Quantitation of Aroclors using congener-specific results

As analytical capabilities have increased over the last 30 years, the standard approach applied to the analysis of polychlorinated biphenyls (PCBs) has slowly shifted from technical grade approximation to component-based analyses. This practice, although improving the quality and toxicologic relevance of the resulting data, has limited the historical database as a useful comparative set for current environmental research and is divergent from existing regulatory practices. Aroclor conversion factors have been calculated for each of 14 PCB congeners (International Union for Pure and Applied Chemistry [IUPAC] numbers 18, 28, 31, 99, 118, 128, 138, 149, 153, 180, 194, 195, 201, and 203), allowing quantification of PCB profiles as Aroclors 1248, 1254, and 1260 using measurements of these congeners. The three specified Aroclors are the dominant forms observed in the California marine environment. Speciation is accomplished by comparing characteristic congener ratios in the technical mixtures (31:118 for 1248 and 1254 and 118:203 for 1260) with those found in samples, providing a means for objectively minimizing biases introduced by cochromatographing Aroclor mixtures. The outlined procedure is shown to accurately detect, speciate, and quantify mixtures of multiple Aroclors. Additionally, comparing the predicted and actual concentration of PCB 153 in a sample provides a working index of weathering for these Aroclors.