[Studies for analyzing the prohibited ingredients such as disodium monofluorophosphate in cosmetics]

Disodium monofluorophosphate is one kind of the prohibited ingredients in cosmetics due to the Japanese Pharmaceutical Affairs Act. We established the analytical method for disodium monofluorophosphate in cosmetics by capillary electrophoresis (CE). The tooth paste of 1 g was put into a 50-ml plastic tube. After adding 7.0 mg of disodium monofluorophosphate and 50 ml of milliQ water into the plastic tube, the mixture was ultrasonicated for 10 min. After centrifuging, the supernatant was filtrated through a milli-pore membrane (0.45 microm). After filtration, the solutionwas put into a 100-ml volumetric flask, made up to 100 ml with milliQ water and used as the test solution. The mouthwash of 1 ml and 7.0 mg of disodium monofluorophosphate were put into a 100-ml volumetric flask, made up to 100 ml with milliQ water and used as the test solution. The testing solution was analyzed by CE. The working curve from 10 to 100 microg/ml showed a linear line between the concentrations of disodium monofluorophosphate and monofluorophosphate peak areas. Detection limit of disodium monofluorophosphate is 0.3 microg/ml. There was no interference of peak of monofluorophosphate with the ingredients in the tooth paste and mouthwash.