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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*[http://www.vrp.com/art/963.asp Here's] another 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''' 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==
 +
*[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.
 +
** This has been proven as unverifiable claims by the FTC... Read the whole controversy issue [http://en.wikipedia.org/wiki/Chelation_therapy#Controversy here]. -[[User:Etienne Robillard|Etienne Robillard]] 10:52, 10 December 2012 (EST)
*EDTA can prolong the life of your [http://www.deathstar.org/~flash/edta.html motorcycle battery]!
*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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* Magnesium and calcium deficiency may be an indicator of long-term EDTA based chelation therapy thus the use EDTA based buffer agents may be disrecommended for patients with bone diseases.
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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]]
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[[Category:Buffers]]
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[[Category:Chemical]]

Revision as of 20:03, 10 December 2012

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.
    • This has been proven as unverifiable claims by the FTC... Read the whole controversy issue here. -Etienne Robillard 10:52, 10 December 2012 (EST)
  • EDTA helps you determine the hidden contents of your hard water.

Safety

  • Magnesium and calcium deficiency may be an indicator of long-term EDTA based chelation therapy thus the use EDTA based buffer agents may be disrecommended for patients with bone diseases.

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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