SHAPE-DISCRIMINATION IN LIQUID-CHROMATOGRAPHY USING CHARGE-TRANSFER PHASES

A variety of factors affect the ability of a given column to discriminate between compounds on the basis of shape (shape selectivity). In reversed-phase systems, bonded phases based on monomeric surface modification exhibit low shape selectivity; phases based on polymeric surface modifications exhibit enhanced shape selectivity. Even greater shape specificity is exhibited by charge-transfer columns, operated in the normal-phase mode. In this work, the retention behavior of electron-acceptor and electron-donor charge-transfer phases was studied for the separation of polycyclic aromatic hydrocarbon isomers (PAHs), methyl-substituted PAHs, and polychlorinated biphenyl congeners (PCBs). In all cases, planar compounds were retained in preference to corresponding nonplanar analogues.