MOPS Stock Buffer Calculator
Scale source-defined MOPS free-acid stock recipes for 0.5 M MOPS-NaOH pH 7.0 or 0.4 M MOPS-KOH pH 7.2.
Select a reviewed preset and enter the final volume to prepare.
| Reagent | Formula | Amount or action |
|---|---|---|
| MOPS free acidfree acid | 20.93 g | |
| Sodium hydroxide | Adjust experimentally to pH 7.0. | |
| Purified water | After pH adjustment, bring the total solution volume to 200 mL. Do not add 200 mL of water; add water only until the total solution reaches 200 mL. |
How to prepare 0.5 M MOPS-NaOH pH 7.0
- Select the required MOPS preset and add the calculated MOPS free acid to approximately 70–80% of the selected final volume of purified water.
- Stir until the MOPS dissolves completely.
- Use NaOH for pH 7.0 or KOH for pH 7.2, and adjust experimentally to the selected target pH.
- Bring to the selected final volume, mix thoroughly, and verify the final pH.
About This Buffer
MOPS is a zwitterionic biological buffer commonly used in biochemical and molecular biology applications near neutral pH. This page contains two source-defined stock formulations: 0.5 M MOPS at pH 7.0 adjusted with NaOH and 0.4 M MOPS at pH 7.2 adjusted with KOH. The two presets are retained as separate formulations rather than treated as interchangeable recipes.
Common questions
What is the difference between the two MOPS presets?
The pH 7.0 preset is 0.5 M and uses NaOH; the pH 7.2 preset is 0.4 M and uses KOH. They are separate source-defined formulations.
Can I switch NaOH and KOH between presets?
The calculator preserves the titrant specified by each reviewed source. Changing the titrant would create a different preparation and should not be treated as the same preset.
Why is there no pH 7.4 option?
A pH 7.4 preset is not published without an exact reviewed preparation or a documented concentration-to-mass derivation.
Sources and review notes
The source for the currently selected preset appears first. Recipe quantities remain tied to the cited article location.
0.5 M MOPS-NaOH pH 7.0
Source location: Solutions — exact 0.5 M MOPS-NaOH pH 7.0 preparation.
Preparation method: Source-stated quantitative composition
- Isolation of Nuclei in Tagged Cell Types, RNA Extraction and Ribosomal RNA Degradation PMC8275268 · open article
View sources for all presets
0.4 M MOPS-KOH pH 7.2
Source location: Reagents — exact 0.4 M MOPS-KOH pH 7.2 preparation.
Preparation method: Source-stated quantitative composition