1 M HEPES Buffer Calculator, pH 7.4
Scale a source-reviewed 1 M HEPES free-acid stock recipe at pH 7.4 and calculate the required HEPES mass for any final volume.
Select a reviewed preset and enter the final volume to prepare.
| Reagent | Formula | Amount or action |
|---|---|---|
| HEPES free acidfree acid | 23.83 g | |
| Sodium hydroxide | Adjust experimentally to pH 7.4. | |
| Purified water | After 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 1 M HEPES pH 7.4
- Add the calculated HEPES free acid to approximately 70–80% of the selected final volume of purified water.
- Stir until the HEPES dissolves completely.
- Add NaOH gradually while monitoring the pH until pH 7.4 is reached.
- Bring to the selected final volume, mix thoroughly, and verify the final pH.
About This Buffer
HEPES is a zwitterionic biological buffer widely used in biochemical and cell-based applications, particularly for buffering near neutral or physiological pH. This page provides a fixed 1 M HEPES free-acid stock formulation at pH 7.4, with the final pH established experimentally using NaOH.
Common questions
Does this recipe use HEPES free acid or a sodium salt?
This preset uses HEPES free acid. The reagent form matters because a different salt form would have a different molecular mass and preparation basis.
Why is the NaOH amount not shown?
NaOH is a nonquantitative pH-adjustment reagent in this fixed recipe. Its required amount must be determined experimentally.
Can I use this page to prepare HEPES at another concentration or pH?
No. This page scales the reviewed 1 M, pH 7.4 preset only. A different concentration or pH should be published as a separate reviewed preset.
Sources and review notes
The source for the currently selected preset appears first. Recipe quantities remain tied to the cited article location.
1 M HEPES pH 7.4
Source location: Solution recipes — 1 M HEPES, pH 7.4; 1 L preparation cross-check.
Preparation method: Mass derived from the published concentration