Store lyophilised peptide powder at –20 °C. Once reconstituted, keep it at 2–8 °C and use it within 28 days. Those two numbers cover most of what goes wrong with peptide storage.
Lyophilised Peptide Storage Temperature
Lyophilised means freeze-dried — the water has been pulled out of the peptide and it arrives as a dry powder or cake. In that dry form, a lyophilised peptide is stable for up to 12–24 months at –20 °C. At room temperature (around 20–22 °C), that window drops to weeks, not months. At 4 °C in a fridge you can stretch it to a few months, but –20 °C is the right long-term answer.
The cold matters because peptide powders degrade faster at higher temperatures and in the presence of moisture. Lyophilisation removes the moisture; low temperature slows everything else down.
One practical point: do not store lyophilised peptides next to the freezer door. Temperature swings from opening and closing the door add up. A dedicated spot at the back of the freezer is better.
Peptide Storage Temperature Chart
Here is how storage location maps to shelf life for lyophilised peptides:
| Location | Temperature | Expected shelf life |
|---|---|---|
| Freezer | –20 °C | 12–24 months |
| Fridge | 2–8 °C | 2–3 months |
| Room temperature | 18–25 °C | Days to a few weeks |
| Above 25 °C | Varies | Degrades rapidly |
If you are storing multiple lyophilised peptides at once, –20 °C is the safe default for all of them.
Peptide Shelf Life After Reconstitution
A reconstituted peptide kept at 2–8 °C is generally usable for up to 28 days. This is the number that matters most for day-to-day laboratory handling.
Reconstitution means adding bacteriostatic water — sterile water containing a small amount of benzyl alcohol — to the powder. The benzyl alcohol slows bacterial growth, which is why reconstituted peptide can last nearly a month instead of a few days. If plain sterile water is used instead of bacteriostatic water, the window drops to 24–48 hours.
Once water is reintroduced, degradation resumes. The clock starts the moment water is added. Label every vial with the reconstitution date.
A few things that shorten that 28-day window:
- Repeated temperature swings from taking the vial in and out of the fridge
- Exposure to light — store the vial in its box or wrapped in foil
- Contamination from non-sterile handling
- Freezing after reconstitution — this can damage the peptide’s structure
Peptide Shelf Life in the Fridge
In the fridge (2–8 °C), a reconstituted peptide holds for up to 28 days. Lyophilised peptide stored in the fridge rather than the freezer is usable for roughly 2–3 months, though –20 °C remains the better choice for anything not needed within that window.
The fridge is not a substitute for the freezer with lyophilised stock. It is a short-term holding option. If you have multiple vials and will not open them for months, keep them in the freezer.
What the fridge is good for: the vial currently in use. Keep that one at 2–8 °C from the moment it is reconstituted. Do not move it back and forth to the freezer.
A practical note on fridge placement: the door shelf has the most temperature variation. The middle shelf near the back is the most stable spot and the right place for peptide vials.
Handling on the Day of Reconstitution
Let a frozen vial warm to room temperature before opening it — around 30 minutes on the bench is enough. This prevents condensation from entering the powder and stops a cold vial from pulling air in when the septum is pierced.
Add bacteriostatic water slowly down the side of the vial rather than directly onto the powder. Swirl gently — do not shake. Shaking can disrupt the peptide’s structure. The solution should go clear. If it stays cloudy or shows visible particles, something has gone wrong.
The practical summary: store lyophilised peptide at –20 °C for long-term stability, move the working vial to the fridge once reconstituted, use it within 28 days, and label everything with the reconstitution date. That routine covers almost every storage error that occurs in a laboratory setting.
NXT Labs products are sold strictly as research chemicals for in vitro research, laboratory testing and analytical purposes only, and are not intended for use in any human or animal application.
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