Stability of ferrous fumarate in medicaments for women: Application of Mössbauer spectroscopy

Determination of the iron state (Fe²⁺ or Fe³⁺) and content of iron in commercial pharmaceutical products containing ferrous fumarate FeC₄H₂O₄ was made by the Mössbauer spectroscopy and X-ray fluorescence method. Also, influence of thermal treatment on stability of ferrous fumarate in selected medicaments has been investigated. The investigated samples were annealed in definite temperature: 373, 473, and 573 K for 5 h. Room temperature Mössbauer spectra of initial samples gave clear evidence that two phases of iron were presented. The major component was connected with ferrous fumarate with a contribution from ≈85% to ≈50%, depending on investigated medicaments. Ferrous fumarate was stable up to annealing temperature 473 K. Above this temperature significant oxidation of Fe²⁺ to Fe³⁺ was observed.