Reference
Peptide storage & stability
How to store research peptides. They are sensitive to heat, light, moisture, and repeated freezing. How long they stay intact depends mostly on whether they're still a sealed dry powder or already mixed into solution. Here's the practical handling reference for each state.
Quick reference
| Form | Temperature | Light | Typical window |
|---|---|---|---|
| Lyophilized (sealed powder) | −20 °C (−4 °F) or colder | Keep dark | Months to years |
| Reconstituted (in solution) | 2–8 °C / 36–46 °F | Keep dark | ~2–4 weeks (varies by peptide) |
Windows are general guidance; the exact figures vary by peptide and by what the supplier's own data states — always defer to the specific compound.
Lyophilized (freeze-dried) powder
This is the most stable form. Sealed and dry, peptides keep best frozen and away from light and moisture. For long holds, a freezer is better than a fridge; short-term, refrigeration is usually fine. Keep the vial sealed until you're ready to reconstitute, and let it return to room temperature before opening so moisture doesn't condense inside.
After reconstitution
Once mixed with bacteriostatic water, a peptide is in solution and less stable. Keep it refrigerated (2–8 °C / 36–46 °F), protected from light, and use it within a few weeks — the benzyl alcohol in bacteriostatic water limits bacterial growth but doesn't stop chemical degradation. Label the vial with the date you reconstituted it.
Handling that protects stability
- Add water gentlyRun the water slowly down the inside wall of the vial rather than blasting it onto the powder.
- Swirl, don't shakeGentle swirling dissolves peptide without the shear and foaming that vigorous shaking causes.
- Avoid freeze–thawRepeated freezing and thawing of a solution degrades peptides. If you must freeze, splitting into single-use aliquots so each is thawed once is gentler.
- Keep it cleanWipe the stopper before each draw; contamination shortens usable life.
What shortens shelf-life
Heat, light, repeated freeze–thaw cycles, contamination, and simply time. Each pushes a peptide toward breakdown, so the cooler, darker, cleaner, and fresher you keep it, the longer it holds.
Common questions
Does lyophilized powder have to be frozen?
For long-term holding, freezing is best. For shorter periods a refrigerator is generally acceptable, as long as the vial stays sealed, dry, and out of light.
How long does a peptide last once reconstituted?
Commonly on the order of a few weeks refrigerated, but it varies by peptide — defer to the specific compound's data rather than a single rule.
Can I freeze a reconstituted solution?
Repeated freeze–thaw is best avoided because it degrades peptides. If freezing is necessary, dividing into single-use aliquots so each is thawed only once is gentler than refreezing one vial repeatedly.
Do research peptides have to ship cold?
Sealed lyophilized powder tolerates the few days of ordinary transit at ambient temperature; the long-term guidance above is for holding, not shipping. Put the vial in the freezer or fridge when it arrives. Solutions are the sensitive form — reconstitute after delivery, not before.
Why protect it from light?
Light can drive chemical breakdown of peptides over time, so dark storage helps preserve them.