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What it is. This EDTA disodium solution contains 0.0575 mole of disodium EDTA dihydrate per liter, supplied in a 1 gallon size. It is a clear, colorless complexometric titrant prepared to a specific molarity for laboratories whose methods call for this exact strength.
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Why a specific molarity matters. Some test methods specify an EDTA strength chosen so titration volumes convert directly into the reporting units the method uses. Buying the titrant already at 0.0575 M avoids preparing and standardizing an unusual concentration in-house and keeps results consistent from lot to lot.
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What 0.0575 M delivers. Each milliliter contains 0.0575 millimole of EDTA, which complexes 2.305 mg of calcium, 1.398 mg of magnesium, or the equivalent of 5.755 mg of calcium carbonate (calculated from atomic weights). Use these equivalence values to convert titration volume into sample concentration.
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How EDTA works. EDTA is a hexadentate chelating agent that binds metal ions in a one-to-one ratio through two nitrogen atoms and four carboxylate groups. The strong, predictable binding gives sharp endpoints when paired with a suitable metal indicator at the correct pH.
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Water hardness reporting. Hardness is usually reported as milligrams of calcium carbonate per liter. With this titrant, multiplying the milliliters used by 5.755 gives milligrams of calcium carbonate equivalent in the titrated sample (calculated), which you then divide by the sample volume in liters.
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Running the titration. For calcium and magnesium, buffer the sample near pH 10 with an ammonia buffer and add Eriochrome Black T; titrate from wine red to a clear blue. Lab Pro offers Eriochrome Black T Indicator, Ammonium Chloride, ACS Grade, and Ammonium Hydroxide 28 to 30% Solution, ACS Grade for that system.
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Size for routine testing. The 1 gallon size supports labs that run this method daily and want one consistent lot for an extended period, reducing re-standardization when switching between batches.
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Standardization and care. For critical work, verify the molarity against a primary standard such as calcium carbonate or zinc, keep the container closed to prevent evaporation, and use deionized water and metal-free labware so trace metals do not consume titrant.
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Related EDTA products. For other strengths, Lab Pro offers EDTA Titrant 0.1 N / 0.05 M, EDTA Disodium Solution, 0.1 M (0.2 N), and the solid EDTA Disodium Salt Dihydrate, ACS Grade for preparing custom concentrations.
Technical Specifications
| Chemical Name |
Ethylenediaminetetraacetic acid disodium salt dihydrate, aqueous solution |
| Synonyms |
Disodium EDTA solution, EDTA titrant |
| 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 |
0.0575 M |
| Normality (divalent metals) |
0.115 N (calculated) |
| EDTA Content |
About 21.4 g/L dihydrate (calculated) |
| EDTA per mL |
0.0575 mmol |
| Titration Equivalence |
1.00 mL = 2.305 mg Ca, 1.398 mg Mg, or 5.755 mg CaCO3 (calculated) |
| Binding Ratio |
1:1 EDTA to metal ion |
| Appearance |
Clear, colorless liquid |
| Physical State |
Liquid, aqueous solution |
| Storage |
Room temperature, tightly closed |
| Package Size |
1 gallon |
Applications / Common Uses
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Method-specific titrations: Supplies the 0.0575 M strength some methods specify.
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Calcium and magnesium: Titrates Ca and Mg with Eriochrome Black T at pH 10.
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Water hardness: Determines total hardness in water samples.
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Metal assays: Quantifies divalent metals in process solutions.
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Routine QC: Provides one consistent lot for daily testing.
Storage, Handling & Shipping
Store the solution tightly closed at room temperature to prevent evaporation, which would raise its concentration. Keep it away from strong oxidizers and metal-containing materials, and use clean, metal-free labware so trace metals do not consume EDTA before titration.
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Incompatible materials: Strong oxidizers, strong acids, and metal salts.
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Personal protection: Safety glasses and nitrile gloves.
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Spill response: Absorb with inert material and rinse the area with water.
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First aid: Eyes: rinse with water for several minutes. Ingestion: rinse mouth and seek medical advice.
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