[Simultaneous determination of nine dyestuffs and dyes intermediates in cosmetics by high performance liquid...

A new analytical method based on high performance liquid chromatography/photodiode array detection (HPLC/PDA) has been established for the simultaneous determination of nine dyestuffs and dyes intermediates in cosmetics. After the cosmetics were treated by ultrasonic extraction using methanol-0.01 mol/L NH4Ac aqueous solution (2 : 1, v/v), the obtained liquid samples were analyzed by HPLC using a Waters Symmetry C18 column (4.6 mm x 250 mm, 5 microm). Methanol-0.01 mol/L NH4Ac aqueous solution (pH 6.2) was used as the mobile phase for gradient elution. Nine dyestuffs and dyes intermediates were completely separated within 15 min. PDA spectrum was used for assistant identification. External standard method was applied for quantitation. The average recoveries (n = 8) were from 81.0% to 105.6% with relative standard deviations between 0.8% and 4.9%. The detection limits (S/N = 3) were in the range of 0.1 - 2 microg. The method is simple, rapid, accurate and suitable for the determination of nine dyestuffs and dyes intermediates in cosmetics.