How to reconstitute a peptide

Peptides ship as a lyophilized (freeze-dried) powder because they are far more stable dry than in solution. Reconstitution is the lab step that returns the powder to a liquid by adding a measured volume of solvent. The procedure below describes the general technique used at the bench; it is a methods reference, not a usage instruction.

For the math — how much solvent to add to reach a target concentration — use the reconstitution calculator, which fills in the vial size from our catalog and shows the resulting concentration per unit volume.

1. Choose the solvent

Bacteriostatic water (sterile water with 0.9% benzyl alcohol) is the conventional choice for laboratory reconstitution because the preservative limits microbial growth over the working life of the vial. Sterile or distilled water can also be used where a preservative is not wanted. The solvent and its volume are chosen to suit the experiment, not the peptide itself — the peptide mass in the vial does not change.

2. Add solvent gently

Let both vials reach room temperature, then introduce the solvent slowly so it runs down the inside wall of the vial rather than landing directly on the powder. Peptides are shear-sensitive: never shake the vial to dissolve them. Swirl gently, or simply set the vial aside and let the powder go into solution on its own over a few minutes.

3. Confirm it is fully in solution

A properly reconstituted peptide solution is clear and free of visible particulate. Cloudy solution, persistent floaters, or undissolved cake suggests the technique was too forceful, the solvent volume was too small, or the material has degraded. Do not heat the vial to force dissolution.

4. Work out the concentration

Concentration is simply the peptide mass divided by the solvent volume. A 10 mg vial reconstituted with 2 mL of water is at 5 mg/mL; the same vial in 1 mL is at 10 mg/mL. The calculator handles this conversion and expresses the result per syringe graduation, which removes most of the arithmetic error at the bench.

5. Storage after reconstitution

Once in solution, peptides are far less stable and should be refrigerated. For longer-term storage, lyophilized material is kept frozen. See handling & storage for the general guidance, and how we verify for the identifiers published on every product page so you can confirm what you are working with before you begin.