tetrasodium 3,3'-[carbonylbis(imino-p-phenyleneazo)]bis[4-amino-5-hydroxy-6-(phenylazo)naphthalene-2,7-disulphonate]

3,3'-[Carbonylbis(imino-4,1-phenyleneazo)]bis[4-amino-5-hydroxy-6-(phenylazo)-2,7-naphthalenedisulfonic acid]tetrasodium salt