disodium 8-[[3-[(ethylphenylamino)sulphonyl]-4-methylphenyl]azo]-7-hydroxynaphthalene-1,3-disulphonate

8-[[3-[(Ethylphenylamino)sulfonyl]-4-methylphenyl]azo]-7-hydroxy-1,3-naphthalenedisulfonic acid disodium salt