Sodium polyphosphate is a chemical compound, disodium salt of diphosphoric acid. Sodium polyphosphates are highly electronegative inorganic polyanionic salts largely due to the numerous phosphate groups comprising these molecules.

Sodium polyphosphate is a synthesised chemical compound and is produced by the rapid melting and cooling of monosodium orthophosphate according to the following reaction: n (NaH₂PO₄) → (NaPO₃)n+nH₂O (1). Polyphosphates are widely distributed in nature and occur in archaebacteria, eubacteria, fungi, algae and protozoa, as well as in higher plants and animals.

It appears in the form of a white powder.

What it is used for and where

Food

It is included in the list of food additives under the number E452 as a thickening agent, stabiliser, emulsifier.

The complete list of E452 polyphosphates includes:

• E452(i) Sodium polyphosphate
• E452(ii) Potassium polyphosphate 
• E452(iii) Sodium calcium polyphosphate
• E452(iv) Calcium polyphosphate or E544
• E452(v) Ammonium polyphosphate  

Cosmetics

Chelating agent. It has the function of preventing unstable reactions and improving the bioavailability of chemical components within a product, and removes calcium and magnesium cations that can cause cloudiness in clear liquids.

Other uses

In contaminated environmental waters, the addition of 0.1 per cent sodium polyphosphate recovered 10 per cent more adenovirus particles than were not permitted (2).

Sodium polyphosphate is an inorganic, polymeric anionic polyelectrolyte with excellent cation sequestration capacity (1).

• fillers
• putties
• plasters
• modelling clay
• adhesives and sealants
• coating products
• laboratory solutions

Sodium polyphosphate studies

• Molecular Formula: H₂Na₂O₇P₂   Na₂H₂P₂O₇
• Molecular Weight: 221.936 g/mol
• UNII: H5WVD9LZUD
• CAS: 7758-16-9  68915-31-1  
• EC Number:  272-808-3    231-835-0 
• PubChem Substance ID 57654563
• MDL number MFCD00014246

Synonyms: 

• Disodium dihydrogen diphosphate
• Disodium dihydrogenpyrophosphate
• Disodium dihydrogen pyrophosphate
• Disodium acid pyrophosphate
• Sodium acid pyrophosphate
• Sodium polyphosphate
• Disodium pytophosphate
• dipotassium diphosphate(2-)
• Diphosphoric acid, disodium salt
• Polyphosphoric acids, sodium salts
• Sodium dihydrogen pyrophosphate
• Sodium polyphosphate, amorphous
• Sodium acid pyrophosphate, SAPP
• Pyrophosphoric acid, disodium salt
• sodium dihydrogendiphosphate

References___________________________________________________________________

(1) Barth AP, Tormena CF, Viotto WH. pH influences hydrolysis of sodium polyphosphate in dairy matrices and the structure of processed cheese.J Dairy Sci. 2017 Nov;100(11):8735-8743. doi: 10.3168/jds.2017-12764. 

(2) McMinn BR, Korajkic A.   A small volume procedure for viral concentration from water. J Vis Exp. 2015 Feb 3;(96). doi: 10.3791/51744.

(3) Kopp, W., Barud, H.S., Paz, M.F. et al. Calcium polyphosphate coacervates: effects of thermal treatment   J Sol-Gel Sci Technol (2012) 63: 219. https://doi.org/10.1007/s10971-012-2749-z