分光光度法测定金荞麦(-)-表儿茶素含量的方法研究

Study on the Determination of Epicatechin in Fagopyrum Dibotrys by Spectrophotometry

为建立香荚兰素-盐酸分光光度法对表儿茶素含量的测定方法,实验分别以乙醇和水作溶剂,在34.79～208.74μg范围内取样置50 mL容量瓶测定,结果发现:①以乙醇作溶剂时,测定波长为508 nm,1%香荚兰浓盐酸添加量应超过40mL(CV≤1.86%),测定时间以40 min后为宜(CV≤2.65%),标准曲线线性关系(R=0.999 3)与精确度(CV=2.66%)、准确度(P>0.05)良好。②以水作溶剂时,测定波长为504 nm,显色反应不稳定,标准曲线线性关系(R=0.988 1)也较一般。③采用乙醇作溶剂时,测得金荞麦块根中(-)-表儿茶素类物质含量占干物质的2.22%(CV≤3.90%),该法操作简便,灵敏度高,重现性好。

In order to establish a spectrophotometric determination of the vanillin - hydrochloric acid method to determine the content of epicatechin, the samples ranging from 34.79 μg to 208.74μg con- tained in the 50mL volumetric flasks are determined with absolute alcohol and water as solvent respective- ly. The results show that： （1） When absolute alcohol is used as dissolvent, the detection wavelength is at 508 nm, the addition of the 1% vanillin- hydrochloric acid should exceed 40 mL （CV≤1.86% ）, and the optimum detection period is 40min （ CV ≤2.65% ）. Meanwhile, the linear relation of the stand- ard curve（ R = 0. 999 3）, the degree of precision （ CV = 2.66% ） and the accuracy of measurement（P 〉 0.05 ） show good. （2） When water is used as dissolvent, the detection wavelength is at 504 nm, but the chromogenic reaction is not stable and the linear relation of the standard curve is rather ordinary. （ 3 ） When absolute alcohol is adopted as dissolvent, the contents of epicatechin in fagopyrum dibotrys＇ tuberous root account for 2.22% of the dry matter content （ C≤3.90% ）. Therefore, this is a research method with convenient operation, high sensibility and good repeatability.