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 present in black, green, and Jasmine tea infusions. Reversed-phase separations were performed on a C18 column using three gradients: acetonitrile-acetate buffer, methanol-acetate buffer, and acetonitrile-acetate buffer with ascorbic acid. The identities of the tea catechins were established by comparing absorbance spectra and retention times to reference 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 consumption can contribute a substantial quantity of flavanols to the diet. Although some differences between the three brewed teas were evident, all were comparably good sources of these catechins.