Synonyms: Tetrasodium 4,4'-((2,2'-dimethyl(1,1'-biphenyl)-4,4'-diyl)bis(azo))bis(3-hydroxynaphthalene-2,7-disulphonate);tetrasodium (4Z,4'Z)-4,4'-[(2,2'-dimethylbiphenyl-4,4'-diyl)di(1Z)hydrazin-2-yl-1-ylidene]bis(3-oxo-3,4-dihydronaphthalene-2,7-disulfonate)