Identification of Illegal Coal Tar Dyes Constituents in Mucous Cosmetics by HPLC Method

Illegal coal tar dyes are reported to possess strong toxicity and carcinogenecity when added in mucous cosmetics. According to CNS, current methods in analyzing organic coloring materials (dyes) are mainly filter paper chromatography and thin-layer chromatography. In this study, we adopted a refined HPLC procedure reaching optimal conditions for the separation and identification of the coloring constituents allegedly added in mucous cosmetics. Ultimately, the analytical efficiency and precision are greatly improved. The optimal conditions for the HPLC method were found with a column of Cosmosil 5C18-AR-II; with the first mobile phase using 0.07 M ammonium acetate solution in 0.01 M tetrabutylammonium bromide (CH3COONH4) : CH3CN : CH3OH = 55:35:10 for analyzing 16 hydrophilic coal tar dyes, while the second mobile phase uses CH3OH : H2O = 95:5 for analyzing 6 hydrophobic dyes and a photodiode array detector within UV-VIS wavelength. By applying this HPLC method, a total of 22 banned coal tar dye constituents can be satisfactorily separated. It is also found that the detection limit can be improved to 0.05 μg/mL.