Synonyms: 2,7-Naphthalenedisulfonicacid, 3-[(2,4-dinitrophenyl)azo]-4-hydroxy-, disodium salt (8CI,9CI);Nitrazineyellow (7CI);C.I. 14890;Delta Paper;Nitrazine Paper;Nitrazol Yellow;Phenaphthazine;disodium 3-(2,4-dinitrophenyl)azo-4-hydroxy-naphthalene-2,7-disulfonate;Disodium 3-[(2,4-dinitrophenyl)diazenyl]-4-hydroxynaphthalene-2,7-disulfonate;2,7-naphthalenedisulfonic acid, 3-[2-(2,4-dinitrophenyl)diazenyl]-4-hydroxy-, sodium salt (1:2);