7-hydroxy-8-[[4'-[(2-hydroxy-8-sulpho-1-naphthyl)azo][1,1'-biphenyl]-4-yl]azo]naphthalene-1,3-disulphonic acid, sodium salt

7-Hydroxy-8-[[4'-[(2-hydroxy-8-sulfo-1-naphthalenyl)azo][1,1'-biphenyl]-4-yl]azo]-1,3-naphthalenedisulfonic acid/sodium,(1:x) salt