HPLC determination of catechins and caffeine in tea. Differentiation of green, black and instant teas

A simple and fast high performance liquid chromatographic method for five c atechins and caffeine using an ODS column and a water-acetonitrile-formic a cid mobile phase system was developed. The catechins (epicatechin, catechin , epigallocatechin, epigallocatechin gallate, epicatechin gallate) and caff eine were separated by an acetonitrile gradient within 20 min. The detectio n limit of the method was approximately 10 ng for all the compounds (by inj ecting 10 mu L). Several green, black and instant teas were analysed using this method. By using the studied compounds as chemical descriptors, linear discriminant analysis was performed and complete differentiation of the gr een, black and instant teas was achieved.