Qsars for K-ow and K-oc of PCB congeners: A critical examination of data, assumptions and statistical approaches

A critical examination of data, assumptions and statistical approaches for previously published QSARs for the octanol-water and soil-water partition c oefficients (K-ow and K-oc) of polychlorinated biphenyl (PCB) congeners ide ntified a number of error sources. A variety of new QSARs were developed ba sed on weighted homogeneity of slopes models. The best type of models used the degree of chlorination in the orthoposition of the PCB molecule as pred ictor variable together with either the calculated molecular total surface area (TSA) or the gas chromatographic relative retention times (RRT). Predi ction of logK(ow) and logK(oc) for all 209 PCB congeners were based on 53 a nd 48 experimenter data points, respectively. The predicted values were com pared to test data sets of 12 and 27 experimental data points, respectively . The QSAR models gave predictions in good agreement with experimental test data. (C) 1999 Elsevier Science Ltd. All rights reserved.