The ratio of 2,2',3,4',5',6-hexachlorobiphenyl (149) to 2,2',4,4',5,5'-hexachlorobiphenyl (153) as a possible degradational and analytical indicator

Hexachlorobiphenyls 149 (2,2',3,4',5',6-HxCB) and 153 (2,2',4,4',5,5'-HxCB) are among the more abundant congeners in many heavy chlorobiphenyl industrial mixtures. The former appears to be one of the most readily degradable congeners in several biotic matrices. In this paper experimental clues suggesting that the ratio of the two congeners cited varies gradually in matrices at different levels in the food chain are reported; in certain matrices the same ratio seems to be under metabolic control, and an abnormally high ratio can indicate possible outside contamination of the sample. (C) 1997 Academic Press.