2,7-Naphthalenedisulfonic acid, 4,5-dihydroxy-3-((4-sulfophenyl)azo)-, trisodium salt 23647-14-5 EINECS 245-803-9 Trisodium 4,5-dihydroxy-3-(4-sulphonatophenylazo)naphthalene-2,7-disulphonate