disodium 4-[[2,4-dihydroxy-5-[(2-hydroxy-4-nitrophenyl)azo]-3-[(4-nitrophenyl)azo]phenyl]azo]-5-hydroxynaphthalene-2,7-disulphonate

4-[[2,4-Dihydroxy-5-[(2-hydroxy-4-nitrophenyl)azo]-3-[(4-nitrophenyl)azo]phenyl]azo]-5-hydroxy-2,7-naphthalenedisulfonic acid disodium salt