[Studies for analyzing prohibited ingredients such as mercury in cosmetics]

Mercury is one kind of prohibited ingredients in cosmetics by the Japanese Pharmaceutical Affairs Act. We established the analytical method for mercury in cosmetics by ICP-MS. Analytical procedures were as followed: Ten microl of 1 g/l mercury solution and 1 g of whitening cream were put into a 50 ml plastic tube. After adding 20 ml of 12% nitric acid into the 50 ml plastic tube, the mixture was sonicated for 10 min. After sonicating, the mixture was centrifuged at 3000 rpm for 10 min and then the supernatant was filtrated through a milli-pore membrane with the pore size of 0.45 microm and 0.1 microm. After filtration, the mixture was made up to 25 ml with 7% nitric acid and used as the test solution. The test solution of 100 microl was analyzed by ICP-MS (HP-4500, monitoring mass 202). The calibration curve from 1 to 1000 microg/l showed a linear line between the concentrations of mercury and the peak areas. Detection limit of mercury was 0.1 microg/l. There was no effect of the ingredients in the whitening cream on mercury determination.