sodium triphosphate

Sodium tripolyphosphate is produced by heating a stoichiometric mixture of disodium phosphate, Na₂HPO₄, and monosodium phosphate, NaH₂PO₄, under carefully controlled conditions.{{Greenwood&Earnshaw}}

:2 Na₂HPO₄ + NaH₂PO₄ → Na₅P₃O₁₀ + 2 H₂O

In this way, approximately 2 million tons are produced annually.

STPP is a colourless salt, which exists both in anhydrous form and as the hexahydrate. The anion can be described as the pentanionic chain [O₃POP(O)₂OPO₃]⁵⁻.{{cite journal |last1=Corbridge |first1=D. E. C. |title=The crystal structure of sodium triphosphate, Na₅P₃O₁₀, phase I |journal=Acta Crystallographica |date=1 March 1960 |volume=13 |issue=3 |pages=263–269 |doi=10.1107/S0365110X60000583 |bibcode=1960AcCry..13..263C }}{{cite journal |last1=Davies |first1=D. R. |last2=Corbridge |first2=D. E. C. |title=The crystal structure of sodium triphosphate, Na₅P₃O₁₀, phase II |journal=Acta Crystallographica |date=1 May 1958 |volume=11 |issue=5 |pages=315–319 |doi=10.1107/S0365110X58000876 |doi-access=free |bibcode=1958AcCry..11..315D }} Many related di-, tri-, and polyphosphates are known including the cyclic triphosphate (e.g. sodium trimetaphosphate). It binds strongly to metal cations as both a bidentate and tridentate chelating agent.

Image:Triphosphate chelation.svg

The majority of STPP is consumed as a component of commercial detergents. It serves as a "builder", industrial jargon for a water softener. In hard water (water that contains high concentrations of Mg²⁺ and Ca²⁺), detergents are deactivated. Being a highly charged chelating agent, TPP⁵⁻ binds to dications tightly and prevents them from interfering with the sulfonate detergent.{{cite book |doi=10.1002/14356007.a19_465.pub3 |chapter=Phosphoric Acid and Phosphates |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2008 |last1=Schrödter |first1=Klaus |last2=Bettermann |first2=Gerhard |last3=Staffel |first3=Thomas |last4=Wahl |first4=Friedrich |last5=Klein |first5=Thomas |last6=Hofmann |first6=Thomas |isbn=978-3527306732 |s2cid=94458523 }}

STPP is a preservative for seafood, meats, poultry, and animal feeds. It is common in food production as E number E451. In foods, STPP is used as an emulsifier and to retain moisture. Many governments regulate the quantities allowed in foods, as it can substantially increase the sale weight of seafood in particular. The United States Food and Drug Administration lists STPP as Generally recognized as safe.{{cite web|url=https://www.hfpappexternal.fda.gov/scripts/fdcc/index.cfm?set=FoodSubstances&id=SODIUMTRIPOLYPHOSPHATE|title=Substances Added to Food (Formerly EAFUS)}}

Other uses (hundreds of thousands of tons/year) include ceramics (decrease the viscosity of glazes up to a certain limit), leather tanning (as masking agent and synthetic tanning agent - SYNTAN), anticaking agents, setting retarders, flame retardants, paper, anticorrosion pigments, textiles, rubber manufacture, fermentation, antifreeze." TPP is used as a polyanion crosslinker in polysaccharide based drug delivery.{{cite journal |last1=Calvo |first1=P. |last2=Remuñán-López |first2=C. |last3=Vila-Jato |first3=J. L. |last4=Alonso |first4=M. J. |title=Novel hydrophilic chitosan-polyethylene oxide nanoparticles as protein carriers |journal=Journal of Applied Polymer Science |date=3 January 1997 |volume=63 |issue=1 |pages=125–132 |doi=10.1002/(SICI)1097-4628(19970103)63:1<125::AID-APP13>3.0.CO;2-4 }} Toothpaste may contain sodium triphosphate.{{cite journal |last1=Saxton |first1=C. A. |last2=Ouderaa |first2=F. J. G. |title=The effect of a dentifrice containing zinc citrate and Triclosan on developing gingivitis |journal=Journal of Periodontal Research |date=January 1989 |volume=24 |issue=1 |pages=75–80 |doi=10.1111/j.1600-0765.1989.tb00860.x |pmid=2524573 }}{{cite journal |last1=Lobene |first1=RR |last2=Weatherford |first2=T |last3=Ross |first3=NM |last4=Lamm |first4=RA |last5=Menaker |first5=L |title=A modified gingival index for use in clinical trials. |journal=Clinical Preventive Dentistry |date=1986 |volume=8 |issue=1 |pages=3–6 |pmid=3485495 }}{{cite journal |last1=Lobene |first1=RR |last2=Soparkar |first2=PM |last3=Newman |first3=MB |title=Use of dental floss. Effect on plaque and gingivitis. |journal=Clinical Preventive Dentistry |date=1982 |volume=4 |issue=1 |pages=5–8 |pmid=6980082 }}{{cite journal |last1=Mankodi |first1=Suru |last2=Bartizek |first2=Robert D. |last3=Leslie Winston |first3=J. |last4=Biesbrock |first4=Aaron R. |last5=McClanahan |first5=Stephen F. |last6=He |first6=Tao |title=Anti-gingivitis efficacy of a stabilized 0.454% stannous fluoride/sodium hexametaphosphate dentifrice. A controlled 6-month clinical trial |journal=Journal of Clinical Periodontology |date=January 2005 |volume=32 |issue=1 |pages=75–80 |doi=10.1111/j.1600-051X.2004.00639.x |pmid=15642062 |doi-access=free }}{{cite journal |last1=Mankodi |first1=S |last2=Petrone |first2=DM |last3=Battista |first3=G |last4=Petrone |first4=ME |last5=Chaknis |first5=P |last6=DeVizio |first6=W |last7=Volpe |first7=AR |last8=Proskin |first8=HM |title=Clinical efficacy of an optimized stannous fluoride dentifrice, Part 2: A 6-month plaque/gingivitis clinical study, northeast USA. |journal=Compendium of Continuing Education in Dentistry |date=1997 |volume=18 Spec No |pages=10–5 |pmid=12206029 }}{{cite journal |last1=Mallatt |first1=Mark |last2=Mankodi |first2=Suru |last3=Bauroth |first3=Karen |last4=Bsoul |first4=Samer A. |last5=Bartizek |first5=Robert D. |last6=He |first6=Tao |title=A controlled 6-month clinical trial to study the effects of a stannous fluoride dentifrice on gingivitis |journal=Journal of Clinical Periodontology |date=September 2007 |volume=34 |issue=9 |pages=762–767 |doi=10.1111/j.1600-051X.2007.01109.x |pmid=17645550 }}{{cite journal |last1=Lang |first1=Niklaus P. |title=Epidemiology of periodontal disease |journal=Archives of Oral Biology |date=1990 |volume=35 |pages=S9–S14 |doi=10.1016/0003-9969(90)90125-t |pmid=2088238 }}

High serum phosphate concentration has been identified as a predictor of cardiovascular events and mortality. Whilst phosphate is present in the body and food in organic forms, inorganic forms of phosphate such as sodium triphosphate are readily adsorbed and can result in elevated phosphate levels in serum.{{cite journal |last1=Ritz |first1=Eberhard |last2=Hahn |first2=Kai |last3=Ketteler |first3=Markus |last4=Kuhlmann |first4=Martin K |last5=Mann |first5=Johannes |title=Phosphate Additives in Food—a Health Risk |journal=Deutsches Ärzteblatt International |date=2012 |volume=109 |issue=4 |pages=49–55 |doi=10.3238/arztebl.2012.0049 |pmid=22334826 |pmc=3278747 }} Salts of polyphosphate anions are moderately irritating to skin and mucous membranes because they are mildly alkaline.

Because it is very water-soluble, STPP is not significantly removed by waste water treatment. STPP hydrolyses to phosphate, which is assimilated into the natural phosphorus cycle. Detergents containing phosphorus contribute to the eutrophication of many fresh waters.

File:Potomac green water.JPG of the Potomac River, caused from phosphate run-off, is evident from the bright green bloom of algae.]]

• Sodium trimetaphosphate, a cyclic triphosphate

• Acceptable daily intake

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{{Sodium compounds}}

Category:Food additives

Category:Sodium compounds

Category:Phosphates

Category:E-number additives