August 17, 2026
Peptide reconstitution guide: bacteriostatic water, dosing math, and storage
This article is for research information purposes only. The products mentioned are for laboratory research use only.
[PLACEHOLDER — launch draft; review and expand before publishing]
Why correct reconstitution matters
Lyophilized peptides (powder) are stable for years at -20°C, but once reconstituted they become sensitive to temperature, light, and microbial contamination. Poor technique degrades the peptide and compromises research results.
Choosing the solvent
- Bacteriostatic water (0.9% benzyl alcohol) — the standard for multi-use vials; inhibits bacterial growth for up to 30 days.
- Sterile water for injection — single use; no preservative.
- 0.6% acetic acid — recommended for some poorly soluble peptides (check the peptide's technical sheet).
Step-by-step protocol
- Bring the lyophilized vial and the solvent to room temperature.
- Disinfect both vial stoppers with 70% isopropyl alcohol.
- Draw the desired solvent volume with a sterile syringe.
- Inject the solvent slowly, down the vial wall — never directly onto the powder.
- Swirl gently until fully dissolved. Do not shake.
- Label the vial with the reconstitution date and concentration.
Concentration math
Formula: concentration (mg/ml) = peptide amount (mg) ÷ solvent volume (ml)
| Peptide in vial | Solvent added | Resulting concentration |
|---|---|---|
| 5 mg | 1 ml | 5 mg/ml |
| 5 mg | 2 ml | 2.5 mg/ml |
| 10 mg | 2 ml | 5 mg/ml |
Storage
- Lyophilized: -20°C, protected from light — stable for years.
- Reconstituted: 2–8°C (refrigerator), protected from light — generally max. 30 days.
- Avoid repeated freeze-thaw cycles.
Conclusion
Correct reconstitution is what separates a reproducible experiment from a compromised one: the right solvent, sterile technique, labelling, and an unbroken temperature chain.
Frequently asked questions
- What solvent is used to reconstitute peptides?
- Bacteriostatic water (sterile water with 0.9% benzyl alcohol) is the standard for most peptides because it allows multi-use of the vial for up to 30 days. Plain sterile water is intended for single use.
- How long does a reconstituted peptide last?
- Stored at 2–8°C, a peptide reconstituted with bacteriostatic water generally remains stable for up to 30 days, depending on the peptide. Lyophilized at -20°C, stability is measured in years.
- How do I calculate concentration after reconstitution?
- Concentration = total peptide amount (mg) divided by solvent volume added (ml). Example: 5 mg reconstituted in 2 ml = 2.5 mg/ml.