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 catechins and caffeine using an ODS column and a water-acetonitrile-formic acid mobile phase system was developed. The catechins (epicatechin, catechin, epigallocatechin, epigallocatechin gallate, epicatechin gallate) and caffeine were separated by an acetonitrile gradient within 20 min. The detection limit of the method was approximately 10 ng for all the compounds (by...