What Is Bacteriostatic Water?

Bacteriostatic water (BAC water) is sterile water for injection that contains 0.9% benzyl alcohol as an antimicrobial preservative. It is the standard solvent for reconstituting lyophilized (freeze-dried) peptides because the benzyl alcohol inhibits bacterial growth, allowing multi-use access over approximately 28 days.

How It Differs from Sterile Water

Sterile water is pure water with no preservative. Once opened, it must be used within a single session or discarded within 24 hours, as bacteria can proliferate rapidly without antimicrobial protection. Bacteriostatic water can be accessed multiple times over its 28-day use window because the benzyl alcohol continuously prevents microbial contamination.

This distinction is critical for peptide research. Most reconstituted peptide solutions are used over days or weeks, making BAC water the appropriate choice for maintaining sample integrity.

Composition and Specifications

Per USP (United States Pharmacopeia) standards, bacteriostatic water contains: purified water meeting USP specifications, 0.9% (w/v) benzyl alcohol as preservative, pH 4.5–7.0, and is sterilized by filtration or autoclaving. It is supplied in multi-dose vials, typically 10mL or 30mL.

Storage and Handling

Store unopened vials at room temperature (20–25°C). Once punctured, refrigerate at 2–8°C and use within 28 days. Always swab the stopper with alcohol before each access. Discard if the solution appears cloudy, discolored, or contains particulate matter.

Related Resources

• How to Reconstitute Peptides: Complete Guide
• Bacteriostatic Water Product Page
• How to Store Peptides

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Written by NorthPeptide Research Team · For laboratory and research use only. Not for human consumption.

Written by NorthPeptide Research Team