Peptide Solubility Planner
Enter a mass and target concentration to get the final volume in mL and µL. Optionally record two test conditions. Solubility comes only from testing your material.
Final volume
Example loaded. Replace the illustrative values with your own.
Enter your sample mass and target concentration to calculate the final volume.
This is a planned final volume. Measure solubility under the intended test conditions.
What if the target changes?
The sample mass stays the same. Choose a target to preview its final volume.
The worksheet uses the target you entered above.
Compare test conditions
Both records share one target. Each holds a medium, optional aqueous pH, temperature (°C) and time (min), and appearance: not recorded, clear, cloudy, or visible material. The planner lists differing fields. It does not suggest solvents, judge suitability, assign pass or fail, or infer saturation. Nothing is sent or saved. You can download a plaintext worksheet.
These diagrams show recorded appearance.
No differences or missing entries to show.
| Field | Condition A | Condition B | Status |
|---|---|---|---|
| Medium | |||
| Aqueous pH | |||
| Temperature | |||
| Time | |||
| Appearance |
Worked example
In this synthetic example, 0.20 mg of material as weighed at a planned target of 1 mg/mL gives 0.20 mg ÷ 1 mg/mL = 0.20 mL, or 200 µL, of final volume. That figure is a nominal concentration of weighed material, not a measured dissolved concentration. Conditions A and B in the example are hypothetical placeholders that show how the comparison works. They are not solvent recommendations or experimental data.
How to interpret a solubility screen
Hold conditions constant and record them
Compare Condition A and Condition B at the same target concentration, on the same mass basis, and with the same material. Where practical, change only one of the medium, pH, temperature, or observation time between records and keep the others the same. Record every value, including pH only for aqueous media. That way any difference between records can be traced to a single recorded change.
Read appearance as an observation only
Record clear, cloudy, or visible material as what you saw at the recorded time. Do not infer what any haze or residue is, how much peptide dissolved, or whether the sample is saturated. A clear appearance does not establish full dissolution or behavior after dilution. Appearance also answers a different question from assay signal.
Quantify when the dissolved amount matters
If your work depends on how much peptide is in solution, quantify the soluble material under the exact recorded conditions. Use a validated method appropriate to the peptide and matrix. The planner's concentration is nominal, not measured. A sequence-based score estimates properties and is not a measurement in your medium, especially if it describes a different sequence. A solvent result from another peptide or condition does not transfer either, because published work reports pH and solvent effects as sequence dependent.
Peptide solubility FAQs
How does the planner calculate the final volume?
It divides the mass you enter in mg by your target concentration in mg/mL and shows the result in mL and µL. The concentration is nominal on the basis you selected, either material as weighed or documented net peptide mass. Chromatographic purity alone cannot convert gross mass to net peptide mass. The calculation describes your plan. It does not tell you whether the peptide will dissolve at that concentration.
Can sequence-based estimates predict peptide solubility?
Sequence features can help you decide which conditions to compare, but they do not give a measured solubility in your specific medium. Bachem's peptide solubility guide separates sequence clues from testing in a particular solvent. A published dissolution study reports that the effects of pH and solvent were sequence dependent. Use the Net Charge and Hydrophobicity calculators for sequence properties, then record what you actually observe here.
Why is my peptide not fully dissolving?
Several recorded factors can differ between preparations, and this planner cannot assign a cause. Check the exact material form and any documented handling information for the lot, along with the medium, pH, salt content, target concentration, temperature, and observation time. Where practical, change one factor at a time between Condition A and Condition B so the difference between records is clear.
Is PBS a suitable starting medium for every peptide?
No single medium suits every peptide. Compatibility depends on the material, the target concentration, and the needs of your assay. If your lot documentation includes applicable handling information, the COA Finder can help you locate it. Record the medium and, for aqueous conditions, the pH so each test can be compared later.
Why does a clear stock precipitate after dilution?
The final medium differs from the stock in composition and concentration, so a clear stock does not establish behavior after dilution. A published polyglutamine study documents a model peptide that aggregated over time after dilution into PBS. That is one specific experiment, not a universal mechanism or a solvent recommendation. Record the final composition, concentration, and elapsed time for each condition.
Does a clear appearance mean the peptide is fully dissolved?
No. Appearance is an observation, so record clear, cloudy, or visible material without assuming what any haze or residue is. Appearance and assay signal also answer different questions. If the dissolved amount matters for your work, quantify the soluble material with a validated method appropriate to the peptide and matrix under the actual conditions.
