4-hydroxy-3-[[4-[[[3-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]amino]carbonyl]phenyl]azo]naphthalene-1-sulphonic acid, sodium salt

4-Hydroxy-3-[[4-[[[3-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]amino]carbonyl]phenyl]azo]-1-naphthalenesulfonic acid/sodium,(1:x) salt