2-Naphthalenesulfonic acid, 3-[[4-[[[4-[4-[(3-chloro-2-hydroxy-5-sulfophenyl)azo]-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-1-yl]phenyl]amino]carbonyl]-2-methylphenyl]azo]-7-[4,5-dihydro-4-[(2-hydroxy-3-nitro-5-sulfophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]