Storage & Handling Guide
Peptides are fragile molecules. Heat, light, oxidation, moisture and freeze-thaw cycles all degrade them — but the timeline is very different for powder vs solution.
The two states
| State | Environment | Typical shelf life | Key rule |
|---|---|---|---|
| Lyophilized (powder) | Cool, dark, dry; fridge is ideal | Months to years when sealed and desiccated | Keep away from moisture & repeated warming |
| Reconstituted (liquid) | Refrigerated (2–8 °C) | Up to ~30 days with BAC | Shorter if using sterile water |
Lyophilized peptide
- Fridge (2–8 °C) is the standard recommendation. Freezer (-20 °C) is acceptable for long-term storage in most cases, provided the vial is sealed and dry.
- Allow the vial to reach room temperature before opening — opening a cold vial pulls in humid air, and moisture is the enemy of a peptide cake.
- Keep peptides away from direct light and heat sources. The top of a fridge or a sunny shelf is not storage.
Reconstituted peptide
- Refrigerate immediately after reconstitution.
- With bacteriostatic water, common practice is to use within ~30 days.
- With sterile water (no preservative), treat the vial as single-use or short-use only — bacterial growth starts at the first puncture.
- Do not refreeze reconstituted peptide. Freeze-thaw cycling degrades many peptides and can crash them out of solution.
How peptides actually degrade
The main degradation pathways are hydrolysis (water slowly cleaves peptide bonds — faster in solution, which is why liquid doesn't last as long), oxidation (methionine and cysteine residues are especially vulnerable), and deamidation (asparagine/glutamine side chains). These processes are slowed by cold and dryness but never fully stopped.
Signs a peptide has gone bad
- Visible particulates, cloudiness or precipitation in a solution that was previously clear
- Color change (many peptides are colorless/white; a yellow or brown tint can signal degradation)
- Unusual smell from the vial (some degradation products are volatile)
- Vial sterility breached — cracked stopper, cloudy BAC, or contamination
When in doubt, discard. A compromised vial is not worth the risk of injecting degraded or contaminated material.