[Studies for analyzing prohibited ingredients such as cadmium sulfide in cosmetics]

Cadmium sulfide is one kind of the prohibited ingredients in cosmetics by the Japanese Pharmaceutical Affairs Act. We established the analytical method for cadmium sulfide in cosmetics by ICP-MS. Analytical procedures were as follows: Cosmetics of 1 g contained inorganic pigment were put into a 100 ml flask glass. After adding 100 ml of 12% nitric acid into the 100 ml flask glass, the filtrate was sonicated for 30 min. After sonicating, the mixture was centrifuged at 3000 rpm for 5 min and then the supernatant was filtrated through a millipore membrane filter (0.45 microm). After filtration, the filtrate was made up to 200 ml with 12% nitric acid. The solution was diluted 100 times with 12% of nitric acid and used as the test solution. The test solution of 100 microl was analyzed by ICP-MS (HP-4500, monitoring mass 111). The working curve from 1 to 1000 microg/l showed a linear line between the concentrations of cadmium and the peak areas. Detection limit of cadmium is 0.02 microg/l. There was no effect of the ingredients in the cosmetics on cadmium sulfide determination.