dipotassium 6-amino-4-hydroxy-5-[[3-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2-sulphonate

6-Amino-4-hydroxy-5-[[3-[[2-(potassiosulfooxy)ethyl]sulfonyl]phenyl]azo]-2-naphthalenesulfonic acid potassium salt