FOSCARNET IMPURITY B;1-Ethoxy-1-hydroxyphosphinecarboxylic acid 1-oxide disodium salt;Disodium (ethoxyoxydophosphanyl)formate;Foscarnet Sodium EP Impurity B;Foscarnet sodium hexahydrate EP Impurity B;Benzenemethanol,3-bromo-7-ethyl-;Foscarnet Sodium Hexahydrate EP Impurity B as Disodium Salt;Foscarnet USP Related Compound B as Disodium Salt