Estimation of vapor pressures for polychlorinated biphenyls: a comparison of eleven predictive methods.
Eleven methods were used to predict vapor pressures at 25.0/sup 0/C for 15 polychlorinated biphenyls with experimental values. These results permitted an assessment of the predictive ability of these methods for compounds with low vapor pressures (<1.0 Pa) and one or less experimental determinations. The error for theoretically based methods was high and increased with decreasing vapor pressure. The correlative methods, based on a set of compounds with known vapor pressures, had much better predictive power. The best correlative method was based on a relationship between ..delta..G/sub v/ and gas-liquid chromatographic retention indexes. The predictive error for this method was estimated to be a factor of 1.75. Vapor pressures obtained by using the three best correlative methods for all polychlorinated biphenyls are reported.