1. Storage before opening
- Temperature — −20 °C is standard for lyophilised research peptides in a TFA or acetate salt. −80 °C extends stability for peptides susceptible to oxidation or deamidation.
- Light — keep the original vial in a closed box rather than a clear rack on a bench.
- Humidity — the most common cause of degradation before use. A vial left open in a humid room can pick up enough moisture to shift its net content and destabilise the lyophilised cake.
- Container — keep the original desiccant, and do not transfer the powder to another container.
- Retest date — stated on the COA. Treat it as a hard boundary.
2. Reconstitution media
| Diluent | Use it for |
|---|---|
| Bacteriostatic water for injection (0.9% benzyl alcohol) | The default for cell-culture and assay work where the vial is used over hours or days. Benzyl alcohol suppresses bacterial growth without interfering with most peptide biology. |
| Sterile water for injection | Additive-free solutions used immediately after reconstitution. |
| Buffered carrier — PBS, or a low-percent serum or albumin carrier | Where the peptide is unstable in plain water, or where a specific pH window is required. |
Some peptides — GHK-Cu and several collagen-class peptides among them — dissolve poorly in plain water and need a small percentage of co-solvent or a pH adjustment. Ask us for the recommended carrier for the specific SKU rather than improvising: a poor reconstitution can destroy a lot that passed QC perfectly well.
3. Technique
- Disinfect the septum before drawing
- Add the diluent slowly down the side of the vial rather than onto the cake, to avoid foaming
- Swirl gently to dissolve. Do not vortex aggressively with a proteinaceous peptide — foaming and local high concentration drive aggregation
- Allow the solution to reach room temperature before use where the buffer is temperature-sensitive
4. Stability after reconstitution
- Aliquot into single-use volumes if the whole vial will not be consumed
- Store aliquots at −20 °C where possible, −80 °C for longer holds
- Minimise freeze-thaw cycles — each cycle costs degradation
- Use a protein carrier (0.1–1% BSA or serum) where the peptide binds to surfaces or is unstable at low concentration
- Discard any visibly cloudy or discoloured solution, and any solution with visible particulate
5. Counter-ion matters
TFA is the most common counter-ion and is aggressive on some analytical workflows. Acetate is gentler and is preferred in some cell-culture and protein-binding applications. HCl is used where a TFA residue would be unacceptable. The counter-ion is stated on every COA we issue, and it should drive your choice of reconstitution medium.
6. Common failure modes
- Foaming on reconstitution — aggressive dilution; slow addition and gentle swirling fixes it
- Cloudiness after dilution — aggregation, usually from an incorrect carrier or an over-concentrated stock
- Lost activity in cell assays — frequently deamidation or oxidation from repeated freeze-thaw, not a supply problem
- Low recovered mass — usually a comparison against total lyophilised weight rather than peptide content
7. Stability data on request
Stability studies and supporting data are available on request for characterisation-grade supply, and are supplied as standard with the API route. If you are running a programme where stability is the gating question, raise it at RFQ stage so it is planned into the specification rather than chased later.
Our longer-form guide covers this in more depth, including what to ask your supplier for: research peptide storage and reconstitution guide.
B2B trade only — request a quote
All peptides are research-grade, for in-vitro use only, and supplied against a valid drug licence. Tell us your sequence, quantity and destination and the trade desk will respond within one business day.