In this study thin-layer chromatography (TLC) was used for analysis of the constituents of extracts of tea (
L.) and Rooibos (
) leaves. In particular, flavonoids, a group of phenolic compounds, for example myrecetin, rutin, catechin, quercetin, and kaempferol were analyzed. Extracts of various types of tea, for example black, green, and Rooibos herbal tea (called red tea) were analyzed. The efficiency of extraction of flavonoids from plant material by classical liquid extraction (LE) and supercritical-fluid extraction (SFE) was also compared. Recoveries of individual flavonoids were approximately ten times higher after use of solvent extraction. Separation of flavonoids from tea extracts on the basis of their polarities was optimized by selection of solvents, stationary phases, and chromatographic conditions. For final analyses glass-backed silica gel 60 F
plates and the mobile phase acetone-chloroform-water 80:20:10 (
) were used. UV detection of TLC chromatograms (254 and 366 nm) was used. Better detection of the flavonoids was achieved at 366 nm. The concentration of some important flavonoids in real tea samples was obtained by high-performance liquid chromatography (HPLC).
A. von Gadow, E. Joubert
, J. Agric. Food Chem.