Peptide storage & handling guide
How to store and handle lyophilised (powder) and reconstituted peptides so they keep their potency. This covers fridge and freezer temperatures, realistic shelf life, a clean step-by-step for mixing, the signs that something should be thrown out, and a quick-reference table. Educational reference for a research setting, not medical advice.
Reference for handling research materials in a lab setting. Educational only — not medical advice.
Lyophilised powder
- Robust — tolerates brief ambient transit
- Short run (1–3 months): fridge, 2–8°C
- Long run (a year+): freezer, −20°C
- Archive (2–3 years): −80°C where available
Reconstituted solution
- Delicate — keep chilled at all times
- Store at 2–8°C only
- With bacteriostatic water: about 4 weeks
- Never freeze a reconstituted vial
Storing the dry powder
Before it is mixed, lyophilised material is comparatively forgiving. A short spell at room temperature in transit will not usually harm it, but the sooner it goes into the cold the better its long-term potency. Keep it sealed in the original vial, shielded from light, and dry — a desiccant packet in the storage box helps.
- 1–3 months: refrigerator at 2–8°C, in a dark corner.
- A year or more: standard freezer at −20°C.
- Longest term: a −80°C unit if you have access to one.
- Stop-gap: a couple of weeks at cool room temperature is tolerable; chill it as soon as you can.
Storing a reconstituted vial
Once water is added the clock starts. Refrigerate the vial straight after mixing and keep it cold between draws. Bacteriostatic water carries a small amount of benzyl alcohol that suppresses microbial growth, which is why a vial mixed with it is commonly treated as usable for around four weeks. Sterile water has no such preservative, so a vial mixed with it is best treated as single-session. Freezing is off the table either way — ice crystals damage the peptide.
Mixing, step by step
- Let both vials sit at room temperature for about 30 minutes so the solution does not turn cloudy on contact.
- Wipe both rubber stoppers with an alcohol pad and work on a clean surface with a fresh syringe.
- Draw your water, then let it run slowly down the inside wall of the peptide vial at an angle — never jet it straight onto the powder.
- Swirl gently to dissolve. Do not shake. Give it a few minutes if any powder remains, then swirl again.
- Look at it: the liquid should be clear and colourless with nothing floating. If it is cloudy or specked, do not use it.
- Return it to the fridge as soon as it is dissolved, and label it with the date you mixed it.
Quick reference
| State | Temperature | Rough shelf life | Where |
|---|---|---|---|
| Powder — short term | 2–8°C | 1–3 months | Fridge |
| Powder — long term | −20°C | 1 year+ | Freezer |
| Powder — archive | −80°C | 2–3 years | Ultra-low freezer |
| Powder — ambient | ~20°C | 2–3 weeks | Dark, dry |
| Reconstituted | 2–8°C | ~4 weeks max | Fridge |
| Bac water (opened) | 2–8°C | ~4 weeks | Fridge |
When to throw it out
- Any cloudiness — it should be glass-clear
- Floating particles
- Any colour change or yellowing
- Past the ~4-week mark
- Left warm for a long stretch, or frozen
- Clumping or caking (moisture got in)
- Shifted away from its original white/off-white
- Past its stated expiry
- Storage chain clearly broken
What actually degrades peptides
- Heat
- Light
- Moisture (for powder)
- Oxygen exposure
- Repeated freeze–thaw
- Harsh pH
- Rough handling / vigorous shaking
- Keep it consistently cold
- Keep it dark
- Keep it sealed
- Desiccant for powder
- Handle gently, swirl don't shake
- Clean technique every time
Common questions
Powder sat at room temperature for a week in transit — is it wasted?
Most likely fine. Dry lyophilised material generally tolerates a couple of weeks at ambient temperature. Refrigerate it on arrival.
A reconstituted vial was out of the fridge for two hours. Still usable?
A short spell out is usually acceptable — just get it back in the cold. If it sat out all day, discard it.
Can I stretch a reconstituted vial past four weeks?
Better not to. The window exists for both microbial-safety and potency reasons; discard past it.
It looks a little cloudy — is that okay?
No. A reconstituted vial should be clear. Cloudiness points to degradation or contamination, so don't use it.
Need the mixing math? Use the reconstitution calculator.