ISOLATION AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ANALYSIS OF THEARUBIGIN FRACTIONS FROM BLACK TEA

Fractions consisting of black tea pigments were isolated and analysed by reversed-phase HPLC. The fractions were shown to be mixtures of the same pigments that had been observed previously, on the HPLC chromatograms of black tea liquor. The thearubigin fractions isolated by Roberts (Roberts' SI and SII thearubigins) were shown to be mixtures of pigments previously classified as group I, II, and III pigments (pigments excluded from, resolved by, and remaining unresolved by HPLC, respectively), showing that the pigments in these three groups were similar to those in groups previously designated as thearubigins by Roberts. The SI and SII fractions were distinguishable by HPLC, and SI-like and SII-like fractions could be isolated by methods different from those of Roberts (e.g., a Sep-Pak C-18 cartridge). Fractions enriched in group I pigments were isolated using a Bond-Elut SCX cation-exchange cartridge (and on a larger scale on a column of Amberlite CG-120 cation-exchange resin). These fractions were shown by paper chromatography and HPLC to be mixtures of ''anthocyanidin'' pigments of various molecular masses. HPLC and mass spectrometry showed that an anthocyanidin, designated by Roberts as tricetinidin, was present in the mixture.