Role of Intermolecular Interactions in Chromatographic Separations

Abstract

A survey is presented of column chromatography, with special emphasis on intermolecular interactions that are at the origin of selectivity in chromatographic separations. In gas chromatography, differences in electronic dispersion, dipole-induced dipole and dipole-dipole interaction as well as differences in hydrogen bonding, E.D.A.-complexation and coordination- compound formation of the stationary phase (liquid or solid) with solutes to be separated may all contribute to selectivity. In addition, differences in the size and shape of solute molecules may also contribute to selectivity in special cases. The characterization of stationary liquids according to their potential for interaction is discussed. Numerous examples are presented to illustrate the role of intermolecular interactions in analytical separations by gas chromatography. Differences in both non-specific and specific intermolecular interactions between solutes to be separated and the stationary as well as the mobile phase may contribute to selectivity in liquid chromatography. In addition, separations may be achieved on the basis of differences in ionic equilibria as well as on the basis of differences in the size and shape of solute molecules, depending on the chromatographic technique employed. A survey of liquid chromatography techniques is given. A number of examples are presented to illustrate the role of intermolecular interactions in liquid chromatography separations.