On the Origins of Flow-Rate Dependence of Elution Volume in Gel Permeation Chromatography

Abstract

The peak elution volume of a narrow polystyrene fraction in a porous silica column is a function of the solvent flow rate through the column. The explanation for this effect offered by Gudzinowicz and Alden and others is that the equilibrium assumption, usually made in size exclusion Chromatography, is no longer valid at high flow rates. An alternative explanation based on a flow-rate-dependent equilibrium distribution coefficient (ratio of intrapore polymer concentration to extrapore polymer concentration) is offered here. This view is supported by experimental results for the equilibrium flow-rate-dependent column retention measured previously in these columns.