Mass spectrometry of selected components of biological interest in green tea extracts

Mass spectrometric methods including EIMS, FABMS, and LC/ESIMS have been surveyed as tools for the detection of catechins in extracts of green tea (Camellia sinensis). EIMS provide both molecular weight and structure information, including epimer differentiation, on compounds 1, 2, and 4 and some structural information with compounds 5 and 6. FABMS gives both molecular weight and structure information, by an retro-Diels-Alder mechanism, on all compounds. LC/ESIMS provides unambiguous molecular weight information on all compounds and some additional structural data are evident in the mass spectra of 5 and 6. LC/ESIMS is, thus, shown to be an appropriate method for the direct analysis of crude extracts of green tea. The information obtained in this work will be of importance in future studies involving identification of the components of green tea and for characterization of synthetic analogues.