How lyophilised and reconstituted peptides behave, and how to keep a research sample intact.
Peptides are sensitive molecules. Four factors drive their degradation on the bench — temperature, moisture, light and repeated freeze–thaw. Handling them carefully keeps a sample representative of the material on its certificate of analysis.
Lyophilised (freeze-dried) vials
In their freeze-dried state, peptides are comparatively stable. For long-term storage of two years or more, −20°C is the usual reference point. For shorter periods — typically up to 12–24 months depending on the peptide — 2–8°C is generally suitable. Keep vials sealed, dry and out of direct light.
After reconstitution
Once reconstituted with bacteriostatic water — which contains 0.9% benzyl alcohol as a preservative — a solution is generally worked with over a period of about four weeks when held at 2–8°C. Reconstituted material is less stable than the dry powder, so it is not kept indefinitely.
Avoid repeated freeze–thaw
Freezing and thawing a reconstituted solution repeatedly is the most common way to degrade it: ice-crystal formation physically disrupts the molecule, and integrity falls with each cycle. Where a solution needs to be held beyond a few weeks, dividing it into single-use aliquots before freezing avoids thawing the whole vial each time.
The four enemies — quick reference
| Factor | Handling note |
|---|---|
| Temperature | −20°C for long-term lyophilised storage; 2–8°C for reconstituted solutions and shorter-term powder. |
| Moisture | Keep lyophilised vials sealed and dry; let a cold vial reach room temperature before opening to avoid condensation. |
| Light | Store away from direct light; UV accelerates breakdown of several sequences. |
| Freeze–thaw | Do not repeatedly freeze and thaw reconstituted solution; aliquot instead. |
For the arithmetic of reconstitution — concentration, diluent volume and unit conversions — see the Reconstitution guide.