trisodium 4-amino-5-hydroxy-3-[[4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2,7-disulphonate

2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3-[[4-[ [2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-, trisodium salt