 | |
| Names | |
|---|---|
| Preferred IUPAC name 2,2′,2′′-Nitrilotriacetic acid[3] | |
| Other names | |
| Identifiers | |
3D model (JSmol) | |
| 1710776 | |
| ChEBI | |
| ChemSpider |
|
| DrugBank |
|
| ECHA InfoCard | 100.004.869 |
| EC Number |
|
| 3726 | |
| KEGG |
|
| MeSH | Nitrilotriacetic+Acid |
| RTECS number |
|
| UNII |
|
| UN number | 2811 |
| |
| |
| Properties | |
| C6H9NO6 | |
| Molar mass | 191.14[4] |
| Appearance | White crystals |
| Melting point | 246[4] °C (475 °F; 519 K) |
| Insoluble. <0.01 g/100 mL at 23°C[4] | |
| Thermochemistry | |
Std enthalpy of formation(ΔfH⦵298) | −1.3130–−1.3108 MJ mol−1 |
| Hazards | |
| GHS labelling: | |
  | |
| Warning | |
| H302,H319,H351 | |
| P281,P305+P351+P338 | |
| Flash point | 100 °C (212 °F; 373 K) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 1.1 g kg−1(oral, rat) |
| Related compounds | |
Related alkanoic acids | |
Related compounds | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Nitrilotriacetic acid (NTA) is theaminopolycarboxylic acid with the formula N(CH2CO2H)3. It is a colourless solid. Its conjugate basenitrilotriacetate is used as achelating agent for Ca2+, Co2+, Cu2+, and Fe3+.[5]
Nitrilotriacetic acid is commercially available as the free acid and as the sodium salt. It is produced fromammonia,formaldehyde, andsodium cyanide orhydrogen cyanide.[6] NTA is also cogenerated as an impurity in the synthesis ofEDTA, arising from reactions of the ammonia coproduct.[7] Older routes to NTA included alkylation of ammonia with chloroacetic acid and oxidation oftriethanolamine.
The conjugate base of NTA is atripodaltetradentate trianionic ligand, formingcoordination compounds with a variety of metal ions.[8]
LikeEDTA, its sodium salt is used forwater softening to remove Ca2+. For this purpose, NTA is a replacement fortriphosphate, which once was widely used in detergents, and cleansers, but can causeeutrophication of lakes.
In one application, sodium NTA removes Cr, Cu, and As from wood that had been treated withchromated copper arsenate.[9]
In the laboratory, this compound is used in complexometric titrations. A variant of NTA is used for protein isolation and purification in theHis-tag method.[10] The modified NTA is used to immobilizenickel on a solid support. This allows purification of proteins containing a tag consisting of six histidine residues at either terminus.[11]
The His-tag binds the metal of metalchelator complexes. Previously,iminodiacetic acid was used for that purpose. Now, nitrilotriacetic acid is more commonly used.[12]
For laboratory uses, Ernst Hochuli et al. (1987) coupled the NTA ligand and nickel ions toagarose beads.[13] This Ni-NTA Agarose is the most used tool to purify His-tagged proteins via affinity chromatography.
![Three views of the structure of [Ni(NTA)(H2O)2]−.](/mt/?noimg=&dark=on&url=http%3a%2f%2fwww.wikipedia.org%2fwiki%2fFile%3aNi(NTA)(aq)23views.png)
![Structure of the nitrilotriacetate anion [Ca(NTA)(H2O)3]−.](/mt/?noimg=&dark=on&url=http%3a%2f%2fwww.wikipedia.org%2fwiki%2fFile%3aCalcium_complex_of_NTA_trianion.svg)
In contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment.[6] 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.[14]
