ChemHBuffer Calculator

0.5 M MES Buffer Calculator

Scale reviewed 0.5 M MES free-acid stock recipes at pH 5.5 or 6.5 with experimental NaOH adjustment.

Select a reviewed preset and enter the final volume to prepare.

Recipe for 100 mL of 0.5 M MES-NaOH pH 5.5
ReagentFormulaAmount or action
MES free acidfree acid9.762 g
Sodium hydroxideAdjust experimentally to pH 5.5.
Purified waterAfter pH adjustment, bring the total solution volume to 100 mL. Do not add 100 mL of water; add water only until the total solution reaches 100 mL.

How to prepare 0.5 M MES-NaOH pH 5.5

  1. Select the pH 5.5 or pH 6.5 preset and add the calculated MES free acid to approximately 70–80% of the final volume of purified water.
  2. Stir until the MES dissolves completely.
  3. Add NaOH gradually while monitoring the pH until the selected target is reached.
  4. Bring to the selected final volume, mix thoroughly, and verify the final pH.

About This Buffer

MES is a zwitterionic biological buffer commonly used for experiments requiring mildly acidic conditions. This calculator provides reviewed 0.5 M MES free-acid stock formulations at pH 5.5 and 6.5, with NaOH used experimentally to reach the selected target pH.

Common questions

Why are only pH 5.5 and pH 6.5 available?

These are the two reviewed production presets. The former pH 6.0 candidate is not published because its cited titration direction is chemically inconsistent.

Does the calculator use MES free acid?

Yes. Both production presets use MES free acid, and the displayed mass corresponds to that exact reagent form.

Does changing pH change the MES mass?

Both available presets are 0.5 M, so the MES mass per unit final volume is the same. The pH is established experimentally with NaOH as a separate operation.

Sources and review notes

The source for the currently selected preset appears first. Recipe quantities remain tied to the cited article location.

View sources for all presets
Browse all buffer calculators