不同茶叶中茶氨酸含量的测定比较

Comparison of Determination of Theanine in Different Tea Species

建立用高效液相色谱法测定茶叶中茶氨酸的方法,用于比较红茶、绿茶、甜茶等各种茶叶中茶氨酸的含量。采用的色谱柱为C18色谱柱,以甲醇和0.05%体积分数的三氟乙酸溶液为流动相进行梯度洗脱。流速为0.8ml/min,紫外检测波长为208nm,柱温30℃,外标法定量。结果表明,在一定浓度的茶氨酸浓度范围内,峰面积与质量浓度具有良好的线性关系,以茶氨酸浓度为横坐标,建立线性回归方程Y=4299.366X+14.828,相关系数R为0.9997。通过对各种茶叶的测定,比较其中含有的茶氨酸的量。茶氨酸的加样回收率为101.06%,对各种茶叶方法精密度相对标准偏差均小于为0.5%,该操作方法简便、快速、准确。测定发现红茶、绿茶、甜茶等各种类型的茶叶中茶氨酸的含量与茶叶类别有关。

High performance liquid chromatography （HPLC） was used for the determination of theanine in different tea species. Theanine can be separated on a Eclipse XDB-C18 column with trifluoroacetic acid （0.05%） as solution and methanol as mobile phase for gradient elution. The UV detection wavelength is set at 208 nm, the flow rate 0.8 ml/min, and the temperature of column 30 ℃. Under the conditions mentioned above, the relative peak area（Y） is linearly related with the concentration（X） Of theanine and its linear regression equation is Y=4299.3 66X＋14.828, R^2=0.9997. The average recovery is 101.06%.The RSD is 〈0.5%. The method is simple and accurate, and can be used in determination of the black tea, green tea, sweet tea and most of the tea species.