Rapid semi-micro method for separating non-ortho chlorinated chlorobiphenyls from other chlorobiphenyls

Abstract

A method for separating common non-ortho chlorinated chlorobiphenyls, namely 3,4,4′-tri-, 3,4,4′,5-, 3,3′,4,4′-tetra, 3,3′,4,4′,5-penta-, and 3,3′4,4′,5,5′-hexachlorobiphenyl (IUPAC Nos. 37, 81, 77, 126, and 169) from other chlorobiphenyls in shellfish tissue at pg g^–1 wet mass concentrations is described. The method is based on saponification followed by extraction into 2,2,4-trimethylpentane, clean-up by gel-permeation chromatography and sulfuric acid treatment, separation of non-ortho chlorinated chlorobiphenyls from other chlorobiphenyls using a Florisil–carbon column and measurement using capillary GC–low resolution MS with selected ion monitoring to eliminate many interfering materials. Recoveries of chlorobiphenyls (20–5000 pg g^–1 wet mass) averaged 84.5 ± 6.5%. The detection limits (3 times the noise level) are 20 pg g^–1 wet mass for IUPAC Nos. 37, 77, 81, and 126 and 50 pg g^–1 wet mass IUPAC No. 169. The method gave results for non-ortho chlorinated chlorobiphenyl concentrations in lobster digestive gland tissues and Aroclors equivalent to those obtained by a conventional procedure.