绿茶中提取咖啡因的方法研究

目的]对从绿茶中提取咖啡因的关键技术问题进行初步探讨。方法]用水相结晶分离法纯化样品，用国标法测定供试品溶液中的咖啡因含量。采用正交实验方法得出提取咖啡因的最佳条件为：用100℃的水为提取剂，浸提5min，固液比为1：20，UV法测定。结果]结果表明，水相结晶分离法纯化的产物的纯度达87．00％，收率为3．56％。采用该方法可将试验时间缩短到1．0～1．5h。咖啡因稳定的最大吸收波长为274mm，其吸光度的线性回归方程为：C=1．096×10^-4＋0．05A（r=0．9999）。影响咖啡因提取的因素为：温度〉固液比〉时间。经水相分离提纯的咖啡因纯度为87．00％。结论]从绿茶中提取出的样品为咖啡因，且杂质含量较少。

Research on the Experimental Technology of Extracting Caffeine from Green-tea

Objective ] The research aimed to preliminarily discuss the key problems in extracting caffeine from green-tea. Method ] The sample was purified by crystallization isolation in water phase and the caffeine content in the sample solution was determined by national stand- ard method. Result ] Through orthogonal experiment, the optimum condition of extracting caffeine was ascertained to be as follows ： with water with temperature at 100 ℃ as extractant, extracting for 5 min and setting solid-liquid ratio at 1：20. The determination results of UV method indicated that the purity of purified products by crystallization isolation in water phase reached 87.00% and the yield rate was 3.56%. The ex- periment time could be shortened to 1.0 - 1.5 h by this method. The stable maximum absorption wavelength of caffeine was 274 nm and the linear regression equation of its absorbance was C = 1. 096 × 10^-4 ＋ 0.05 A （ r = 0. 999 9 ）. The factors influencing the extraction of caffeine were as follows ： temperature 〉 solid-liquid ratio 〉 time. The purity of caffeine isolated and purified in water phase was 87.00%, Conclusion] The sample extracted from green-tea was caffeine and it contained little impurity.