2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-((2-methylphenyl)azo)-, disodium salt 7,7'-(Carbonyldiimino)bis(4-hydroxy-3-((2-methylphenyl)azo)-2-naphthalenesulfonic acid), disodium salt 72749-87-2