Lyophilized (freeze-dried) peptides are remarkably stable when handled correctly and remarkably fragile when handled poorly. This guide covers the standard laboratory practices for receiving, storing, and reconstituting research peptides. It is a general reference — it does not provide dosing or concentration guidance for any specific compound or experimental design.
Receiving and inspecting a new vial
When a shipment arrives, do a brief visual check before storage. A lyophilized peptide should appear as a fluffy white powder or compact cake at the bottom of the vial. If you see discolouration, moisture, or evidence of melt-and-resolidify behaviour during shipping, photograph the vial and contact your supplier before opening it.
If the vial was shipped with a cold pack, transfer it to the freezer promptly. A few hours at ambient temperature during shipping is not normally a problem for lyophilized material — the protein is desiccated and inactive — but extended periods of warmth combined with any moisture exposure can degrade stability.
Long-term storage of lyophilized material
For lyophilized peptides in their original sealed vial, the standard storage condition is −20 °C or colder, protected from light and moisture. A −80 °C freezer is preferred for peptides stored for more than a few months, particularly those containing oxidation-prone residues (methionine, cysteine, tryptophan).
Two practical points:
- Always allow the vial to reach room temperature before opening it. Opening a cold vial in a humid lab causes condensation on the powder, which dramatically accelerates hydrolysis.
- Use desiccant in storage boxes. Even freezer air carries some moisture; a sachet of silica gel in the storage box helps protect partially used vials.
Reconstitution: choosing a solvent
The solvent you reconstitute in is determined by the peptide’s solubility profile, not by convenience. Most research peptides reconstitute well in bacteriostatic water, sterile water, or dilute acetic acid. Hydrophobic sequences may require a small amount of DMSO as a co-solvent. Consult published methods for your specific peptide before reconstituting.
Whatever solvent you choose, add it gently along the side of the vial — do not shake vigorously, which causes foaming and can denature the peptide. Allow the powder to dissolve fully (it may take several minutes) before proceeding.
Post-reconstitution storage
Once in solution, peptides are far less stable than in lyophilized form. General guidelines:
- Refrigerate (2–8 °C) for short-term use within a few weeks
- Aliquot and freeze (−20 °C or −80 °C) for longer storage to avoid repeated freeze-thaw cycles, which degrade most peptides
- Track concentration and date on the storage vial; reconstituted peptide is easy to forget about
Common pitfalls
- Opening cold vials — covered above; condensation is the silent killer of lyophilized peptide stability
- Vortexing instead of gentle inversion — mechanical shear degrades peptide structure
- Reconstituting at high concentration without testing solubility first — leads to cloudy solutions and inaccurate downstream concentrations
- Re-freezing reconstituted material multiple times — degradation compounds with each cycle
If you have questions about a specific peptide
Reconstitution and storage details vary peptide by peptide. Our product pages list specific recommendations where they differ from the generic guidance above. For general questions, see the FAQ or use the chat bubble at the bottom of any page.
For in-vitro research use only. Not for human or veterinary consumption.