Determination and Survey of Starting Materials, Intermediates, and Subsidiary Colors in Sunset Yellow FCF by High Performance Liquid Chromatography

A determination method by HPLC for starting materials [sulfanilic acid (SA), G-salt (GS), R-salt (RS), Schaeffer's salt (SS)], intermediates [6, 6′-oxybis(2-naphthalenesulfonic acid) (DONS), 4, 4′-(diazoamino)-dibenzenesulfonic acid (DAADBSA)] and subsidiary colors [3-hydroxy-4-[(4-sulfophenyl)azo]-2, 7-naphthalenedisulfonic acid (RS-SA), 4-[(2-hydroxy-1-naphthalenyl)azo] benzenesulfonic acid (2N-SA), 6-hydroxy-5-(phenylazo)2-naphthalenesulfonic acid (SS-AN)] in sunset yellow FCF was developed. The following conditions were used for analysis: column, Inertsil ODS-2 (4.6mm i. d.×250mm); solvent, gradient elution system of 0.02M ammonium acetate and 40v/v% acetonitrile in 0.02M ammonium acetate; detection, SA, GS, RS, SS and DONS at 232nm, DAADBSA at 358nm and subsidiary colors at 482nm.Recoveries of each impurity from sunset yellow FCF averaged 99.4-102.2%. Sixteen samples of commercial sunset yellow FCF in Japan were examined, with the following results: SA, N. D. -0.170%; GS, N. D. -0.080%; RS, N. D. -0.050%; SS, N. D. -0.281%; DONS, N. D. -0.250%; DAADBSA, N. D. -0.210%; RS-SA, 0.024-3.54%; mixtures of SS-AN and 2N-SA (as SS-AN); 0.015-0.360%. The detection limit was 0.05μg/g for each impurity.