Reverse Phase Liquid Chromatographic Determination of Intermediates and Subsidiary Colors in D&C Green No. 5

Abstract

Abstract A reverse phase liquid chromatographic method is presented for the simultaneous determination of 2-amino-5-methylbenzenesulfonic acid, 5-amino-2-methylbenzenesulfonic acid, External D&C Violet No. 2, and the lower sulfonated subsidiary color in D&C Green No. 5. The method uses octadecylsilanized silica gel as the stationary phase and gradient elution with a mobile phase of aqueous acetonitrile solutions containing ammonium acetate. A wide dynamic range is achieved in a single analysis with quantitation of the intermediates at relatively low levels, up to 0.2% (w/w) each, and subsidiary colors at relatively high levels, up to 3.0% (w/w) each. In addition, the method separates the 3 primary disulfonated isomers of D&C Green No. 5 as well as numerous unidentified components. The results of a recovery study and a survey of 16 commercial samples and the pharmacology sample are presented. Recoveries of the intermediates and subsidiary colors from samples of D&C Green No. 5 ranged from 96.8 to 103.8%. The calibration and recovery data are treated statistically to evaluate the performance of the method.