Instructions for Use: Ethylenediaminetetraacetic Acid Disodium Salt (EDTA-Na2)

1. Chemical Identity & Properties

Property Detail

Chemical Formula C₁₀H₁₄N₂Na₂O₈·2H₂O (dihydrate)

CAS Number 6381-92-6 (dihydrate)

Molecular Weight 372.24 g/mol (dihydrate)

Appearance White crystalline powder

Solubility Soluble in water (~10 g/100 mL at 20°C); insoluble in organic solvents

pH (1% solution) ~4.0–5.5

Stability Stable under normal conditions; store in a cool, dry place

2. Common Applications

Application Area Specific Use

Pharmaceuticals As a chelating agent for treating hypercalcemia and digitalis toxicity (requires prescription)

Food Industry As a food additive (E385) – preservative, antioxidant stabilizer

Laboratory Reagent Metal ion chelation for enzymatic inhibition, buffer preparation

Water Treatment Softening agent to remove hardness (Ca²⁺, Mg²⁺)

Cosmetics Chelating agent to improve product stability

Cleaning Products Enhances cleaning efficiency by removing mineral ions

Bioprocessing EDTA is commonly used in protein purification and as a protease inhibitor

3. Laboratory Usage Guide

Preparation of 0.5 M EDTA-Na₂ Stock Solution (pH 8.0)

This is the most commonly used solution in molecular biology.

Step Instructions

Step 1 Weigh 186.1 g of EDTA-Na₂·2H₂O

Step 2 Add to 800 mL of deionized water

Step 3 Add NaOH pellets (~19 g) slowly while stirring – the solution will dissolve as pH increases

Step 4 Adjust pH to 8.0 using NaOH

Step 5 Bring total volume to 1,000 mL with deionized water

Step 6 Sterilize by autoclaving (121°C, 15 min) if required

Critical Note: EDTA-Na₂ dissolves only when pH is raised above 8.0. Do not autoclave before it is fully dissolved.

Working Concentrations

Application Recommended Concentration

Cell culture (chelating) 0.5–5 mM

Trypsinization (harvesting cells) 0.5–1 mM

DNA/RNA extraction 1–10 mM (in TE buffer)

Inhibition of metal-dependent enzymes 0.1–1 mM

Blood anticoagulant ~0.5–1 mg per mL of blood

4. Food Industry Usage

EDTA-Na₂ is permitted as food additive E385 in many countries.

Application Usage Notes

Mayonnaise & dressings Prevents oxidative rancidity and color change

Canned foods Prevents discoloration caused by metal ions

Preservatives Enhances efficacy of other preservatives (synergistic effect)

Beverages Stabilizes flavors and prevents precipitation

Regulatory Limit (US FDA, EU): Typically ≤ 75 mg/kg in foods, but varies by product category. Always check local regulations (e.g., FDA 21 CFR, EU Regulation 1333/2008).

5. Industrial & Cosmetics Usage

Application Recommended Dosage

Water softening 5–50 ppm (mg/L), dependent on water hardness

Cosmetic formulations 0.1–2% of total formulation

Household cleaners 0.5–5% as chelating builder

Textile processing 0.1–1 g/L in dye baths

6. Important Safety & Handling Information

Parameter Details

Hazard classification Irritant (may cause skin/eye irritation)

PPE required Safety goggles, lab gloves, lab coat

First aid (skin contact) Wash with soap and plenty of water

First aid (eye contact) Rinse thoroughly with water for 15 min; seek medical attention

First aid (ingestion) Rinse mouth; drink plenty of water; do NOT induce vomiting; consult a physician

Storage Tightly sealed container; cool, dry, well-ventilated area; avoid light

Incompatibility Strong oxidizers, h3 acids (releases EDTA acid precipitate), Cu²⁺, Fe³⁺

7. Special Considerations

Consideration Details

Solubility EDTA-Na₂ dissolves slowly; stirring and heating accelerate dissolution.

pH sensitivity Effectiveness of chelation is pH-dependent; optimal chelation typically occurs between pH 7.0–9.0.

Metal affinity order Fe³⁺ > Cu²⁺ > Ni²⁺ > Pb²⁺ > Co²⁺ > Zn²⁺ > Fe²⁺ > Mn²⁺ > Ca²⁺ > Mg²⁺

Biodegradability Poorly biodegradable; dispose of according to local environmental regulations.

Autoclaving EDTA-Na₂ solutions can be autoclaved (121°C, 15 min) but may partially degrade if alkaline.

8. Research Applications (With Examples)

Cell biology: EDTA is commonly used to dissociate adherent cells and break cell–cell junctions.

Molecular biology: EDTA is frequently included in TE buffer (10 mM Tris-Cl, 1 mM EDTA, pH 8.0) to protect DNA from DNase.

Microbiology: EDTA can be used to destabilize the outer membrane of Gram-negative bacteria.