MOPS (Free acid, C7H15NO4S, Molecular weight: 209.26) is a zwitterionic buffer, useful for several cell and molecular biology applications due to its pH range between 6.5 – 7.9. It is soluble in water.
Reagents and solutions
MOPS (Free acid, Molecular weight: 209.26)
Deionized or Milli-Q water
Equipment and disposables
Conical flask / Beaker
Sterile filter unit (for filter sterilization)
1 M MOPS
Preparation of 500 ml of 1 M MOPS, pH 7.4 stock solution
Step 1: To prepare 500 ml of 1 M MOPS solution, weigh out 104.65 g MOPS in a 1 Liter conical flask/beaker. Add 400 ml deionized/Milli-Q water. Stir until all solute is completely dissolved.
Do not dissolve in 500 ml of deionized / Milli-Q water. In most cases, solution volume increases when a large amount of solutes dissolve in a solvent.
It is always a good practice to dissolve the solute in a small volume of solvent (≈ 80% of the final solution volume). After the solute is completely dissolved and pH is adjusted, make up the correct volume with the solvent.
Step 2: Adjust the pH of the solution to 7.4 using 10N NaOH
You need to add ≈ 30 – 40 ml of 10N NaOH to adjust the pH 7.4.
You can adjust to any desired pH between 6.5 – 7.9 (MOPS pH range).
Step 2: Adjust the volume to 500 ml with deionized/Milli-Q water. Mix it again.
Step 3: Sterilize the solution by filtering through a sterile filter unit containing a membrane with porosity 0.22 µm or less.
We don’t recommend autoclaving the solution.
Freshly prepared solution will appear clear colourless liquid which can turn into yellowish with time.
Stored the solution at 4° C in a brown bottle
Protect the solution from light.
|Follow the table to prepare MOPS solutions of different concentrations and volumes.|
|Conc. / Volume||100 ml||250 ml||500 ml||1000 ml|
|10 mM||0.21 g||0.52 g||1.05 g||2.09 g|
|50 mM||1.05 g||2.62 g||5.23 g||10.46 g|
|100 mM||2.09 g||5.23 g||10.46 g||20.93 g|
|0.5 M||10.46 g||26.16 g||52.32 g||104.63 g|
|1 M||20.93 g||52.32 g||104.63 g||209.26 g|