2,7-Naphthalenedisulfonic acid, 5-((2,4-dihydroxy-5-((4-nitrophenyl)azo)phenyl)azo)-4-hydroxy-3-((4-nitrophenyl)azo)-, disodium salt 70210-24-1 Disodium 5-((2,4-dihydroxy-5-((4-nitrophenyl)azo)phenyl)azo)-4-hydroxy-3-((4-nitrophenyl)azo)naphthalene-2,7-disulphonate EINECS 274-421-5