tetrasodium 2,2'-[vinylenebis(3-sulphonato-4,1-phenylene)]bis[2H-naphtho[1,2-d]triazole-7-sulphonate]

2,2'-[1,2-Ethenediylbis(3-sodiosulfo-4,1-phenylene)]bis[2H-naphtho[1,2-d]triazole-7-sulfonic acid]disodium salt