Determination of N-Acyl-l-glutamates Surfactants by Capillary Electrophoresis Using Organic Modifier

Capillary electrophoresis was applied to the separation of C12–C18N-acyl-l-glutamates surfactants, used for cosmetic ingredients. Using the aqueous buffer of 10 mM borate at pH 9.2, unstable mobility and peak-broadening of the surfactant ions were observed. The effect of addition of organic solvents to the borate buffer system was investigated by means of the determination of electrophoretic mobility and zone width of the solutes. The results indicated that the addition of methanol, capable of hydrogen bonding, was more effective than that of acetonitrile to avoid micelle formation of the surfactant and to stabilize the electrophoretic behavior. An optimized condition was established by adding 15%(v/v) methanol to the borate buffer. The application to a cosmetic product was also briefly examined using the optimized condition.