The chemical composition of green tea is complex and includes polyphenols, alkaloids, amino acids, and other unidentified compounds. The contents of catechins and caffeine are considered a standard of green tea quality evaluation. In this study, an ultra performance liquid chromatography (UPLC) method was developed for the quantitative determination of five marker constituents in green tea; epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate, and caffeine. Reversed-phase UPLC analysis was conducted quantitatively to identify individual catechins and caffeine in teas extracted with 25% (v/v) aqueous ethanol. Content (mg/g, dry weight) of tea catechins decreased in the following order: Jeju-do 168.9 mg/g> Gyeongsangnam-do 156.8 mg/g> Jeollanam-do 148.2 mg/g. Based on their dry weights, the green teas contained 7.3 to 26.1 mg/g of caffeine. These results will be valuable as basic data for standardization of Korean green tea.

Keywords: green tea, catechin, caffeine, UPLC