for the following products
3-(2-Pyridyl)-1,2,4-triazine-5,6-difurylsulfonic acid sodium salt | 3-(2-Pyridyl)-5,6-bis-[2-(5-furylsulfonic acid)]-1,2,4-triazine disodium salt | Ferene | Ferene disodium salt and 3-(2-Pyridyl)-5,6-di(2-furyl)-1,2,4-triazine-5',5''-sulfonic acid disodium salt
