Calcium phosphate is a family of materials and minerals containing calcium ions (Ca 2+ )
together with inorganic phosphate anions. They usually appear as white solids and have
high nutritional value. Calcium phosphates are found in many living organisms. 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 manufacture of phosphoric acid and fertilizers. Certain
forms of calcium phosphate can lead to surface runoff rich in nutrients and subsequent
adverse effects upon receiving such waters such as growth of algae and eutrophication.
Calcium phosphate is produced commercially by treating hydroxyapatite with phosphoric
acid and slaked lime.
It cannot be precipitated directly from aqueous solution. Typically, double decomposition
reactions are employed, involving a soluble phosphate and calcium salts, e.g. (NH 4 ) 2 HPO 4 +
Ca(NO 3 ) 2 . is performed under carefully controlled pH conditions. The precipitate will either
be "amorphous calcium phosphate", ATCP, or calcium deficient hydroxyapatite, CDHA,
Ca 9 (HPO 4 )(PO 4 ) 5 (OH), (note CDHA is sometimes termed apatitic calcium
triphosphate). Crystalline calcium phosphate can be obtained by calcining the precipitate. β-
Ca 3 (PO 4 ) 2 is generally formed, higher temperatures are required to produce α-Ca 3 (PO 4 ) 2 .
An alternative to the wet procedure entails heating a mixture of a calcium pyrophosphate
and calcium carbonate:
CaCO 3 + Ca 2 P 2 O 7 → Ca 3 (PO 4 ) 2 + CO 2
Calcium Phosphate is used as a nutritional supplement and occurs naturally in cow milk
It can be used as a tissue replacement for repairing bony defects when autogenous bone
graft is not feasible or possible. It may be used alone or in combination with
a biodegradable, resorbable polymer such as polyglycolic acid.
Porous beta-Tricalcium phosphate scaffolds are employed as drug carrier systems for local
drug delivery in bone.