LABORATORY EVALUATIONS OF SOLUBILITY AND STRUCTURAL INTEGRITY OF COMPLEXED AND CHELATED TRACE MINERAL SUPPLEMENTS

Commercially complexed and chelated mineral supplements (5 Cu, 5 Zn, a nd 5 Mn products) were evaluated for solubility of their metals at con centrations of .1 25, .25, .5, 2.5, and 12.5 mg/ml in buffers at pH 5 and 2. At pH 5, solubility was related inversely to concentration, and most products were highly soluble at the lowest concentration tested. At pH 2, metals from all products were nearly 100% soluble at all con centrations. The relationships among soluble metals and proteinaceous (ninhydrin-reactive) substances in filtrates from solubility tests wer e evaluated using gel filtration chromatography. Chromatographs reveal ed that ninhydrin reactants in all pH 5 filtrates eluted in fractions earlier than, and separately from, the fractions containing metals. Ni nhydrin reactants and metals in filtrates eluted in the same general r anges of fractions as did ninhydrin reactants and metals from mixtures prepared from pure AA and atomic absorption standards. The minerals s olubilized from these products apparently no longer were chelated.