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建立了HPLC法测定茶叶中咖啡因含量的方法。色谱柱为Eclipse XDB-C18柱(4.6mm×250mm);以甲醇—水(90:10,V:V)为流动相;流速为1.0ml/min;检测波长为254nm;柱温为25℃。咖啡因的提取方法为超声萃取法,超声时间为10min。咖啡因含量在0.15-0.35mg/ml范围内线性关系良好,相关系数R=0.9980;精密度试验RSD为1.38%(n=5);重现性试验RSD为1.55%(n=5)。两种茶样的咖啡因平均回收率分别为96.42%(龙井)和101.46%(本地茶)。测定9种茶样中咖啡因的百分含量为3.683%-5.446%。该法快捷方便,为检测茶叶中咖啡因含量奠定了理论和技术基础。
A method for the determination of caffeine in tea by HPLC was established. The column was an Eclipse XDB-C18 column (4.6 mm × 250 mm). The mobile phase was methanol-water (90:10, V: V). The flow rate was 1.0 ml / min. The detection wavelength was 254 nm. Caffeine extraction method for the ultrasonic extraction method, ultrasound time was 10min. The correlation coefficient R = 0.9980; RSD of precision test was 1.38% (n = 5); RSD of reproducibility test was 1.55% (n = 5). The average recoveries of caffeine for both tea samples were 96.42% (Longjing) and 101.46% (native tea), respectively. The percentage of caffeine in 9 kinds of tea samples was 3.683% -5.446%. The method is fast and convenient, which has laid a theoretical and technical foundation for the detection of caffeine in tea.