Polychlorinated biphenyls: congener-specific analysis of a commercial mixture and a human milk extract

On the basis of the relative retention times and response factors of all 209 synthetic polychlorinated biphenyls (PCBs), this paper reports the first congener-specific analysis of a commercial PCB preparation, Aroclor 1260, and the PCB composition of a human milk extract. The analysis indicates that Aroclor 1260 contains nearly 80 different PCB congeners with the major components identified as 2,2',3,4',5',6-, 2,2,3,4,4',5,5'-, 2,2'3,4,5,5'-, and 2,2'3,4,4',5'-hexachlorobipheny l and 2,2'3,3',4,4',5-, 2,2',3,3',4,5,6'-, 2,2',3,4,4',5,5'-, and 2,2',3,4',5,5',6-heptachlorobiphenyl. In contrast, the major PCB components of the human milk fraction were the 2,4,4'-tri-, 2,4,4',5-tetra-, 2,2',4,4'5-penta-, 2,3',4,4',5-penta-, 2,2',3,4,4',5'-hexa-, 2,2',4,4',5,5'-hexa-, 2,2'3,3',4,4',5-hepta-, and 2,2'3,4,4',5,5'-heptachlorobiphenyls. The significance of congener-specific PCB analysis is dicussed in terms of the structure-activity effects on PCB persistence, bioaccumulation, and toxicity.