Nitrilotriacetic acid

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Nitrilotriacetic acid
Skeletal formula of nitrilotriacetic acid
Preferred IUPAC name
2,2',2''-Nitrilotriacetic acid
Other names
2-[Bis(carboxymethyl)amino]acetic acid[1]
3D model (JSmol)
ECHA InfoCard 100.004.869
EC Number 205-355-7
MeSH Nitrilotriacetic+Acid
RTECS number AJ0175000
UN number 2811
Molar mass 191.14 [3]
Appearance White crystals
Melting point 246[3] °C (475 °F; 519 K)
Insoluble. <0.01 g/100 mL at 23℃ [3]
−1.3130–−1.3108 MJ mol−1
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word WARNING
H302, H319, H351
P281, P305+351+338
Flash point 100 °C (212 °F; 373 K)
Lethal dose or concentration (LD, LC):
1.1 g kg−1 (oral, rat)
Related compounds
Related alkanoic acids
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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, which forms coordination compounds with metal ions (chelates) such as Ca2+, Cu2+, and Fe3+.[4]

Production and use[edit]

Nitrilotriacetic acid is commercially available as the free acid and as the sodium salt. It is produced from ammonia, formaldehyde, and sodium cyanide or hydrogen cyanide. Worldwide capacity is estimated at 100 thousand tonnes per year.[5] NTA is also cogenerated as an impurity in the synthesis of EDTA, arising from reactions of the ammonia coproduct.[6]

Coordination chemistry and applications[edit]

NTA is a tripodal tetradentate trianionic ligand.[7]

The uses of NTA are similar to those of EDTA, both being chelating agents. It is used for water softening and as a replacement to sodium and potassium triphosphate in detergents, and cleansers.

In one application, NTA as a chelating agent removes Cr, Cu, and As from wood that had been treated with chromated-copper arsenate (CCA).[8]

Laboratory uses[edit]

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.[9] The modified NTA is used to immobilize nickel to a solid support. This allows purification of proteins containing a tag consisting of six histidine residues at either terminus.[10]

Toxicity and Environment[edit]

Nitroloacetic acid can cause eye, skin, and respiratory tract irritation; and can cause kidney and bladder damage. The compound is anticipated to have the potential to cause human cancers.[1]

In contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment.[5] The environmental impacts of NTA are minimal. Despite widespread use in cleaning products, the concentration in the water supply is too low to have a sizeable impact on human health or environmental quality. [11]


  1. ^ a b "Nitrilotriacetic Acid - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 13 July 2012. 
  2. ^ Nitrilotriacetic acid
  3. ^ a b c ChemBK Chemical Database
  4. ^ NITRILOTRIACETIC ACID AND ITS SALTS, International Agency for Research on Cancer (IARC)
  5. ^ a b Charalampos Gousetis, Hans-Joachim Opgenorth (2005), "Nitrilotriacetic Acid", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a17_377 
  6. ^ Hart, J. Roger (2005) "Ethylenediaminetetraacetic Acid and Related Chelating Agents" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. doi:10.1002/14356007.a10_095
  7. ^ B. L. Barnett, V. A. Uchtman "Structural investigations of calcium-binding molecules. 4. Calcium binding to aminocarboxylates. Crystal structures of Ca(CaEDTA).7H2O and Na(CaNTA)" Inorg. Chem., 1979, volume 18, pp 2674–2678. doi:10.1021/ic50200a007
  8. ^ Fang-Chih, C.; Ya-Nang, W.; Pin-Jui, C.; Chun-Han, K. Factors affecting chelating extraction of Cr, Cu, and As from CCA-treated wood. J. Environ. Manag. 2013, 122.
  9. ^ Liu, Weijing (2016). "Layer-by-Layer Deposition with Polymers Containing Nitrilotriacetate, A Convenient Route to Fabricate Metal- and Protein-Binding Films". ACS Applied Materials&Interfaces. 8 (16): 10164. doi:10.1021/acsami.6b00896. 
  10. ^ qiaexpressionist
  11. ^ Brouwer, N.; Terpstra, P. Ecological and Toxicological Properties of Nitrilotriacetic Acid (NTA) as a Detergent Builder. Tenside Surfactants Detergents 1995, 32, 225-228.