Intermolecular Interactions Involved in Solute Retention on Carbon Media in Reversed-Phase High-Performance Liquid Chromatography

Carbon adsorbents for RPLC separations are greatly underutilized due to the poor chromatographic properties of the earliest commercially available materials and our limited understanding of solute interactions with the solid surface. Previously, we reported on the properties of a carbon surface prepared by vapor deposition on porous zirconia microspheres. The resulting material is a new type of carbon sorbent with considerably improved chromatographic properties. Here we present a fundamental study of the intermolecular interactions influencing solute retention on these novel carbon phases under RPLC conditions. Retention on seven unique carbon phases has been correlated with solute descriptors of dispersion, dipolarity/polarizability, and hydrogen bond basicity through the use of linear solvation energy relationships (LSERs). In stark contrast, conventional bonded phases do not show the large contribution from dipolarity/ polarizability that is observed on these types of carbon. The presence of this interaction indicates a distinct difference between carbon and conventional bonded RPLC phases. Other results suggest that solvent sorption plays a significant role in controlling solute retention on carbon. In addition, we investigated the temperature dependence of retention on carbon and found typical RPLC-like behavior.