关键词: 整体式毛细管柱, 光引发聚合, 分子印迹聚合物, 咖啡因

Abstract: Anovel and simple method for the in situ preparation of monolithic molecularly imprinted flowthrough polymers is described. The polymers were prepared inside UVtransparent fused silica capillaries by photoinitiated polymerization of a mixture of caffeine as the template, methacrylic acid as the functional monomer , trimethylolpropane trimethacrylate as the crosslinking agent in the presence of a porogenic solvent consisting of toluene and isooctane . Scanning electron micrographs confirmed the presence of the clusters of globules separated by large pores on the monolithic structure. The effectiveness of the imprinted polymer monolithic column was demonstrated in microcolumn liquid chromatography(μHPLC)mode by the screening of caffeine from a mixture of four structural analogues, the resolution factor Rs of 2.57 and 2.97 for the separation of caffeine against theophylline and theobromine, respectively, were obtained, while the nonimprinted column showed no specific selectivity. It is considered that the template was effectively imprinted in monolithic polymer by photoinitiated in situ polymerization at a low temperature. Several factors such as the molar ratio of the functional monomer to the imprint molecule and polymerization time affecting the flowthrough properties of a MIPcolumn were also investigated. The results show that the obtained columns exhibit higher resolution and column efficiency against the structural analogues than do columns packed with MIPprepared by bulk polymerization and columns packed with continuous molecularly imprinted polymer rod prepared by in stiu method.

Key words: Monolithic capillary column, Photoinitiated polymerization, Molecularly imprinted polymer, Caffeine