Laboratory technique
How to reconstitute peptides: the step-by-step guide
Lyophilised peptides arrive as freeze-dried powder and must be dissolved before laboratory use. Done carelessly, reconstitution is where good material gets ruined. This guide covers the technique, the concentration maths with worked examples, and storage afterwards.
The five steps
1. Equilibrate. Let the vial reach room temperature before opening — condensation on cold powder degrades peptides and adds unmeasured water.
2. Sanitise. Wipe both the peptide vial stopper and the bacteriostatic-water vial stopper with an alcohol swab.
3. Draw the solvent. Draw your chosen volume of bacteriostatic water into a syringe — 1–3 ml is typical (the volume sets concentration; see the maths below).
4. Add it slowly. Insert the needle at an angle and run the water down the inside wall of the vial, never directly onto the powder. Peptide chains are shear-sensitive.
5. Swirl, don’t shake. Gently swirl or let the vial stand until the solution is fully clear — usually a few minutes. Cloudiness or visible particles after settling indicates a problem with the material.
The concentration maths
Concentration (mcg/ml) = peptide (mg) × 1000 ÷ water (ml). Draw volume for a target amount = amount (mcg) ÷ concentration. On a U-100 insulin syringe, ml × 100 = units. Worked examples:
| Vial | Water added | Concentration | 250 mcg draw | U-100 units |
|---|---|---|---|---|
| 5 mg | 1 ml | 5,000 mcg/ml | 0.05 ml | 5 units |
| 10 mg | 2 ml | 5,000 mcg/ml | 0.05 ml | 5 units |
| 10 mg | 1 ml | 10,000 mcg/ml | 0.025 ml | 2.5 units |
| 20 mg | 2 ml | 10,000 mcg/ml | 0.025 ml | 2.5 units |
After reconstitution
Reconstituted vials belong in the fridge at 2–8°C, protected from light, and are typically stable for 3–4 weeks with bacteriostatic water. Never freeze a reconstituted vial — ice crystals shear peptide chains. And note that pre-mixed pens skip this entire process: the solution arrives at a verified concentration with dial-dose measurement.
Pre-mixed pens: no reconstitution needed
RegenMed pens arrive pre-mixed at verified concentrations — third-party tested, for laboratory research use.
Frequently asked questions
What do you mix peptides with?
What do you mix peptides with?
How much water do you add to a peptide vial?
How much water do you add to a peptide vial?
Why shouldn't peptides be shaken?
Why shouldn't peptides be shaken?
How long do reconstituted peptides last?
How long do reconstituted peptides last?
Related reading
All products sold by RegenMed are supplied strictly for laboratory research purposes only and are not for human consumption. Nothing on this page is medical advice, and no statement has been evaluated by the MHRA or FDA. Content summarising published research is provided for educational purposes.