Abstract:

A method for the determination of 14 prohibited ingredients in hair dye products by high performance liquid chromatography （HPLC） and liquid chromatography-tandem mass spectrometry （LC-MS/MS） was developed. The hair dye product was ultrasonically extracted in mixed solvent of aqueous sodium bisulfite solution and ethanol. The mobile phase for HPLC determination was acetonitrile and 20 mmol/L ammonium acetate. Chromatographic separation was carried out on a TechMate AQUA-STIII column （4.6 mm×250 mm, 5 µm） by isocratic elution. The detection wavelengths of the diode array detector were 240, 290 and 616 nm. Quantification was performed by external standard method. Further verification for positive sample was performed by LC-MS/MS. The 14 prohibited ingredients have good linearities, with the correlation coefficients （r） higher than 0.999. The limits of detection （LODs） of the 14 ingredients are from 2.4 mg/kg to 52 mg/kg, and the limits of quantification （LOQs） are from 10 mg/kg to 207 mg/kg. At two different content levels, the precision and stability within 48 hours of each target ingredient is good, with the relative standard deviation （RSD） less than 5%. The average spiked recoveries at four levels in both cream and liquid substrates are from 89.4% to 112.8%, with the RSDs from 0.4% to 4.6%. Under the conditions of this experiment, the detection of 14 prohibited ingredients is not affected by the interference of frequently-used permitted dyes in hair dye products.

Key words: prohibited ingredients, hair dye products, high performance liquid chromatography, liquid chromatography-tandem mass spectrometry