Determination of Catechins and Purine Alkaloids in Tea by High Performance Liquid Chromatography

Abstract

With a novel internal standard, 8-chlorotheophylline, a high-performance liquid chromatography method was successfully developed for simultaneous determination of six catechins, three purine alkaloids, and gallic acid in green tea, oolong tea, and black tea. The analysis was carried out on a C18 column with the temperature of 35°C, and a gradient elution was adopted with a mobile phase composed by aqueous solution (containing 0.2% acetic acid, v/v) and acetonitrile. The optimal detection wavelength was 278 nm, of which both of the analytes and internal standard displayed the highest UV adsorption. Both the internal standard (ISTD) method and external standard (ESTD) method had wide linear range, good precision (coefficients of variation CV ≤ 3.65%), good intermediate precision (CV ≤ 5.82%), and good accuracy (recovery 92%–120%). Compared with the ESTD method, the ISTD method had better precision and lower test costs.