1-Naphthalenesulfonic acid, 3-hydroxy-4-((2-hydroxy-1-naphthalenyl)azo)-, zinc salt (2:1) 2538-85-4 3-Hydroxy-4-((2-hydroxy-1-naphthalenyl)azo)-1-naphthalenesulfonic 3-Hydroxy-4-((2-hydroxy-1-naphthalenyl)azo)-1-naphthalenesulfonic acid, monozinc salt 5410-93-5 EINECS 226-486-6 NSC 4203 Zinc 2,2'-dihydroxy-1,1'-azonaphthalene-4-sulphonate