Laboratory product profile
Bacteriostatic Water for Injection, USP is the reference solvent for reconstituting lyophilised peptides in the laboratory. It is sterile water for injection with 0.9% benzyl alcohol added (9 mg/mL), a bacteriostatic agent that inhibits microbial growth after the stopper is first punctured. That preservative is what separates bacteriostatic water from plain sterile water, and what makes multi-dose vials possible in research protocols. Velia Labs supplies it in multi-dose vials, for laboratory use only.
Research use only. The bacteriostatic water sold by Velia Labs is a laboratory solvent intended exclusively for in vitro research and experimental protocols. It is not intended for injection, nor for human or animal consumption, and nothing on this page constitutes medical advice or an administration protocol.
Reconstitution is the step where a lyophilised peptide is returned to solution before experimental use. The choice of solvent governs both the stability of the molecule and the microbiological safety of the vial. Bacteriostatic water answers both requirements: its sterile, pyrogen-free water respects the chemistry of the peptide, and its 0.9% benzyl alcohol exerts a documented bacteriostatic action — disruption of bacterial membranes and surface structures — that limits microbial proliferation when the septum stopper is punctured repeatedly.
The USP “Bacteriostatic Water for Injection” monograph defines the composition (water for injection plus 0.9% benzyl alcohol), a pH of around 5.7 (range 4.5 to 7.0) and presentation in a multi-dose container. The effectiveness of the preservative system is assessed under USP general chapter <51> (Antimicrobial Effectiveness Testing), which requires minimum log reductions across a panel of reference micro-organisms.
Good laboratory practice for reconstitution: disinfect the septum stopper with alcohol before every puncture, use sterile single-use consumables, direct the stream of solvent against the wall of the vial rather than straight onto the lyophilised powder, and mix by gentle swirling — never by vigorous shaking, which can degrade some peptide chains. Writing the reconstitution date on the vial is part of basic traceability.
Unlike a molecule, bacteriostatic water is governed first and foremost by pharmacopoeial standards. The sources below define its composition, its quality control and the limits on its use.
United States Pharmacopeia / DailyMed (NLM) — Pharmacopoeial standard
Defines the composition (0.9% benzyl alcohol, i.e. 9 mg/mL), the pH range 4.5–7.0 and the multi-dose presentation. The DailyMed labels set out the specifications lot by lot.
View on DailyMedUnited States Pharmacopeia — USP–NF general chapter
The harmonised method for assessing the effectiveness of antimicrobial preservatives (benzyl alcohol among them) in multi-dose preparations.
View the USP–NF standardGershanik J, Boecler B, Ensley H, et al. — New England Journal of Medicine, 1982
The historic publication behind the neonatal contraindication for benzyl alcohol: it illustrates why the limits on preservative use are part of the safety data worth knowing in the laboratory.
Read on PubMed (PMID: 7133084)It is the concentration set by the United States Pharmacopeia, high enough to give bacteriostatic activity that allows several punctures of the same vial while staying compatible with most research peptides. Without a preservative, a solvent reverts to strictly single-dose.
Once a peptide has been reconstituted, standard laboratory practice is refrigerated storage (2–8 °C), protected from light, with the preparation date recorded. Pharmaceutical standards for multi-dose preparations usually set a maximum of 28 days after first puncture — though the peptide’s own chemical stability may call for a shorter window.
Sterile Water for Injection contains no preservative: it comes in a single-dose container and any unused portion must be discarded. Bacteriostatic water, thanks to its 0.9% benzyl alcohol, is designed for multi-dose containers.
No. Some sensitive proteins and peptides can be destabilised by benzyl alcohol, or require a different pH. Always check the solvent’s compatibility with your molecule in the literature or the technical data sheet before reconstituting.
No. The product sold by Velia Labs is a laboratory solvent for research use only. It is not intended for administration to humans or animals, in line with our terms of sale.
Reconstitution solvent with 0.9% benzyl alcohol, meeting USP specifications, fast shipping across France and Europe. Research use only.
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