Gas chromatographic determination of polychlorinated biphenyls and some chlorinated pesticides in sewage sludge using a glass capillary column.

Gas chromatographic methods for the determination of polychlorinated biphenyls and DDT (with some of its metabolites) in sewage sludge samples and similar materials are described. The sample is extracted with a mixture of hexane, acetone and water. After separation, the hexane phase is reduced in volume and divided into two aliquots, one of which is first shaken with 7% fuming sulphuric acid to remove lipids, and then with potassium cyanide to eliminate interference by elemental sulphur. The other aliquot is evaporated to dryness and heated with ethanolic potassium hydroxide. The two aliquots are injected into a gas chromatograph fitted with a glass capillary column and an electron capture detector. Hexabromobenzene is used as an internal standard. Polychlorinated biphenyls are determined quantitatively by comparing the peaks of the sample with those of Clophen A 50 or A 60. The individual percentage composition of the chlorobiphenyls in the polychlorinated biphenyl oils is used. The capillary column is coated with silicone oil SF 96 according to a described procedure.