为了对茶叶样品中微量儿茶素进行快速准确分析,利用分子印迹固相萃取（MIPs-SPE）与电喷雾质谱（EIMS）联用技术进行了茶叶中四种儿茶素—表儿茶素（EC）、表没食子儿茶素（EGC）、表儿茶素没食子酸酯（ECG）、表没食子儿茶素没食子酸酯（EGCG）的分离测定。首先以表儿茶素（EC）为模板分子,采用紫外聚合方法合成分子印迹聚合物（EC-MIPs）,功能单体为甲基丙烯酸(MAA),交联剂为乙烯二醇二甲基丙烯酸酯(EDMA),引发剂为偶氮二异丁腈(AIBN)。利用EC-MIPs作为固定相制备EC-MIPs-SPE柱,对茶叶样品进行分离萃取后采用EIMS对洗脱液中儿茶素单体进行检测,分别与常规C18和非分子印迹聚合物（NIP）固相萃取方法进行比较。结果表明EC-MIPs-SPE法对儿茶素类单体有特异性识别能力,对茶中主要干扰物质咖啡因、茶碱的结合能力远小于儿茶素分子。最佳萃取条件为：水相上样,用50%（v/v）甲醇/水溶液淋洗除去非特异性结合干扰物,1%（v/v）醋酸的甲醇洗脱特异性结合的四种儿茶素单体。对真实茶叶样品测试发现：经过EC-MIPs-SPE法预富集,可以去除94.2%的咖啡因和全部茶碱干扰,同时可得四个主要儿茶素信号,相对强度分别为：EC（12.1%）,EGC（8.2%）,ECG（35.4%）,EGCG（45.7%）。本法可特异性地识别和分离儿茶素单体,有效消除咖啡因和茶碱干扰,可用于茶叶中微量儿茶素分离鉴定。
A rapid method using molecular imprinted polymers (MIPs) as solid phase extraction (SPE) sorbent in pretreatment and electrospray mass spectrometry (EIMS) were investigated to separate and determine trace amount of four main catechins, such as epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGEG) respectively in tea samples. MIPs for EC (EC-MIPs) were prepared using methacrylic acid (MAA) as a monomer, ethylene glycol dimethacrylate (EDMA) as a cross linker, and azo-bis-isobutyronitrile (AIBN) as an initiator by UV radical polymerization method; and EC-MIPs were used as SPE sorbents (EC-MIPs-SPE) for selectively trapping and preconcentrating four catechins from eluate, and were then analysed by EIMS. The results showed EC-MIPs-SPE could selectively recognize catechins. Its binding capability and selectivity for catechins were better than that of caffeine and theophylline. The optimal extraction protocol was to load samples in the aqueous phase (v/v), to wash with 50% methanol and to elute with methanol containing 1% acetatic acid. Under above conditions, the interference of caffeine was eliminated to 94.2%, and of theophylline, 100%. The relative intensity was 12.1%, 8.2%, 35.4%, and 45.7% for EC, EGC, ECG, and EGCG respectively.
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