LIQUID CHROMATOGRAPHY STUDIES OF ACETONITRILE SORPTION ON SILICA-BASED OCTYL PHASES

A complex mechanism of the reverse-phase chromatography can be envisioned as a combination of partition and adsorption processes. In the partition-displacement (P-D) model, partition accounts for the distribution of solute between the mobile and stationary phases, while displacement mostly involves competitive adsorption of solvents in the stationary phase. Therefore, chromatographic properties of a given stationary phase are largely dependent on the intercalation of solvents in the surface layer. The current work is a continuation of the ongoing studies of the factors affecting the surface composition of the stationary phase. Specifically, the goal of this work was the investigation of chromatographic behavior of two octyl phases of a similar surface coverage, which were synthesized from different silica supports. Analysis of methylene selectivity data showed that sorption of acetonitrile on both octyl phases was similar. This outcome could be related to a significant similarity of their structural and surface properties as demonstrated by analysis of the corresponding nitrogen adsorption and solid-state NMR data.