The term calcium phosphate refers to a family of materials and minerals containing

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

ions (Ca²⁺) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and

hydroxide Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water ...

as well. Calcium phosphates are white solids of nutritious value and are found in many living organisms, e.g., bone mineral and

tooth enamel Tooth enamel is one of the four major tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are denti ...

. In milk, it exists in a colloidal form in micelles bound to casein protein with magnesium, zinc, and citrate–collectively referred to as colloidal calcium phosphate (CCP). Various calcium phosphate minerals are used in the production of

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solutio ...

and

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

s. Overuse of certain forms of calcium phosphate can lead to nutrient-containing

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

and subsequent adverse effects upon receiving waters such as algal blooms and eutrophication (over-enrichment with nutrients and minerals).

Orthophosphates, di- and monohydrogen phosphates

These materials contain Ca²⁺ combined with , , or : * Monocalcium phosphate, E341 (CAS# 7758-23-8 for anhydrous; CAS#10031-30-8 for monohydrate: Ca(H₂PO₄)₂ and Ca(H₂PO₄)₂(H₂O) * Dicalcium phosphate (dibasic calcium phosphate), E341(ii) (CAS# 7757-93-9): CaHPO₄ (mineral: monetite), dihydrate CaHPO₄(H₂O)₂ (mineral: brushite) and monohydrate CaHPO₄(H₂O) * Tricalcium phosphate (tribasic calcium phosphate or tricalcic phosphate, sometimes referred to as calcium phosphate or calcium orthophosphate, whitlockite), E341(iii) (CAS#7758-87-4): Ca₃(PO₄)₂ * Octacalcium phosphate (CAS# 13767-12-9): Ca₈H₂(PO₄)₆·5H₂O * Amorphous calcium phosphate, a glassy precipitate of variable composition that may be present in biological systems.

Di- and polyphosphates

These materials contain Ca²⁺ combined with the polyphosphates, such as and triphosphate : * Dicalcium diphosphate (CAS#7790-76-3]: Ca₂P₂O₇ * Calcium triphosphate (CAS# 26158-70-3): Ca₅(P₃O₁₀)₂

Hydroxy- and oxo-phosphates

These materials contain other anions in addition to phosphate: *

Hydroxyapatite Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), but it is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities ...

Ca₅(PO₄)₃(OH) *

Apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common ...

Ca₁₀(PO₄)₆(OH,F,Cl,Br)₂ *

Tetracalcium phosphate Tetracalcium phosphate is the compound Ca4(PO4)2O, (4CaO·P2O5). It is the most basic of the calcium phosphates, and has a Ca/P ratio of 2, making it the most phosphorus poor phosphate. It is found as the mineral hilgenstockite, which is formed ...

(CAS#1306-01-0): Ca₄(PO₄)₂O

References

{{DEFAULTSORT:Calcium Phosphate Calcium compounds Phosphates Excipients E-number additives