Ethanedioic acid,1-methyl ester, potassium salt (1:1) Potassium 2-methoxy-2-oxoacetate Tiotropium Bromide Impurity 8 Potassium Salt potassium oxalate monomethyl ester Ethanedioic acid,1-methyl ester, potassium salt Methyl potassium oxalate 95% Ethanedioic acid, monomethyl ester, potassium salt Ethanedioicacid,monomethylester,potassiumsalt(1:1)