Peptide reference materials are commonly documented with storage conditions that differ between the lyophilized (powder) state and the reconstituted (solution) state. This article summarizes the general considerations that appear in laboratory storage documentation. Specific conditions for a given material should follow its accompanying documentation.
Lyophilized powder
In powder form, peptides are typically documented as stable for extended periods when stored frozen, often at −20 °C or colder, and protected from moisture and light. The freeze-dried state, with water removed, is generally the most stable form for long-term storage.
Reconstituted solution
Once dissolved, a peptide solution is generally documented with a shorter usable window and refrigerated storage, commonly cited around 2–8 °C, with protection from light. Because reintroducing water increases the potential for degradation, solutions are usually prepared in quantities that match the timeframe of the protocol.
Freeze-thaw cycles
Repeated freezing and thawing can affect peptide integrity. Where long-term storage of a solution is required, documentation often references dividing it into single-use aliquots so that only the portion needed is thawed, avoiding repeated cycles on the full volume.
- Powder: frozen, dry, protected from light.
- Solution: refrigerated, protected from light, used within a limited window.
- Aliquot before freezing solutions to minimize freeze-thaw cycles.