In order to devise a simple and reliable method for the analysis of main components contained in oxidative hair dyes, determination by thin layer densitometry was examined and the following procedure was recommended. Sample and standard solutions were spotted on a silica gel plate. The plate was developed with benzene-ethylacetate (1 : 1 v/v) for the separation of 2-nitro-p-phenylenediamine, 4-nitro-o-phenylenediamine, o-aminophenol, m-aminophenol, p-aminophenol, resorcinol and with ethylacetate for p-phenylenediamine, toluene-2, 5-diamine, p-methoxy-m-phenylenediamine. The plate was sprayed with Ehrlich's reagent and each ingredient was visualized by heating for 30 min at 70°C. Densitometric determination was carried out with dual-wavelength TLC scanner. The proposed method was applicable to the analysis of hair dye ingredients without influence of contaminants in commercial hair dyes.
