Laboratory guide
How to reconstitute research peptides
A practical, step-by-step protocol for dissolving lyophilised peptides with bacteriostatic water, calculating concentration, and storing the solution correctly.
What you need
Step-by-step protocol
1. Prepare a clean workspace
Work on a disinfected bench. Wipe the vial stoppers of both the lyophilised peptide and the bacteriostatic water with a fresh alcohol swab and allow them to air dry before piercing.
2. Let the peptide reach room temperature
Remove the lyophilised vial from cold storage and allow it to equilibrate to room temperature. Adding cold solvent to a cold vial encourages condensation and can degrade the powder.
3. Draw the bacteriostatic water
Using a sterile syringe, draw the volume of bacteriostatic water your dilution calls for. Bacteriostatic water contains 0.9% benzyl alcohol, which suppresses microbial growth during multi-use storage.
4. Add the solvent slowly down the vial wall
Angle the needle so the stream runs down the inside glass wall rather than directly onto the powder. Injecting straight into the peptide cake can shear the peptide chain.
5. Dissolve without shaking
Swirl or roll the vial gently until the solution is completely clear. Never shake or vortex — agitation denatures peptides. Full dissolution usually takes under a minute.
6. Label and refrigerate
Label the vial with the peptide, concentration and reconstitution date. Store at 2–8 °C and protect from light. Reconstituted peptides are typically used within a few weeks.
Dilution reference
Concentration is simply the vial mass divided by the solvent volume. The table below shows common combinations and the amount contained in a 10-unit mark on a standard 100-unit insulin syringe.
| Vial | Water added | Concentration | Per 10 units |
|---|---|---|---|
| 5 mg | 1 mL | 5000 mcg/mL | 500 mcg |
| 5 mg | 2 mL | 2500 mcg/mL | 250 mcg |
| 10 mg | 2 mL | 5000 mcg/mL | 500 mcg |
| 10 mg | 3 mL | 3333 mcg/mL | 333 mcg |
| 20 mg | 3 mL | 6667 mcg/mL | 667 mcg |
| 40 mg | 5 mL | 8000 mcg/mL | 800 mcg |
Storage and handling
Keep lyophilised vials in a freezer for long-term stock and reconstitute only what a study requires. Once in solution, refrigerate at 2–8 °C, keep the vial out of direct light, and avoid repeated freeze–thaw cycles, which cause aggregation and loss of activity. Discard any solution that becomes cloudy or shows particulates.
Frequently asked questions
- What water should be used to reconstitute research peptides?
- Bacteriostatic water is the standard solvent for multi-use laboratory vials because the 0.9% benzyl alcohol suppresses microbial growth. Sterile water can be used for single-use preparations but offers no preservative.
- How much bacteriostatic water should be added to a vial?
- Volume is chosen to give a convenient concentration rather than a fixed rule. Dividing the vial mass in micrograms by the millilitres of water added gives the concentration in mcg/mL.
- How long does a reconstituted peptide last?
- Once in solution, peptides are far less stable than the lyophilised powder. Stored at 2–8 °C and protected from light, most reconstituted research peptides remain usable for a few weeks.
- Can a reconstituted peptide be frozen?
- Freezing solutions is generally avoided because freeze–thaw cycles cause aggregation. Long-term stock is best kept as the lyophilised powder in a freezer and reconstituted as required.
Research use only
This guide describes laboratory handling of research materials. Strand products are sold strictly for in vitro and controlled research purposes and are not for human consumption, diagnostic use, or therapeutic application.