Abstract:

A method for simultaneous determination of 4 banned substances in anti-acne cosmetics, including lincomycin, clindamycin, tretinoin and isotretinoin was developed by high performance liquid chromatography （HPLC）. The above four substances were extracted ultrasonically with methanol. The analytes were separated on a Waters SunFire C₁₈（4.6×250 mm,5 µm）column by gradient elution with 0.02 moL/L diammonium hydrogen phosphate- methanol as mobile phase,and detected at the wavelengths of 210 and 340 nm, respectively. The flow rate was set at 1.0 mL/min and the column temperature was 30 ℃. Quantification analysis was performed by the external standard method. The calibration curves are linear in the range of 5-500 mg/L for lincomycin and clindamycin, and 0.5-50 mg/L for the rest analytes, with the correlation coefficients more than 0.999. The detection limits of lincomycin and clindamycin are 0.005%, while that of tretinoin and isotretinoin are 0.000 2%. The average recoveries at three spiked levels range from 95% to 102% with RSDs of 0.1%-1.5%. The results indicate that the method is simple, sensitive and accurate, and is suitable for the determination of 4 banned substances in anti-acne cosmetics．

Key words: anti-acne cosmetics, banned substances, high performance liquid chromatography （HPLC）