Similarity of an Aroclor-based and a full congener-based method in determining total PCBs and a modeling approach to estimate Aroclor speciation from congener-specific PCB data.

Polychlorinated biphenyls (PCBs) have entered the environment in North America as Aroclor technical mixtures. Most methods used for the determination of total PCB levels in environmental samples visually match patterns of sample peaks to those in Aroclor standards. Concern over the accuracy of Aroclor-based measurements on compositionally modified samples coupled with advancements in analytical techniques have led to congener-specific PCB analysis. In this study, the PCB data from 27 tissue samples determined by an Aroclor-based method and a full congener method were compared in terms of total PCB concentration to assess the reliability of this Aroclor technique for total PCB determination. Our data show a strong correlation between the sum of Aroclors and the total PCBs obtained from the full congener determinations. We also developed a model using the compositional data from three Aroclors (1242, 1254, and 1260) to determine the amount of compositional alteration from original Aroclor patterns in environmental samples. Full congener data, from a variety of tissue types and trophic levels, examined using this method showed that compositional modification from original Aroclor patterns increases with trophic level, with the greatest modification observed in seal and killer whale samples. This result agrees both with expectation and with what has been found in other studies. Such techniques, which connect congener-specific PCB data to Aroclor contamination, may prove useful to investigations into environmental and metabolic fate and transfer processes.