| An ion-pair chromatographic method was developed for the determination of zinc 4-hydroxybenzene sulphonate in cosmetics with different matrixes.Lotion and shampoo samples were ultrasonically extracted with 20% acetonitrile aqueous solution,cream and powder samples were ultrasonically extracted with 80% acetonitrile aqueous solution,and lipstick samples were ultrasonically extracted with tetrahydrofuran and 80% acetonitrile aqueous solution,and then the extracts were centrifuged and filtered.Using tetrabutylammonium hydroxide as an ion pair reagent,the retention behavior of zinc 4-hydroxybenzene sulphonate and the optimum chromatographic conditions were investigated.The optimal conditions were as follows:stationary phase:Kromasil C18（4.6 mm×250 mm,5 μm）,mobile phase:A （5 mmol/L tetrabutylammonium hydroxide and 25 mmol/L sodium dihydrogen phosphate at pH 2.5）∶B （acetonitrile）=80 ∶ 20,flow rate:1.0 mL/min,column temperature:30 ℃,detection wavelength:230 nm.Under the optimal conditions,the quantitation limits of zinc 4-hydroxybenzene sulphonate were 24 mg/kg for lotion and shampoo,120 mg/kg for cream and lipstick,and 60 mg/kg for powder.The calibration curve of zinc 4-hydroxybenzene sulphonate was linear in the range of 0.5-50 mg/L with a correlation coefficient of 0.999 8.The average recoveries at three spiked levels were between 94% and 99%,with relative standard deviations of 0.57%-3.9%.The method was rapid,simple and accurate,and could be used for the determination of zinc 4-hydroxybenzene sulphonate in cosmetics. |