Review

Disodium EDTA: properties, uses, pros, cons, safety, alternatives

Disodium EDTA (Ethylenediaminetetraacetic acid disodium salt) is a chemical compound, disodium salt of EDTA, a chelator of calcium ions and, among EDTA salts, the most important.

Disodium EDTA is a chelating agent, meaning a substance able to bind metal ions such as calcium, magnesium, and iron by forming stable complexes.
This action reduces the presence of trace metals that can catalyze oxidation reactions, improving the stability of color, odor, and overall formulation performance.
For this reason, it is used mainly in cosmetics and detergents, where it also helps manage the effects of hard water and support the effectiveness of certain preservatives and surfactants.
From a chemical standpoint, it belongs to polyaminocarboxylates and is generally used at low concentrations.
Its suitability for use and applicable limits depend on the product type and the relevant regulatory framework. 

The name describes the structure of the molecule:

• "Disodium" refers to the presence of two sodium ions in the molecule. Sodium is a chemical element with the symbol Na and the atomic number 11.
• "EDTA" stands for ethylenediaminetetraacetic, a type of polyamine carboxylic acid. It is known for its ability to chelate metal ions, meaning that it can form multiple bonds with a single metal ion.

The synthesis process takes place in several stages:

• Step 1: Preparation of raw materials: ethylenediaminetetraacetic acid and sodium hydroxide or sodium carbonate.
• Step 2: Neutralization reaction. Ethylenediaminotetraacetic acid is reacted with sodium hydroxide or sodium carbonate. This reaction is a type of neutralization reaction, in which the acid (EDTA) reacts with the base (sodium hydroxide or sodium carbonate) to form water and a salt (disodium EDTA).
• Step 3: Crystallization and purification. The resulting disodium EDTA is crystallized and purified to obtain the final product.

It appears in the form of a white, odourless, tasteless powder, easily soluble in water, ammonia, aqueous solutions of sodium hydroxide, sodium carbonate, and hardly soluble in organic solvents such as diethyl ether or alcohol.

Studies

In chemistry, it is a six-atom complexation agent that regulates the equilibrium between ligand and metal ions, often added to lysate with magnesium and calcium complex ions to stabilise nucleic acid and degrade nuclease activity. It controls the polymerisation rate. It also functions as a chelating agent, i.e. an agent that binds to another to promote elimination or harmful reactions caused by metal ions and to form a stable water-soluble complex. These studies explain the mechanism (1).  It can chelate with a large majority of different metal ions other than alkali metals such as calcium, magnesium, iron, copper and other polyvalent ions.

It also works as a descaler (2) and as an antioxidant method also called the Fenton method (3).

Widely used to prevent oxidation caused by metals.

Food

Labelled with the number E385 in the list of European food additives, Disodium EDTA is a chemical compound that is added to food as a preservative and chelating agent to prevent spoilage of the product in which it is included and to counteract other ingredients.

It is found in carbonated drinks, jellies, canned beans, mayonnaise and others.

To check for its presence in food, a convenient HPLC method was developed for the quantitative determination of EDTA in food. EDTA in food samples was easily extracted with water using ultrasound. After conversion to Fe (III) complex in the presence of Fe (III) ions, EDTA was separated on a reversed-phase C30 column and detected by ultraviolet detection (260 nm). Citrate and malate, which are present in many foods, also formed Fe (III) complexes but did not interfere with the chromatographic detection of EDTA. The method allowed the determination of EDTA in food at concentrations down to 0.01 mmol/kg. Good recoveries (95.2-101%) were obtained with the standard addition method on four samples with high repeatability (RSD, 0.8-3.4%). The method was successfully applied to the analysis of EDTA in carbonated drinks, jellies, canned beans, canned maize and food supplements (4). 

Disodium EDTA is a known enhancer of iron absorption, yet the results of this study suggest that in the presence of EDTA, iron absorption occurs mainly from the paracellular rather than the regulated cellular mode, which could potentially increase its toxicity (5).

There is a maximum ADI (Acceptable Daily Intake) or GDA (Acceptable Daily Allowance) of 2.5 grams per kg body weight for this food additive (6).

Cosmetics

It acts as a chelating agent and pH adjuster in cosmetic formulations. Chelating agents are known to be cytotoxic and weakly genotoxic, but not carcinogenic as confirmed by the final report of the Expert Panel for the Review of Cosmetic Ingredients (7).

Chelating agent. It has the function of preventing unstable reactions and improving the bioavailability of chemical components within a product, and removes calcium and magnesium cations that can cause cloudiness in clear liquids.

Viscosity control agent. It controls and adapts viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions. 

Alternatives

Medical

Disodium EDTA is used in the form of intravenous administration in chelation therapy for lead and heavy metal poisoning, in the treatment of calcified tendonitis, as an anticoagulant and bactericide due to its low cost.

Other uses

• additive, bleaching and fixing agent for processing colour-sensitive materials
• water purifier and cleaner
• agricultural chemicals
• plant growth inhibitor
• chemical plating, cyanide-free electroplating

For more information:

Disodium EDTA studies

Typical commercial product characteristics Ethylenediaminetetraacetic acid disodium salt

Appearance	White powder
pH	4.0-5.0
Boiling Point	>100°C    614.2°C at 760 mmHg
Melting Point	248°C
Flash Point	325.2ºC
Density	1.01 g/mL at 25°C
Vapor Pressure	1.15E-16mmHg at 25°C
Chlorides	0.01% Max
Sulphates	0.1% Max
Iron	0.001% Max
Heavy metal	0.001% Max
Chelating value	221
NTA	0.2%
Water insoluble matter	≤0.005%
Loss on drying	8.7- 11.4%
Aminotriacetic acid	≤10 ppm
Storage	2-8°C
Chemical Risk

• Molecular Formula    C₁₀H₁₈N₂Na₂O₁₀    C₁₀H₁₄N₂O₈Na₂.₂H₂O
• Linear Formula    [-CH₂N(CH₂CO₂Na)CH₂CO₂H]₂
• Molecular Weight  336.21
• Exact Mass    336.054565
• CAS    139-33-3     6831-92-6 (Ethylenediaminetetraacetic acid disodium salt dihydrate)
• UNII    
• EC Number   205-358-3
• DSSTox Substance ID  DTXSID9027073
• IUPAC  disodium;2-[2-[carboxylatomethyl(carboxymethyl)amino]ethyl-(carboxymethyl)amino]acetate
• InChl=1S/C10H16N2O8.2Na/c13-7(14)3-11(4-8(15)16)1-2-12(5-9(17)18)6-10(19)20;;/h1-6H2,(H,13,14)(H,15,16)(H,17,18)(H,19,20);;/q;2*+1/p-2
• InChl Key      ZGTMUACCHSMWAC-UHFFFAOYSA-L
• SMILES   C(CN(CC(=O)O)CC(=O)[O-])N(CC(=O)O)CC(=O)[O-].[Na+].[Na+]
• MDL number  MFCD00070672
• PubChem Substance ID    329747771
• RTECS  AH4410000
• NCI    C65508
• FEMA     4520  
• HS Code          2922499990
• Beilstein     3822669
• eCl@ss    39030907
• NACRES NA.25

Synonyms : 

Ethylenediaminetetraacetic acid, Disodium salt, Disodic EDTA, Disodic edetate, Acid Edetic