Synonyms: disodium 3,3'-[iminobis(4,1-phenyleneazo)]bis[5-(benzoylamino)-4-hydroxynaphthalene-2,7-disulphonate];2,7-Naphthalenedisulfonic acid, 3,3-iminobis(4,1-phenyleneazo)bis5-(benzoylamino)-4-hydroxy-, sodium salt;3,3'-[Iminobis(4,1-phenyleneazo)]bis[5-(benzoylamino)-4-hydroxy-2,7-naphthalenedisulfonic acid]/sodium,(1:x) salt