EPA Method 8020A Aromatic Volatile Organics by Gas Chromatography - Revision 1
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FD95C36F99754F82BBC68F5681832734 |
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文件大小(MB)： |
0.09 |
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页数： |
14 |
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日期： |
2008-2-26 |
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CD-ROM 8020A - 1 Revision 1,September 1994,METHOD 8020A,AROMATIC VOLATILE ORGANICS BY GAS CHROMATOGRAPHY,1.0 SCOPE AND APPLICATION,1.1 Method 8020 is used to determine the concentration of various,aromatic volatile organic compounds. The following compounds can be determined,by this method:,______________________________________________________________________________,Appropriate Technique,Direct,Compound Name CAS No.a Purge-and-Trap Injection,Benzene 71-43-2 b b,Chlorobenzene 108-90-7 b b,1,2-Dichlorobenzene 95-50-1 b b,1,3-Dichlorobenzene 541-73-1 b b,1,4-Dichlorobenzene 106-46-7 b b,Ethylbenzene 100-41-4 b b,Toluene 108-88-3 b b,Xylenes b b,______________________________________________________________________________,a Chemical Abstract Services Registry Number.,b adequate response by this technique.,1.2 Table 1 lists the method detection limit for each target analyte in,organic-free reagent water. Table 2 lists the estimated quantitation limit (EQL),for other matrices.,2.0 SUMMARY OF METHOD,2.1 Method 8020 provides chromatographic conditions for the detection of,aromatic volatile compounds. Samples can be introduced into the GC using direct,injection or purge-and-trap (Method 5030). Ground water samples must be,determined using Method 5030. A temperature program is used in the gas,chromatograph to separate the organic compounds. Detection is achieved by a,photo-ionization detector (PID).,2.2 If interferences are encountered, the method provides an optional gas,chromatographic column that may be helpful in resolving the analytes from the,interferences and for analyte confirmation.,3.0 INTERFERENCES,3.1 Refer to Method 5030 and 8000.,CD-ROM 8020A - 2 Revision 1,September 1994,3.2 Samples can be contaminated by diffusion of volatile organics,(particularly chlorofluorocarbons and methylene chloride) through the sample,container septum during shipment and storage. A field sample blank prepared from,organic-free reagent water and carried through sampling and subsequent storage,and handling can serve as a check on such contamination.,4.0 APPARATUS AND MATERIALS,4.1 Gas chromatograph,4.1.1 Gas Chromatograph - Analytical system complete with gas,chromatograph suitable for on-column injections or purge-and-trap sample,introduction and all required accessories, including detectors, column,supplies, recorder, gases, and syringes. A data system for measuring peak,heights and/or peak areas is recommended.,4.1.2 Columns,4.1.2.1 Column 1: 6 ft x 0.082 in ID #304 stainless steel,or glass column packed with 5% SP-1200 and 1.75% Bentone-34 on,100/120 mesh Supelcoport, or equivalent.,4.1.2.2 Column 2: 8 ft x 0.1 in ID stainless steel or,glass column packed with 5% 1,2,3-Tris(2-cyanoethoxy)propane on,60/80 mesh Chromosorb W-AW, or equivalent.,4.1.3 Detector - Photoionization (PID) (h-Nu Systems, Inc. Model,PI-51-02 or equivalent).,4.2 Sample introduction apparatus - Refer to Method 5030 for the,appropriate equipment for sample introduction purposes.,4.3 Syringes - A 5 mL Luerlok glass hypodermic and a 5 mL, gas-tight with,shutoff valve.,4.4 Volumetric flask, Class A - Appropriate sizes with ground glass,stoppers.,4.5 Microsyringe - 10 and 25 μL with a 0.006 in ID needle (Hamilton 702N,or equivalent) and a 100 μL.,4.6 Analytical balance - 0.0001 g.,5.0 REAGENTS,5.1 Organic-free reagent water. All references to water in this method,refer to organic-free reagent water, as defined in Chapter One.,5.2 Methanol (CH3OH) - pesticide quality or equivalent. Store away from,other solvents.,CD-ROM 8020A - 3 Revision 1,September 1994,5.3 Stock standards - Stock solutions may be prepared from pure standard,materials or purchased as certified solutions. Prepare stock standards in,methanol using assayed liquids. Because of the toxicity of benzene and,1,4-dichlorobenzene, primary dilutions of these materials should be prepared in,a hood.,5.3.1 Place about 9.8 mL of methanol in a 10 mL tared ground glass,stoppered volumetric flask. Allow the flask to stand, unstoppered, for,about 10 min or until all alcohol wetted surfaces have dried. Weigh the,flask to the nearest 0.0001 g.,5.3.2 Using a 100 μL syringe, immediately add two or more drops of,assayed reference material to the flask; then reweigh. The liquid must,fall directly into the alcohol without contacting the neck of the flask.,5.3.3 Reweigh, dilute to volume, stopper, and then mix by inverting,the flask several times. Calculate the concentration in milligrams per,liter (mg/L) from the net gain in weight. When compound purity is assayed,to be 96% or greater, the weight may be used without correction to,calculate the concentration of the stock standard. ……
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