Numerical correction for asymmetrical peak profiles for moment analysis of chromatographic behavior

Abstract

A numerical correction method is proposed for the moment analysis of some properties of chromatographic columns, even when the profiles of their elution peaks exhibit some asymmetry. Information on the retention equilibrium and the mass transfer kinetics of a C18-silica gel packing material is derived by the moment analysis from the experimental data obtained under three different sets of conditions: (1) the tailing peaks eluted from the column used; they are not corrected by the numerical method; (2) the same peaks are corrected by the numerical method, which provides the information on the column radial heterogeneity and on the efficiency at its center; and (3) symmetrical peaks having nearly Gaussian profiles eluted from another column packed with the same material; these peaks are not corrected by the numerical method. The analytical results obtained under the three different conditions are compared. The results demonstrate that the numerical correction method allows the determination of the information on the chromatographic behavior of columns from asymmetrical peak profiles, i.e., column efficiency at radial center, order of the polynomial functions for representing the radial distributions of mobile phase flow velocity and column efficiency, ratio of the flow velocity near the wall to that at the column center, and ratio of the column efficiency near the wall to that at the column center.