Preparation and evaluation of amphiphilic silica-based monolithic column having surface-bound octanoyl-aminopropyl moieties for capillary electrochromatography.

Abstract

A novel amphiphilic silica-based monolithic column having surface-bound octanoyl-aminopropyl moieties was successfully prepared by a one-step in situ derivatization process. As expected, the amphiphilic monolithic column exhibited RP chromatographic behavior toward non-polar solutes (e.g., alkyl benzenes) with high column performance. As the pH of the buffer inside the column increases, the EOF changed from -2.65 x 10(-8) m(2) V(-1) s(-1) at pH 3.0 to 1.20 x 10(-8) m(2) V(-1) s(-1) at pH 8.0 with the reversion of EOF at about pH 6.4. Using acidic mobile phase, five aromatic acids can be efficiently separated in less than 6 min under co-EOF conditions. For basic compounds, symmetrical peaks were obtained due to the existence of hydrophilic acyl amide group, which can effectively minimize the adsorption of the positively charged basic analyte to the silica-based surface of the capillary column.