Determination of Carboxybetaine Amphoteric Surfactants in Household and Cosmetic Products by High Performance Liquid Chromatography with Prelabeling

A high performance liquid chromatographic (HPLC) method is described for the determination of carboxybetaine amphoteric surfactants in commercial household and cosmetic products. The surfactants are prelabeled with 4-bromomethyl-7-methoxycoumarin and then are separated by reversed phase HPLC with a gradient elution. The determination of carboxybetaines in shampoos was carried out by an internal standard method. The calibration curve was linear in the range from 0.007 to 4.6nmol. The relative standard deviation was found to be 1.0% for 0.46nmol injection. By using the proposed method, carboxybetaines in commercial household and cosmetic products were determined with high sensitivity and high selectivity.