咖啡因分子印迹固相萃取柱的制备及应用

以咖啡因作为模板分子,α-甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,制备了咖啡因分子印迹聚合物(MIP)。与非印迹聚合物(NIP)相比,MIP对咖啡因具有更高的吸附容量和选择性,MIP和NIP对咖啡因的最大静态吸附量分别为28.1和16.5mg/g,相对选择因子为1.25。以咖啡因分子印迹聚合物为固相萃取填料,结合高效液相色谱(HPLC),建立了茶水中咖啡因浓度及人饮茶后血清中咖啡因浓度的检测方法。考察了洗脱剂种类和用量对咖啡因回收率的影响。当萃取柱依次以2mL水活化,水溶液上样,2mL水淋洗,6mL甲醇-乙酸(9∶1,V/V)洗脱,咖啡因在MIP固相萃取柱上的回收率达到97.5%,而在NIP柱上的回收率仅为54.9%。

Preparation of Caffeine Molecularly Imprinted Polymers and Application on Solid Phase Extraction

The molecular imprinted polymer(MIP) was synthesized by precipitation polymerization with caffeine as template,methacrylic acid(MAA) as functional monomer and ethylene glycol dimethacrylate(EDMA) as cross-linker.Compared with non-imprinted polymer(NIP) particles,the prepared MIP sorbent showed high adsorption capacity and selectivity for caffeine.The maximum static adsorption capacity of the MIP and NIP sorbent for caffeine was 28.1 mg/g and 16.5 mg/g,respectively.The relatively selective factor value was 1.25.Using the caffeine-imprinted polymer as a solid phase extraction(SPE) sorbent,a novel sample pretreatment technique that can be coupled to high performance liquid chromatography(HPLC) had been developed for the determination of caffeine in tea and human plasma after administration of tea.The effects of the type and amount of elution solvents on the recovery of caffeine were investigated.After optimization of SPE profile,the caffeine extraction recovery of 97.5% was obtained when the following procedure was applied to MIPs cartridge: conditioning with 2 mL water,loading with water,washing with 2 mL water,eluting with 6 mL methanol-acetic acid(9∶1,/V.The recovery of caffeine on NIPs cartridge was only 54.9%.