Preparation and Evaluation of C18 Modified Capillary Open-Tubular Column Based on Thiol-ene Click Chemistry for Capillary Electrochromatography

A novel C18 open-tubular column (C18 capillary) for capillary electrochromatography was prepared based on thiol-ene click chemistry between n-octadecanethiol and vinyl-functionalized capillary (vinyl capillary). The inner wall of capillary was chemically modified with vinyltrimethoxysilane to provide ene-functionality. Then n-octadecanethiol was chemically bonded on the surface of vinyl capillary via thiol-ene click chemistry. The surface features of the prepared C18 capillary was investigated using scanning electron microscopy. The effects of buffer pH on the electroosmotic flow of C18 capillary, vinyl capillary was compared with bare capillary. The experiment results indicated that the lowest EOF profile was obtained on the C18 capillary under the same experimental conditions compared with vinyl capillary and bare capillary. To evaluate the column performance, test mixture of three polycyclic aromatic hydrocarbons (PAHs) were electrochromatographic separation on C18 capillary, vinyl capillary and bare capillary. The electrochromatographic retention behavior of the selected model PAHs on C18 capillary was also investigated. The experiment results showed that C18 capillary exhibits typical reversed-phase electrochromatographic behavior toward PAHs. Compared with vinyl capillary, the relatively good peak shape and no peak tailing was observed for the separation of basic model analytes on C18 capillary, which may be attributed to embedded polar sulphur groups on the surface of the C18 capillary that effectively shield the adsorption of basic analytes onto the residual silanol groups.