EPA-NERL: 508A: PCBs by GCECD
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Official Method Name
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Screening for Polychlorinated Biphenyls by Perchlorination and Gas Chromatography |
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Current Revision
| Revision 1.0, 1989 |
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Media
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WATER |
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Instrumentation
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Gas Chromatography with Electron Capture Detection |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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A 1-L sample is placed into a separatory funnel and extracted with methylene chloride or one of several optional solvents. The extract is dried, concentrated, and the solvent is exchanged to chloroform. The PCBs are then reacted with antimony pentachloride (SbCl5) (in the presence of an iron catalyst and heat) to form DCB. The DCB is extracted with hexane from the reaction mixture; after the extract is purified, PCBs in the extract are detected by measuring the DCB product using a gas chromatography (GC) system equipped with an electron capture detector (ECD). |
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Scope and Application
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This method can be used to screen for polychlorinated biphenyls (PCBs) in finished drinking water, raw source water, or drinking water in any treatment stage. This procedure is applicable to samples containing PCBs as single congeners or as complex mixtures such as weathered, intact, or mixtures of commercial Aroclors. The procedure is incapable of identifying the parent PCBs because the original PCBs are chemically converted to a common product, decachlorobiphenyl (DCB). The procedure has only been evaluated using Aroclors and 2-chlorobiphenyl as a source of PCBs. |
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Applicable Concentration Range
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0.5 ug/L (will accurately measure DCB to 5.0 ug/L) |
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Interferences
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(A) Glassware contamination: Thoroughly clean glassware, including baking or solvent rinse. (B) Reagent contamination: Use high purity reagents. (C) Non-PCB-compounds which form DCB: Biphenyl, polyhalogenated biphenyls, hydrogenated biphenyls, and polyhalogenated terphenyls can form DCBs, generating false positives for PCBs. (D) Variable solvents: Use the same solvent for each analysis. |
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Quality Control Requirements
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Initial demonstration of laboratory capability, initial calibration checks, continuing calibration checks, extract matrix effect evaluation, laboratory reagent blanks (LRB), laboratory fortified blanks (LFBs), and laboratory fortified samples. |
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Sample Handling
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Collect duplicate samples in 1 L glass containers sealed with a Teflon-lined screw cap, filling bottles to about 90-95% full. If suspended solids are present in the source, a representative portion of solids must also be included in the water sample. No chemical preservation reagents are recommended. Store samples at 4oC until analysis. |
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Maximum Holding Time
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14 days. Extracts and perchlorinated extracts up to 30 days. |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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