Trisodium citrate

Last updated
Sodium citrate
Natriumcitrat V1.svg
Trisodium Citrate taken with my iPhone SE in my kitchen.jpg
Names
Preferred IUPAC name
Trisodium 2-hydroxypropane-1,2,3-tricarboxylate
Other names
Sodium citrate
Trisodium citrate
Citrosodine
Trisodium salt
E331
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.000.614 OOjs UI icon edit-ltr-progressive.svg
E number E331iii (antioxidants, ...)
PubChem CID
RTECS number
  • GE8300000
UNII
  • InChI=1S/C6H8O7.3Na/c7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;3*+1/p-3 X mark.svgN
    Key: HRXKRNGNAMMEHJ-UHFFFAOYSA-K X mark.svgN
  • InChI=1/C6H8O7.3Na/c7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;3*+1/p-3
    Key: HRXKRNGNAMMEHJ-DFZHHIFOAL
  • C(C(=O)[O-])C(CC(=O)[O-])(C(=O)[O-])O.[Na+].[Na+].[Na+]
Properties
Na3C6H5O7
Molar mass 258.06 g/mol (anhydrous), 294.10 g/mol (dihydrate)
AppearanceWhite crystalline powder
Density 1.7 g/cm3
Melting point >300 °C (572 °F; 573 K) (hydrates lose water ca. 150 °C)
Boiling point Decomposes
Anhydrous form:57 g/100 g H2O (25 °C) [1] Pentahydrate form: 92 g/100 g H2O (25 °C) [2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Irritant
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Lethal dose or concentration (LD, LC):
1548 mg/kg (intraperitoneal, rat) [3]
Safety data sheet (SDS) External MSDS
Related compounds
Related compounds
Monosodium citrate
Disodium citrate
Calcium citrate
Citric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Trisodium citrate is a chemical compound with the molecular formula Na3C6H5O7. It is sometimes referred to simply as "sodium citrate", though sodium citrate can refer to any of the three sodium salts of citric acid. It possesses a saline, mildly tart taste, and is a mild base.

Contents

Uses

Foods

Sodium citrate is primarily used as a food additive, usually for flavor or as a preservative. Its E number is E331. Sodium citrate is employed as a flavoring agent in certain varieties of club soda. It is common as an ingredient in bratwurst, and is also used in commercial ready-to-drink beverages and drink mixes, contributing a tart flavor. It is found in gelatin mix, ice cream, yogurt, jams, sweets, milk powder, processed cheeses, carbonated beverages, wine, and butter chicken, [4] amongst others.

Sodium citrate can be used as an emulsifying stabilizer when making cheese. It allows the cheese to melt without becoming greasy by stopping the fats from separating. [5] This effect makes cheese particularly suitable as a topping for nachos - coincidentally echoing its chemical formula Na3C6H5O7. [6]

Buffering

Speciation diagram for a 10-millimolar solution of citric acid. The violet curve corresponds to the trisodium citrate. Citric acid speciation.svg
Speciation diagram for a 10-millimolar solution of citric acid. The violet curve corresponds to the trisodium citrate.

As a conjugate base of a weak acid, citrate can perform as a buffering agent or acidity regulator, resisting changes in pH. It is used to control acidity in some substances, such as gelatin desserts. It can be found in the milk minicontainers used with coffee machines. The compound is the product of antacids, such as Alka-Seltzer, when they are dissolved in water.[ citation needed ] The pH range of a solution of 5 g/100 ml water at 25 °C is 7.5 to 9.0. It is added to many commercially packaged dairy products to control the pH impact of the gastrointestinal system of humans[ citation needed ], mainly in processed products such as cheese and yogurt, although it also has beneficial effects on the physical gel microstructure. [7]

Chemistry

Sodium citrate is a component in Benedict's qualitative solution, often used in organic analysis to detect the presence of reducing sugars such as glucose.

Sodium (tri)citrate, crystallized by evaporation from solution at room temperature. Sodium citrate crystals.png
Sodium (tri)citrate, crystallized by evaporation from solution at room temperature.

Medicine

In 1914, the Belgian doctor Albert Hustin and the Argentine physician and researcher Luis Agote successfully used sodium citrate as an anticoagulant in blood transfusions, with Richard Lewisohn determining its correct concentration in 1915. It continues to be used in blood-collection tubes and for the preservation of blood in blood banks. The citrate ion chelates calcium ions in the blood by forming calcium citrate complexes, disrupting the blood clotting mechanism. Recently, trisodium citrate has also been used as a locking agent in vascath and haemodialysis lines instead of heparin due to its lower risk of systemic anticoagulation. [8]

In 2003, Ööpik et al. showed the use of sodium citrate (0.5 g/kg body weight) improved running performance over 5 km by 30 seconds. [9]

Sodium citrate is used to relieve discomfort in urinary-tract infections, such as cystitis, to reduce the acidosis seen in distal renal tubular acidosis, and can also be used as an osmotic laxative. It is a major component of the WHO oral rehydration solution.

It is used as an antacid, especially prior to anaesthesia, for caesarian section procedures to reduce the risks associated with the aspiration of gastric contents.

Boiler descaling

Sodium citrate is a particularly effective agent for removal of carbonate scale from boilers without removing them from operation [10] and for cleaning automobile radiators. [11]

See also

References

  1. "Sodium citrate | 68-04-2" . Retrieved 14 December 2023.
  2. "CRC Handbook of Chemistry and Physics" . Retrieved 22 November 2013.
  3. Chambers, Michael. "ChemIDplus - 68-04-2 - HRXKRNGNAMMEHJ-UHFFFAOYSA-K - Sodium citrate anhydrous - Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.nlm.nih.gov.
  4. "Permitted Emulsifying Salt (E331)". 5 March 2018.
  5. "For The Creamiest Nacho Cheese Sauce Ever, Use This Secret Ingredient". HuffPost UK. 6 November 2014. Retrieved 27 August 2025.
  6. Milligan, Ceara (16 February 2022). "You've Probably Never Noticed This Quirky Fact About Sodium Citrate". Mashed. Retrieved 27 August 2025.
  7. Ozcan-Yilsay, T; Lee, W.-J. (2007). "Effect of Trisodium Citrate on Rheological and Physical Properties and Microstructure of Yogurt". Journal of Dairy Science. 90 (4): 1644–1652. doi: 10.3168/jds.2006-538 . PMID   17369204.
  8. "Locking Solutions for Hemodialysis Catheters" (PDF).
  9. V. Ööpik; I. Saaremets; L. Medijainen; K. Karelson; T. Janson; S. Timpmann (2003). "Effects of sodium citrate ingestion before exercise on endurance performance in well trained college runners". British Journal of Sports Medicine. 37 (6): 485–489. doi:10.1136/bjsm.37.6.485. PMC   1724692 . PMID   14665584.
  10. U.S. patent 3,095,862
  11. "MSDS" (PDF).