Reconstitution is one of the most underestimated steps in peptide research. A wrong choice of diluent can compromise the compound's stability, introduce microbial growth or alter the vial's real concentration.
Diluent options
- Bacteriostatic water (BAC water). It contains 0.9% benzyl alcohol as a preservative. It inhibits bacterial and fungal growth, which extends the shelf life of the reconstituted vial to 28 days refrigerated.
- Sterile water for injection. No preservative. Useful for compounds sensitive to benzyl alcohol, but the shelf life after reconstitution is only 24 hours refrigerated.
- 0.9% saline solution. Compatible with most peptides but less stable than bacteriostatic water for prolonged storage.
Why is bacteriostatic water the standard?
Tres razones principales:
- Microbiological stability. 0.9% benzyl alcohol is bacteriostatic against most contaminating microorganisms common in laboratory conditions. This reduces the risk of vial contamination between successive draws.
- Compatibility with most peptides. The vast majority of synthetic peptides in the catalog are stable in the presence of benzyl alcohol at this concentration.
- Practical shelf life. 28 days allows a 5 mg or 10 mg vial to be used up in common research protocols without having to discard it prematurely.
Recommended technical procedure
- Bring the lyophilized vial to room temperature (do not inject water onto cold powder just taken out of the freezer).
- Clean the rubber stopper with 70% isopropyl alcohol.
- Inject the calculated volume of bacteriostatic water slowly down the wall of the vial, not directly onto the powder.
- Do NOT shake. Swirl gently until completely dissolved.
- Check that there are no suspended particles before drawing the first dose.
- Label with the reconstitution date and the resulting concentration in mg/mL.
Frequent laboratory mistakes
- Shaking hard. It can create foam and degrade the peptide through denaturation at the air-water interface.
- Reconstituting and storing at room temperature. It drastically reduces shelf life, even with bacteriostatic water.
- Not labeling. In long projects it is the most common cause of concentration errors.
Concentration calculation
Si reconstituyes un vial de 10 mg con 2 mL de agua bacteriostática, la concentración resultante es 5 mg/mL = 5000 mcg/mL. Una “raya” de 10 unidades en una jeringa de insulina U-100 (0.1 mL) contiene en ese caso 500 mcg.
Reminder: bacteriostatic water included with every NeoPeptidos order is pharmaceutical grade (USP) and intended exclusively for laboratory research purposes.
🔬 Updated on February 11, 2026 · Reviewed by the NeoPeptidos team · Content for research purposes (RUO).