METHOD ,2-DIBROMOETHANE AND 1,2-DIBROMO-3-CHLOROPROPANE BY MICROEXTRACTION AND GAS CHROMATOGRAPHY

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1 METHOD ,2-DIBROMOETHANE AND 1,2-DIBROMO-3-CHLOROPROPANE BY MICROEXTRACTION AND GAS CHROMATOGRAPHY 1.0 SCOPE AND APPLICATION 1.1 This methd is applicable t the determinatin f the fllwing cmpunds in drinking water and grund water: Cmpund Name CAS N. a 1,2-Dibrmethane (EDB) ,2-Dibrm-3-chlrprpane (DBCP) a Chemical Abstract Services Registry Number. 1.2 Fr cmpunds and matrices ther than thse listed in Sectin 1.1, the labratry must demnstrate the usefulness f the methd by cllecting precisin and accuracy data n actual samples and prvide qualitative cnfirmatin f results by gas chrmatgraphy/mass spectrmetry (GC/MS). 1.3 The experimentally determined methd detectin limits (MDL) fr EDB and DBCP were calculated t be 0.01 µg/l. The methd has been shwn t be useful fr these analytes ver a cncentratin range f apprximately 0.03 t 200 µg/l. Actual detectin limits are highly dependent upn the characteristics f the gas chrmatgraphic system, sample matrix, and calibratin. 1.4 This methd is restricted t use by r under the Supervisin f analysts experienced in the use f gas chrmatgraphy and in the interpretatin f gas chrmatgrams. Each analyst must demnstrate the ability t generate acceptable results with this methd using the prcedure described in Sectin ,2-Dibrmethane and 1,2-Dibrm-3-chlrprpane have been tentatively classified as knwn r suspected human r mammalian carcingens. Pure standard materials and stck standard slutins f these cmpunds shuld be handled in a hd. A NIOSH/MESA apprved txic gas respiratr shuld be wrn when the analyst handles high cncentratins f these txic cmpunds. 2.0 SUMMARY OF METHOD 2.1 Thirty five ml f sample are extracted with 2 ml f hexane. Tw µl f the extract are then injected int a gas chrmatgraph equipped with a linearized electrn capture detectr fr separatin and analysis. Aqueus matrix spikes are extracted and analyzed in an identical manner as the samples in rder t cmpensate fr pssible extractin lsses. CD-ROM Revisin 0

2 2.2 The extractin and analysis time is 30 t 50 minutes per sample depending upn the analytical cnditins chsen. See Table 1 and Figure Cnfirmatry evidence is btained using a different clumn (Table 1). 3.0 INTERFERENCES 3.1 Impurities cntained in the extracting slvent (hexane) usually accunt fr the majrity f the analytical prblems. Reagent blanks shuld be analyzed fr each new bttle f hexane befre use. Indirect daily checks n the hexane are btained by mnitring the reagent blanks. Whenever an interference is nted in the methd r instrument blank, the labratry shuld reanalyze the hexane. Lw level interferences generally can be remved by distillatin r clumn chrmatgraphy, hwever, it is generally mre ecnmical t btain a new surce f hexane slvent. Interference-free hexane is defined as cntaining less than 0.01 µg/l f the analytes. Prtect interference-free hexane by string it in an area knwn t be free f rganchlrine slvents. 3.2 Several instances f accidental sample cntaminatin have been attributed t diffusin f vlatile rganics thrugh the septum seal int the sample bttle during shipment and strage. Trip blanks must be used t mnitr fr this prblem. 3.3 This liquid/liquid extractin technique extracts a wide biling range f nn-plar rganic cmpunds and, in additin, extracts sme plar rganic cmpunds. 3.4 EDB at lw cncentratins may be masked by very high cncentratins f dibrmchlrmethane (DBCM), a cmmn chlrinated drinking water cntaminant, when using the cnfirmatin clumn. 4.0 APPARATUS AND MATERIALS 4.1 Micrsyringe - 10, 25, and 100 µl with a 2 in. x in. needle (Hamiltn 702N r equivalent). 4.2 Gas Chrmatgraph The GC must be capable f temperature prgramming and shuld be equipped with a linearized electrn capture detectr and a capillary clumn splitless injectr Clumns Clumn A mm ID x 30 m fused silica capillary with dimethyl silicne mixed phase (Durawax-DX 3, 0.25 µm film, r equivalent) Clumn B (cnfirmatin clumn) mm ID x 30 m fused silica capillary with methyl plysilxane phase (DB-1, 0.25 µm film, r equivalent). CD-ROM Revisin 0

3 4.3 Vlumetric flasks, Class A - 10 ml. 4.4 Glass bttles - 15 ml, with Tefln lined screw caps r crimp tps. 4.5 Analytical balance g. 4.6 Graduated cylinder - 50 ml. 4.7 Transfer pipet. 5.0 REAGENTS 5.1 Reagent grade chemicals shall be used in all tests. Unless therwise indicated, it is intended that all reagents shall cnfrm t the specificatins f the Cmmittee n Analytical Reagents f the American Chemical Sciety, where such specificatins are available. Other grades may be used, prvided it is first ascertained that the reagent is f sufficiently high purity t permit its use withut lessening the accuracy f the determinatin. 5.2 Organic-free reagent water - All references t water in this methd refer t rganic-free reagent water, as defined in Chapter One. 5.3 Hexane, C H - UV grade (Burdick and Jacksn #216 r equivalent) Methyl alchl, CH OH - Demnstrated t be free f analytes Sdium chlride, NaCl - Pulverize a batch f NaCl and place it in a muffle furnace at rm temperature. Increase the temperature t 400 C fr 30 minutes. Stre in a capped bttle ,2-Dibrmethane (99%), C H Br, (Aldrich Chemical Cmpany, r equivalent) ,2-Dibrme-3-chlrprpane (99.4%), C H Br C1, (AMVAC Chemical Crpratin, Ls Angeles, Califrnia, r equivalent). 5.8 Stck standards - These slutins may be purchased as certified slutins r prepared frm pure standards using the fllwing prcedures: Place abut 9.8 ml f methanl int a 10 ml grund glass stppered vlumetric flask. Allw the flask t stand, unstppered, fr abut 10 minutes and weigh t the nearest g Use a 25 µl syringe and immediately add tw r mre drps (. 10 µl) f standard t the flask. Be sure that the standard falls directly int the alchl withut cntacting the neck f the flask Reweigh, dilute t vlume, stpper, and then mix by inverting the flask several times. Calculate the cncentratin in milligrams per liter (mg/l) frm the net gain in weight. When cmpund purity is assayed t be 96% r greater, the weight may be used withut crrectin t calculate the cncentratin f the stck standard. CD-ROM Revisin 0

4 5.8.4 Stre stck standards in 15 ml bttles equipped with Tefln lined screw-caps r crimp tps. Stck standards are stable fr at least fur weeks when stred at 4 C and away frm light. 5.9 Intermediate standard - Use stck standards t prepare an intermediate standard that cntains bth analytes in methanl. The intermediate standard shuld be prepared at a cncentratin that can be easily diluted t prepare aqueus calibratin standards that will bracket the wrking cncentratin range. Stre the intermediate standard with minimal headspace and check frequently fr signs f deteriratin r evapratin, especially just befre preparing calibratin standards. The strage time described fr stck standards als applies t the intermediate standard Quality cntrl (QC) reference sample - Prepare a QC reference sample cncentrate at 0.25 mg/l f bth analytes frm standards frm a different surce than the standards used fr the stck standard Check standard - Add an apprpriate vlume f the intermediate standard t an aliqut f rganic-free reagent water in a vlumetric flask. D nt add mre than 20 µl f an alchlic intermediate standard t the water r pr precisin will result. Use a 25 µl micrsyringe and rapidly inject the alchlic intermediate standard int the expanded area f the almst filled vlumetric flask. Remve the needle as quickly as pssible after injectin. Mix by inverting the flask several times. Discard the cntents cntained in the neck f the flask. Aqueus calibratin standards shuld be prepared every 8 hurs. 6.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE 6.1 See the intrductry material t this chapter, Organic Analytes, Sectin PROCEDURE 7.1 Recmmended Chrmatgraphic Cnditins Tw gas chrmatgraphy clumns are recmmended. Clumn A is a highly efficient clumn that prvides separatins fr EDB and DBCP withut interferences frm trihalmethanes. Clumn A shuld be used as the primary analytical clumn unless rutinely ccurring analytes are nt adequately reslved. Clumn B is recmmended fr use as a cnfirmatry clumn when GC/MS cnfirmatin is nt available. Retentin times fr EDB and DBCP n these clumns are presented in Table 1. Clumn A: Injectr temperature: 200 C. Detectr temperature: 290 C. Carrier gas (Helium)Linear velcity: 25 cm/sec. Temperature prgram: Initial temperature: Prgram: 40 C, hld fr 4 min. 40 C t 190 C at 8 C/min. CD-ROM Revisin 0

5 Final temperature: 190 C, hld fr 25 min., r until all expected analytes have eluted. See Figure 1 fr a sample chrmatgram and Table 1 fr retentin data. Clumn B: Injectr temperature: 200 C. Detectr temperature: 290 C. Carrier gas (Helium)Linear velcity: 25 cm/sec. Temperature prgram: Initial temperature: Prgram: Final temperature: See Table 1 fr retentin data. 7.2 Calibratin 40 C, hld fr 4 min. 40 C t 270 C at 10 C/min. 270 C, hld fr 10 min., r until all expected analytes have eluted Prepare at least five calibratin standards. One shuld cntain EDB and DBCP at a cncentratin near, but greater than, the methd detectin limit (Table 1) fr each cmpund. The thers shuld be at cncentratins that bracket the range expected in the samples. Fr example, if the MDL is 0.01 µg/l, and a sample expected t cntain apprximately 0.10 µg/l is t be analyzed, aqueus calibratin standards shuld be prepared at cncentratins f 0.03 µg/l, 0.05 µg/l, 0.10 µg/l, 0.15 µg/l, and 0.20 µg/l Analyze each calibratin standard and tabulate peak height r area respnse versus the cncentratin in the standard. Prepare a calibratin curve fr each cmpund. Alternatively, if the rati f respnse t cncentratin (calibratin factr) is a cnstant ver the wrking range (< 10% relative standard deviatin), linearity can be assumed and the average rati r calibratin factr can be used in place f a calibratin curve. 7.3 Sample preparatin Remve samples and standards frm strage and allw them t reach rm temperature Fr samples and field blanks cntained in 40 ml bttles, remve the cntainer cap. Discard a 5 ml vlume using a 5 ml transfer pipet. Replace the cntainer cap and weigh the cntainer with cntents t the nearest 0.1 g and recrd this weight fr subsequent sample vlume determinatin Fr calibratin standards, check standards, QC reference samples, and blanks, measure a 35 ml vlume using a 50 ml graduated cylinder and transfer it t a 40 ml sample cntainer. 7.4 Extractin CD-ROM Revisin 0

6 7.4.1 Remve the cntainer cap and add 7 g f NaCl t all samples Recap the sample cntainer and disslve the NaCl by shaking by hand fr abut 20 secnds Remve the cap and using a transfer pipet, add 2.0 ml f hexane. Recap and shake vigrusly by hand fr 1 minute. Allw the water and hexane phases t separate. If stred at this stage, keep the cntainer upside dwn Remve the cap and carefully transfer a sufficient amunt ( ml) f the hexane layer int a vial using a dispsable glass pipet Transfer the remaining hexane phase, being careful nt t include any f the water phase, int a secnd vial. Reserve this secnd vial at 4 C fr reanalysis if necessary. 7.5 Analysis Transfer the first sample vial t an autsampler set up t inject 2.0 µl prtins int the gas chrmatgraph fr analysis. Alternately, 2 µl prtins f samples, blanks and standards may be manually injected, using the slvent flush technique, althugh an aut sampler is strngly recmmended. 7.6 Determinatin f sample vlume Fr samples and field blanks, remve the cap frm the sample cntainer. Discard the remaining sample/hexane mixture. Shake ff the remaining few drps using shrt, brisk wrist mvements. Reweigh the empty cntainer with riginal cap and calculate the net weight f sample by difference t the nearest 0.1 g. This net weight is equivalent t the vlume f water extracted. 7.7 Calculatins Identify EDB and DBCP in the sample chrmatgram by cmparing the retentin time f the suspect peak t retentin times generated by the calibratin standards and the check standard Use the calibratin curve r calibratin factr t directly calculate the uncrrected cncentratin (C i) f each analyte in the sample (e.g. calibratin factr x respnse) Calculate the sample vlume (V ) as equal t the net sample s weight: V (ml) = grss weight (grams) - bttle tare (grams) s Calculate the crrected sample cncentratin as: Cncentratin (µg/l) = C x 35 i V s CD-ROM Revisin 0

7 7.7.5 Reprt the results fr the unknwn samples in µg/l. Rund the results t the nearest 0.01 µg/l r tw significant figures. 8.0 QUALITY CONTROL 8.1 Each labratry that uses this methd is required t perate a frmal quality cntrl prgram The labratry must make an initial determinatin f the methd detectin limits and demnstrate the ability t generate acceptable accuracy and precisin with this methd. This is established as described in Sectin In recgnitin f labratry advances that are ccurring in chrmatgraphy, the labratry is permitted certain ptins t imprve the separatins r lwer the cst f measurements. Each time such a mdificatin is made t the methd, the analyst is required t repeat the prcedure in Sectin 7.1 and The labratry must analyze a reagent and calibratin blank t demnstrate that interferences frm the analytical system are under cntrl every twenty samples r per analytical batch, whichever is mre frequent The labratry must, n an nging basis, demnstrate thrugh the analyses f QC reference samples and check standards that the peratin f the measurement system is in cntrl. The frequency f the check standard analyses is equivalent t 5% f all samples r every analytical batch, whichever is mre frequent. On a weekly basis, the QC reference sample must be run. 8.2 T establish the ability t achieve lw detectin limits and generate acceptable accuracy and precisin, the analyst must perfrm the fllwing peratins: Prepare seven samples each at a cncentratin f 0.03 µg/l Analyze the samples accrding t the methd beginning in Sectin 7.0. _ Calculate the average cncentratin (X) in µg/l and the standard deviatin f the cncentratins (s) in µg/l, fr each analyte using the seven results. Then calculate the MDL at 99% cnfidence level fr seven replicates as 3.143s. _ Fr each analyte in an aqueus matrix sample, X must be between 60% and 140% f the true value. Additinally, the MDL may nt exceed the 0.03 µg/l spiked cncentratin. If bth analytes meet the acceptance criteria, the system perfrmance is acceptable and analysis f actual samples can begin. If either analyte fails t meet a criterin, repeat the test. It is recmmended that the labratry repeat the MDL determinatin n a regular basis. CD-ROM Revisin 0

8 8.3 The labratry must demnstrate n a frequency equivalent t 5% f the sample lad r nce per analytical batch, whichever is mre frequent, that the measurement system is in cntrl by analyzing a check standard f bth analytes at 0.25 µg/l Prepare a check standard (0.25 µg/l) by diluting the intermediate standard with water t 0.25 µg/l Analyze the sample accrding t Sectin 7.0 and calculate the recvery fr each analyte. The recvery must be between 60% and 140% f the expected value fr aqueus matrices. Fr nn-aqueus matrices, the U.S. EPA will set criteria after mre interlabratry data are gathered If the recvery fr either analyte falls utside the designated range, the analyte fails the acceptance criteria. A secnd calibratin verificatin standard cntaining each analyte that failed must be analyzed. Repeated failure, hwever, will cnfirm a general prblem with the measurement system. If this ccurs, lcate and crrect the surce f the prblem and repeat the test. 8.4 On a weekly basis, the labratry must demnstrate the ability t analyze a QC reference sample Prepare a QC reference sample at 0.10 µg/l by diluting the QC reference sample cncentrate (Sectin 5.9) Fr each analyte in an aqueus matrix, the recvery must be between 60% and 140% f the expected value. When either analyte fails the test, the analyst must repeat the test nly fr that analyte which failed t meet the criteria. Repeated failure, hwever, will cnfirm a general prblem with the measurement system r faulty samples and/r standards. If this ccurs, lcate and crrect the surce f the prblem and repeat the test. Fr nn-aqueus matrices, the U.S. EPA will set criteria after mre interlabratry data are gathered. 8.5 Instrument perfrmance - Check the perfrmance f the entire analytical system daily using data gathered frm analyses f blanks, standards, and replicate samples Peak tailing significantly in excess f that shwn in the chrmatgram (Figure 1) must be crrected. Tailing prblems are generally traceable t active sites n the GC clumn r t the detectr peratin Check the precisin between replicate analyses. A prperly perating system shuld perfrm with an average relative standard deviatin f less than 10%. Pr precisin is generally traceable t pneumatic leaks, especially at the injectin prt. 9.0 METHOD PERFORMANCE 9.1 Methd detectin limits are presented in Table 1. Single labratry accuracy and precisin at several cncentratins in tap water are presented in Table 2. CD-ROM Revisin 0

9 9.2 In a preservatin study extending ver a 4 week perid, the average percent recveries and relative standard deviatins presented in Table 3 were bserved fr rganic-free reagent water (acidified), tap water and grund water. The results fr acidified and nn-acidified samples were nt significantly different REFERENCES 1. Optimizatin f Liquid-Liquid Extractin Methds fr Analysis f Organics in Water, EPA-600/S , Hendersn, J.E.; Peytn, G.R.; Glaze, W.H. Identificatin and Analysis f Organic Pllutants in Water; Keith, L.H., Ed; Ann Arbr Sci.: Ann Arbr, MI; Richard J.J.; Junk, G.A. Jurnal AWWA 1977, 69, Budde, W.L.; Eichelberger, J.W. Organic Analyses Using Gas Chrmatgraphy- Mass Spectrmetry; Ann Arbr Science: Ann Arbr, MI; Glaser, J.A.; et al. Envirnmental Science and Technlgy 1981, 15, Methds fr the Determinatin f Organic Cmpunds in Finished Drinking Water and Raw Surce Water; U.S. Envirnmental Prtectin Agency. Office f Research and Develpment. Envirnmental Mnitring and Supprt Labratry. ORD Publicatin Offices f Center fr Envirnmental Research Infrmatin: Cincinnati, OH CD-ROM Revisin 0

10 TABLE 1. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION LIMITS (MDL) FOR 1,2-DIBROMOETHANE (EDB) AND 1,2-DIBROMO-3-CHLOROPROPANE (DBCP) Retentin Time, Minutes Analyte Clumn A Clumn B MDL (µg/l) EDB DBCP Clumn A: Durawax-DX 3 Clumn B: DB-1 TABLE 2. SINGLE LABORATORY ACCURACY AND PRECISION FOR EDB AND DBCP IN TAP WATER Relative Number Spike Average Standard f Cncentratin Recvery Deviatin Analyte Samples (µg/l) (%) (%) EDB DBCP CD-ROM Revisin 0

11 TABLE 3. ACCURACY AND PRECISION AT 2.0 µg/l OVER A 4-WEEK STUDY PERIOD Average Relative Number Accuracy Std. Dev. Analyte 1 Matrix f Samples (% Recvery) (%) EDB RW-A GW GW-A TW TW-A DBCP RW-A GW GW-A TW TW-A RW-A = Organic-free reagent water at ph 2 GW = Grund water, ambient ph GW-A = Grund water at ph 2 TW = Tap water, ambient ph TW-A = Tap water at ph 2 CD-ROM Revisin 0

12 FIGURE 1. SAMPLE CHROMATOGRAM FOR EXTRACT OF WATER SPIKED AT µg/l WITH EDB AND DBCP CD-ROM Revisin 0

13 METHOD ,2-DIBROMOETHANE AND 1,2-DIBROMO-3-CHLOROPROPANE BY MICROEXTRACTION AND GAS CHROMATOGRAPHY CD-ROM Revisin 0