The qualitative analysis of the green tea extract using ESI-MS method

Abstract

The aim of this paper was the identification of the bioactive compounds in the green tea extract enriched with quercetin. The extraction was performed under reflux for 60 min using absolute ethanol at the solid-to-liquid ratio of 1:18 (m/v). The mass spectrometry method with an electrospray interface was applied and tuned with the quercetin standard. Mass spectra were recorded in negative and positive ionization modes with the ion source voltage of 4.95 kV, the source current of 2.61 μA, the capillary temperature of 275 °C, the capillary voltage of 50 V, the sheath gas pressure of 137 KPa and auxiliary gas pressure of 13.9 KPa. In addition to quercetin, the presence of gallic acid, (-)-gallocatechin, 3-O-caffeoylquinic acid, theobromine, 5-O-galloylquinic acid, (+)-catechin, caffeine, epicatechin-3-gallate, (-)-epigallocatechin-3-gallate, 4-p-coumaroylquinic acid, quercetin-3-O-rutinoside, quercetin-3-galactoside, kampferol-3-O-glucoside, apigenin glycoside, theaflavin-3,3’-digallate, thafla- vin-3-gallate and the kaempferol-rhamnose-hexose-rhamnose conjugate was confirmed based on fragmentation patterns available in literature.