Research peptides are supplied as a lyophilised (freeze-dried) powder because in that state they're stable and easy to transport. Handled correctly, that stability carries through to the bench. Handled carelessly, even a high-purity peptide can degrade before it's used. Here's the practical side of storage and reconstitution.

Storing the lyophilised powder

Before reconstitution, lyophilised peptides are at their most robust. The key points:

  • Keep it cold. Long-term storage is best at −20°C (a standard freezer). For short periods, a fridge is fine.
  • Keep it dark and sealed. Light and moisture are the enemies. Leave the vial sealed until you're ready to use it, and keep it away from direct light.
  • Avoid repeated temperature swings. Taking a vial in and out of the freezer over and over is worse than a single stable storage temperature. This is also why stock that spends less time in transit tends to arrive in better condition.

What you reconstitute with

The standard diluent is bacteriostatic water — sterile water containing 0.9% benzyl alcohol, which acts as a preservative and allows the solution to be drawn from over a period rather than used immediately. Sterile or distilled water can be used where a single, immediate use is intended, but bacteriostatic water is the usual choice for research work. We stock it alongside the peptides for exactly this reason.

Reconstitution technique

The goal is to dissolve the powder gently and completely without damaging it:

  • Let the vial come to room temperature first if it's been in the freezer.
  • Add the diluent slowly, down the side of the vial — aim the stream at the glass wall, not directly onto the powder. A forceful stream straight onto the peptide can shear it.
  • Do not shake. Swirl gently, or simply leave it to dissolve on its own. Shaking introduces foam and mechanical stress.
  • Give it a few minutes. Most peptides go into solution readily; a little patience beats aggressive mixing.

After reconstitution

Once mixed, the peptide is in solution and less stable than the dry powder:

  • Refrigerate the reconstituted vial (2–8°C). Don't leave it at room temperature.
  • Use it within a reasonable window. Reconstituted peptides are generally usable for a number of weeks when refrigerated and made with bacteriostatic water, but this varies by compound — check the batch label and CoA.
  • Keep it out of light and avoid freezing and re-thawing the solution, which can degrade many peptides.

A note on quality upstream

Good handling protects a good product — it can't rescue a poor one. Storage technique only matters if the peptide was high-purity and correctly stored before it reached you. That's why independent batch testing and a short, cold supply chain matter as much as anything you do at the bench. Each of our products lists its handling notes on the product card, and every tested batch has its Certificate of Analysis published.

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All products are supplied strictly for laboratory and in-vitro research use only. Not for human or veterinary consumption. This article is general information about laboratory handling and is not medical or veterinary advice.