Bacteriostatic Water
Diluent
Sterile water with 0.9% benzyl alcohol, used to reconstitute lyophilized peptides and permit multi-dose withdrawal.
How it works
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative, used to reconstitute lyophilized peptides that are shipped and stored in a freeze-dried powder form. Unlike plain sterile water, the benzyl alcohol allows a single vial to be used for multiple withdrawals over time without introducing bacterial growth.
The preservative works by inhibiting bacterial replication rather than sterilizing the solution outright, which is why reconstituted peptide vials still carry a defined, time-limited stability window rather than indefinite shelf life. Stability literature generally supports around 28 days of refrigerated storage after reconstitution for most peptides.
Choosing the diluent volume added to a given vial is a practical decision that determines the resulting concentration, and researchers typically use a reconstitution calculator to translate a chosen vial size and diluent volume into a usable concentration and corresponding syringe unit marks.
What research has shown
Stability work generally supports 28 days refrigerated after reconstitution for most peptides.
Reported ranges in the literature
Low end
1 mL per vial (higher concentration)
Optimal
2 mL per vial (typical)
High end
3 to 5 mL per vial (finer dose granularity)
Frequency reported in the literature: As needed for reconstitution. Note: Use the Peptide Calculator to convert vial size and diluent volume into unit marks.
Frequently asked questions
What is bacteriostatic water?
Bacteriostatic water is sterile water preserved with 0.9% benzyl alcohol, used to reconstitute lyophilized peptides and allow multiple withdrawals from one vial.
How does bacteriostatic water differ from plain sterile water?
Plain sterile water contains no preservative and is generally intended for single-use reconstitution, while bacteriostatic water's benzyl alcohol content inhibits bacterial growth, supporting extended, multi-dose vial use within its stability window.
What does the stability research show?
General stability work supports roughly 28 days of refrigerated storage after reconstitution for most peptides, though specific compounds may have different documented windows.
How is bacteriostatic water stored?
It is generally stored at room temperature or refrigerated before use, and reconstituted peptide vials mixed with it should be kept refrigerated afterward.
How much should be used per vial?
The volume used depends on the desired concentration and the peptide's total mass; researchers commonly use a reconstitution calculator to convert a chosen vial size and diluent volume into precise dosing unit marks.
Related compounds
Further reading
Research use only
All content on this page is general reference information for laboratory research contexts. It is not medical advice, is not intended to direct human use, and does not replace guidance from a licensed healthcare professional. Not for human consumption. Must be 18+.