CHEMICALLY MODIFIED C SILICA-BASED COLUMNS: UNIVERSAL STATIONARY PHASES FOR HPLC SEPARATIONS

We tested the retention of phenolic acids in full mobile phase (acetonitrile/water containing buffer) composition range on two chemically modified hydrosilated (C silica-based) columns in order to show versatility of those stationary phases. Cogent UDC cholesterol (TM) and Cogent bidentate C18 (TM) columns show significant dual reversed-phase/normal-phase retention behavior, hence those stationary phases can be used both in aqueous normal-phase (ANP) and in reversed-phase (RP) modes. The effect of the aqueous acetate buffer concentration on retention factors of phenolic acids over the full mobile phase composition range, including both ANP and RP mechanisms, can be described by a four-parameter equation for dual-retention mechanism.