Properties of Ethylenediaminetetraacetic acid disodium salt (EDTA.Na2)

Ethylenediaminetetraacetic acid disodium salt (EDTA.Na₂), commonly known as disodium edetate, is a white, odorless crystalline powder that functions as a powerful chelating agent. Its chemical formula is C₁₀H₁₄N₂Na₂O₈·2H₂O with a molecular weight of 372.24 g/mol.

Physical and Chemical Properties

Appearance: White, odorless crystalline granules or powder.

Solubility: Freely soluble in water (approx. 100 g/L at 20°C) and practically insoluble in ethanol.

pH: A 5% aqueous solution is typically acidic, with a pH range of 4 – 6.

Melting Point: Decomposes above 220°C.

Stability: Stable under normal conditions. The dihydrate form loses water of crystallization when heated to 120°C.

Primary Function: Chelation

As a chelating agent, EDTA.Na₂ binds to metal ions (such as calcium, magnesium, and iron) to form stable, water-soluble complexes. This property is the basis for its widespread use in industrial, pharmaceutical, and food applications.

Safety and Handling Summary

Toxicity: Low acute oral toxicity (LD50 > 2 g/kg in rats).

Hazards: Causes serious eye irritation and mild skin irritation.

Precautions: Avoid dust formation. Use gloves, safety goggles, and adequate ventilation. Store in a tightly closed container away from h3 oxidizers and h3 bases.

Common Applications

Industrial: Used as a sequestrant to prevent metal-catalyzed oxidation and scale formation in cleaning products and water treatment.

Pharmaceuticals & Food: Acts as an antioxidant synergist and preservative. The disodium calcium salt is used as a food additive (INS 386).

Medical & Laboratory: Used as an anticoagulant for blood samples (by chelating calcium) and in various analytical procedures.