EPA Method 8151A Chlorinated Herbicides by GC Using Methylation or Pentafluorobenzylation Derivatization - Revision 1
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8C4297B437294BA700EE999DF341C603 |
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文件大小(MB)： |
0.18 |
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页数： |
31 |
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日期： |
2003-1-16 |
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CD-ROM 8151A - 1 Revision 1,December 1996,METHOD 8151A,CHLORINATED HERBICIDES BY GC USING METHYLATION OR,PENTAFLUOROBENZYLATION DERIVATIZATION,1.0 SCOPE AND APPLICATION,1.1 Method 8151 is a capillary gas chromatographic (GC) method for determining certain,chlorinated acid herbicides and related compounds in aqueous, soil and waste matrices.,Specifically, Method 8151 may be used to determine the following compounds:,Compound CAS No.a,2,4-D 94-75-7,2,4-DB 94-82-6,2,4,5-TP (Silvex) 93-72-1,2,4,5-T 93-76-5,Dalapon 75-99-0,Dicamba 1918-00-9,Dichloroprop 120-36-5,Dinoseb 88-85-7,MCPA 94-74-6,MCPP 93-65-2,4-Nitrophenol 100-02-1,Pentachlorophenol 87-86-5,a Chemical Abstract Service Registry Number,1.2 Because these compounds are produced and used in various forms (i.e., acid, salt, ester,etc.), Method 8151 describes a hydrolysis step that can be used to convert herbicide esters into the,acid form prior to analysis. Herbicide esters generally have a half-life of less than one week in soil.,1.3 When Method 8151 is used to analyze unfamiliar samples, compound identifications,should be supported by at least one additional qualitative technique. Sec. 8.4 provides gas,chromatograph/mass spectrometer (GC/MS) criteria appropriate for the qualitative confirmation of,compound identifications.,1.4 The estimated detection limits for each of the compounds in aqueous and soil matrices,are listed in Table 1. The detection limits for a specific waste sample may differ from those listed,depending upon the nature of the interferences and the sample matrix.,1.5 The following compounds may also be determined using this method:,CD-ROM 8151A - 2 Revision 1,December 1996,Compound CAS No.a,Acifluorfen 50594-66-6,Bentazon 25057-89-0,Chloramben 133-90-4,DCPA diacidb 2136-79-0,3,5-Dichlorobenzoic acid 51-36-5,5-Hydroxydicamba 7600-50-2,Picloram 1918-02-1,a Chemical Abstract Service Registry Number,b DCPA monoacid and diacid metabolites included in method scope; DCPA diacid,metabolite used for validation studies. DCPA is a dimethyl ester.,1.6 This method is restricted to use by or under the supervision of analysts experienced in,the use of gas chromatography and skilled in the interpretation of gas chromatograms. Each analyst,must demonstrate the ability to generate acceptable results with this method.,1.7 Only experienced analysts should be allowed to work with diazomethane due to the,potential hazards associated with its use (explosive, carcinogenic).,2.0 SUMMARY OF METHOD,2.1 Method 8151 provides extraction, derivatization, and gas chromatographic conditions for,the analysis of chlorinated acid herbicides in water, soil, and waste samples. An option for the,hydrolysis of esters is also described.,2.2 Water samples are extracted with diethyl ether and then esterified with either,diazomethane or pentafluorobenzyl bromide. The derivatives are determined by gas chromatography,with an electron capture detector (GC/ECD). The results are reported as acid equivalents.,2.3 Soil and waste samples are extracted and esterified with either diazomethane or,pentafluorobenzyl bromide. The derivatives are determined by gas chromatography with an electron,capture detector (GC/ECD). The results are reported as acid equivalents.,2.4 If herbicide esters are to be determined using this method, hydrolysis conditions for the,esters in water and soil extracts are described.,2.5 The sensitivity of Method 8151 depends on the level of interferences in addition to,instrumental limitations. Table 1 lists the GC/ECD and GC/MS detection limits that can be obtained,in aqueous and soil matrices in the absence of interferences. Detection limits for a typical waste,sample should be higher.,CD-ROM 8151A - 3 Revision 1,December 1996,3.0 INTERFERENCES,3.1 Refer to Method 8000.,3.2 Method interferences may be caused by contaminants in solvents, reagents, glassware,and other sample processing hardware that lead to discrete artifacts or elevated baselines in gas,chromatograms. All these materials must be routinely demonstrated to be free from interferences,under the conditions of the analysis, by analyzing reagent blanks.,3.2.1 Glassware must be scrupulously cleaned. Clean each piece of glassware as,soon as possible after use by rinsing it with the last solvent used in it. This should be followed,by detergent washing with hot water and rinses with tap water, then with organic-free reagent,water. Glassware should be solvent-rinsed with acetone and pesticide-quality hexane. After,rinsing and drying, glassware should be sealed and stored in a clean environment to prevent,any accumulation of dust or other contaminants. Store glassware inverted or capp……
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