Steps in the procedure for the analysis of 25 chlorinated pesticides and polychlorinated biphenyls were studied. Two gas chromatographic columns and two detectors (electron capture and Hall electrolytic conductivity) were evaluated. Extractions were performed with two solvents (dichloromethane and 15 percent dichloromethane in hexane) at 3 pH's to determine extraction efficiencies. The effects of storage for 7 days, in the presence of residual chlorine, at two temperatures were determined. Florisil and alumina were compared as adsorbents for the cleanup of extracts. Recoveries of the substances from clean water and wastewater were measured, and assessments of accuracy and precision were made. The method is satisfactory for the analysis of clean waters and wastewaters having a relatively low background of interferences. However, it does not work well against medium to high levels of background interferences produced by substances that are electron capture sensitive, especially halogenated ones. Use of the Hall detector is indicated when nonhalogenated electron capture sensitive interferences are a problem, even though some loss in sensitivity will occur. When halogenated interferences are overwhelming, altered gas chromatography conditions and columns, such as temperature programming and columns which produce better resolution than the ones studied in this work, will be required.

"April 1982." Microfiche.