Abstract: An analysis method was established to determine phenacetin in hair dye by ultra-high performance liquid chromatography with a diode array detector (UPLC-PDA).The hair dye sample was extracted with 70% (volume fraction) methanol-water solution,reverse extracted with n-hexane,and analyzed by UPLC-PDA on a BEH C₁₈ column,with acetonitrile-water as the mobile phase in gradient elution mode.The targets were qualitatively determined by retention time,confirmed by the ultraviolet spectrum,and quantified by standard graph.Test results indicated that in the phenacetin mass concentration range of 0.5-50.0 mg·L^-1,the content shows a good linearity with the peak value with correlation coefficient (r) higher than 0.999 3.The detection limit of phenacetin is 3.0 mg·kg^-1.When the spiking level is 10,20 and 50 mg·kg^-1,the spiked recoveries of phenacetin are ranged within 85.6% and 97.9%,and the precision (RSD) ranges from 3.7% to 5.3% (n=6).

Key words: hair dye, ultra-high performance liquid chromatography, phenacetin