Abstract: An analytical method based on high performance liquid chromatography with diode array detector (HPLC-DAD) has been established for the simultaneous determination of 9 water-soluble colorants (Solvent Green 7, Food Yellow 3, Food Red 17, Acid Yellow 1, Acid Red 33, Food Red 4, Food Red 1, Orange I, Acid Orange 7) in cosmetics. The different kinds of samples were treated with different preparation methods. The obtained liquid samples were analyzed by HPLC using a Diamonsil C18 column (250 mm×4.6 mm, 5 μm). Acetonitrile-potassium dihydrogen phosphate (KH2PO4) buffer solution (pH 6) was used as the mobile phase for gradient elution. The 9 water-soluble colorants were well separated within 15 min. The average recoveries (n=9) were from 85.33% to 100.2% with the relative standard deviations (RSDs) between 3.68% and 8.20%. The limits of detection (LOD) were in the range of 0.01~0.1 mg/L. The method is simple, rapid, accurate and suitable for the determination of 9 water-soluble colorants in cosmetics.

Key words: cosmetics , diode array detection (DAD), water-soluble colorants, high performance liquid chromatography (HPLC)