Preparation and Characterization of Butylaminopropyl Silica Monolithic Column for Capillary Electrochromatography

A novel silica monolithic stationary phase functionalized with butylaminopropyl ligands for capillary electrochromatography (CEC) has been presented. The monolithic capillary columns were prepared by a sol-gel process and a subsequent chemical modification followed. The amino groups on the surface of the stationary phase generate a substantial anodic electroosmotic flow (EOF) and the butyl groups together with propyl groups provide sufficient hydrophobic properties. To evaluate the column performance, effects of buffer pH on the EOF and electrochromatographic retention behavior of alkylbenzenes, organic acids, and anilines were investigated. The monolithic stationary phase exhibited reversed-phase (RP) chromatographic behavior toward neutral solutes. The standard organic acid anion solutes were separated by a mixed mode mechanism, which comprised of RP interaction, weak anion-exchange, and electrophoresis. Basic compounds such as anilines were well separated on the butylaminopropyl silica monolithic column without peak tailing.