Ferrous Fumarate

Ferrous fumarate is the iron(II) salt of fumaric acid, C4H2FeO4 (CAS 141-01-5, molecular weight 169.90). The USP monograph requires not less than 97.0% and not more than 101.0% of C4H2FeO4 calculated on the dried basis, with loss on drying not more than 1.5% and ferric iron not more than 2.0%. Theoretical elemental iron is 32.9%, one of the highest payloads available from an organic iron salt, which is why the material dominates solid dosage forms where the iron dose has to be delivered inside a tablet of acceptable size. It presents as a reddish-orange to red-brown fine powder. Unlike ferrous sulphate, ferrous fumarate is only slightly soluble in water and very slightly soluble in ethanol, dissolving readily in dilute mineral acids. That low aqueous solubility is a formulation advantage in dry blends and compressed dosage forms, since less free ionic iron is available to interact with other actives, but it rules the salt out of clear liquid applications. Iron supplied in this form performs the same established nutrient role, being a constituent of haemoglobin and of a range of iron-dependent enzymes. Milled and granular grades are both offered; the granular grade compresses and flows better on high-speed tablet presses, while the milled grade is used where content uniformity in a low-dose premix is the controlling factor. The strong colour should be accounted for at formulation stage, particularly in uncoated tablets and light-coloured powders. Batches are released against a certificate of analysis covering assay on the dried basis, appearance, loss on drying, ferric iron, particle size distribution and microbiological limits, with arsenic not more than 3 ppm, lead not more than 10 ppm and mercury not more than 3 micrograms per gram to the USP limits. Third-party heavy-metal reconfirmation, retention samples, and kosher, halal, non-GMO and allergen statements are supplied on request. Export packing, documentation and stability data are prepared to the destination market's requirements.