3-((2,4-Dihydroxy-5-((4-nitro-2-sulfophenyl)azo)phenyl)azo)-4-methoxybenzenesulfonic acid, disodium salt 72906-17-3 Benzenesulfonic acid, 2-((2,4-dihydroxy-5-((2-methoxy-5-sulfophenyl)azo)phenyl)azo)-5-nitro-, disodium salt