Tripolyphosphates

Tripolyphosphates are a class of inorganic polyphosphates consisting of three phosphate units linked in a linear chain by P–O–P bonds. The predominant tripolyphosphate species in solution is the tripolyphosphate anion, P3O10^5−, which forms salts with various cations such as sodium, potassium, or calcium (for example, sodium tripolyphosphate). They are produced by condensation of phosphate units with dehydration.

These compounds are typically water-soluble and can hydrolyze over time to shorter phosphates or orthophosphate, depending on pH and enzymes. They have strong chelating and sequestrant properties, allowing them to bind metal ions such as calcium and magnesium and to inhibit mineral scale formation in some applications.

Applications of tripolyphosphates are broad. In detergents, they act as builders that soften water and improve cleaning efficiency. In the food industry, they serve as texture enhancers, moisture retainers, emulsifiers, and stabilizers. They are also used in ceramics, paper, cosmetic formulations, and certain industrial processes to control moisture and binding.

Safety and regulation vary by jurisdiction. In many countries, tripolyphosphates are permitted food additives within specified usage limits, though concerns have been raised about high phosphate intake and potential health effects for individuals with kidney disease. Environmental use, particularly as detergent additives, has prompted concerns about phosphate runoff and eutrophication, leading to restrictions or phase‑outs in some regions.