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EDTA

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EDTA

Chemical name	EDTA
Other names	EDTA H₄EDTA Diaminoethanetetraacetic acid Edetic acid Edetate Ethylenedinitrilotetraacetic acid Versene
Chemical formula	C₁₀H₁₆N₂O₈
Molecular mass	292.25 g/mol
CAS number	[60-00-4]
Density	0.86 g/cm³
Melting point	237-245 °C (dec.)
SMILES	OC(CN(CC(O)=O)C- CN(CC(O)=O)CC(O)=O)=O
Hazards
MSDS	External MSDS
Main hazards	irritant
R/S statement	R: 36 S: 26
RTECS number	AH4025000
Disclaimer and references

EDTA is the acronym for the chemical compound ethylenediaminetetraacetic acid.

EDTA refers to the chelating agent that is widely used to sequester di- and trivalent metal ions such as magnesium ion in molecular biology.

EDTA features four carboxylic acid and two amine groups that can all bind to metals. EDTA forms specially strong complexes with Mn(II), Cu(II), Fe(III), and Co(III).^[1]

1 Popular vs. chemical nomenclature
2 Coordination chemistry principles
3 Research Applications of EDTA
4 0.5 M EDTA Buffer Recipe Preparation
5 References
6 See also

Popular vs. chemical nomenclature

To describe EDTA and its various protonated forms, chemists use a more cumbersome but more precise acronym that distinguishes between EDTA⁴⁻, the conjugate base that is the ligand, and H₄EDTA, the precursor to that ligand.

Coordination chemistry principles

In coordination chemistry, H₄EDTA is a member of the aminocarboxylate family of ligands that includes imidodiacetic acid ("H₂IDA") and nitrilotriacetic acid ("H₃NTA"). More specialized relatives include N,N'-ethylenediaminediacetic acid ("H₂EDDA") and 1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid ("H₄CyDTA"). These ligands are all formally derived from the amino acid glycine.

H₄EDTA forms highly stable coordination compounds that are soluble in water. In these complexes, the ligand is usually either hexa- or pentadentate, EDTA⁴⁻ or HEDTA³⁻, respectively. Such complexes are chiral, and [Co(EDTA)]⁻ has been resolved into enantiomers.^[2]

Metal-EDTA chelate

Research Applications of EDTA

In research and the laboratory, EDTA is also used for:

Scavenging metal ions such as magnesium (Mg).

In biochemistry and molecular biology, ion depletion is commonly used to inactivate metal-dependent enzymes such as DNAses and Proteases that can damage and degrate DNA or proteins respectively.

Complexometric titrations.

EDTA is commonly used in Buffer solutions such as TAE and TBE used to separate DNA and RNA molecules during gel electrophoresis.

EDTA can be used to determine water hardness.

EDTA is used often in medical and laboratory equipment as an anticoagulant.

0.5 M EDTA Buffer Recipe Preparation

To make 0.5 M EDTA pH 8.0, you must mix the following.

For 1 liter add:

186.1 g Na2EDTA.2H2O

800 ml Milli-Q H2O

Adjust the pH to 8 with NaOH pellets (you will need about about 20 g) or NaOH solution.

The reason to adjust the pH is that the EDTA will not dissolve until the pH is about 8. Bring volume up to 1 L with double distilled water (ddH2O), put in vessel or container, and autoclave.

References

↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
↑ Kirchner, S. Barium (Ethylenediaminetetracetato) Cobalt(III) 4-Hydrate" Inorganic Syntheses, McGraw-Hill: New York, 1957; Vol. 5, pages 186-188.

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