A reversed-phase thin-layer chromatography/scanning densitometric method for the qualitative analysis of carthamus yellow in foods

A technique for the analysis of carthamus yellow using reversed-phase TLC and scanning densitometry is described. The technique involves the following three steps: (1) clean-up of the color with a C18 and a DEA cartridge: (2) separation of the colors on the reversed-phase C18-TLC using 2-butanone: methanol: 5% sodium sulfate: 5% acetic acid (3:2 : 5:5) as the solvent system; and (3)) measurement of visible absorption spectrum of the color using scanning densitometry without isolation of the color. In order to investigate the capability of the present method. 35 commercial foods were analyzed, and their chromatographic behavior and spectra were observed. The obtained separation and the spectra were not affected by coexisting substances in the foods and the spots always gave the same R-f values and spectra as the standards with good reproducibility. The present method is considered to be useful for the rapid analysis of carthamus yellow in foods.