Determination of the iron state in ferrous iron containing vitamins and dietary supplements: Application of Mössbauer spectroscopy

Determination of the iron state in commercially manufactured iron containing vitamins and dietary supplements is important for evaluation of pharmaceuticals quality. Mössbauer (nuclear gamma-resonance) spectroscopy was used for analyzing the iron state in commercial pharmaceutical products containing ferrous fumarate (FeC4H2O4), ferrous sulfate (FeSO4), ferrous bisglycinate chelate (Ferrochel®) and ferrous iron (hydrolyzed protein chelate). Mössbauer parameters and the iron states were determined for iron compounds in the studied pharmaceuticals. Various ferric and ferrous impurities were found in all of the commercial products. The quantities of ferric impurities exceeded the FDA limitation of 2% in products containing ferrous fumarate. The quantities of ferric impurities exceeded 58% and 30% in products containing ferrous bisglycinate chelate and ferrous iron (hydrolyzed protein chelate), respectively. The presence of ferrous and ferric impurities was not related to the ageing of the vitamins and dietary supplements. Two pharmaceutical products contained major iron compounds, the Mössbauer parameters of which did not correspond to the ferrous fumarate or ferrous bisglycinate chelate claimed by the manufacturer.