茶叶中总黄酮含量测定方法的研究

茶叶中富含羟基苯甲酸类、肉桂酸类及原花色素等多酚类物质,这些物质都具有邻苯二羟基结构,碱性环境下与铝离子形成络合物,影响总黄酮的测定。本实验用亚硝酸钠-硝酸铝法和三氯化铝法测定茶叶总黄酮含量的结果作了比较。实验结果表明,亚硝酸钠-硝酸铝法的测定结果比三氯化铝法约高60mg/g,三氯化铝法在酸性环境下进行,酸度实验显示,适宜酸度为pH≥5.0。鞣酸干扰实验表明,平均误差为0.017mg,随着鞣酸量的增加,测得值无上升趋势。三氯化铝法的线性方程:y=0.000638 0.8623x,相关系数:r=0.9998;样品加标回收率为98.05%。因此,对含酚类较多的植物应采用三氯化铝法测定其总黄酮的含量。

Study on the Determination Method of Flavone Content in Tea

Polyphenols, such as hydroxybenzoic acid, cinnamic acid and proanthocyanidin, are rich in tea. They all have the structure of phenolic o-dihydroxyl, and can form complex with aluminium ions under alkaline condition, which effects the determination of flavones. A comparison was made for determination of flavones in teas by both NaNO2-Al(NO3)3 method and AlCl3 method. It concluded that the result of NaNO2-Al(NO)3 method was higher about 60 mg/g than that of AlCl3 method. The acidic condition is requisite for the determination for AlCl3 method, the fittest pH is 5.0. Experiment and research on interference of tannic acid indicates that average errors is 0.017 mg, there is no increasing trend with the rising of tannic acid. Linear equation of AlCl3 method is y=0.000638 0.8623x (r=0.9998), the recovery of standard addition is 98.05%. So, the plants containing more polyphenols should be adopted AlCl3 method to determine of flavones.