Simultaneous Determination of Four Catechins and Caffeine in Tea by the Internal Standard Curve Method Using HPLC

An internal standard curve method with puerarin as an internal standard was established for measuring five components in tea simultaneously by HPLC,they are epigallocatechin(EGC),epigallocatechin gallate(EGCG),epicatechin(EC) and epicaechin gallate(ECG)and caffeine.The tea extract was separated using a C18 column(4.5×250mm,5um) with methanol-0.05% trifluoroacetic acid as the eluent in gradient elution mode.All components were baseline separated peaks at 278nm accurately.This reproducibility,high sensitivity and high recovery rate are acceptable for determining the catechins and caffeine in 26 tea samples with satisfactory results.The cluster analysis has been used to discuss the results of tea samples from different origins.