Overview
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.
REQUIREMENTS
Reagents and solutions
MOPS (Free acid, Molecular weight: 209.26)
Deionized or Milli-Q water
Equipment and disposables
Measuring cylinder
Conical flask / Beaker
Magnetic stirrer
Sterile filter unit (for filter sterilization)
Composition
1 M MOPS
pH 7.4
Objective
Preparation of 500 ml of 1 M MOPS, pH 7.4 stock solution
PROCEDURE
Use appropriate personal protective equipment (lab coat, gloves, goggles, etc) for your safety and follow the guidelines of your institute.
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.
Precaution
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.
Tip:
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
Note:
You need to add ≈ 30 – 40 ml of 10N NaOH to adjust the pH 7.4.
Tip:
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.
Precaution:
We don’t recommend autoclaving the solution.
Note:
Freshly prepared solution will appear clear colourless liquid which can turn into yellowish with time.
Storage
Stored the solution at 4° C in a brown bottle
Precautions
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 |
REFERENCES
Goldbio: https://www.goldbio.com/documents/3551/MOPS+Buffer+1M+Stock+Solution+with+table.pdf
