Abstract
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).