How To Make 0.5M EDTA pH 8.0

About EDTA solution

Ethylenediaminetetraacetic acid (EDTA) solution, at 0.5 M pH 8.0, is a commonly used solution utilised as a ligand and chelating agent. EDTA is particularly useful at sequestering metal ions, such as Ca2+ and Mg2+. Since nucleases require metal ions, EDTA solutions are used to protect DNA and RNA from degradation.


The recipe below is used to prepare a 100 mL 0.5M EDTA pH 8.0 solution.

Reagent Mass / Volume Final concentration
EDTA disodium salt, dihydrate 18.61 g 0.5 M
Distilled H2O 80 mL

How to make 0.5M EDTA pH 8.0

  1. Weigh out 18.61 g EDTA disodium salt, dihydrate and add to a 100 mL Duran bottle.
  2. Measure out 80 mL distilled water and add to the Duran bottle.
  3. Add a magnetic flea and place on a magnetic stirring plate to mix the solution. The EDTA salt will not go into solution until the pH reaches 8.0.
  4. Add a pH meter into the solution to observe the pH.
  5. To dissolve the salt, add sodium hydroxide (NaOH) pellets to the solution. Add a few pellets at a time and wait until the pellets have fully dissolved before adding more. It may take around 2 g of NaOH pellets before the pH is at 8.0.
  6. Once fully dissolved (this will take some time so be patient), top up the solution to 100 mL using distilled water, if necessary.
  7. To sterilise, autoclave the solution on a liquid cycle (20 min at 15 psi).

Storage of 0.5M EDTA pH 8.0 solution

Store 0.5M EDTA pH 8.0 solution at room temperature (+15oC – +25oC).


The final 0.5M EDTA pH 8.0 solution is not classified as hazardous. However, always be sure to read the safety data sheet before use.


    • Hello Barend,
      The MW of the EDTA disodium salt dihydrate I used from Sigma is 372.24 g/mol – which would mean 18.61 should be added in this case.


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