How to Store Lyophilized and Reconstituted Peptides

Most research peptides arrive lyophilized, meaning freeze-dried into a powder or cake. In that form they are fairly stable. Once dissolved, the clock starts running much faster. Good storage protects the material you paid for and keeps your results comparable over time.

Lyophilized powder

• Cold: a freezer at around -20°C is the usual long-term choice. A fridge is fine for the short term.
• Dry: moisture is the main enemy. Keep vials sealed, and let a cold vial reach room temperature before opening it so condensation doesn't form inside.
• Dark: store vials in their box or an opaque container. Some peptides are light-sensitive.

After reconstitution

A peptide in solution degrades faster than the dry powder.

• Keep solutions refrigerated, not at room temperature.
• Use sterile technique and sterile diluent to avoid contamination.
• Label each vial with the compound, the date it was reconstituted and the diluent used.
• Check the supplier's or the literature's stability data for that specific compound. Stability varies a lot from one peptide to another.

Avoid repeated freeze-thaw

Freezing and thawing a solution again and again can break peptides down. If you need to store a solution frozen, split it into single-use aliquots first, so each thaw only affects what you are about to use.

Signs a sample has degraded

• Cloudiness or particles in a solution that was clear
• A change in color
• A cake that has collapsed or turned sticky before reconstitution, which suggests moisture got in

If you see any of these, don't rely on that sample for results. Testing it against a fresh vial is the only way to know for sure.

For research use only. Nothing here is medical advice.