Abstract:

The differences in qualitative and quantitative analysis between menthol of different configurations were compared. A method for simultaneous determination of menthol and menthyl lactate by GC-MS was established. The injection mode, extraction solvent, extraction time, column, split ratio and other parameters were studied. Samples were ultrasonically extracted by methanol, separated by a VF-WAXms column （30 m×0.25 mm×0.25 μm）, detected with selected ion monitoring （SIM） scanning mode by direct liquid introduction, and quantified by external standard method. The results show that, there are no significant differences in response, retention time and SCAN mass spectra for menthol with different configurations; the linearity is good for menthol and menthyl lactate in the range of 0.1-100 mg/L, with the correlation coefficient above 0.999; the detection mass concentrations are 0.009 and 0.002 mg/L, the detection limits are 0.9 and 0.2 mg/kg; the quantification mass concentrations are 0.027 and 0.006 mg/L, and the quantification limits are 2.7 and 0.6 mg/kg; the recovery rates of the spiked standards are 96.3%-100.7% with the relative standard deviations of 1.9%-3.5%. Four products （a facial cleanser, two shampoos and a hair conditioner） were tested by this method. This method is simple, sensitive, and accurate, and it is suitable for the determination of menthol and menthyl lactate in cosmetics.

Key words: cosmetics, menthol, menthyl lactate, GC-MS