Abstract: A method for the determination of 2,4,5,6-tetraaminopyrimidine sulfate (TAOS) in hair dye by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established.Hair dye sample was extracted by 0.3% (volume fraction) formic acid aqueous solution under ultrasonic assistance.The separation was performed with a Waters BEH-C₁₈ column (100 mm×2.1 mm,1.7 μm) and isocratictly eluted by a mixed solution of V(0.3% formic acid aqueous solution)∶V(acetonitrile)=95∶5.Under electrospray positive ion mode,the qualitative and quantitative analysis were performed adopting the multiple reaction monitoring (MRM) mode.The results showed that good linear relationship displays within the range 0.020~5.0 mg/L with the correlation coefficients (R²) more than 0.99.The limit of detection (S/N=3) is 0.17 mg/kg,while the limit of quantification (S/N=10) is 0.56 mg/kg.The average recovery of the spiked samples is in the range of 87.5%~96.0% with the relative standard deviation (RSD,n=6) of 5.7%~8.7%.

Key words: hair dye, ultra high performance liquid chromatography-tandem mass spcetrometry, 2,4,5,6-tetraaminopyrimidine sulfate