How a peptide is stored decides how long it stays the compound it was when it was tested. Lyophilized powder is robust if it is kept cold, dry and dark; a reconstituted solution is far less forgiving. Here is how labs keep both.
Lyophilized (powder) peptides
| Situation | Temperature | Notes |
|---|---|---|
| Long-term storage | -20 °C | -80 °C for sequences with sensitive residues. Keep sealed. |
| Use within weeks to months | 2-8 °C (fridge) | Adequate for vials that will be used soon. |
| In transit / on arrival | Ambient for a short time | Lyophilized peptides tolerate shipping; move them to cold storage on arrival. |
The three things that degrade a stored peptide are moisture, heat and light, and the fourth is repeated freeze-thaw cycles.
- Keep it dry. Peptides are often hygroscopic. Store vials sealed, ideally with desiccant, and let a cold vial reach room temperature before opening it so condensation does not form inside.
- Keep it dark. Some amino acids are light-sensitive. Store in the box or in amber containers.
- Avoid frost-free freezers. They warm up periodically to defrost; those temperature swings are exactly what stored peptides should avoid.
- Avoid freeze-thaw cycles. If a peptide will be used in portions, aliquot it rather than repeatedly warming and re-freezing one vial.
Reconstituted (solution) peptides
- Short term: refrigerate at 2-8 °C. Do not leave solutions at room temperature.
- Longer term: divide into single-use aliquots and freeze them (typically -20 °C), so no portion is thawed twice. Stability in solution is sequence-dependent, so follow the peptide's data sheet where it gives one.
- Label each vial with the date of reconstitution and the concentration.
- Protect from light.
- Choose the diluent specified for the peptide and intended assay; where a preserved diluent is allowed, it suits a vial that will be accessed more than once - see bacteriostatic vs sterile water.
- When in doubt, reconstitute only what will be used.
A simple routine
- On arrival, check labels and lot numbers, then move vials to the freezer (long term) or fridge (soon).
- When needed, let the vial warm to room temperature before opening.
- Reconstitute with a planned volume and label it; refrigerate for short-term use or aliquot and freeze for longer.
- Keep a log of reconstitution dates so older solutions are used first.
Frequently asked questions
Do lyophilized peptides need to be frozen?
For long-term storage, yes: -20 °C, or -80 °C for sensitive sequences. A fridge at 2-8 °C is fine for vials that will be used within weeks.
Why let a vial warm up before opening it?
Peptide powder attracts moisture. Opening a cold vial lets condensation form inside it; letting it reach room temperature first avoids that.
Is a frost-free freezer a problem?
It can be. Frost-free freezers cycle their temperature to defrost, and those swings are what stored peptides should avoid.
Sources
- JPT Peptide Technologies - How to store peptides
- LifeTein - Handling and storage of synthetic peptides
Research use only. All products sold by Moleano Peptides are intended solely for laboratory research. They are not for human or veterinary use and are not drugs, supplements or medical devices. This guide is educational and is not medical advice.