How To
Reconstitute
a Peptide
Reconstitution is the process of dissolving a lyophilised (freeze-dried) peptide back into solution with a solvent such as bacteriostatic water. Done carefully — solvent added slowly, swirled rather than shaken — it returns the material to a usable solution for laboratory research. This guide covers the technique and the concentration arithmetic; it does not provide dosing or usage guidance of any kind.
What reconstitution is
Research peptides are supplied lyophilised — as a dry, freeze-dried powder or cake — because they are far more stable dry than in solution. Reconstitution is simply the step of dissolving that powder back into a liquid so it can be used in solution-phase laboratory research. It is not a step that can be skipped: a lyophilised compound cannot be used in solution until a solvent is added.
This article describes the physical laboratory technique and the arithmetic for knowing the concentration of the solution produced. It is not, and must not be read as, guidance on quantities to use in any application. We do not provide dosing or administration guidance of any kind.
The technique, step by step
- Bring both vials to room temperature. Cold glass encourages condensation and slows dissolution.
- Decide the solvent volume for the concentration you want (see the arithmetic below).
- Draw the solvent — usually bacteriostatic water — into a clean syringe.
- Add it slowly down the inside wall of the vial, not directly onto the powder. Letting it run down the glass is gentler than blasting the cake.
- Let it dissolve. Leave it to stand, then swirl gently if needed. Most peptides dissolve within a few minutes.
- Never shake vigorously. Shaking introduces shear forces and foaming that can denature or aggregate a peptide. Swirl, don't shake.
- Inspect the solution. It should be clear. Persistent cloudiness or particulates suggest incomplete dissolution — see our guide to peptide solubility.
Working out the concentration
The concentration of the resulting solution is simple arithmetic: the mass of peptide divided by the volume of solvent added.
Concentration (mg/ml) = peptide mass (mg) ÷ solvent volume (ml)
You can work this out instantly with our reconstitution calculator.
For example, dissolving a 10 mg vial in 2 ml of solvent gives a solution at 5 mg/ml. Dissolving the same 10 mg in 1 ml gives 10 mg/ml. The mass is fixed by the vial; the concentration is set purely by how much solvent is added.
This tells you the strength of the solution you have prepared. It is a statement about the solution, not a recommendation about quantities for any purpose.
After reconstitution
Once in solution a peptide is far less stable than it was dry — the degradation processes that lyophilisation held off resume in water. Reconstituted solutions are generally refrigerated, protected from light, and used within a limited window. See how to store research peptides for detail.
Frequently Asked Questions
Reconstitution is dissolving a lyophilised (freeze-dried) peptide powder back into a liquid solution using a solvent, so it can be used in solution-phase laboratory research. Lyophilised compounds cannot be used in solution until reconstituted.
Bacteriostatic water is the standard laboratory solvent for reconstituting most research peptides. Some hydrophobic peptides require a different solvent — see our guide to peptide solubility.
Divide the mass of peptide by the volume of solvent added: concentration (mg/ml) = peptide mass (mg) ÷ solvent volume (ml). For example, 10 mg dissolved in 2 ml gives 5 mg/ml. This describes the strength of the prepared solution only.
No. Shaking introduces shear forces and foaming that can denature or aggregate a peptide. Add the solvent slowly down the inside wall of the vial and swirl gently rather than shaking.