4-(4,6-Dichloro-s-triazin-2-ylamino)-5-hydroxy-6-(2-hydroxy-5-nitrophenylazo)-2,7-naphthalenedisulfonic acid

(3E)-5-[(4,6-dichloro-1,3,5-triazin-2-yl)amino]-3-[(2-hydroxy-5-nitro-phenyl)hydrazinylidene]-4-oxo-naphthalene-2,7-disulfonic acid