Ammonium ferric citrate

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Ammonium ferric citrate
Ferric ammonium citrate.png
Ferric amm citrate1.jpg Ferric amm citrate2.jpg
CAS number 1185-57-5 YesY
PubChem 3080636
ChemSpider 2338386 YesY
EC number 214-686-6
ATC code V08CA07
Jmol-3D images Image 1
Molecular formula C6H5+4yFexNyO7
Molar mass Variable
Appearance Reddish-brown powder
MSDS [1]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Ammonium ferric citrate is a food additive with E number E381 used as an acidity regulator.[citation needed] It is a green or 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.[1] 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. The green type is more readily reduced by light than the brown.[2]

Other uses for ammonium ferric citrate include water purification and printing (cyanotype). It is used as a reducing agent of metal salts of low activity like gold and silver and is also in a commonly used recipe with potassium ferricyanide to make cyanotype prints. Ammonium ferric citrate is also used in Kligler iron deeps to determine hydrogen sulfide production in microbial metabolism.

Ammonium ferric citrate is present in Scottish carbonated soft drink Irn-Bru.[3]

In medicine, ammonium ferric citrate is used as a contrast medium. It is also used as a hematinic.[2]

Compendial status[edit]

See also[edit]