CAPS Transfer Buffer Calculator, pH 11.0
Scale a fixed 10 mM CAPS transfer buffer containing 10% methanol from a source-defined 100 mM CAPS stock adjusted to pH 11.0 before mixing.
Select a reviewed preset and enter the final volume to prepare.
| Reagent | Formula | Amount or action |
|---|---|---|
| 100 mM CAPS stock, pH 11.0prepared aqueous stock | 100 mLStock preparation basis: 22.13 g CAPS per liter; adjust the stock experimentally to pH 11.0 with NaOH, then bring the stock to its own final volume. Do not predict a NaOH amount. | |
| Methanollaboratory-grade liquid | 100 mL | |
| Purified water | Bring the total solution volume to 1 L. Do not add 1 L of water; add water only until the total solution reaches 1 L. |
How to prepare 10 mM CAPS, 10% methanol, pH 11.0
- Prepare the 100 mM CAPS stock before assembling the transfer buffer: dissolve 22.13 g CAPS per liter, adjust the stock experimentally to pH 11.0 with NaOH, and bring the stock to its own final volume.
- Measure the calculated volume of prepared 100 mM CAPS stock, pH 11.0.
- Add the calculated methanol volume and mix thoroughly.
- Bring the transfer buffer to the selected final volume with purified water, preserving the 1:1:8 CAPS stock:methanol:water ratio.
- Mix thoroughly.
About This Buffer
CAPS is a high-pH biological buffer that can be used as an alternative protein-transfer system, including applications where a glycine-containing transfer buffer is undesirable. This calculator prepares a fixed transfer formulation containing 10 mM CAPS and 10% methanol. The source-defined 100 mM CAPS stock is adjusted experimentally to pH 11.0 with NaOH before it is mixed with methanol and water; no separate final-mixture titration is specified.
Common questions
What is the fixed composition of this CAPS transfer buffer?
The preset contains 10 mM CAPS and 10% v/v methanol at pH 11.0.
Why is NaOH not shown as a calculated volume?
NaOH is used experimentally when preparing the 100 mM CAPS stock, before methanol and water are added. Its required amount is not source-defined and is therefore not calculated.
Where is the pH 11.0 adjustment performed?
Adjust the 100 mM CAPS stock to pH 11.0 with NaOH before combining one volume of that stock with one volume of methanol and eight volumes of water. Do not reassign this adjustment to the diluted final mixture.
Sources and review notes
The source for the currently selected preset appears first. Recipe quantities remain tied to the cited article location.
10 mM CAPS, 10% methanol, pH 11.0
Source location: PMC3157917 — prepare 100 mM CAPS stock, adjust that stock to pH 11.0 with NaOH, then mix CAPS stock:methanol:water at 1:1:8 to obtain final 10 mM CAPS and 10% methanol; the NaOH amount is not quantified. Independent composition cross-checks are retained.
Preparation method: Calculated equivalent of the published stock-based formulation
- Detection of SPO11-Oligonucleotide Complexes From Mouse Testes PMC3157917 · open article
- Search for amyloid-binding proteins by affinity chromatography PMC3665336 · open article
- Examination of an absolute quantity of less than a hundred nanograms of proteins by amino acid analysis PMC3777156 · open article