New tests for microscale identification of anthocyanidins on thin-layer chromatograms

Five color tests, three of which are based on exposure to NH3, one on ammonium molybdate, and the other on lead acetate for identification of the six common anthocyanidins in quantities far below 1 μg, are presented. Anthocyanidin fluorescence is intensified by an NH3 chamber test so that concentrations well below the visible range can be detected. Each of the six anthocyanidins is identified individually by its characteristic serial fluorescent modifications produced on treatment with formic acid or sulfuric acid prior to extended NH3 exposure. The visible and u.v. colors produced following ammonium molybdate or lead acetate sprays are distinctive, and also diagnostic of O-dihydroxylated anthocyanidins.