Identification and determination of unknown subsidiary colors Identification and determination of unknown subsidiary colors Identification and determination of unknown subsidiary colors Identification and determination of unknown subsidiary colors

Three subsidiary colors (Sub-A, Sub-B, and Sub-E) were isolated from commercial Food Green No.3 (G-3) by using preparative HPLC and their structures were determined by MS and NMR. The structures of Sub-A, Sub-B, and Sub-E were the disodium salt of 2-[[4-[N-ethylN-(3-sulfophenylmethyl)amino]phenyl][4-[N-(3-sulfophenylmethyl)amino]phenyl]methylio]-4hydroxybenzenesulfonic acid [abbreviated as HSBA-(m-BASA)(m-EBASA)], the disodium salt of 2-[bis[4-[N-ethyl-N-(4-sulfophenylmethyl)amino] phenyl]methylio]-4-hydroxybenzenesulfonic acid (abbreviated as p,p-G-3), and the disodium salt of 2-[[4-[N-ethyl-N-(2-sulfophenylmethyl) amino]phenyl][4-[N-ethyl-N-(3-sulfophenylmethyl)amino]phenyl]methylio]-4-hydroxybenzenesulfonic acid (abbreviated as o,m-G-3), respectively. HPLC analyses revealed that the contents of seven subsidiary colors (Sub-A, B, C, E, F, G, and H) including the four subsidiary colors (Sub-C, F, G, and H) reported previously in 4 commercial G-3 products were 0.45~1.20%, 0.19~2.60%, 8.49~27.0%, 0.05~1.52%, 1.15~2.37%, 0.05~0.22%, and ND~0.24%, respectively.