3-Hydroxy[4,4'-[6-[(sodiooxy)sulfonyl]naphthalene-1,4-diylbisazo]bis(2,7-naphthalene-disulfonic acid disodium)] salt

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