Determination of the contents of vitamin C and its derivatives in cosmetics by high performance liquid chromatography

A method has established for the detection of vitamin C (VC) and its derivatives (ascorbyl glucoside, AA-2G; magnesium ascorbyl phosphate, AA-2P; ascorbic acid ethyl ether, Only VCE) in cosmetics by high performance liquid chromatography (HPLC). Low fat cosmetic samples such as make-up water and lotion were extracted directly with 30 mL 0.02 mol/L potassium dihydrogen phosphate solution (pH 3.0). High fat cosmetic samples such as face cream and gel were well dispersed with 1.0 mL dichloromethane first, then extracted with 25 mL 0.02 mol/L potassium dihydrogen phosphate solution (pH 3.0). The sample solution was centrifuged with a speed of 12,000 r/min, then filtered through a 0.22 mu m syringe filter. The filtrate was analyzed on a column of YMC-Triart C18 (250 mm x 4.6 mm, 5 mu m) using 0.02 mol/L potassium dihydrogen phosphate solution (pH 3.0) and methanol as mobile phases with a flow rate of 1.0 mL/min. The temperature of the column was 25 degrees C and the detection wavelength was 250 nm. The standard working curves of the four analytes had good linear relationship (r(2)>0.9999). The detection limits of the four analytes were 0.04-0.08 g/kg (S/N=10). The recoveries were 95.6%-101.0% with the relative standard deviations of 0.62%-3.0% at the spiked levels of 0.25-5.0 g/kg. This method is a simple, rapid, exact and reliable for the determination of the contents of vitamin C and its derivatives in cosmetics.