Osmotic Effects in Gel Permeation Chromatography with Multicomponent Solvents

Abstract

Secondary separation mechanisms are important in a GPC-column when multicomponent eluents are used. The solvent will be at a lower potential in the injected sample than in the eluent, leading to a separation or redistribution of components by the osmotic pressure differences. The smallest components will dominate the separation due to the highest diffusion rates. When charged macromolecules are present, the Donnan equilibrium also contributes to the redistribution of salt. For some surfactant systems, the micellar size is very sensitive to salt concentration, which can give quite complex GPC-chromatograms. In order to discuss GPC-results from polymer-surfactant systems with repulsive interactions, these secondary separation mechanisms must be included.