trisodium 6-[(2,4-diaminophenyl)azo]-4-hydroxy-3-[(4-sulphonato-1-naphthyl)azo]naphthalene-2,7-disulphonate

6-[(2,4-Diaminophenyl)azo]-4-hydroxy-3-[[4-(sodiosulfo)-1-naphtyl]azo]-2,7-naphthalenedisulfonic acid disodium salt