How to Reconstitute Peptides: Step-by-Step Lab Protocol

A vial of lyophilised peptide, a vial of sterile bacteriostatic water, a sterile syringe and needle, alcohol swabs, and a clean working surface. Bacteriostatic water is the standard reconstitution solvent for research peptides because it includes 0.9 percent benzyl alcohol to inhibit bacterial growth.

1. Bring both the peptide vial and the bacteriostatic water to room temperature. This prevents condensation inside the lyophilised vial and helps preserve compound integrity.

2. Wipe both vial stoppers with an alcohol swab.

3. Draw the required volume of bacteriostatic water into the syringe.

4. Insert the needle into the peptide vial at an angle so the water flows down the side of the vial onto the lyophilised cake. Do not jet water directly onto the cake, this causes mechanical degradation.

5. Allow the cake to dissolve passively. Gently swirl, never shake. Shaking introduces air bubbles and can denature the peptide.

6. Once fully dissolved, label the vial with the date of reconstitution and store at 2 to 8 degrees Celsius.

Concentration is total peptide mass divided by reconstitution volume. For example, a 5 mg vial reconstituted with 2 ml of bacteriostatic water yields a concentration of 2.5 mg/ml. Standardising reconstitution volume across your protocol simplifies downstream measurement.

Always use a fresh sterile syringe and needle. Never reuse needles between vials. Bacteriostatic water inhibits bacterial growth but is not a substitute for clean technique.