Understanding Lyophilized Peptides
Most research peptides are supplied in lyophilized (freeze-dried) powder form. This process removes water under vacuum while frozen, creating a stable powder that resists degradation far longer than liquid peptide solutions. Before use, lyophilized peptides must be reconstituted with a sterile liquid.
Reconstitution Solvent Options
The two most common solvents used in peptide research are:
- Bacteriostatic water (BW) — Sterile water containing 0.9% benzyl alcohol as a preservative. BW extends the usable life of reconstituted peptide solutions to approximately 28–30 days when refrigerated. This is the most common choice for research use.
- Sterile water for injection — No preservative. Suitable for single-use vials; reconstituted solution should be used within a few days and kept refrigerated.
Reconstitution Protocol
Standard practice for research reconstitution:
- Allow the lyophilized vial to reach room temperature before opening to prevent moisture condensation on the powder
- Clean the rubber stopper with an alcohol swab and allow to dry
- Draw the desired volume of bacteriostatic water into a sterile syringe
- Inject the solvent slowly down the inside wall of the vial — do not aim directly at the powder cake
- Gently swirl (do not vortex or shake vigorously) until fully dissolved
- Inspect for clarity — a properly reconstituted peptide solution should be clear and colourless
Concentration and Dosing Calculations
Standard calculation: if a 5 mg vial is reconstituted with 2 mL of bacteriostatic water, the concentration is 2.5 mg/mL (2,500 mcg/mL). A 100 mcg research dose would therefore require 0.04 mL (40 µL), measured with an insulin syringe.
Storage Guidelines
Lyophilized (unreconstituted): store at -20°C for long-term stability, or at 4°C (refrigerator) for up to 3–6 months depending on the peptide. Reconstituted solutions: refrigerate at 2–8°C and use within 28–30 days for BW-reconstituted peptides.
Important Disclaimer
This guide is for educational purposes only. Research peptides are not intended for human use unless approved by relevant regulatory authorities.
