Simultaneous Analysis of Eight Catechins in Tea Drinks by Gas Chromatography/Mass Spectrometry

Trimethylsilyl (TMS) derivatives of catechins in tea drink were analyzed by gas chromatography/mass spectrometry (GC/MS) in this study. The polyphenols of green-tea leaves are composed of four major catechins : (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG). Bottled teas contain not only these epicatechins, but also their epimers : namely (+)-catechin (C), (-)-gallocatechin (GC), (-)-catechin gallate (CG), and (-)-gallocatechin gallate (GCG). Although the GC/MS is an analytical method useful for identification of unknown compounds, the simultaneous determination of these eight catechins has not been reported because of difficulty in separation between CG and GCG. GC/MS analysis under the analytical condition proposed in this study showed that the eight catechins could be successfully separated and identified. This analysis was very useful for discrimination between a hot water extract of tea leaves and bottled tea, and was applicable to discrimination between green tea and other types of teas, such as oolong tea and black tea.