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What it is. EDTA tetrasodium salt (tetrasodium EDTA) is the fully neutralized sodium salt of ethylenediaminetetraacetic acid, supplied as an ACS grade white crystalline powder in a 1 lb size. It is highly water-soluble and gives strongly alkaline solutions.
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How it differs from disodium EDTA. All four of EDTA's carboxylic acid groups are carried by sodium in the tetrasodium salt, compared with two in disodium EDTA. As a result, tetrasodium EDTA dissolves readily without pH adjustment, and its solutions are alkaline (pH about 10 to 12 for dilute solutions), while disodium EDTA solutions are mildly acidic.
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Hydrate forms. Tetrasodium EDTA is sold in several hydrate forms: anhydrous (CAS 64-02-8), dihydrate (CAS 10378-23-1, 416.20 g/mol), tetrahydrate (CAS 13235-36-4), and unspecified hydrate. The form determines the molecular weight used in calculations, so check the label or certificate before preparing molar solutions.
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Why choose the tetrasodium salt. Because it dissolves easily and works in alkaline conditions, tetrasodium EDTA is preferred when solutions must stay basic: alkaline cleaners, scale removers, textile and pulp processing, and buffers above pH 10. It chelates calcium, magnesium, iron, and other metal ions in stable, soluble complexes.
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Chelation chemistry. EDTA binds metal ions through two nitrogen atoms and four carboxylate groups, forming one-to-one complexes. In alkaline solution, where tetrasodium EDTA naturally sits, EDTA is fully deprotonated and binds metals most strongly, which makes the salt especially effective at sequestering hardness ions.
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Laboratory uses. In the lab, tetrasodium EDTA is used to prepare alkaline chelating solutions, remove metal ions from samples and equipment, remove scale and deposits from glassware and water baths, and formulate cleaners and personal care products.
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Choosing the right EDTA salt. For titrants and near-neutral buffers, disodium EDTA is the standard choice; see Lab Pro's EDTA Disodium Salt Dihydrate, ACS Grade. Choose tetrasodium EDTA when you need high solubility and an alkaline solution without adding base.
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Handling at a glance. Tetrasodium EDTA dust and concentrated solutions irritate the skin and eyes. Wear safety glasses and gloves, avoid creating dust, and keep the powder in a tightly closed container, since it can absorb moisture from the air.
Technical Specifications
| Chemical Name |
Ethylenediaminetetraacetic acid tetrasodium salt |
| CAS Numbers |
10378-23-1 (dihydrate); 64-02-8 (anhydrous); 13235-36-4 (tetrahydrate). Confirm form on SDS |
| EC Number |
200-573-9 |
| Synonyms |
Tetrasodium EDTA, EDTA-4Na, tetrasodium ethylenediaminetetraacetate |
| Formula |
C10H12N2Na4O8 (anhydrous); C10H12N2Na4O8·2H2O (dihydrate) |
| Molecular Weight |
380.17 g/mol (anhydrous); 416.20 g/mol (dihydrate) |
| Grade |
ACS |
| Appearance |
White crystalline powder |
| pH (1% solution) |
About 10.5 to 12.0 |
| Water Solubility |
Highly soluble; clear, colorless solution |
| Melting Point |
About 300 °C (dihydrate) |
| Binding Ratio |
1:1 EDTA to metal ion |
| Hazard Statements (typical) |
Causes skin irritation; causes serious eye irritation (H315, H319) |
| Storage |
Room temperature, tightly closed, dry |
| Package Size |
1 lb |
Applications / Common Uses
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Alkaline chelating solutions: Sequesters metals in solutions that must stay basic.
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Scale and deposit removal: Dissolves calcium deposits from glassware and equipment.
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Cleaner formulation: Serves as the chelating agent in alkaline cleaners.
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Sample metal removal: Binds interfering metal ions before analysis.
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Process water treatment: Controls hardness ions in alkaline process streams.
Storage, Handling & Shipping
Store tightly closed in a cool, dry place at room temperature, since the salt can absorb moisture. Keep it away from strong acids and oxidizers, and avoid generating dust when weighing.
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Incompatible materials: Strong acids, strong oxidizers, and metal salts.
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Personal protection: Safety glasses, nitrile gloves, and dust control when weighing.
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Spill response: Sweep up without raising dust and place in a closed container for disposal.
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First aid: Eyes: rinse with water for several minutes. Skin: wash with soap and water.
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