Bacteriostatic Water

Compound Overview

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative. In laboratory peptide workflows, that preservative helps inhibit bacterial growth and supports repeated withdrawals from a single vial while researchers reconstitute lyophilized compounds and maintain sterility across controlled in-vitro use.

Bacteriostatic Water vs. Sterile Water

The practical difference between bacteriostatic water (often called bac water) and plain sterile water is the preservative. Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol, a preservative that inhibits bacterial growth and lets a single multi-dose vial be punctured repeatedly for up to 28 days. Plain sterile water carries no preservative and is intended for a single withdrawal, after which any remainder is discarded. In peptide research workflows where a lyophilized compound is reconstituted and then drawn down across multiple in-vitro experiments, the multi-dose stability of bacteriostatic water is the reason it is the standard reconstitution diluent rather than single-use sterile water.

How Much Bacteriostatic Water Is Used per Vial in Research Workflows

The volume of bacteriostatic water used to reconstitute a vial depends on the target working concentration set by the laboratory protocol and the mass of lyophilized compound being brought into solution — not on any human-use guidance, which Nexus does not provide. As a general in-vitro reference point, many peptide research protocols reconstitute a single vial with 1–2 mL of bacteriostatic water and adjust from there to reach the concentration a given assay requires; a larger reconstitution volume yields a lower concentration per unit volume. Researchers typically calculate the exact volume from the vial's labeled mass and their intended stock concentration, then aliquot and store the reconstituted material according to their institutional standard operating procedures.

Research Background & Published Literature

Bacteriostatic water is a core laboratory supply in peptide research workflows because it allows lyophilized peptides to be brought into solution for experimental use. Unlike plain single-use sterile water, which is discarded after one withdrawal, the 0.9% benzyl alcohol preservative supports sterility for up to 28 days after the first puncture.

Storage, Handling & Stability Guidelines

Store sealed material at room temperature (15–30°C) away from direct light, and do not freeze. After first puncture, use within 28 days. Use proper aseptic technique, including alcohol swabs before withdrawal, throughout every research-handling step.

• Limit ambient-temperature exposure during handling to help preserve compound integrity.
• Reseal vials promptly after each withdrawal to reduce moisture exposure.
• Use appropriate personal protective equipment and follow institutional chemical safety protocols at all times.
• For traceability, label aliquots with compound name, concentration, date of reconstitution, and operator initials.

Quality Assurance & Release Testing

As a sterile, preserved diluent, Bacteriostatic Water is released against solvent-appropriate testing categories — sterility, bacterial endotoxin (LAL), pH, and particulate matter — rather than the HPLC area-percent purity and mass-spectrometry identity used for peptide compounds. Its specification is sterile water for injection preserved with 0.9% benzyl alcohol (USP grade). A finalized third-party Certificate of Analysis is published once a lot's verification is complete; until then the lot is shown as certificate pending.

Lab Verification

Nexus publishes batch-level certificates for independently verified compounds in the Lab Verified archive. Solvents and accessories are released against the sterility, endotoxin, pH, and particulate categories described above; a published certificate appears once the lot is finalized.