3-[(4-acetamidophenyl)diazenyl]-4-amino-5-oxo-6-(phenylhydrazinylidene)naphthalene-2,7-disulfonate;disodium 3-[[4-(acetylamino)phenyl]azo]-4-amino-5-hydroxy-6-(phenylazo)naphthalene-2,7-disulphonate;3-[4-(Acetylamino)phenylazo]-4-amino-5-hydroxy-6-(phenylazo)-2,7-naphthalenedisulfonic acid disodium salt