How to Store Lyophilized Peptides: A Researcher’s Guide
Most research peptides ship as a lyophilized (freeze-dried) powder because that is their most stable form. How you store that powder, and what happens once it becomes a solution, decides whether the material in your vial still matches its Certificate of Analysis weeks later. These are the storage practices that protect your results.
Why lyophilized peptides are stable
For a step-by-step look at the freeze-drying process itself, see what is lyophilization.
Lyophilization removes water by freezing the peptide and then drawing the ice off under vacuum. Without water, the reactions that break peptides down, such as hydrolysis, oxidation and deamidation, slow dramatically. A sealed, dry vial kept cold can hold its purity for a long time. The moment moisture, heat or light gets in, that protection starts to fade.
The four things that degrade peptides
- Moisture: the biggest risk to dry powder. Water restarts hydrolysis and lets the powder clump.
- Heat: speeds up every degradation reaction. Short trips at room temperature are fine for most lyophilized peptides; long periods are not.
- Light: UV light can damage light-sensitive residues such as tryptophan and tyrosine.
- Oxygen: oxidizes methionine, cysteine and tryptophan. Compounds with free thiols, such as glutathione, are especially sensitive.
Storing sealed, lyophilized vials
| Situation | Recommended |
|---|---|
| Long-term storage | -20°C, sealed, in the dark |
| Short-term storage (weeks) | 2–8°C refrigerator, sealed, in the dark |
| Shipping and brief handling | Room temperature is generally acceptable for lyophilized powder |
Keep vials in their outer box or an opaque container, away from the freezer door where temperature swings are largest. A frost-free freezer cycles its temperature to defrost, so a manual-defrost unit or a closed container inside the freezer gives steadier conditions.
Opening a vial: avoid condensation
The most common storage mistake happens on the bench, not in the freezer. A cold vial opened in room air pulls moisture straight onto the powder. Let the sealed vial come to room temperature first, usually 15–30 minutes, then open it. If you only need part of the material, work quickly and reseal.
Once a peptide is in solution
A solution is far less stable than dry powder. General lab practice:
- Store prepared solutions refrigerated at 2–8°C and use them within the stability window for that compound.
- For longer storage, split the solution into single-use aliquots and freeze them. Thaw each aliquot once.
- Avoid repeated freeze-thaw cycles. Each cycle can aggregate or fragment the peptide.
- Use sterile technique and a suitable diluent to keep solutions free of bacterial growth. Our guide to reconstitution supplies explains the common diluents.
Signs a peptide may have degraded
- Powder that has collapsed, looks wet or sticky, or has changed color
- Material that will not dissolve in a solvent it normally dissolves in
- Cloudiness or particles in a solution that should be clear
- Results that drift from earlier runs using the same lot
If any of these appear, the material may no longer match its certificate. Retesting or replacing the lot is the safer choice.
Just received an order? Use our receiving checklist.
How we ship
We store lyophilized inventory cold and ship every order sealed and labeled from New York, same day for orders placed before 2pm ET. Each vial carries its lot number, so you can match it to its entry in our COA Library on arrival. If an order arrives damaged, contact us and we will reship it.
For laboratory research use only. Not for human or veterinary use. Storage guidance is general laboratory practice; always follow the specifications for the individual compound.