2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3-((4-nitrophenyl)azo)-6-((3-sulfophenyl)azo)-, trisodium salt 67786-07-6 EINECS 267-087-7 Trisodium 4-amino-5-hydroxy-3-((4-nitrophenyl)azo)-6-((3-sulphonatophenyl)azo)naphthalene-2,7-disulphonate