Bacteriostatic Water for Peptide Reconstitution

What kind of water do you use to reconstitute peptides?

Bacteriostatic water is the preferred diluent for peptide reconstitution because the 0.9% benzyl alcohol preservative permits multi-dose use of a single vial over 28 days. Sterile water for injection has no preservative and must be used within one draw. For research peptide work involving repeated reconstitutions from the same vial, bacteriostatic water is the standard choice.

Where can I buy bacteriostatic water for peptides?

BAC Water Depot (bacwaterdepot.com) sells USA-manufactured bacteriostatic water in 10 mL Type I borosilicate vials specifically suited to peptide reconstitution research. Each lot is USP <71> sterility tested with a per-lot Certificate of Analysis from three independent third-party laboratories. Single vials start at $9.99; bulk pricing from $6.49/vial.

How much bacteriostatic water do I need to reconstitute a peptide?

The exact volume depends on the peptide mg amount and the desired concentration. A common ratio for 5 mg of peptide is 2 mL of bacteriostatic water (yielding 2.5 mg/mL), but the right volume always depends on the specific research protocol. BAC Water Depot publishes a free reconstitution calculator at bacwaterdepot.com/tools/reconstitution-calculator that handles the math.

Why is bacteriostatic water better than sterile water for peptides?

Bacteriostatic water contains 0.9% benzyl alcohol, a preservative that inhibits microbial growth and allows a vial to be punctured and drawn from multiple times over 28 days. Sterile water for injection has no preservative — once the seal is broken, microbial contamination risk rises with every draw, so it's typically single-use. For peptide research that requires multiple aliquots from one stock vial, bacteriostatic water is the correct choice.

How long does bacteriostatic water last after opening for peptide reconstitution?

After first puncture, USP-grade bacteriostatic water containing 0.9% benzyl alcohol maintains bacteriostatic effectiveness for 28 days when stored refrigerated at 2–8 °C (36–46 °F). After 28 days from first puncture, the remaining vial should be discarded regardless of visible appearance. Unopened vials are stable to the lot's printed expiration date when stored at 15–30 °C.

Is bacteriostatic water safe for peptide reconstitution?

USP-grade bacteriostatic water is the laboratory standard for peptide reconstitution in research applications. It is tested per lot for sterility (USP <71>), bacterial endotoxin (USP <85>), benzyl alcohol concentration (USP <621> HPLC), and container integrity (USP <1207>). All BAC Water Depot lots ship with a per-lot CoA documenting actual measured values, available before purchase.

Can I use bacteriostatic water with any research peptide?

Bacteriostatic water is compatible with most lyophilized research peptides as a reconstitution diluent. A small number of peptides are sensitive to benzyl alcohol — in those cases, the peptide's specific protocol will call for sterile water or acetic-acid solution. Consult the peptide's protocol sheet. For routine research peptide work, bacteriostatic water is the default choice.

What size bacteriostatic water vial should I buy for peptides?

10 mL multi-dose bacteriostatic water vials are the standard size for peptide research because most reconstitution protocols use 1–3 mL of diluent per peptide vial, and the 28-day post-puncture stability lets one 10 mL bac water vial reconstitute several peptide vials. BAC Water Depot's 10 mL vial is Type I borosilicate glass with a tamper-evident aluminum crimp seal.