How to store peptides

Most peptide degradation comes from moisture, heat, oxidation and repeated freezing and thawing. Exact stability depends on the sequence, so treat the ranges below as general lab practice and follow the documentation for each compound.

Lyophilized (dry) peptides

• Long term: frozen. Bachem recommends storage below −15 °C, with lower temperatures preferred; Sigma-Aldrich gives −20 °C for short-term and −80 °C for longer storage [1][2].
• Short term: refrigerated. Storage at 4 °C is acceptable for short periods, and peptides are routinely shipped at room temperature in dry form [1].
• Keep moisture out. Peptides are hygroscopic. Let a cold vial reach room temperature (ideally in a desiccator) before opening, weigh out quickly and reseal tightly [1][2].
• Protect from light and keep vials capped when not in use [2].

Peptides in solution

• Solution is the least stable form. Bachem advises against storing peptides in solution at all, even sterile solutions [1]. Sigma-Aldrich describes solutions as generally stable for up to about a week at 4 °C [2].
• For longer, aliquot and freeze. Split the solution into single-use aliquots and keep them frozen (−20 °C or colder). Avoid repeated freeze–thaw cycles [1][2].
• Mind the pH. Sterile buffers around pH 5–6 extend storage life; avoid pH above 8 [2].
• Label every vial with the date it was dissolved.

Sequences that need extra care

Peptides containing cysteine (C), methionine (M) or tryptophan (W) are prone to oxidation, and those with asparagine (N) or glutamine (Q) are less stable, especially in solution [1][2]. Oxygen-free solvents, minimal air exposure and frozen aliquots help.

Signs a solution shouldn't be used

Cloudiness, particles, color change, or a solution that was left warm for an extended time. When in doubt, prepare a fresh solution from dry material.

How XS ships

XS vials ship lyophilized. Once delivered, store them frozen at −20 °C, away from light, until use.

Questions

How should lyophilized peptides be stored?

Frozen for the long term: below −15 °C per Bachem, with −20 °C to −80 °C common. Short periods at 4 °C are acceptable. Keep them dry, sealed and away from light.

How long do peptides last after reconstitution?

Not long, compared with powder. Sigma-Aldrich describes solutions as generally stable up to about a week at 4 °C; Bachem advises against storing solutions. For longer, freeze single-use aliquots and avoid freeze–thaw cycles. Stability varies by sequence.

Can you freeze reconstituted peptides?

Yes, as single-use aliquots at −20 °C or colder. Avoid freezing and thawing the same aliquot repeatedly.