Selectivity at the Solid-Liquid Interface on Bonded Sorbents

Abstract

The rapid growth in the use of bonded phase silica adsorbents for reversed-phase liquid chromatography (RPLC) and solid-phase extraction (SPE) in recent years has sparked an interest in obtaining more than a working understanding of the surface chemistry of these systems. The dificulty in providing a descriptive model of the surface interactions on these materials lies in the complexity of the system. A structurally complex surface is presented by the highly porous silica support and the surface layer has contributions from solvents, the chemically bonded species, and the chemistry of the silica surface itself. All of these provide interactions with solutes of widely differing polarity and geometry in both chromatographic separations and selective adsorption experiments. The experimental investigations described in this work will address the three dimensional structure of the surface solvated layer, which acts as the stationary phase or extracting phase, in terms of a temperature and solvation dependent conformation change of the bonded hydrocarbon.