Abstract
A simple and rapid analytical method of oil-soluble coal tar dyes in cosmetics was established using reversed-phase TLC/scanning densitometry. Eleven kinds of oil-soluble coal tar dyes were able to be separated completely on reversed-phase TLC plates by the complementary use of 2 solvent systems. The solvent systems were A; n-hexane/2-butanone solution (5 : 1, v/v), solvent system B; acetonitrile/methanol solution (5 : 1, v/v). Then we measured visible absorption spectra of spots developed on the reversed-phase TLC plates by scanning densitometer to identify these coal tar dyes. The proposed method was successfully applied to the identification of oil-soluble coal tar dyes in commercial cosmetics.
