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EDTA Disodium Solution, 0.1 M (0.2 N), 1 L

$56.00
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SKU: ED1006-1
California prop 65
Description
  • What it is. This EDTA disodium solution contains 0.1 mole of ethylenediaminetetraacetic acid disodium salt dihydrate (disodium EDTA) per liter (0.2 N) and is supplied in a 1 L size. It is a clear, colorless titrant for complexometric titrations and a ready-made chelating solution.
  • Chemical identity. Disodium EDTA dihydrate (CAS 6381-92-6, C10H14N2Na2O8·2H2O, 372.24 g/mol) is the most widely used form of EDTA for preparing volumetric solutions. A 0.1 M solution contains about 37.2 g of the dihydrate per liter, roughly 3.7% by weight.
  • Why 0.1 M is also 0.2 N. EDTA binds most metal ions in a one-to-one ratio. When normality is expressed for divalent ions such as calcium, magnesium, and zinc, each mole of EDTA reacts with two equivalents of charge, so a 0.1 M solution is labeled 0.2 N. Molarity is the more direct basis for calculations, since one mole of EDTA complexes one mole of metal.
  • How EDTA works. EDTA is a hexadentate chelating agent: its two nitrogen atoms and four carboxylate groups wrap around a metal ion, forming a stable, water-soluble complex. That strong, predictable binding is what makes EDTA titrations accurate and what lets EDTA sequester metal ions in buffers and cleaning formulations.
  • Complexometric titration. In a typical titration, you add EDTA to a sample buffered to the right pH with a metal indicator. For calcium and magnesium, an ammonia buffer near pH 10 with Eriochrome Black T gives a wine-red to blue endpoint. Lab Pro offers Eriochrome Black T Indicator, Ammonium Chloride, ACS Grade, and Ammonium Hydroxide 28 to 30% Solution, ACS Grade for that buffer system.
  • Why 0.1 M strength. A 0.1 M EDTA solution suits samples with relatively high metal content, such as metal assays, plating baths, and concentrated hardness samples, where weaker titrants would require impractically large volumes. For dilute samples, Lab Pro also offers EDTA Titrant 0.1 N / 0.05 M and, in larger volumes, EDTA Titrant 0.2 N / 0.1 M, 1 gallon.
  • Chelating uses beyond titration. Add disodium EDTA to buffers and reagents to bind trace metal ions that would otherwise catalyze unwanted reactions, inhibit metal-dependent enzymes, and prevent scale in cleaning solutions. A ready-made 0.1 M stock allows quick, accurate additions.
  • Standardization and care. For the most accurate results, standardize EDTA against a primary standard such as calcium carbonate or zinc before critical work, and store it tightly closed to prevent evaporation from changing its concentration. Use deionized water for all dilutions to avoid introducing calcium or magnesium.

Technical Specifications

Chemical Name Ethylenediaminetetraacetic acid disodium salt dihydrate, aqueous solution
Synonyms Disodium EDTA, EDTA-Na2, edetate disodium
CAS Numbers 6381-92-6 (disodium EDTA dihydrate); 7732-18-5 (water)
EC Number (active) 205-358-3
Formula (active) C10H14N2Na2O8·2H2O
Molecular Weight (active) 372.24 g/mol
Concentration 0.1 M (0.2 N)
EDTA Content About 37.2 g/L dihydrate, about 3.7% (calculated)
Appearance Clear, colorless liquid
Density About 1.02 to 1.03 g/mL
Alternate CAS (anhydrous disodium salt) 139-33-3
Free-Acid CAS (reference) 60-00-4
EDTA per mL 0.100 mmol
Titration Equivalence 1.00 mL = 4.008 mg Ca, 2.431 mg Mg, or 10.01 mg CaCO3 (calculated)
Binding Ratio 1:1 EDTA to metal ion
Physical State Liquid, aqueous solution
Boiling Point About 100 °C
Storage Room temperature, tightly closed to prevent evaporation
Package Size 1 L

Applications / Common Uses

  • Complexometric titration: Determines calcium, magnesium, zinc, and other metals.
  • Metal assays: Quantifies metal content in plating baths and process solutions.
  • Water hardness: Titrates concentrated hardness samples with Eriochrome Black T.
  • Chelating additive: Binds trace metals in buffers and reagents.
  • Enzyme inhibition: Removes metal cofactors to stop metal-dependent enzyme activity.

Storage, Handling & Shipping

Store the solution tightly closed at room temperature, protected from evaporation, which would raise its concentration. Keep it away from strong oxidizers and metal-containing materials, and use clean, metal-free labware to avoid consuming EDTA before titration.

  • Incompatible materials: Strong oxidizers, strong acids, and metal salts.
  • Personal protection: Safety glasses and nitrile gloves.
  • Spill response: Absorb with inert material and rinse the area with water.
  • First aid: Eyes: rinse with water for several minutes. Ingestion: rinse mouth and seek medical advice.

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FAQs

Why is 0.1 M EDTA also labeled 0.2 N?

EDTA reacts with divalent metal ions such as calcium and magnesium in a one-to-one mole ratio, but each mole corresponds to two equivalents of charge. Expressed as normality, a 0.1 M solution is therefore 0.2 N. Most modern methods use molarity, since one mole of EDTA binds one mole of metal.

What is disodium EDTA used for?

Disodium EDTA is a chelating agent. In the lab, it is used as a titrant for calcium, magnesium, zinc, and other metals, and as an additive that binds trace metal ions in buffers, reagents, and cleaning solutions. It also inhibits metal-dependent enzymes in biochemical work.

Which indicator is used with EDTA titrations?

The indicator depends on the metal. For calcium and magnesium in water hardness, Eriochrome Black T in an ammonia buffer near pH 10 gives a wine-red to blue endpoint. Other metals use indicators such as murexide, xylenol orange, or calmagite, each at a specific pH.

Should I standardize EDTA before use?

For critical work, yes. Standardize against a primary standard such as calcium carbonate or zinc metal to confirm the exact molarity, and repeat periodically. Evaporation, contamination, or metal leaching from labware can shift the concentration over time, so verification keeps titration results accurate. Record the standardized molarity on the label.

When should I choose 0.1 M instead of a weaker EDTA titrant?

Choose 0.1 M when samples contain relatively high metal levels, such as plating baths or concentrated hardness samples, so titration volumes stay practical. For drinking water and other dilute samples, a weaker titrant such as 0.05 M or 0.01 M gives finer resolution near the endpoint.