Storing lyophilized peptides: temperature, light, and moisture
Lyophilization (freeze-drying) removes almost all of the water from a peptide, which is what makes it stable enough to ship. How the material holds up after that depends mostly on four things: temperature, moisture, light, and oxygen.
Sealed, lyophilized vials
- Short term (days to weeks): a sealed vial is generally stable at room temperature, which is why it can be shipped without ice.
- Medium term (weeks to months): refrigerate at 2–8 °C.
- Long term: freeze at −20 °C or colder.
- Keep vials in their box or another dark container. UV and strong light can degrade some residues.
Avoid condensation
Lyophilized powder pulls moisture from the air. Before opening a vial that has been refrigerated or frozen, let it come to room temperature while still sealed, so water does not condense on the cold powder.
After reconstitution
Once a peptide is in solution it is far less stable than as a dry powder. Keep reconstituted material refrigerated, and set your lab's own use-by window based on the compound and solvent.
- Avoid repeated freeze-thaw cycles. If material will be stored frozen, split it into single-use aliquots first.
- Use sterile technique and a clean solvent to limit contamination.
- Record the reconstitution date and solvent on the vial.
Sequences that need extra care
Peptides containing cysteine, methionine, or tryptophan are prone to oxidation. Those containing asparagine or glutamine can slowly deamidate in solution. Minimizing air exposure and time in solution helps with both.