Axial dispersion of solute zones in gel permeation chromatography

Abstract

The two essential aspects of axial dispersion in gel permeation chromatography have been studied: (1) the relationship of axial dispersion to the continuity equations of chromatographic transport, and (2) the relationship to molecular size and the system parameters of an individual column. Theoretical analyses are presented for both of these problems and are applied to an experimental study of axial dispersion by both zonal (small‐zone) and frontal (large‐zone) experiments with a series of macromolecular species having discrete, precisely known molecular weights. Theoretically predicted non‐Gaussian elution profiles were observed for the small‐zone experiments, and axial dispersion coefficients for each molecular species were determined as a function of flow rate. Resulting values were found to be in good agreement with the theoretical equation relating axial dispersion to molecular size, flow rate, and two “calibration constants” of the column. These results provide a rational basis for axial dispersion effects in terms of the fundamental processes and system parameters of gel columns. Extension of the analysis to multicomponent systems is discussed.