The use of catechins and purine alkaloids as descriptors for the differentiation of tea beverages

A high performance liquid chromatography method using a C-18 reversed-phase column, a gradient elution system of acetonitrile-water-formic acid and a photodiode array detector was used to determine catechins and purine alkaloids in tea beverages. (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, (-)-epigallocatechin gallate, (-)-epicatechin gallate, gallic acid, caffeine, theophylline and theobromine were analysed in different tea beverages made of black, green and instant tea. Other products containing tea were also considered. Principal component, cluster, linear discriminant analysis and soft independent modelling class analogy were applied to the data in order to differentiate tea beverages according to the catechin and purine alkaloid profiles of the different samples considered.