How to Reconstitute Peptides

What reconstitution means

Research peptides are supplied as a lyophilised (freeze-dried) powder for stability during storage and transport. Before they can be measured and used in a research setting, the powder must be dissolved into a liquid. This process is called reconstitution. Getting it right protects the integrity of the material; getting it wrong can degrade or contaminate the peptide and waste the vial.

Which liquid to use

The solvent of choice for most research peptides is bacteriostatic water: sterile water containing 0.9% benzyl alcohol. The benzyl alcohol inhibits bacterial growth, which allows a vial to be accessed multiple times over roughly 28 days without spoiling.

• Bacteriostatic water: preferred for multi-use vials. Stable and preserved.
• Sterile non-preserved water: no bacteriostatic agent, suitable only for single-use scenarios.
• Avoid tap water: impurities, chlorine and bacteria compromise the material immediately.
• Avoid saline unless specified: electrolytes can degrade certain peptides.

Calculating concentration for laboratory solutions

The concentration of a laboratory stock solution is simply the amount of peptide divided by the volume of solvent added:

The amount of peptide is fixed by the vial. The volume of solvent sets how concentrated the stock solution is. Worked example:

Adding more solvent gives a more dilute stock that is easier to pipette accurately; adding less gives a more concentrated stock. The total amount of peptide never changes.

Step-by-step technique

1. Prepare a clean workspace. Work on a clean bench or in a laminar-flow hood and let the vial reach room temperature before opening.
2. Measure the solvent. Measure the calculated volume of solvent with a calibrated pipette.
3. Add slowly. Dispense the solvent slowly down the inside wall of the vial, not directly onto the powder. Direct impact can damage the peptide.
4. Dissolve gently. Swirl the vial gently until the solution is clear. Do not shake, as agitation can degrade peptide chains.
5. Label and store. Label the vial with concentration and date, refrigerate and protect from light.

Storage

• Lyophilised (before reconstitution):store at -20°C for maximum shelf life.
• Reconstituted:refrigerate at 2 to 8°C and use within approximately 28 to 30 days.
• Avoid repeated freeze-thaw cycles and prolonged light exposure, both of which reduce peptide integrity.

Common mistakes

• Using the wrong liquid (tap water, plain saline).
• Adding solvent directly onto the powder.
• Shaking the vial instead of swirling.
• Working on an unclean bench or with non-sterile labware.
• Miscalculating concentration or pipetting inaccurately.

Frequently asked questions