[Studies for analyzing the prohibited ingredients such as selenium disulfide in cosmetics].

Selenium disulfide is one kind of prohibited ingredients in cosmetics by the Japanese Pharmaceutical Affairs Act. We established the analytical method for selenium disulfide in cosmetics by ICP-MS. Selenium disulfide of 20 mg was put into a teflon vessel. After adding 5 ml of concentrated nitric acid and 2 ml of the shampoo into the teflon vessel, the mixture was digested with microwave-oven. After digesting, the mixture was made up to 25 ml with milliQ water and then it was filtrated through a milli-pore membrane (0.45 micro). After filtration, the solution was diluted with 7% of nitric acid and used as the test solution. The test solution of 100 microl was analyzed by ICP-MS (HP-4500, monitoring mass 82). The working curve from 10 to 1000 microg/l showed a linear line between the concentrations of selenium and the peak areas. Detection limit of selenium disulfide is 22 microg/l. There was no effect of the ingredients in the shampoo on selenium disulfide determination.