trisodium 2-[[4-[(4-amino-1-naphthyl)azo]-6-sulphonato-1-naphthyl]azo]benzene-1,4-disulphonate

2-[[4-[(4-Amino-1-naphthalenyl)azo]-6-(sodiooxysulfonyl)-1-naphthalenyl]azo]-1,4-benzenedisulfonic acid disodium salt