Abstract:

A gas chromatographic method was established for determination of squalane in cosmetics. The GC instrument conditions and sample pretreatment process were optimized. The water-soluble cosmetics were extracted with petroleum ether, while the fat-soluble cosmetics were saponified with potassium hydroxide-ethanol solution and then extracted by n-hexane. The extraction liquid was concentrated by nitrogen-blowing, redissolved with n-hexane and brought to volume with n-hexane. The sample was analyzed on an HP-5 column with temperature programming, detected by an FID detector, and quantitated using external standard method. The results showed that, the optimal injection volume was 1 μL, the best saponification temperature was 80 ℃, the optimal saponification time was 30 min, the optimal number of times for extraction was 3, the relative standard deviation of instrument repeatability was 1.13%, and a good linear relationship was obtained between the mass concentration range of squalane from 1 to 1 000 μg/mL with the correlation coefficient of 1.The limits of detection and quantitation were 1 mg/kg and 3 mg/kg, respectively. At low, medium and high levels, the spiked recoveries ranged from 92.7% to 103.5%, and the range of relative standard deviation was 1.83%-5.39%. This method is simple in experimental operation, and has good repeatability, good precision, high sensitivity and reliable accuracy. It can accurately determine the content of squalane in cosmetics.

Key words: gas chromatography, cosmetics, squalane