135-53-5 2,3-Dihydroxynaphthalene-6-sodium sulfonate 2-Naphthalenesulfonic acid, 6,7-dihydroxy-, monosodium salt 6,7-Dihydroxy-2-naphthalenesulfonic acid sodium salt NSC7203 Sodium 2,3-dihydroxynaphthalene-6-sulfonate Sodium 2,3-dioxynaphthalene-6-sulfonate