Effect of the Type of Organic Modifiers on Mass Transfer in Reversed-Phase Liquid Chromatography

Abstract

The mass-transfer characteristics were studied in a reversed-phase liquid chromatography consisting of an octadecylsilyl-silica gel and acetonitrile/water mixture (70/30, vol), and were compared with those obtained by using methanol/water (70/30, vol). In the two chromatographic systems, similar tendencies were observed for various adsorption characteristics. However, their absolute values were not entirely identical. Irrespective of the type of organic modifiers, surface diffusion was dominant for intraparticle diffusion. Similar correlations were also demonstrated with regard to the surface diffusion, i.e., the enthalpy-entropy compensation and the linear free-energy relation, suggesing a similarity in the surface migration mechanism in the two chromatographic systems. A few estimation procedures of the surface diffusion coefficient were proposed.