Reconstitution Guide
Reconstitution is the process of dissolving a lyophilized peptide into a usable liquid form. Following a careful protocol preserves the integrity of the compound and ensures accurate dosing for your research.
What you'll need
Gather your materials before starting so the vial spends as little time outside controlled conditions as possible. Work in a clean, well-lit area free of drafts and clutter.
- Lyophilized peptide vial (allowed to reach room temperature)
- Bacteriostatic water (sterile water containing 0.9% benzyl alcohol)
- Sterile syringes with appropriate gauge needles
- Alcohol swabs
- A clean, dry workspace
- Lab notebook or label for recording the dilution
Why bacteriostatic water
Bacteriostatic water contains a small amount of benzyl alcohol that inhibits microbial growth, allowing reconstituted peptides to be stored in the refrigerator for weeks rather than days. Plain sterile water can be used for very short-term work but provides no protection against contamination. Avoid tap, distilled, or deionized water — none are sterile or buffered for research use.
Step-by-step procedure
Wipe both vial stoppers with an alcohol swab and let them air dry. Draw the desired volume of bacteriostatic water into a syringe. Insert the needle through the stopper of the peptide vial at an angle and inject the water slowly, letting it run down the inside wall of the glass — never directly onto the powder cake. Once the water is in, gently swirl or roll the vial between your palms until the solution becomes clear. Do not shake. Shaking creates foam, denatures the peptide, and traps air in the solution.
Calculating concentration
Concentration equals peptide mass divided by liquid volume. For example, 5 mg of peptide reconstituted in 2 mL of bacteriostatic water yields 2.5 mg/mL, or 2,500 µg/mL. Always document the dilution factor on the vial label and in your lab notebook so you can calculate accurate aliquot volumes later.
Common mistakes to avoid
Most reconstitution problems trace back to a few avoidable errors. Watching for them up front saves both material and experimental time.
- Injecting water directly onto the powder cake (causes clumping)
- Shaking the vial instead of swirling (denatures the peptide)
- Using the wrong solvent — never use saline or buffer without checking compatibility
- Failing to label the vial with the date and concentration
- Reconstituting more material than you can realistically use within the storage window
After reconstitution
Place the vial in the refrigerator immediately. Inspect the solution before each use — it should remain clear and free of particulates throughout its storage window. Discard any vial that becomes cloudy, changes color, or develops sediment.