Lyophilised peptide is a stable form, which is exactly why it is the form we ship. Stability is conditional, though, and the conditions are easy to get wrong in a busy laboratory.
Temperature
Store lyophilised material at or below −20 °C. A standard laboratory freezer is sufficient for the powder. Short periods at ambient temperature during shipping are expected and accounted for; what causes trouble is a vial that sits on a bench for a week.
Moisture is the real enemy
The most common handling error is opening a cold vial. Condensation forms on the cold surface the moment it meets room air, and that water stays in the vial when it goes back to the freezer.
Let a vial reach room temperature fully before breaking the seal. It costs twenty minutes and it is the single most useful habit in this list.
Light and air
Keep vials sealed and protected from light. Peptides containing tryptophan, methionine, cysteine or tyrosine are more prone to oxidation, so limit the time a vial spends open.
Freeze-thaw cycles
Each cycle is a small insult. Where a protocol calls for a solution, prepare it and split it into single-use aliquots rather than returning to one tube repeatedly. Label aliquots with the compound, the lot number and the date.
Record keeping
Note the lot number in your records alongside the result. When something behaves unexpectedly six months later, the lot is usually the first thing you want and the first thing that has been forgotten.
These are general laboratory practices for research materials. They are not instructions for any use outside a controlled laboratory environment; everything we supply is for in-vitro research only.
