Protocol
How to reconstitute a peptide
- 1 Sanitize the stoppers. Wipe the rubber stopper of both the peptide vial and the bacteriostatic water vial with a fresh alcohol swab. Let them air-dry.
- 2 Draw the bacteriostatic water. Using a sterile syringe, draw the calculated volume of bacteriostatic water from its vial.
- 3 Inject slowly down the vial wall. Insert the needle into the peptide vial and inject the water slowly, aiming the stream against the inside glass wall rather than directly onto the lyophilized powder.
- 4 Let it dissolve. Allow the vial to sit undisturbed for a minute or two. If solids remain, swirl the vial gently in a circular motion. Never shake — agitation shears peptide bonds.
- 5 Inspect for clarity. The solution should be clear and free of particulates or cloudiness. Discard if it is not.
- 6 Label with concentration and date. Mark the vial with the resulting concentration (mg/mL) and the reconstitution date.
- 7 Refrigerate. Store the reconstituted vial at 2–8 °C (refrigerated). Keep away from light.
The Math
Concentration = mass ÷ volume
The concentration of a reconstituted vial is simply the peptide mass divided by the volume of water added: mg ÷ mL = mg/mL. To find the volume to draw for a target amount in micrograms, convert the concentration to mcg/mL (multiply by 1,000) and divide: mcg ÷ (mcg/mL) = mL. Multiply that mL value by 100 for U-100 insulin-syringe units.
| Vial | Bacteriostatic water | Concentration |
|---|---|---|
| 5 mg | 2 mL | 2.5 mg/mL |
| 10 mg | 2 mL | 5 mg/mL |
| 30 mg | 3 mL | 10 mg/mL |
Diluent
Bacteriostatic vs sterile water
Bacteriostatic water contains roughly 0.9% benzyl alcohol, a preservative that suppresses microbial growth — which makes it the standard diluent for a vial that will be accessed multiple times over several days. Sterile water for injection has no preservative and is better suited to a single-use preparation. For most research peptide work involving a multi-use vial, bacteriostatic water is the right call. View our bacteriostatic water or read the full reconstitution guide.
Avoid These
Common mistakes
- Shaking the vial. Agitation and foaming shear the peptide. Swirl gently instead.
- Spraying water onto the powder. Inject slowly down the glass wall so the powder dissolves without being blasted.
- Using the wrong diluent. Sterile water for a multi-day vial leaves it unprotected; check what the compound calls for.
- Room-temperature storage. Reconstituted peptides belong in the refrigerator, away from light.
- Over-diluting. Too much water makes accurate small-volume draws difficult on an insulin syringe. Pick a volume that keeps your target measurement in a readable range.
Questions
Frequently asked
How do I calculate peptide concentration?
Divide the peptide mass in the vial (mg) by the volume of bacteriostatic water added (mL). A 10 mg vial reconstituted with 2 mL yields 5 mg/mL.
What are insulin-syringe units?
A standard U-100 insulin syringe is marked in units where 100 units equals 1 mL. To convert a draw volume in mL to units, multiply by 100. So 0.2 mL is 20 units.
Can I use sterile water instead of bacteriostatic water?
For a single-use preparation, sterile water works. For a vial that will be accessed repeatedly over several days, bacteriostatic water — which contains 0.9% benzyl alcohol — limits microbial growth and is the standard choice.
Why should I never shake the vial?
Shaking introduces shear forces and foaming that can fragment or denature the peptide. Gentle swirling is sufficient; most lyophilized peptides dissolve on their own within a minute or two.
How long does a reconstituted peptide last?
Stored refrigerated and protected from light, most reconstituted research peptides remain usable for several weeks. Always inspect for cloudiness or particulates before use and follow the Certificate of Analysis guidance.
Is this calculator a dosing tool?
No. It is a laboratory reference for preparing research solutions. These compounds are sold for in-vitro and research use only and are not for human consumption.
Disclaimer
All information on this page is provided strictly as a laboratory research-preparation reference. Nothing here is medical, clinical, or dosing advice. Products referenced by Elyte Peptides are intended solely for in-vitro and laboratory research and development — they are not manufactured, sold, or intended for human consumption. These statements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease.