Quantitative correlations between reversed-phase LC data and molecular parameters for some weakly related pesticides

Retention in reversed-phase liquid chromatography for some polar and weakly related pesticides(urea derivatives or containing the thiophosphate group), using two types of stationary phases (C8 and C18), was studied for different compositions of mobile phase in order to estimate extrapolated values of capacity factor for entirely aqueous content of mobile phase. Two organic modifiers were used in composition of mobile phase: methanol or acetonitrile. The inter-correlations between extrapolated values for the two types of stationary phase were very high. The extrapolated values for studied pesticides were correlated by linear and multilinear regressions with molecular parameters, computed by means of different theoretical approaches (PM3 quantum chemical model, and DFT computational scheme). The best correlations were obtained for extrapolated values from retention study using acetonitrile as organic modifier in mobile phase composition.