Quantitative structure-retention relationships for polychlorinated biphenyls and chlorobenzenes on selected normal-phase liquid chromatographic stationary phases

Linear regression between capacity factors and solute properties is performed to evaluate quantitative structure-retention relationships. A general increase in retention on porous graphitic carbon (PGC) and 2-(1-pyrenyl)ethyldimethyl silica (PYE) stationary phases operated in normal-phase liquid chromatography is shown to correlate with increasing polarizability and decreasing energy of the lowest unoccupied molecular orbital of the solutes. The best prediction of capacity factors is achieved when the retention model is restricted to chlorinated benzenes or non-ortho-substituted chlorobiphenyls (i.e., solutes with a low degree of steric hindrance). The retention of chlorinated benzenes on PCC and PYE is successfully described by only one parameter, the third order valence path molecular connectivity index (3χvp ). The coefficients of determination between measured and predicted log k1 values are 0.994 and 0.992 for PGC and PYE, respectively. A 2,4-dinitroanilinopropyl silica column demonstrated other retention characteristics clearly different from PGC and PYE.