Nitrilotriacetic acid
Structural formula | ||||||||||||||||||||||
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General | ||||||||||||||||||||||
Surname | Nitrilotriacetic acid (NTA) | |||||||||||||||||||||
other names |
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Molecular formula | C 6 H 9 NO 6 | |||||||||||||||||||||
Brief description |
colorless crystals |
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properties | ||||||||||||||||||||||
Molar mass | 191.14 g mol −1 | |||||||||||||||||||||
Physical state |
firmly |
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Melting point |
241.5 ° C (decomposition) |
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pK s value |
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solubility |
heavy in water (1.28 g l −1 at 20 ° C) |
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safety instructions | ||||||||||||||||||||||
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Toxicological data | ||||||||||||||||||||||
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Nitrilotriacetic acid, or NTA for short, is a complexing agent . In aqueous solution, NTA forms stable complex compounds with metal ions .
properties
NTA forms stable complexes with metal ions such as Ca 2+ , Cu 2+ , Ni 2+ or Fe 3+ .
use
NTA is partially used for water softening . Its use as a softening additive in detergents has declined in recent years, despite the biodegradability of NTA in sewage treatment plants , since the dissolving power of heavy metals is viewed as problematic. In analytical chemistry it is known as complexone I and is used in complexometry to determine metal ions. In 1999, 20,000 tons of NTA were used in Europe.
Use in research
It is also used in affinity chromatography as a chelate ligand (usually with Ni 2+ as the central ion) for the purification of poly- histidine - tagged proteins. The purification effect comes about because the polyhistidine binds to the metal of the metal- chelator complex. Examples of suitable metals are nickel, copper or zinc. In the past, iminodiacetic acid (IDA) was mainly used as a chelator. However, this was replaced by NTA in the course of time. In 1987 Ernst Hochuli coupled the NTA ligand to agarose beads for biological research . This Ni-NTA agarose is by far the most frequently used tool to purify His-Tag proteins via affinity chromatography.
Biological importance
It has long been assumed that NTA can mobilize heavy metals from sediment in water bodies . In practice this is not the case, as NTA is present in natural waters as a stable calcium complex. There is a suspicion that this substance is carcinogenic .
proof
NTA can be detected with a copper sulfate solution and a complex indicator.
Individual evidence
- ↑ a b c d e f Entry on nitrilotriacetic acid. In: Römpp Online . Georg Thieme Verlag, accessed on April 7, 2014.
- ↑ a b Entry on nitrilotriacetic acid in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
- ↑ Entry on nitrilotriacetic acid in the ChemIDplus database of the United States National Library of Medicine (NLM) .
- ↑ Sabine A. Lauer, John P. Nolan: Development and characterization of Ni-NTA-bearing microspheres . In: Cytometry . tape 48 , no. 3 , 2002, ISSN 1097-0320 , p. 136-145 , doi : 10.1002 / cyto.10124 .
- ↑ E. Hochuli, H. Döbeli, A. Schacher: New metal chelate adsorbent selective for proteins and peptides containing neighboring histidine residues. In: Journal of Chromatography A . Volume 411, 1987, pp. 177-184, doi : 10.1016 / S0021-9673 (00) 93969-4 .
- ↑ Ni-NTA agarose