Surface Heterogeneity Effects in Liquid-Solid Chromatography with Mixed Eluents

Abstract

Equations describing liquid-solid chronatography (LSC) systems with ideal surface and bulk phases and heterogeneous adsorbents are derived and discussed. It is shown that for a nixed surface phase formed on a heterogeneous solid surface the dependence of In k_s on In x^l ₁ is linear for higher concentrations of the first solvent and its slope is a function of the ratio of molecular sizes of solute and solvents, heterogeneity parameters and equilibrium constants describing phase exchange between solute and solvent molecules. However, for complete coverage of the surface by molecules of the first solvent this linear dependence becomes the Snyder-Soczewiński relationship, in which the slope depends solely on the ratio of molecular sizes of the solute and solvents. These results and an analysis presented herein also demonstrate that a recently proposed interpretation of the Snyder-Soczewiński equation in incorrect.