EDTA

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[http://www.chm.bris.ac.uk/motm/edta/edtah.htm Here's] a great page about [[EDTA]], including [http://www.cem.msu.edu/~cem333/EDTATable.html formation constant] (K<sub>f</sub>) values for metal-EDTA complexes.
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[[Image:EDTA.png|right|thumb|200px|chemical structure of '''EDTA''' - ethylene-diamine-tetraacetic acid]]
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[[Image:EDTA with ligand.png|right|thumb|200px|'''EDTA''' (black) with coordinate bonds to a metal ion (red)]]
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'''EDTA''' stands for '''ethylene-diamine-tetraacetic acid'''. It chelates divalent cations and is therefore used in many buffers. Its relative [[EGTA]] has a higher affinity for calcium than for magnesium ions.
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==Purpose==
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*EDTA is a synthetic amino acid and chelating agent for divalent metals.
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*Most enzymes that synthesize or modify nucleic acids (e.g. polymerases, ligases, kinases, nucleases) are Mg<sup>2+</sup>-dependent. The addition of EDTA is a convenient way to stop these reactions.
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*EDTA is a component of many buffers used to store DNA, such as [[TE buffer]], where the EDTA removes the metal cofactors (typically Mg<sup>++</sup> required for activity of DNAses and other DNA damaging enzymes.
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==Procurement==
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*Usually sold as the disodium salt (CAS 6381-92-6) (Sigma E1644).
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==Use==
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*Molecular Weight, disodium salt dihydrate: 372.24
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*EDTA is essentially insoluble in water, and will only dissolve when neutralized with sodium hydroxide to a pH = 8.0
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*Standard stock solutions are 0.5M at pH 8.0.  A 1M solution cannot be made.  Autoclave.
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*Making the standard solution from disodium EDTA (the typical form sold) requires approximately 1 molar equivalent of NaOH
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*pK<sub>1</sub> = 1.99
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*pK<sub>2</sub> = 2.67
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*pK<sub>3</sub> = 6.16
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*pK<sub>4</sub> = 10.26
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== EDTA stock solution recipes ==
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=== 0.5 M EDTA stock ===
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* 18.61 g EDTA (Sodium Salt)
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* dH2O to 90 ml
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* adjust pH to 7.0
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* adjust volume to 100 ml
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=== 0.5M 500ml pH 8.0 with NaOH pre-calculated ===
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* 93.05g of Na2.EDTA (FW 372.2)
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* 10.14g of NaOH (FW 40)
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* 500 ml dH2O
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[http://www.molecularstation.com/forum/protocols-methods-forum/16909-egta-stock-solution.html]
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== Storage and stability ==
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* store at room temperature
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* stable for years
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==Interesting facts==
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*[http://www.vrp.com/art/963.asp Here's] an article that speaks of the wonders of EDTA and how it can help treat Aunt Edna's cardiovascular disease, enhance your enjoyment of the Friday night happy hour, and act as a "get out of jail free" card.
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*EDTA can prolong the life of your [http://www.deathstar.org/~flash/edta.html motorcycle battery]!
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*EDTA helps you  determine the hidden contents of your [http://homepages.ius.edu/DSPURLOC/c121/week13.htm hard water].
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==Safety==
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?
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==References==
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*[http://www.chm.bris.ac.uk/motm/edta/edtah.htm Here's] a great page about EDTA, including [http://www.cem.msu.edu/~cem333/EDTATable.html formation constant] (K<sub>f</sub>) values for metal-EDTA complexes. Note that many heavy metal ions (like Fe<sup>3+</sup>, Co<sup>2+</sup>, and Zn<sup>2+</sup>) are chelated much more strongly than Mg<sup>2+</sup>. A little bit of EDTA in your reaction will go a long way to keep these evildoers out of trouble and away from your precious biomolecules without interfering with your Mg<sup>2+</sup>-dependent reactions.
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[[Category:Material]] [[Category:Chemical]]

Current revision

chemical structure of EDTA - ethylene-diamine-tetraacetic acid
chemical structure of EDTA - ethylene-diamine-tetraacetic acid
EDTA (black) with coordinate bonds to a metal ion (red)
EDTA (black) with coordinate bonds to a metal ion (red)

EDTA stands for ethylene-diamine-tetraacetic acid. It chelates divalent cations and is therefore used in many buffers. Its relative EGTA has a higher affinity for calcium than for magnesium ions.

Contents

Purpose

  • EDTA is a synthetic amino acid and chelating agent for divalent metals.
  • Most enzymes that synthesize or modify nucleic acids (e.g. polymerases, ligases, kinases, nucleases) are Mg2+-dependent. The addition of EDTA is a convenient way to stop these reactions.
  • EDTA is a component of many buffers used to store DNA, such as TE buffer, where the EDTA removes the metal cofactors (typically Mg++ required for activity of DNAses and other DNA damaging enzymes.

Procurement

  • Usually sold as the disodium salt (CAS 6381-92-6) (Sigma E1644).

Use

  • Molecular Weight, disodium salt dihydrate: 372.24
  • EDTA is essentially insoluble in water, and will only dissolve when neutralized with sodium hydroxide to a pH = 8.0
  • Standard stock solutions are 0.5M at pH 8.0. A 1M solution cannot be made. Autoclave.
  • Making the standard solution from disodium EDTA (the typical form sold) requires approximately 1 molar equivalent of NaOH
  • pK1 = 1.99
  • pK2 = 2.67
  • pK3 = 6.16
  • pK4 = 10.26

EDTA stock solution recipes

0.5 M EDTA stock

  • 18.61 g EDTA (Sodium Salt)
  • dH2O to 90 ml
  • adjust pH to 7.0
  • adjust volume to 100 ml

0.5M 500ml pH 8.0 with NaOH pre-calculated

  • 93.05g of Na2.EDTA (FW 372.2)
  • 10.14g of NaOH (FW 40)
  • 500 ml dH2O

[1]

Storage and stability

  • store at room temperature
  • stable for years

Interesting facts

  • Here's an article that speaks of the wonders of EDTA and how it can help treat Aunt Edna's cardiovascular disease, enhance your enjoyment of the Friday night happy hour, and act as a "get out of jail free" card.
  • EDTA helps you determine the hidden contents of your hard water.

Safety

?

References

  • Here's a great page about EDTA, including formation constant (Kf) values for metal-EDTA complexes. Note that many heavy metal ions (like Fe3+, Co2+, and Zn2+) are chelated much more strongly than Mg2+. A little bit of EDTA in your reaction will go a long way to keep these evildoers out of trouble and away from your precious biomolecules without interfering with your Mg2+-dependent reactions.
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