Determination of 12 Whitening Functional Substances in Whitening Cosmetics by High Performance Liquid Chromatography

The whitening cosmetic sample (0.20 g) was extracted by ultrasound in 8 mL of 50% (volume fraction, the same below) methanol solution for 15 min, and then the volume was made up to 10 mL with 50% methanol solution. After centrifugation, the supernatant was filtered with 0.45 μm organic filter membrane, in which 12 whitening functional substances were determined simultaneously by high performance liquid chromatography, using SHIMADZU Shim pack GIS-C₁₈ column as the stationary phase and the mixture of methanol and 0.02 mol·L^-1 potassium dihydrogen phosphate solution (pH 6.00) at different volume ratios as the mobile phase for gradient elution. As shown by the results, linear relationships between values of peak area and mass concentration of 12 whitening functional substances were found in definite ranges, with detection limits (3S/N) in the range of 0.000 1%-0.003 2%. Test for recovery was made by standard addition method, giving results in the range of 71.6%-103%, with RSDs (n=6) of the determined values less than 8.0%. This method was applied to the analysis of 52 whitening cosmetic samples, and the detection rate of nicotinamide was the highest (48%), with detection amounts of 0.004%-4.7%. In addition, it was also found that the labels of whitening cosmetics were confused, which should be attracted attention.