pentasodium 4-[[4-[(3,6-disulphonato-1-naphthyl)azo]-7-sulphonato-1-naphthyl]azo]-3-hydroxynaphthalene-2,7-disulphonate

4-[[4-[(3,6-Disulfo-1-naphthalenyl)azo]-7-sulfo-1-naphthalenyl]azo]-3-hydroxy-2,7-naphthalenedisulfonic acid pentasodium salt