Ammonium ferric citrate
Encyclopedia
Ammonium ferric citrate is a food additive
Food additive
Food additives are substances added to food to preserve flavor or enhance its taste and appearance.Some additives have been used for centuries; for example, preserving food by pickling , salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines...

 with E number
E number
E numbers are number codes for food additives that have been assessed for use within the European Union . They are commonly found on food labels throughout the European Union. Safety assessment and approval are the responsibility of the European Food Safety Authority...

 E381 used as an acidity regulator
Acidity regulator
Acidity regulators, or pH control agents, are food additives added to change or maintain pH . They can be organic or mineral acids, bases, neutralizing agents, or buffering agents....

. 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)2 to an aqueous solution of citric acid
Citric acid
Citric acid is a weak organic acid. It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks...

 and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

. 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.

Other uses for ammonium ferric citrate include water purification and printing (cyanotype
Cyanotype
Cyanotype is a photographic printing process that gives a cyan-blue print. The process was popular in engineering circles well into the 20th century. The simple and low-cost process enabled them to produce large-scale copies of their work, referred to as blueprints...

). 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
Potassium ferricyanide
Potassium ferricyanide is the chemical compound with the formula K3[Fe6]. This bright red salt contains the octahedrally coordinated [Fe6]3− ion. It is soluble in water and its solution shows some green-yellow fluorescence.-Preparation:...

 to make cyanotype prints. Ammonium ferric citrate is also used in Kligler iron deeps to determine hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

 production in microbial metabolism.

Ammonium ferric citrate is present in Scottish carbonated soft drink Irn-Bru
Irn-Bru
Irn-Bru is a carbonated soft drink produced in Westfield, Cumbernauld, Scotland. It is made by A.G. Barr of Glasgow since moving out of their original Parkhead factory in the mid-1990s and at a second manufacturing site in Mansfield, England...

.

In medicine, ammonium ferric citrate is used as a contrast medium
Contrast medium
A medical contrast medium is a substance used to enhance the contrast of structures or fluids within the body in medical imaging...

. It is also used as a hematinic
Hematinic
A hematinic is a medicine that increases the hemoglobin content of the blood. Hematinics are used to treat iron-deficiency anemia. Hematinics are usually vitamins or minerals that are essential for normal erythropoiesis-External links:***...

.

Compendial status

  • Martindale: The Extra Pharmacopoeia 


See also

  • Ammonium citrate tribasic
  • Food additive
    Food additive
    Food additives are substances added to food to preserve flavor or enhance its taste and appearance.Some additives have been used for centuries; for example, preserving food by pickling , salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines...

  • List of food acidity regulators
  • List of food additives
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