How to Reconstitute Peptides with Bacteriostatic Water
Quick Answer
To reconstitute a lyophilized research peptide, calculate the bacteriostatic water volume for your target concentration, disinfect both vial stoppers, draw the water with a sterile syringe, run it slowly down the inside wall of the peptide vial, swirl gently (never shake) until clear, then label and refrigerate at 2–8°C. For laboratory research use only.
Step-by-Step Reconstitution
- 1
Gather supplies
Assemble the lyophilized peptide vial, bacteriostatic water, an alcohol prep pad, and a sterile syringe. Work on a clean, disinfected surface. Allow the refrigerated vial to reach room temperature before handling.
- 2
Calculate the water volume
Decide your target concentration and use the reconstitution calculator to find the bacteriostatic water volume. Concentration (mg/mL) = peptide amount (mg) ÷ water added (mL). Record the figure before drawing.
- 3
Disinfect both vial stoppers
Wipe the rubber stopper of the peptide vial and the bacteriostatic water vial with a fresh alcohol pad. Let them air-dry to maintain sterility of the research material.
- 4
Draw the bacteriostatic water
Draw the calculated volume of bacteriostatic water into the sterile syringe, inverting and tapping to clear air bubbles so the measured volume is accurate.
- 5
Add water slowly down the vial wall
Insert the needle at an angle and let the bacteriostatic water run slowly down the inside wall of the peptide vial. Aiming the stream at the glass — not directly onto the lyophilized powder — protects the fragile peptide structure.
- 6
Swirl gently to dissolve — do not shake
Gently swirl or roll the vial until the powder fully dissolves into a clear solution. Never shake vigorously: agitation can shear and denature peptides. Allow a minute for complete dissolution.
- 7
Label and refrigerate
Label the vial with the concentration and date. Store the reconstituted peptide refrigerated at 2–8°C (fridge), protected from light. Reconstituted research peptides are generally used within their tested stability window.
Peptide Concentration Formula
Concentration (mg/mL) = Peptide amount (mg) ÷ Bacteriostatic water added (mL).
Example: a 10 mg vial reconstituted with 2 mL of bacteriostatic water yields a 5 mg/mL solution. The reconstitution calculator performs this math and the draw-volume conversion for you.
Frequently Asked Questions
What water do you use to reconstitute peptides?
Bacteriostatic water (sterile water containing 0.9% benzyl alcohol) is the standard reconstitution solvent for research peptides because the benzyl alcohol inhibits bacterial growth, supporting stability over a multi-use window. For laboratory research use only.
How much bacteriostatic water should I add to a peptide vial?
It depends on your target concentration. Concentration (mg/mL) equals the peptide amount in milligrams divided by the millilitres of bacteriostatic water added. Use the reconstitution calculator to get an exact figure for your vial.
Why should you not shake a peptide vial?
Vigorous shaking creates shear forces and foaming that can denature or fragment the peptide. Swirl or gently roll the vial instead, and direct the water down the glass wall rather than onto the powder.
How do you store reconstituted peptides?
Store reconstituted peptides refrigerated at 2–8°C, protected from light, and labeled with concentration and date. Lyophilized (un-reconstituted) peptides are stored frozen at -20°C. For laboratory research use only.
How long are reconstituted peptides stable in the fridge?
Stability varies by compound and is defined by each product’s Certificate of Analysis and testing window. As a general research practice, reconstituted peptides are kept refrigerated and used within the validated stability period.