| A method was established for the simultaneous determination of tetramethylpyrazine,liquiritin and nuciferine in toner,emulsion,cream and gel skin care products by ultra-high performance liquid chromatography with a diode array detector(UPLC-PDA).The different kinds of cosmetic samples were extracted with methanol by ultrasonic wave,then the extracts were centrifuged,filtrated,and analyzed by UPLC-PDA on a Waters BEH C18 column(2.1 mm×50 mm,1.7 μm),employing acetonitrile-0.05% phosphoric acid aqueous solution as mobile phase by gradient elution.The targets were qualitatively determined by retention time,and confirmed by ultraviolet spectra.The external standard method was applied for the quantification analysis.The results indicated that the linear correlation coefficients of three targets ranged from 0.999 4 to 0.999 9 within the linear range of 0.05-50.0 mg/L.The detection limits(S/N=3) of tetramethylpyrazine,liquiritin and nuciferine were 0.6,0.6,0.3 mg/kg,and the limits of quantitation(S/N=10) were 2.0,2.0,1.0 mg/kg,respectively.The spiked recoveres of three compounds at spiked levels of 1-200 mg/kg were between 85.6% and 98.2%,with RSDs(n=6) of 1.1%-6.1%.The results showed that this method was stable,accurate and precise,and could be used to assay the three mentioned compounds in different skin care products. |