storage
Cold-Chain Storage and Handling
Lyophilised peptides are robust compared with solutions, but they are not indifferent to their environment. Three factors drive most degradation: heat, light and moisture.
Temperature
The default working recommendation for the lyophilised powder is storage at −20 °C, protected from light, unless the product page or your protocol says otherwise.
Freezer temperature should be stable. A frost-free freezer that cycles is worse than a slightly warmer but stable one. Where a batch is in regular use, keep a small working aliquot at refrigerator temperature rather than repeatedly returning the whole lot to the freezer.
Light
Several peptide side chains are photosensitive. Amber glass, an opaque secondary container, or simply a closed drawer is enough protection for routine storage. Do not leave vials on a sunlit bench between uses.
Moisture
This is the most common cause of avoidable loss. A vial taken straight from a freezer into a warm room will draw condensation onto the powder when opened. Let vials equilibrate to room temperature while still sealed — 20 to 30 minutes is usually enough — before you break the seal.
Never store a partly used vial in a humid environment. If a batch is opened frequently, split it into smaller aliquots at first opening.
Handling routine
- Keep vials upright and in their original labelled containers
- Do not reuse stoppers or transfer between containers unless your protocol requires it
- Wipe the bench and swab stoppers before every entry
- Record every opening in the batch log
Freeze–thaw
Each freeze–thaw cycle costs you material. Where a study will run over weeks, plan the aliquot sizes at the start so that a single aliquot is consumed per session, rather than returning one container to the freezer repeatedly.
Signs a batch should be reviewed
Discoloration of the powder, a solution that will not clear, visible particulate, or a certificate that no longer matches the vial label are all reasons to stop and check with your supplier before proceeding.