Citric acid, trisodium salt
3D model (JSmol)
|Molar mass||258.06 g/mol (anhydrous), 294.10 g/mol (dihydrate)|
|Appearance||White crystalline powder|
|Melting point||>300 °C|
hydrates lose water ca. 150 C
|Pentahydrate form: 92 g/100 g H2O (25 °C)|
|Safety data sheet||External MSDS|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|1548 mg/kg (intraperitoneal, rat)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Trisodium citrate has the chemical formula of 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 flavor. It is mildly basic and can be used along with citric acid to make biologically compatible buffers.
Sodium citrate is chiefly 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, and wine, amongst others.
Sodium citrate can be used as an emulsifier when making cheese. It allows the cheese to melt without becoming greasy.
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. The pH of a solution of 5 g/100 ml water at 25°C is 7.5 – 9.0.
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 today 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.
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.
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.
- "CRC Handbook of Chemistry and Physics". Retrieved 22 November 2013.
- "Locking Solutions for Hemodialysis Catheters" (PDF).
- 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 . PMID 14665584.
- U.S. Patent 3,095,862
- "MSDS" (PDF).