of the basic ammonium salt of the carboxyl ate the water soluble metal salt is added to the ammonium carboxyl ate base and the mixture is allowed to react at room temperature in the initial period followed by reaction at a lower temperature in a chiller the temperature is carefully controlled through out the process in the present invention in which at the reaction was carried out at room temperature 22 30 u00b0 c in the initial period followed by reaction at lower temperature 0 16 u00b0 c a reducing agent maybe also added in the reaction mixture to prevent the rapid oxidation of divalent metal m 2 to trivalent metal m 3 when an easily oxidized divalent metal is used such as ferrous salt the products of the present invention have applicability as sources of metal in dietary supplements for humans and other animals accordingly it is preferred that the starting materials as well as the by product are acceptable for consumption at the levels it is present in the completed reaction either before or after purification step the preferred embodiment of the present invention uses the ammonium salt of carboxyl ate as the basic carboxyl ate salt the carboxylates component being the carboxyl ate moiety of the straight chain monocarboxylic or polycarboxylic acid possessing 1 to 20 carbon atoms such as formic acid acetic acid prop ionic.