McClean: EDTA (0.5M)

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EDTA is a synthetic amino acid and an agent that contains a typically organic ligand that bonds to a central metal atom. Enzymes that synthesize or modify nucleic acids (like polymerases, ligases, kinases, or nucleases) depend on Mg2+. With EDTA, it can stop the reactions between the enzymes and nucleic acids. EDTA is also in many buffers that store DNA (like TE buffer) removes the metal cofactors.


  1. 186.1g disodium ethylenediamine tetraacetate •2H2 (Na2EDTA)
  2. 800mL of dH2O
  3. 50mL NaOH
  4. Aliquots


  • Step 1 - Measure out 186.1g of Na2EDTA into a tall graduated cylinder
  • Step 2 - Add in 800mL of dH2O and stir vigorously on a magnetic stirrer with a stir bar
  • Step 3 - Using glass electrode (?), identify the pH of the solution
  • Step 4 - If the pH is not around 8.0, carefully add in NaOH to adjust the pH
  • Step 5 - Bring the solution up to 1L and stir
  • Step 6 - Dispense the solution into aliquots
  • Step 7 - Sterilize by autoclaving

Other Information

  1. If the pH of the solution is not adjusted to 8.0, EDTA will not dissolve.
  2. Store at room temperature
  3. For more chemical information, go to


Please feel free to post comments, questions, or improvements to this protocol. Happy to have your input!

  1. List troubleshooting tips here.
  2. You can also link to FAQs/tips provided by other sources such as the manufacturer or other websites.
  3. Anecdotal observations that might be of use to others can also be posted here.


Promega Corporation. "Recipes for Common Laboratory Solutions" Promega: Technical Reference (2010)

Department of Ecology and Evolutionary Biology-University of Michigan. "Recipe for Stock Solution" Genomic Diversity Laboratory


or instead, discuss this protocol.