disodium 3-[[4-[(4-amino-1-naphthyl)azo]-2,5-dimethylphenyl]azo]naphthalene-1,5-disulphonate

3-[[4-[(4-Amino-1-naphthalenyl)azo]-2,5-dimethylphenyl]azo]-1,5-naphthalenedisulfonic acid disodium salt