Separation Mechanisms in Gel Permeation Chromatography

Abstract

This paper presents flow rate studies, vacancy chromatography, and a static mixing experiment. Data obtained on an unpacked column (a straight tube) and on a column packed with nonporous glass beads are also reported. The results reveal that peak dispersion in GPC arises mainly from lateral diffusion in the stationary phase (permeation in and out of the porous substrate) and from lateral diffusion in the mobile phase. GPC peak separation is mainly dominated by the process of steric exclusion. Pore size distribution data obtained on Bio-Rad porous glass are shown to illustrate the preference of random coil theories over theories of the equivalent sphere in the interpretation of steric exclusion of flexible polymers. The data are discussed in terms of Herman's diffusion theory and Cassasa's exclusion theory.