Ammonium ferric citrate is a food additive with E number E381 used as an acidity regulator. It is a reddish-brown powder which is very soluble in water. The molecular formula of ammonium iron(III) citrate is variable. It can be prepared by adding Fe(OH)3 to an aqueous solution of citric acid and ammonia. The brown form is approximately 9% NH3, 16.5–18.5% Fe, and 65% hydrated citric acid; the green form is approximately 7.5% NH3, 14.5–16% Fe, and 75% hydrated citric acid. Ammonium ferric citrate is present in Scottish carbonated soft drink Irn-Bru. In medicine, ammonium ferric citrate is used as a contrast medium. It is also used as a hematinic.

Acidity regulator
Water Purification R
educing Agent for Metal Salts
Used in making Cyanotype prints inconjunction with Potassium Ferrocyanide

Minimum Assay (Fe): >18%
Molecular Formula: C6H8O7.xFe3+.yNH3
Colour: Brown
pH: 6.0-8.0
Chloride (CI): <0.053%
Sulphate (SO4): <1.5

Hazard Phrases: Not considered harmful under normal laboratory conditions

Cas No: 1185-57-5
Einecs No: 214-686-6