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In this work, 57Fe Mössbauer spectroscopy was used to investigate various iron-containing anti-anemic pharmaceutical products, with the aim of characterizing the oxidation state and type of iron in these products. The commercial products studied (active ingredient as declared by the manufacturer): Fermarato Tablets (Ferrous Fumarate), Fermafolic 60 (Ferrous Fumarate), Nature´s Blend (Ferrous Sulfate), Gentle Iron® (Ferrous Bis-glycinate), and Ferrum Hausmann® (Iron (III) hydroxide - polymaltose complex). The room temperature spectra of Fermarato Tablets and Fermafolic 60 gave clear evidence of the presence of two phases: one ferrous (Fe2+) as the main one, with a contribution equal to or greater than 96%, and the other ferric (Fe3+) (~4%). The first corresponds to ferrous fumarate FeC4H2O4, while the second would be related to a high-spin ferric compound derived from the oxidation of ferrous fumarate or could belong to another ferric salt included during production. Meanwhile, in Nature's Blend, in addition to partially hydrated ferrous sulfate, FeSO4 · H2O, as the main component (80%), a second component (16%) was observed that could be related to an Fe2+-citrate complex, and an additional component (4%) was identified as ferric sulfate. The Mössbauer spectrum of Gentle Iron® was fitted with several paramagnetic components that can be assigned to ferrous bisglycinate chelate, ferrous sulfate, and the products of their modifications and/or transformations or oxidation due to the instability of the ferrous bisglycinate chelate. The total fraction of ferric iron in the complex was approximately 4%. Finally, the spectrum corresponding to the Ferrum Hausmann® supplement was fitted with two typical high-spin ferric iron quadrupolar doublets associated with the iron (III) hydroxide complex polymaltose. This compound would combine akaganeite ?-FeOOH wrapped in polymaltose. It can be concluded that there was a good correspondence between the manufacturers' statements and the results of the Mössbauer analysis.
