Dicalcium phosphate is an inorganic salt with the formula CaHPO4. It is commonly encountered as a white, odorless powder used for its calcium and phosphate content. In chemical terms it is a calcium hydrogen phosphate; for a general definition see chemical compound. The substance contains the elements calcium, hydrogen and the phosphate anion, and is often discussed alongside other calcium phosphates in nutrition and materials science. For further references consult more information.
Forms and structure
Dicalcium phosphate exists in more than one crystalline form. The hydrated form, dicalcium phosphate dihydrate (commonly called brushite), contains water of crystallization; the anhydrous form is sometimes called monetite. These forms differ in crystal habit, density and solubility, which affects their behavior in processing and biological applications.
Properties and preparation
It is mildly soluble in water compared with more soluble phosphate salts and tends to form fine particulate solids. Industrially it is produced by treating phosphoric acid or phosphate-containing solutions with lime or calcium salts, or as a byproduct of phosphate fertilizer processing. Its chemical stability, low cost and relative insolubility make it useful where a stable source of calcium and phosphate is needed.
Uses and applications
- As a food additive and dietary calcium supplement (often labeled among calcium phosphates) to fortify products or act as an anti-caking agent.
- In pharmaceuticals and tablet manufacture as a diluent and binder because it compresses well and is chemically inert in many formulations.
- In oral care products and toothpastes as a mild polishing agent and remineralization aid.
- In animal feed to supply dietary phosphorus and calcium, and in some fertilizers as a slow-release phosphate source.
- In biomedical materials: certain forms are used in bone grafts, cements and coatings because they are biocompatible and support bone mineralization.
Distinctions and safety
Dicalcium phosphate should be distinguished from related compounds such as monocalcium phosphate (more acidic and more soluble) and tricalcium phosphate (more basic and less soluble). Regulatory agencies generally accept it as safe for food and pharmaceutical uses when employed within established limits. Excessive intake of phosphorus-containing additives can affect mineral balance, so use is regulated and evaluated by health authorities.
Overall, dicalcium phosphate is valued for delivering calcium and phosphate in a stable, inexpensive form across food, health and industrial sectors. For technical specifications and regulatory details consult authoritative sources or product datasheets referenced via compound databases and specialized literature such as those linked from elemental or chemical resources.