EPA Method 8121 Chlorinated Hydrocarbons by Gas Chromatography_ Capillary Column Technique - Revision 0
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DA0F8209970D4F839B473401BBA4EDDC |
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文件大小(MB)： |
0.23 |
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页数： |
25 |
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日期： |
2003-1-16 |
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CD-ROM 8121 - 1 Revision 0,September 1994,METHOD 8121,CHLORINATED HYDROCARBONS BY GAS CHROMATOGRAPHY: CAPILLARY COLUMN TECHNIQUE,1.0 SCOPE AND APPLICATION,1.1 Method 8121 describes the determination of chlorinated hydrocarbons,in extracts prepared from environmental samples and RCRA wastes. It describes,wide-bore open-tubular, capillary column gas chromatography procedures using both,single column/single detector and dual-column/dual-detector approaches. The,following compounds can be determined by this method:,Compound Name CAS Registry No.a,Benzal chloride 98-87-3,Benzotrichloride 98-07-7,Benzyl chloride 100-44-7,2-Chloronaphthalene 91-58-7,1,2-Dichlorobenzene 95-50-1,1,3-Dichlorobenzene 541-73-1,1,4-Dichlorobenzene 106-46-1,Hexachlorobenzene 118-74-1,Hexachlorobutadiene 87-68-3,-Hexachlorocyclohexane ( -BHC) 319-84-6,-Hexachlorocyclohexane ( -BHC) 319-85-7,-Hexachlorocyclohexane ( -BHC) 58-89-9,-Hexachlorocyclohexane ( -BHC) 319-86-8,Hexachlorocyclopentadiene 77-47-4,Hexachloroethane 67-72-1,Pentachlorobenzene 608-93-5,1,2,3,4-Tetrachlorobenzene 634-66-2,1,2,4,5-Tetrachlorobenzene 95-94-2,1,2,3,5-Tetrachlorobenzene 634-90-2,1,2,4-Trichlorobenzene 120-82-1,1,2,3-Trichlorobenzene 87-61-6,1,3,5-Trichlorobenzene 108-70-3,a Chemical Abstract Services Registry Number.,1.2 The dual-column/dual-detector approach involves the use of two,30 m x 0.53 mm ID fused-silica open-tubular columns of different polarities, thus,different selectivities towards the target compounds. The columns are connected,to an injection tee and two identical detectors. When compared to the packed,columns, the megabore fused-silica open-tubular columns offer improved,resolution, better selectivity, increased sensitivity, and faster analysis.,1.3 Table 1 lists method detection limits (MDL) for each compound in an,organic-free reagent water matrix. The MDLs for the compounds of a specific,sample may differ from those listed in Table 1 because they are dependent upon,CD-ROM 8121 - 2 Revision 0,September 1994,the nature of interferences in the sample matrix. Table 2 lists the estimated,quantitation limits (EQL) for other matrices.,1.4 Table 3 lists the compounds that have been determined by this method,and their retention times using the single column technique. Table 4 lists dual,column/dual detector retention time data. Figures 1 and 2 are chromatograms,showing the single column technique. Figure 3 shows a chromatogram of the target,analytes eluted from a pair of DB-5/DB-1701 columns and detected with electron,capture detectors (ECD) under the prescribed GC conditions listed in Table 2.,1.5 This method is restricted to use by or under the supervision of,analysts experienced in the use of a gas chromatograph and in the interpretation,of gas chromatograms.,2.0 SUMMARY OF METHOD,2.1 Method 8121 provides gas chromatographic conditions for the detection,of ppb concentrations of chlorinated hydrocarbons in water and soil or ppm,concentrations in waste samples. Prior to use of this method, appropriate sample,extraction techniques must be used for environmental samples (refer to Chapt. 2).,Both neat and diluted organic liquids (Method 3580) may be analyzed by direct,injection. Spiked samples are used to verify the applicability of the chosen,extraction technique to each new sample type. Analysis is accomplished by gas,chromatography utilizing an instrument equipped with wide bore capillary columns,and single or dual electron capture detectors.,3.0 INTERFERENCES,3.1 Refer to Methods 3500, 3600, and 8000.,3.2 The electron capture detector responds to all electronegative,compounds. Therefore, interferences are possible by other halogenated compounds,as well as phthalates and other oxygenated compounds, and, organonitrogen,organosulfur and organophosphorus compounds. Second column confirmation or GC/MS,confirmation are necessary to ensure proper analyte identification unless,previous characterization of the sample source will ensure proper identification.,3.3 Contamination by carryover can occur whenever high-concentration and,low-concentration samples are sequentially analyzed. To reduce carryover, the,syringe used for injection must be rinsed out between samples with solvent.,Whenever an extract concentration exceeds that of the highest calibration,standard, it should be followed by the analysis of a solvent blank to check for,cross-contamination. Additional solvent blanks interspersed with the sample,extracts should be considered whenever the analysis of a solvent blank indicates,cross-contamination problems.,3.4 Phthalate esters, if present in a sample, will interfere only with,the BHC isomers because they elute in ……
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