Ethylenediaminetetraacetic acid

Source: Wikipedia, the free encyclopedia.
(Redirected from
Disodium EDTA
)
This article is about the chemical. For the medication, see Sodium calcium edetate.
"EDTA" redirects here. For other uses, see EDTA (disambiguation).
"Versene" redirects here. Not to be confused with Versine.
Ethylenediaminetetraacetic acid
3-dimensional formula of ethylenediaminetetraacetic acid
Names
IUPAC name
N,N′-(Ethane-1,2-diyl)bis[N-(carboxymethyl)glycine][1]
Systematic IUPAC name
2,2′,2′′,2′′′-(Ethane-1,2-diyldinitrilo)tetraacetic acid[1]
Other names
  • EthyleneDiamineTetraAcetic acid
  • Diaminoethane-tetraacetic acid
  • Edetic acid (
    conjugate base edetate) (INN, USAN
    )
  • Versene
Identifiers
3D model (
JSmol
)
Abbreviations EDTA, H4EDTA
1716295
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
 100.000.409 Edit this at Wikidata
EC Number
  • 200-449-4
144943
KEGG
MeSH Edetic+Acid
RTECS number
  • AH4025000
UNII
UN number 3077
  • InChI=1S/C10H16N2O8/c13-7(14)3-11(4-8(15)16)1-2-12(5-9(17)18)6-10(19)20/h1-6H2,(H,13,14)(H,15,16)(H,17,18)(H,19,20) checkY
    Key: KCXVZYZYPLLWCC-UHFFFAOYSA-N checkY
  • OC(=O)CN(CCN(CC(O)=O)CC(O)=O)CC(O)=O
Properties
C10H16N2O8
Molar mass 292.244 g·mol−1
Appearance Colourless crystals
Density 0.860 g cm−3 (at 20 °C)
log P −0.836
Acidity (pKa) 2.0, 2.7, 6.16, 10.26[2]
Thermochemistry
Std enthalpy of
formation
(ΔfH⦵298)
 −1765.4 to −1758.0 kJ mol−1
Std enthalpy of
combustion
(ΔcH⦵298)
 −4461.7 to −4454.5 kJ mol−1
Pharmacology
S01XA05 (WHO) V03AB03 (WHO) (salt)
  • Intramuscular
  • Intravenous
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H319
P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Lethal dose or concentration (LD, LC):
1000 mg/kg (oral, rat)[3]
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).
☒N verify (what is checkY☒N ?)

Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid after its own abbreviation, is an aminopolycarboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, water-insoluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly.[4]

Uses

Textiles and paper

In industry, EDTA is mainly used to

chlorine-free bleaching
.

Food

In a similar manner, EDTA is added to some food as a preservative or stabiliser to prevent catalytic oxidative decolouration, which is catalysed by metal ions.[5]

Water softener

The reduction of water hardness in laundry applications and the dissolution of scale in boilers both rely on EDTA and related

clinkers.[6][page needed
]

The solubilisation of Fe3+ ions at or below near neutral pH can be accomplished using EDTA. This property is useful in agriculture including hydroponics. However, given the pH dependence of ligand formation, EDTA is not helpful for improving iron solubility in above neutral soils.[7] Otherwise, at near-neutral pH and above, iron(III) forms insoluble salts, which are less bioavailable to susceptible plant species.

Scrubbing

Aqueous [Fe(EDTA)]− is used for removing ("

scrubbing") hydrogen sulfide
from gas streams. This conversion is achieved by oxidising the hydrogen sulfide to elemental sulfur, which is non-volatile:

2 [Fe(EDTA)]− + H2S → 2 [Fe(EDTA)]2− + S + 2 H+

In this application, the iron(III) centre is reduced to its iron(II) derivative, which can then be reoxidised by air. In similar manner, nitrogen oxides are removed from gas streams using [Fe(EDTA)]2−.

The oxidising properties of [Fe(EDTA)]− are also exploited in photography, where it is used to solubilise silver particles.[4]

Ion-exchange chromatography

EDTA was used in separation of the

countercurrent solvent extraction, ion exchange is now used only to obtain the highest purities of lanthanides (typically greater than 99.99%).[citation needed
]

Medicine

thalassaemia
.

Dentistry

endodontists use EDTA solutions to remove inorganic debris (smear layer) and lubricate the root canals in endodontics. This procedure helps prepare root canals for obturation. Furthermore, EDTA solutions with the addition of a surfactant loosen up calcifications
inside a root canal and allow instrumentation (canal shaping) and facilitate apical advancement of a file in a tight or calcified root canal towards the apex.

Eyedrops

It serves as a

eyedrops
.

Analysis

In

glomerular filtration rate (GFR) in nuclear medicine.[10]

EDTA is used extensively in the analysis of blood. It is an anticoagulant for blood samples for CBC/FBCs, where the EDTA chelates the calcium present in the blood specimen, arresting the coagulation process and preserving blood cell morphology.[11] Tubes containing EDTA are marked with lavender (purple) or pink tops.[12] EDTA is also in tan top tubes for lead testing and can be used in royal blue top tubes for trace metal testing.[12]

EDTA is a slime dispersant, and has been found to be highly effective in reducing bacterial growth during implantation of intraocular lenses (IOLs).[13]

Alternative medicine

Some

free radicals from injuring blood vessel walls, therefore reducing atherosclerosis.[14] These ideas are unsupported by scientific studies, and seem to contradict some currently accepted principles.[15] The U.S. FDA has not approved it for the treatment of atherosclerosis.[16]

Cosmetics

In shampoos, cleaners, and other personal care products, EDTA salts are used as a sequestering agent to improve their stability in air.[17]

Laboratory applications

In the laboratory, EDTA is widely used for scavenging metal ions: In

water hardness or as a masking agent
to sequester metal ions that would interfere with the analyses.

EDTA finds many specialised uses in the biomedical labs, such as in

passaging. In histopathology, EDTA can be used as a decalcifying agent making it possible to cut sections using a microtome
once the tissue sample is demineralised.

EDTA is also known to inhibit a range of metallopeptidases, the method of inhibition occurs via the chelation of the metal ion required for catalytic activity.[22] EDTA can also be used to test for bioavailability of heavy metals in sediments. However, it may influence the bioavailability of metals in solution, which may pose concerns regarding its effects in the environment, especially given its widespread uses and applications.

EDTA is also used to remove crud (corroded metals) from fuel rods in nuclear reactors.[23]

Side effects

EDTA exhibits low acute toxicity with LD50 (rat) of 2.0 g/kg to 2.2 g/kg.[4] It has been found to be both cytotoxic and weakly genotoxic in laboratory animals. Oral exposures have been noted to cause reproductive and developmental effects.[17] The same study[17] also found that both dermal exposure to EDTA in most cosmetic formulations and inhalation exposure to EDTA in aerosolised cosmetic formulations would produce exposure levels below those seen to be toxic in oral dosing studies.

Synthesis

The compound was first described in 1935 by Ferdinand Münz,[24] who prepared the compound from ethylenediamine and chloroacetic acid.[25] Today, EDTA is mainly synthesised from ethylenediamine (1,2-diaminoethane), formaldehyde, and sodium cyanide.[26] This route yields the tetrasodium EDTA, which is converted in a subsequent step into the acid forms:

H2NCH2CH2NH2 + 4 CH2O + 4 NaCN + 4 H2O → (NaO2CCH2)2NCH2CH2N(CH2CO2Na)2 + 4 NH3
(NaO2CCH2)2NCH2CH2N(CH2CO2Na)2 + 4 HCl → (HO2CCH2)2NCH2CH2N(CH2CO2H)2 + 4 NaCl

This process is used to produce about 80,000 tonnes of EDTA each year. Impurities cogenerated by this route include glycine and nitrilotriacetic acid; they arise from reactions of the ammonia coproduct.[4]

Nomenclature

To describe EDTA and its various

conjugate base that is the ligand, and H4EDTA, the precursor
to that ligand. At very low pH (very acidic conditions) the fully protonated H6EDTA2+ form predominates, whereas at very high pH or very basic condition, the fully deprotonated EDTA4− form is prevalent. In this article, the term EDTA is used to mean H4−xEDTAx−, whereas in its complexes EDTA4− stands for the tetraanion ligand.

Coordination chemistry principles

chelate
as found in Co(III) complexes
Structure of [Fe(EDTA)(H2O)]−, showing that the EDTA4− ligand does not fully encapsulate Fe(III), which is seven-coordinate[27]

In

octahedral geometry. Although of little consequence for its applications, these octahedral complexes are chiral. The cobalt(III) anion [Co(EDTA)]− has been resolved into enantiomers.[28] Many complexes of EDTA4− adopt more complex structures due to either the formation of an additional bond to water, i.e. seven-coordinate complexes, or the displacement of one carboxylate arm by water. The iron(III) complex of EDTA is seven-coordinate.[29] Early work on the development of EDTA was undertaken by Gerold Schwarzenbach in the 1940s.[30] EDTA forms especially strong complexes with Mn(II), Cu(II), Fe(III), Pb(II) and Co(III).[31][page needed
]

Several features of EDTA's complexes are relevant to its applications. First, because of its high denticity, this ligand has a high affinity for metal cations:

[Fe(H2O)6]3+ + H4EDTA ⇌ [Fe(EDTA)]− + 6 H2O + 4 H+  Keq = 1025.1

Written in this way, the

metal oxides and carbonates
.

The

amino groups).[32]

Environmental concerns

Abiotic degradation

EDTA is in such widespread use that questions have been raised whether it is a

abiotically in the presence of sunlight.[33]

The most important process for the elimination of EDTA from surface waters is direct

photolysis at wavelengths below 400 nm.[34] Depending on the light conditions, the photolysis half-lives of iron(III) EDTA in surface waters can range as low as 11.3 minutes up to more than 100 hours.[35] Degradation of FeEDTA, but not EDTA itself, produces iron complexes of the triacetate (ED3A), diacetate (EDDA), and monoacetate (EDMA) – 92% of EDDA and EDMA biodegrades in 20 hours while ED3A displays significantly higher resistance. Many environmentally-abundant EDTA species (such as Mg2+ and Ca2+
) are more persistent.

Biodegradation

In many

microorganisms.[36] Resulting byproducts are ED3A and iminodiacetic acid (IDA) – suggesting that both the backbone and acetyl groups were attacked. Some microorganisms have even been discovered to form nitrates out of EDTA, but they function optimally at moderately alkaline conditions of pH 9.0–9.5.[37]

Several bacterial strains isolated from sewage treatment plants efficiently degrade EDTA. Specific strains include

aerobic respiration and are classified as gram-negative bacteria. Unlike photolysis, the chelated species is not exclusive to iron(III) in order to be degraded. Rather, each strain uniquely consumes varying metal–EDTA complexes through several enzymatic pathways. Agrobacterium radiobacter only degrades Fe(III) EDTA[39] while BNC1 and DSM 9103 are not capable of degrading iron(III) EDTA and are more suited for calcium, barium, magnesium and manganese(II) complexes.[41]
EDTA complexes require dissociation before degradation.

Alternatives to EDTA

Interest in environmental safety has raised concerns about biodegradability of

aminopolycarboxylates such as EDTA. These concerns incentivize the investigation of alternative aminopolycarboxylates.[33] Candidate chelating agents include nitrilotriacetic acid (NTA), iminodisuccinic acid (IDS), polyaspartic acid, S,S-ethylenediamine-N,N′-disuccinic acid (EDDS), methylglycinediacetic acid (MGDA), and L-Glutamic acid N,N-diacetic acid, tetrasodium salt (GLDA).[42]

Iminodisuccinic acid (IDS)

Commercially used since 1998, iminodisuccinic acid (IDS) biodegrades by about 80% after only 7 days. IDS binds to calcium exceptionally well and forms stable compounds with other heavy metal ions. In addition to having a lower toxicity after chelation, IDS is degraded by Agrobacterium tumefaciens (BY6), which can be harvested on a large scale. The enzymes involved, IDS epimerase and C−N lyase, do not require any cofactors.[43]

Polyaspartic acid

Polyaspartic acid, like IDS, binds to calcium and other heavy metal ions. It has many practical applications including corrosion inhibitors, wastewater additives, and agricultural polymers. A Polyaspartic acid-based laundry detergent was the first laundry detergent in the world to receive the EU flower ecolabel.[44] Calcium binding ability of polyaspartic acid has been exploited for targeting of drug-loaded nanocarriers to bone.[45] Preparation of hydrogels based on polyaspartic acid, in a variety of physical forms ranging from fiber to particle, can potentially enable facile separation of the chelated ions from a solution.[46] Therefore, despite being weaker than EDTA, polyaspartic acid can still be regarded as a viable alternative due to these features as well as biocompatibility, and biodegradability.[47]

S,S-Ethylenediamine-N,N′-disuccinic acid (EDDS)

A structural isomer of EDTA, ethylenediamine-N,N′-disuccinic acid (EDDS) is readily biodegradable at high rate in its S,S form.[48]

Methylglycinediacetic acid (MGDA)

kidney stones.[49]

Methods of detection and analysis

The most sensitive method of detecting and measuring EDTA in biological samples is selected reaction monitoring

mass spectrometry (SRM-CE/MS), which has a detection limit of 7.3 ng/mL in human plasma and a quantitation limit of 15 ng/mL.[50] This method works with sample volumes as small as 7–8 nL.[50]

EDTA has also been measured in non-alcoholic beverages using high performance liquid chromatography (HPLC) at a level of 2.0 μg/mL.[51][52]

In popular culture

In the movie Blade (1998), EDTA is used as a weapon to kill vampires, exploding when in contact with vampire blood.[53]

References

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    .
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  12. ^ a b "Order of draw for multiple tube collections" (PDF). Michigan Medicine Laboratories. 2019-09-15. Archived from the original (PDF) on 2019-11-26. Retrieved 2020-03-27.
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  16. ^ "Postmarket Drug Safety Information for Patients and Providers – Questions and Answers on Edetate Disodium (marketed as Endrate and generic products)". U.S. Food and Drug Administration.
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  24. ^ Paolieri, Matteo (December 2017). "Ferdinand Münz: EDTA and 40 years of inventions". Bull. Hist. Chem. 42 (2). ACS: 133–140.
  25. ^ US 2130505, Münz, Ferdinand, "Polyamino carboxylic acids and process of making same", published 1938-09-20, assigned to General Aniline Works Ltd. . Also DE 718981, Münz, Ferdinand, "Verfahren zum Unschädlichmachen der Härtebildner des Wassers [Process for rendering the hardness components of water harmless]", published 1938-09-20, assigned to I. G. Farbenindustrie 
  26. ^ "Industrial Synthesis of EDTA". University of Bristol.
  27. doi:10.1107/S0108270184005151
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  29. doi:10.1107/S0108270184006338
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  30. ^ Sinex, Scott A. "EDTA – A Molecule with a Complex Story". University of Bristol.
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  34. ^ Kari, F. G. (1994). Umweltverhalten von Ethylenediaminetetraacetate (EDTA) under spezieller Berucksuchtigung des photochemischen Ab-baus (PhD). Swiss Federal Institute of Technology.
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  53. ^ "Blade (1998)". Internet Movie Database (IMDb). Retrieved 2022-11-14.

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Ethylenediaminetetraacetic_acid&oldid=1215706344"