tetrasodium 5,5'-[ethylenebis[(3-sulphonato-4,1-phenylene)-ONN-azoxy]]bis[8-(phenylazo)naphthalene-2-sulphonate]

5,5'-[1,2-Ethenediylbis[(3-sulfo-4,1-phenylene)-ONN-azoxy]]bis[8-(phenylazo)-2-naphthalenesulfonic acid]tetrasodium salt