Calcium phosphate
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Calcium phosphate is a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. They are white solids of nutritious value.[1] Calcium phosphates are found in many living organisms, e.g., bone mineral and tooth enamel. 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).[2] Various calcium phosphate minerals are used in the production of phosphoric acid and fertilizers. Overuse of certain forms of calcium phosphate can lead to nutrient-containing surface runoff and subsequent adverse effects upon receiving waters such as algal blooms and eutrophication.
Orthophosphates, di- and monohydrogen phosphates
These materials contain Ca2+ combined with PO43−,H2PO4− , and/or HPO42−:
- 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) and a dihydrate CaHPO4(H2O)2 (mineral: brushite)
- 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 P2O74− and triphosphate [P3O10]5−:
- 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 Ca5(PO4)3(OH)
- Apatite Ca10(PO4)6(OH, F, Cl, Br)2
- Tetracalcium phosphate (CAS#1306-01-0): Ca4(PO4)2O
References
- ^ Klaus Schrödter; Gerhard Bettermann; Thomas Staffel; Friedrich Wahl; Thomas Klein; Thomas Hofmann (2008). Phosphoric Acid and Phosphates. Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
- ^ A. Y. Tamime, ed. (2006). Brined cheeses - The Society of Dairy Technology (SDT). Wiley-Blackwell. ISBN 978-1-4051-2460-7.