especially the components of technical Toxaphene and Chlordane. NWQL SCHEDULE 79 -- Chlorophenoxy Acid Herbicides with Dicamba and Picloram, Total Recoverable An approximate 1 L volume water sample is fortified with a surrogate standard solution and transferred to a separatory funnel containing 200 g of NaCl. The sample is acidified to pH 2 2 using H2SO4 solution and extracted with 100 mL diethyl ether, and repeated with two 50 mL portions of diethyl ether. The extracts are combined into a K-D apparatus and 15 mL H2O plus 2 mL of 37% KOH are added to provide a pH 3 12. The extract is then boiled on a steam bath to remove the diethyl ether, and then for another 90 minutes to hydrolyze any chlorinated acid esters present. The extract is transferred to a separatory funnel, washed with three 10 mL portions of diethyl ether, acidified to pH 2 2 with 25% H2SO4, and extracted with three 10 mL portions of diethyl ether, which are combined and dried with acid-washed sodium sulfate. The extract is transferred to a K-D apparatus containing 0.5 mL benzene and concentrated to 1 mL. Another 0.5 mL of benzene is added to the extract and it is further reduced to 0.5 mL using N2 blowdown. The chlorinated acids are converted to their methyl ester derivatives using a gaseous diazomethane derivatization procedure. The extract is transferred to a 15% water-deactivated Florisil column, and eluted with 2 mL benzene (fraction 1, which contains all the chlorinated acid herbicides except picloram) followed by 2 mL of 20% diethyl ether in benzene (fraction 2, contains picloram). Both fractions are analyzed separately by dual capillary column GC-ECD using 2 5L injections of the fraction per column. The GC columns used are identical to schedule 1319. NWQL SCHEDULE 1359 -- Carbamate Insecticides, Total Recoverable (O-3106-83) An approximate 1 L volume water sample is buffered to pH 7.5 using phosphate buffer, fortified with a surrogate standard solution, and extracted with 75 mL of dichloromethane, and repeated with two 50 mL portions of dichloromethane. The extracts are combined, dried with nonacid anhydrous sodium sulfate, transferred to a K-D apparatus and concentrated to 3-5 mL. The extract is further concentrated to 1 mL and solvent exchanged to acetonitrile using N2 blowdown. A 400 5L aliquot of the 1 mL extract is concentrated to dryness, reconstituted with 350 5L of 0.04% acetonitrile/water and analyzed by injecting 250 5L of this aliquot on a HPLC with photodiode array ultraviolet detection (UV). The HPLC column is a 25 cm x 2.1 mm ID reverse phase C-18 column (Beckmann Ultrasphere ODS). REFERENCES Code of Federal Regulations 40, Part 136, Appendix B, July 1, 1989 - Definition and Procedure for the Determination of the Method Detection Limit - Revision 1.11. EPA, 1988, Methods for the Determination of Organic Compounds in Drinking Water. EPA/600-4-88-039. Foreman, W. T., Zaugg, S.D., and Rogerson, P.F., 1990, Analytical interferences of HgCl2 preservative in environmental water samples: 1. Determination of semivolatile organic compounds isolated by liquid-liquid extraction (under review). Wershaw, R.L., Fishman, M.J., Grabbe, R.R., and Lowe, L.E., 1987, Methods for the Determination of Organic Substances in Water and Fluvial Sediments. USGS Techniques of Water-Resources Investigations, Book 5 Chapter A3.