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Region 9 Laboratory SOP 212
Extraction of Water Samples by Continuous Liquid-Liquid Extraction of Water Sample
Summary
This standard operating procedure (SOP) describes the procedures used to extract semivolatile organic compounds (SVOCs) and organochlorine pesticides and polychlorinated biphenyls (PCBs) from water samples using continuous liquid-liquid extraction. Extracts produced by this procedure are suitable for analysis by EPA Region 9 (R9) Lab. SOP #315 Semivolatile Organics Analysis, #330 Pesticides & PCB (Water, Sediment, Soil) by GC, and #335 Polychlorinated Biphenyls (PCBs) by GC. This procedure is applicable to finished water, groundwater, and waste water samples. This SOP is based on procedures in SW-846 Method 3520C, Continuous Liquid- Liquid Extraction, Revision 3, December 1996.
A measured volume of aqueous sample, approximately one liter, is placed in a continuous liquidliquid extractor. The pH of the sample is adjusted, if necessary, then the sample is fortified with a surrogate solution and extracted with methylene chloride for 18 to 24 hours.
Extracts for SVOC analysis are dried with sodium sulfate and concentrated to 1.0 mL using a Kuderna-Danish apparatus and nitrogen evaporation. The concentrated extracts are then analyzed by gas chromatography/mass spectrometry (GC/MS) according to R9 Lab. SOP #315.
Extracts for organochlorine pesticides and PCB analysis are dried with sodium sulfate and the solvent exchanged for hexane then concentrated to 10.0 mL using a Kuderna- Danish apparatus and nitrogen evaporation. The concentrated extracts are then analyzed by gas chromatography/electron capture detector (GC/ECD) using R9 Lab. SOP #330. Extracts may be cleaned up using Florisil cartridge if the analyst deems it necessary. Extracts may be prepared for the analysis of PCBs only which includes an acid cleanup step prior to analysis by SOP #335.