Evaluation of retention behavior and separation of pesticides were studied by supercritical fluid chromatography (SFC). In part I, SFC separations of the two analogous-structure groups with opposite polarities, synthetic pyrethroids and organophosphorus pesticides, were investigated using four packed columns and five capillary columns. Followed by successful separations of the pesticides in each group, the characteristic differences in the elution order of the pesticides among the stationary phases were discussed considering the polarization and molecular interaction. These considerations enable partial qualitative interpretation of the retention behaviors of some characteristic compounds. In part II, quantitative evaluation of retention behavior was examined. The parameters affecting the retention of synthetic pyrethroids and organophosphorus pesticides on five stationary phases in capillary SFC were evaluated. Par pyrethroid groups, the molecular weight had the highest correlation between the logarithms of the capacity factor (ln k'). For the evaluation of more polar organophosphorus pesticide groups, a new parameter for chromatographic retention, the inorganicity/organicity ratio (I/O), was introduced. While polarizability, a conventional steric parameter, gave poor results through all of the stationary phases, satisfactory correlation coefficients were obtained between ln k' and I/O. Thermodynamic considerations based on the definitions of this parameter supported the validity of the linearity. This descriptor was useful for evaluating the retention behavior of polar complex-structure chemicals as well as the polarities of stationary phases.
