trisodium 4-[[1-hydroxy-8-[[1-oxo-3-(phenylsulphonyl)propyl]amino]-3,6-disulphonato-2-naphthyl]azo]benzoate

4-[[1-Hydroxy-8-[[1-oxo-3-(phenylsulfonyl)propyl]amino]-3,6-bis(sodiosulfo)-2-naphthalenyl]azo]benzoic acid sodium salt