Nitrilotriacetic acid (NTA) is the aminopolycarboxylic acid with the formula N(CH2CO2H)3. It is a colourless solid that is used as a chelating agent, it which forms coordination compounds with metal ions (chelates) such as Ca2+, Cu2+, and Fe3+.

Production and use

This compound is commercially available as the free acid and as the sodium salt. It is produced fromammonia, formaldehyde, and sodium cyanide or hydrogen cyanide. Worldwide capacity is estimated at 100 thousand tonnes per year.

Coordination chemistry and applications

The uses of NTA are similar to that of EDTA, both being chelating agents. In contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment. It is used for water softening and as a replacement to sodium and potassium triphosphate in detergents, and cleansers.NTA is a tripodal tetradentate trianionic ligand. In the laboratory, this compound is used in complexometric titrations. A variant of NTA is used for protein isolation and purification in the His-tag method. The modified NTA is used to immobilize nickel to a solid support. This allows separation of proteins containing “tag” containing six histidine residues at either terminus.


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