Determination of estrogens in cosmetics by ultrahigh performance liquid chromatography

A method was established for the determination of five estrogens(diethylstilbestrol,17-α-estradiol,17-β-estradiol,dihydroethylstilbestrol and 17-α-ethinyl estradiol) in cosmetics by ultrahigh performance liquid chromatography(UPLC).The cosmetic sample was firstly dispersed by saturated NaCl solution and then the dispersion was extracted with acetonitrile.The extract was treated by potassium ferrocyanide and zinc acetate to cause the precipitation of big molecular compounds.The clear phase was enriched and purified by a Oasis HLB solid phase extraction cartridge.Then the five estrogens were separated and detected within 5 min on a chromatograph column of Waters ACQUITY UPLC BEH C18(2.1 mm×100 mm,1.7 μm) by gradient elution with acetonitrile-water system.In the range of 0.5~8.0 mg/L,the calibration curves of five estrogens show good linearity with the correlation coefficients larger than 0.999 5.The mean recoveries at the three spike levels(0.10,0.20,0.50 mg/kg) were 83.1%~95.4% with less than 7.4% of relative standard deviations.