METHOD FOR DETERMINING THE CONTENT OF CATECHINS IN TEA INFUSIONS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A high-performance liquid chromatography method employing diode array detection was developed to determine levels of the major catechins pre sent in black, green, and Jasmine tea infusions. Reversed-phase separa tions were performed on a C-18 column using three gradients: acetonitr ile-acetate buffer, methanol-acetate buffer, and acetonitrile-acetate buffer with ascorbic acid. The identities of the tea catechins were es tablished by comparing absorbance spectra and retention times to refer ence standards chromatographed under identical conditions. Epicatechin , epigallocatechin, epicatechin gallate, and epigallocatechin gallate were found in all the tea infusions examined, ranging in concentration from 1-13 mg dl(-1). These levels indicate that even moderate tea con sumption can contribute a substantial quantity of flavanols to the die t. Although some differences between the three brewed teas were eviden t, all were comparably good sources of these catechins. 1998 Published by Elsevier Science B.V.