Reconstitution Guide
Bacteriostatic Water: The Complete Reconstitution Guide
Every lyophilized research peptide — retatrutide, tirzepatide, semaglutide, BPC-157, GHK-Cu, TB-500 — has to be reconstituted before it can be used in laboratory work. The standard diluent is bacteriostatic water. This guide explains what it is, how to mix peptides, dosing math, and storage.
What is bacteriostatic water?
Bacteriostatic water (often shortened to bac water) is sterile water with 0.9% benzyl alcohol added as a bacteriostatic preservative. The benzyl alcohol prevents bacterial growth in the vial after the rubber stopper is first punctured, allowing the same vial to be safely used for multiple draws over up to 28 days when refrigerated.
Why it matters for peptide research
Plain sterile water and saline contain no preservative — once punctured, they're considered single-use. Bacteriostatic water lets you reconstitute a lyophilized peptide once and draw from the same vial across multiple days of research protocol without microbial contamination.
How to reconstitute a peptide (step by step)
- Let the lyophilized peptide vial reach room temperature.
- Wipe both vial stoppers with an alcohol pad.
- Draw the desired volume of bacteriostatic water into a sterile syringe.
- Slowly inject the water against the inside wall of the peptide vial — never directly onto the powder.
- Swirl gently to dissolve. Do not shake.
- Label the vial with the date, peptide name, and concentration. Refrigerate at 2–8°C.
Peptide dosing math
The concentration after reconstitution is simply the peptide mass divided by the diluent volume. For example:
- 10mg peptide + 2mL bac water = 5mg/mL = 5,000 mcg/mL.
- 10mg peptide + 1mL bac water = 10mg/mL = 10,000 mcg/mL.
- 30mg peptide + 3mL bac water = 10mg/mL = 10,000 mcg/mL.
A standard U-100 insulin syringe is graduated in 100 units per mL — so at 10mg/mL, every "1 unit" mark equals 100 mcg of peptide.
Storage & shelf life
- Unreconstituted lyophilized peptides: store sealed at -20°C, stable for 24+ months.
- Reconstituted with bacteriostatic water: refrigerate at 2–8°C, use within 28 days.
- Protect from light. Do not freeze reconstituted vials — freeze-thaw degrades peptides.
Buy bacteriostatic water
HerAmino stocks sterile bacteriostatic water (0.9% benzyl alcohol) in 3mL and 10mL vials. Shop bacteriostatic water →
For in-vitro laboratory research use only. Not for human or veterinary use.