Photochemical technique for the elimination of chlorinated aromatic interferences in the gas-liquid chromatographic analysis for chlorinated paraffins.

A method is described for eliminating chlorinated aromatic interferences in the analysis for the more volatile chlorinated paraffins. Sample extracts are irradiated in aliphatic hydrocarbon solvents with high intensity ultraviolet light prior to detection of the chlorinated paraffin by microcoulometric gas-liquid chromatography. Chlorinated aromatic and unsaturated materials, including DDT and polychlorinated biphenyls, are selectively degraded to compounds containing little or no chlorine. Cycloaliphatic pesticides such as toxaphene, chlordane, and mirex are only partially degraded. Analysis of fish fillets fortified with 1 and 5 ppm of a chlorinated paraffin gave recoveries greater than 90%.