| Abstract: | Polychlorinated biphenyls (PCBs) are an important group of environmental pollutants, there being a total of 209 theoretical congeners. Residue analysis of the adipose tissue of five species of fish-eating sea birds from British and Irish coastal waters revealed the presence of up to 60 different congeners. By GC-MS, GC-MSD and high resolution capillary GC-ECD using authentic standards, it was possible to identify and quantify 40 different congeners. Despite the large number of PCB congeners identified only 10 accounted for > 80% of the total PCBs. A PCB congener was identified accounting for 5% of the total PCBs (2,3′,4,4′,5′,6-hexachlorobiphenyl) 168] not usually reported in biological samples. Comparison of the molecular structure for the persistent PCB congeners revealed the lack of meta-para unsubstituted adjacent carbon atoms. It has been shown that meta-para unsubstituted adjacent carbon atoms facilitate the metabolism of PCBs and it is hypothesised that the formation of hydroxy derivatives may depend upon such a requirement. |
