ABSTRACT:
Abstract of the study:
Advanced analytical approaches consisting of both LC-LTQ-Orbitrap Fourier transformed (FT)-MS and LC-time-of-flight-(TOF)-MS coupled to solid-phase extraction (SPE) NMR were used to obtain more insight into the complex phenolic composition of tea. On the basis of the combined structural information from (i) accurate mass fragmentation spectra, derived by using LC-Orbitrap FTMSn, and (ii) proton NMR spectra, derived after LC-TOFMS triggered SPE trapping of selected compounds, 177 phenolic compounds were annotated. Most of these phenolics were glycosylated and acetylated derivatives of flavan-3-ols and flavonols. Principal component analysis based on the relative abundance of the annotated phenolic compounds in 17 commercially available black, green, and white tea products separated the black teas from the green and white teas, with epicatechin-3,5-di-O-gallate and prodelphinidin-O-gallate being among the main discriminators. The results indicate that the combined use of LC-LTQ-Orbitrap FTMS and LC-TOFMS-SPE-NMR leads to a more comprehensive metabolite description and comparison of tea and other plant samples.
Sample description:
Black, green, and white tea samples were obtained from different origins: a local store (bought on June 5, 2011) and a dedicated tea shop (bought on June 4, 2011) that also ordered several special tea samples at http://www.wollenhaupt.com/ (article no. in brackets) with a packaging date of May 19, 2011, indicated with an asterisk. The tea products were stored under dark conditions at room temperature until use (about 6 weeks). Tea samples were labeled as follows: green tea (GT), China Yunnan (Y) [article no. 00518]*, China Sencha (S) [article no. 00515]*, Chinese Huangshan Green Tea from laboratory (GL) (local store), China Bancha (B) [article no. 00568], China Chun Mee (CCM) [article no. 00500]*, China Lung Ching (CLC), China Gunpowder (CG); white tea (WT), China Mao Feng (CMF) [article no. 00519]*, China Pai Mu Tan (PMT) [article no. 00509]*, Jasmijn and Oranjebloesem (WTJ) (local store); black tea (BT), Darjeeling FTGFOP1 (D) [article no. 00312]*, Ceylon OP Adawatte (CAD) [article no. 00203]*, Assam TGFOP1 Hazelbank (A) [article no. 00109]*, English Earl Gray–Ceylon Black Tea with bergamot (CB) [article no. 10861], Irish Breakfast (IB) [article no. 00418], Ceylon OP Pettiagalla (CP) [article no. 00209], Pickwick English Tea Blend (BL) (local store).
Justin van der Hooft 
