Preliminary investigation into development of HPLC with UV and MS-electrospray detection for the analysis of tea catechins

There is an increasing interest in the biological and technological role of natural antioxidants present in green tea extracts. This is due to the inhibition of the oxidative process showed by tea catechins, which is higher than those of synthetic antioxidants (such as BHT) and other vegetal extracts (rosemary, oregano, grape seeds). In a first step of the work a rapid reversed phase HPLC method for the determination of catechins in green tea extracts, using a binary gradient system, was developed. Commercial green tea extracts were analyzed and the different catechins quantified. EGCG ((-)-epigallocatechin-3-gallate) and EGC ((-)-epigallocatechin) were proposed as index of the antioxidant quality of tea extracts. Subsequentely, the previous chromatographic method was applied on a HPLC-MS system in order to verify the accuracy of some HPLC-DAD results and compare the two detection modes, on such a polyphenolic mixture. The use of mass spectrometry detection in quantification of catechins ensured an higher specificity of the method and a constant qualitative control of the identity of chromatographic peaks thanks to the concurrent acquisition of more than one mass signal (as M + 1 and M + Na pseudomolecular peaks). (C) 2002 Published by Elsevier Science Ltd.