Trisodium Citrate

CAS Number:

68-04-2

Chemical / IUPAC Name:

Trisodium 2-hydroxypropane-1,2,3-tricarboxylate

INCI Name:

Trisodium Citrate

EC Number:

200-675-3

Molecular Formula:

C6H5Na3O7 (anhydrous); also exists as dihydrate (C6H5Na3O7·2H2O) and pentahydrate forms .

Molecular Weight:

258.07 g/mol (anhydrous) .

Other Names:

Sodium Citrate, Citric Acid Trisodium Salt, E331(iii), Trisodium Salt of Citric Acid

Uses:

Trisodium citrate is the sodium salt of citric acid, appearing as white crystals or a granular powder. It has a saline, mildly tart taste and functions primarily as a buffer, emulsifier, and sequestrant . It is extremely versatile and used across a wide range of industries .

· Food & Beverage Industry: Widely used as a food additive (E331) . It acts as a buffering agent to control pH in products like gelatin desserts and jams, and as an emulsifying salt in processed cheeses to prevent fats from separating, ensuring smooth melting . It is also used as a flavoring agent in club soda and as a preservative .

· Pharmaceutical & Medical Applications: Functions as an anticoagulant in blood collection tubes and for blood preservation in blood banks; the citrate ion chelates calcium, disrupting the clotting mechanism . It is a key component of the WHO Oral Rehydration Solution (ORS) and is used to relieve discomfort in urinary tract infections and as an osmotic laxative .

· Cosmetics & Personal Care: Acts as a buffering agent and pH adjuster to maintain the desired acidity in products like creams, lotions, and shampoos. It also functions as a sequestering agent to bind metal ions that could otherwise destabilize formulations .

· Industrial Applications: Used as an effective agent for removing carbonate scale from boilers and for cleaning automobile radiators without needing to remove them from operation . It also finds use in electroplating and photography .

Origin

Trisodium citrate is a semi-synthetic compound derived from natural citric acid. It is produced by neutralizing citric acid (obtained via fermentation of carbohydrates like molasses or corn) with a sodium base such as sodium hydroxide or sodium bicarbonate

What does Trisodium Citrate do in a formulation?

• Buffering Agent / pH Adjuster: Resists changes in pH, helping to maintain the acidity of a product within a desired range. A 5% aqueous solution typically has a pH between 7.5 and 9.0 .
• Sequestrant / Chelating Agent: Binds to metal ions (like calcium and magnesium) in formulations, preventing them from causing instability, discoloration, or rancidity .
• Emulsifying Agent / Stabilizer: Helps stabilize oil-in-water emulsions, particularly in processed cheese products, by preventing fat separation .
• Anticoagulant: Chelates calcium ions in blood, thereby disrupting the clotting cascade .
• Flavoring Agent: Imparts a characteristic tart, saline taste to foods and beverages .

Safety Profile:

· General Hazard Classification: Trisodium citrate is generally recognized as safe (GRAS) for its intended uses in food and pharmaceuticals . According to CLP/GHS regulations, some notifications classify it as causing skin irritation (H315) and serious eye irritation (H319), though other sources state it is not a hazardous substance .

· Toxicity: Low acute toxicity. LD50 values are available: 1548 mg/kg (intraperitoneal, rat) and 1364 mg/kg (intraperitoneal, mouse) . It is not considered a carcinogen .

· Irritation & Sensitization: May cause mild irritation to skin and eyes upon direct contact. It is not considered a skin sensitizer .

· Handling & Storage: Should be stored in a cool, dry, well-ventilated area, away from direct sunlight and strong oxidizing or reducing agents, as it is incompatible with them . It is combustible but difficult to ignite

· Regulatory Status: Approved as a food additive (E331) in the EU and by the FDA in the USA . It is included in major pharmacopoeias (USP) .

Technical profile: