Journal of Separation Science
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Online ISSN: 1615-9314
July 31, 2007
Separation of Basic and Acidic Compounds by Capillary Electrochromatography using Monolithic Silica Capillary Columns with Zwitterionic Stationary PhaseJiwei Hu, Chuanhui Xie, Ruijun Tian, Zhike He, and Hanfa Zou, prepared a novel monolithic silica column with zwitterionic stationary phase by in situ covalent attachment of phenylalanine onto the 3-glycidoxypropyltriethoxysilane-modified silica monolith. Due to the zwitterionic nature of the resultant stationary phase, the density and sign of the net surface charge, and accordingly the direction and magnitude of electroosmotic flow (EOF) on this column in capillary electrochromatography (CEC), could be manipulated by adjusting the pH values of mobile phase. Separations of various acidic and basic compounds on the prepared column were performed under anodic and weak cathodic EOF modes in CEC, respectively. The peak tailing of basic compounds in CEC with silica column could be alleviated under optimized buffer compositions. Besides electrophoretic mechanism and weak hydrophobic interaction, weak cation- and anion- exchange interactions are involved in the separations of acids and bases on the zwitterionic column, respectively. The combination of oppositely charged groups and hydrophobic groups on the surface of the stationary phase provides unique properties for the separation acidic and basic compounds in CEC.
Jiwei Hu, Chuanhui Xie, Ruijun Tian, Zhike He, Hanfa Zou, J. Sep. Sci. 2007, 30 (6), 891-899.
Full article online, DOI: 10.1002/jssc.200600173