亲水作用色谱法测定茶叶中茶氨酸的方法学研究

Research on the method of determination of theanine in tea by hydrophilic interaction chromatography

目的建立亲水作用色谱快速测定茶氨酸含量的方法,并应用于茶叶中茶氨酸的测定,为茶叶中茶氨酸的质量控制提供方法参考。方法茶叶样品粉碎混匀后,经水溶液加热提取过滤后,上清液采用Phenomenex Luna NH2（250 mm×4.6 mm,5μm）亲水色谱柱分离,以乙腈∶水=70∶30为流动相洗脱,流速1.0 ml/min,柱温25℃,紫外检测波长为203 nm。根据保留时间定性,外标峰面积法定量。结果茶氨酸的浓度与峰面积呈良好的线性相关性,相关系数r=0.9999,方法检测限为0.12μg/ml,相对标准偏差RSD为0.46%（n=9）;2个浓度水平的样品加标回收率在94%-104%之间。结论本方法克服了传统反相液相色谱测定中使用离子对和衍生等方法的缺点,具有分离效果好、快速简易、平衡时间短、精密度和准确性高的特点,可用于茶叶中茶氨酸的质量控制方法。

Objective A method was developed for determination of Theanine by hydrophilic interaction liquid chromatography and to provide a reference for cotrol the quality of theanine in tea. Methods The tea was smashed first and then extracted by hot water. After filtration,the supernatant was determined by HPLC. The HPLC separations was performed on a Phenomenex Luna NH2250 mm × 4. 6 mm column,acetonitrile-water（ 70∶30） solution was used as the mobile phase at 1. 0 ml / min and the detection was done at the wavelength of 203 nm. Results The linearity was satisfactory,with correlation coefficients（ r） =0. 9999. And the limit detection of Theanine was 0. 12 μg / ml,The RSD was 0. 46% and the recovery rate of the marked samples with the same concentrate level was 94% - 104%. Conclusion This method overcomes the defect of using ion pair reagent and derivatization in traditional RP-HPLC method. And it was accurate,precise and selective,can used as quality control method for Theanine in tea quality.