5ml bac water (bacteriostatic water) is a sterile, non-pyrogenic diluent containing 0.9% (9 mg/mL) benzyl alcohol dissolved in purified water for injection. Developed specifically for laboratory environments, it functions as the standard solvent for reconstituting lyophilized research peptides in preclinical in vitro and in vivo models.
5ml bac water (bacteriostatic water) is a sterile, non-pyrogenic diluent containing 0.9% (9 mg/mL) benzyl alcohol dissolved in purified water for injection. Developed specifically for laboratory environments, it functions as the standard solvent for reconstituting lyophilized research peptides in preclinical in vitro and in vivo models.
In analytical chemistry and preclinical research, 5ml bac water (bacteriostatic water) serves as an essential universal diluent for reconstituting lyophilized protein and peptide compounds. Chemically, the solution consists of high-purity, non-pyrogenic water combined with 0.9% (9 mg/mL) benzyl alcohol (C7H8O) acting as a bacteriostatic preservative. This precise concentration inhibits microbial proliferation without destabilizing the secondary or tertiary structures of sensitive target molecules.
When laboratory researchers work with synthetic research peptides, maintaining solution sterility across multiple sampling events is paramount. Standard sterile water for injection lacks an antimicrobial agent, exposing reconstituted aliquots to rapid microbial contamination upon initial septum entry. By contrast, a dedicated 5ml bacteriostatic water diluent provides an active preservative barrier, enabling researchers to perform repeated needle punctures over an extended experimental window without compromising assay integrity.
The inclusion of 0.9% benzyl alcohol provides a robust bacteriostatic effect by targeting bacterial cell membranes. At a molecular level, benzyl alcohol alters membrane fluidity and permeability, leading to the disruption of the proton motive force and the inhibition of essential membrane-bound enzymatic pathways. This mechanism prevents bacterial cells from dividing and replicating within the aqueous medium.
It is critical to distinguish between bacteriostatic and bactericidal actions in bench research. While bactericidal agents induce immediate cell lysis—often releasing endotoxins (lipopolysaccharides) that can interfere with cell culture assays or animal physiological readouts—a bacteriostatic agent like benzyl alcohol halts cellular reproduction while maintaining a low-toxicity environment suitable for in vitro research models. This controlled microbial suppression ensures that reconstituted peptides remain structurally intact and free from enzymatic degradation caused by bacterial contaminants.
Proper reconstitution technique is vital to preserve the biological activity of lyophilized research compounds. When introducing 5ml bac water into a peptide vial, researchers should maintain strict aseptic conditions inside a certified Class II laminar flow hood. The recommended workflow involves cleaning the vial rubber septum with an isopropyl alcohol swab, allowing it to air dry, and utilizing a sterile syringe to draw the exact volume of diluent required.
To prevent shear stress and physical denaturation of the peptide chain, the diluent stream should be directed gently against the inner glass wall of the vial rather than sprayed directly onto the lyophilized cake. Allowing the liquid to slowly stream down encourages natural dissolution. Gentle rotational swirling—never violent shaking—should be applied until the solute is fully clarified. Researchers requiring exact volumetric calculations for multi-dose assay series can refer to our peptide reconstitution calculator for standardized laboratory dilution tables.
Common preclinical peptides requiring precise diluent selection include tissue repair factors such as BPC-157 and TB-500, as well as secretagogues like CJC-1295. Selecting high-grade 5ml bac water ensures that these distinct amino acid sequences remain stable across extended assay timelines.
Selecting the correct diluent depends directly on the experimental design, storage duration, and analytical endpoints of the study. Below is a comparative overview of common laboratory diluents utilized alongside peptides for research:
1. 5ml Bac Water (0.9% Benzyl Alcohol): Designed specifically for multi-dose applications. Offers antimicrobial suppression for up to 28 days post-initial puncture when stored at 2°C–8°C. Ideal for longitudinal preclinical studies requiring repeated sampling from a single vial.
2. Sterile Water for Injection (SWFI): Unpreserved, pure H2O. Recommended strictly for immediate, single-use assays or applications where benzyl alcohol may induce cytotoxicity in delicate cell lines during in vitro screening.
3. 0.9% Normal Saline (Sodium Chloride): Provides isotonic parity with biological fluids, which can be advantageous for specific acute animal model injections. However, unpreserved saline carries the same microbial contamination risks as SWFI once the vial seal is broken.
For the majority of multi-vial laboratory protocols, 5ml bac water balances physical stability, antimicrobial protection, and cost efficiency across small-to-medium research trials.
Reagents used in preclinical research must comply with stringent purity and endotoxin specifications to prevent confounding experimental variables. Bacterial endotoxins—lipopolysaccharides originating from Gram-negative bacterial outer membranes—can trigger severe inflammatory responses in animal models and alter cellular pathways in cell culture assays. Consequently, research-grade 5ml bac water must undergo rigorous analytical testing prior to release.
PX1 Research ensures that every lot of bacteriostatic diluent undergoes independent third-party testing in ISO 17025 accredited facilities. Quality validation includes United States Pharmacopeia (USP) <71> Sterility Testing and USP <85> Bacterial Endotoxin Testing using quantitative Limulus Amebocyte Lysate (LAL) assays. The threshold for PX1 Research 5ml bac water is verified at < 0.25 EU/mL. Gas Chromatography (GC) and High-Performance Liquid Chromatography (HPLC) are further utilized to confirm that benzyl alcohol concentration remains strictly within the target specification of 0.85% to 0.95% w/v.
Unopened vials of 5ml bac water should be stored at controlled room temperature between 20°C to 25°C (68°F to 77°F), shielded from direct light exposure and extreme thermal fluctuations. Freezing the diluent must be avoided, as ice crystal formation can alter benzyl alcohol distribution and potentially fracture the glass vial or compromise the rubber stopper integrity.
Once the flip-off cap is removed and the rubber septum is punctured, the 28-day laboratory countdown begins. Under standard laboratory safety protocols, any reconstituted solution containing benzyl alcohol should be refrigerated at 2°C–8°C and discarded 28 days post-puncture. Using smaller 5mL formats significantly reduces reagent waste in laboratories where high-volume 30mL vials would exceed their 28-day stability window prior to complete utilization.
A critical yet frequently overlooked variable in laboratory reagent handling is rubber septum coring. Repeated punctures using large-gauge needles (e.g., 18G–21G) can shear microscopic rubber particles off the vial stopper, introducing insoluble particulates into the reconstitution liquid. This particulate matter can interfere with spectrophotometric analysis, HPLC column pressure, or microfluidic assays.
To mitigate coring and maintain a pristine diluent supply, research personnel should utilize high-gauge laboratory needles (27G–30G) inserted at a 45-degree angle with the bevel facing up, transitioning to 90 degrees as the septum is penetrated. Distributing punctures across different quadrant areas of the 5ml vial septum further preserves the self-sealing elastomeric closure throughout its operational lifespan.
Reliable experimental outcomes require absolute batch-to-batch consistency. Sourcing diluents from unverified international vendors introduces risks of substandard preservative levels, heavy metal contamination, or elevated endotoxin loads. PX1 Research supplies USA-manufactured 5ml bac water produced in cGMP-compliant facilities.
Every batch is fully traceable and supplied with a downloadable Certificate of Analysis (COA) detailing HPLC purity verification, endotoxin testing results, and sterility screening. With dual dispatch hubs located in California and Arizona, PX1 Research provides same-day shipping (Monday–Friday) for orders placed before standard cutoff times, ensuring your laboratory maintains uninterrupted workflow integrity. For institutional purchases, laboratory setups, or bulk reagent contracts, explore our dedicated wholesale laboratory accounts or review our full catalog at the PX1 Research storefront.
What is the exact chemical composition of 5ml bac water?
5ml bac water consists of sterile, non-pyrogenic purified water for injection compounded with 0.9% (9 mg/mL) benzyl alcohol, which acts as a bacteriostatic preservative to inhibit microbial growth.
How long is 5ml bac water viable after the first septum puncture?
Following initial puncture, 5ml bac water is stable for up to 28 days when stored under refrigerated conditions (2°C to 8°C) in an aseptic laboratory environment.
Why is 0.9% benzyl alcohol preferred over other preservatives for peptide reconstitution?
A 0.9% benzyl alcohol concentration provides an optimal balance between effective broad-spectrum antimicrobial suppression and minimal chemical interaction with delicate peptide secondary structures.
Can 5ml bac water be frozen for long-term storage?
No. Freezing 5ml bac water can cause physical phase separation of the benzyl alcohol, stress the glass vial, and compromise the integrity of the elastomeric stopper seal. Store unopened vials at 20°C–25°C.
What is the difference between 5ml bac water and sterile water for injection (SWFI)?
5ml bac water contains 0.9% benzyl alcohol preservative to allow repeated multi-entry sampling over 28 days. SWFI contains no preservative and must be discarded immediately after a single use.
What endotoxin thresholds apply to PX1 Research 5ml bac water?
PX1 Research 5ml bac water is verified via Limulus Amebocyte Lysate (LAL) testing to contain endotoxin levels strictly below < 0.25 EU/mL, adhering to USP <85> standards for laboratory reagents.
Why choose 5mL vials instead of 30mL vials for research assays?
The 5mL format is ideal for smaller experimental series or low-frequency testing. It minimizes reagent waste by allowing laboratories to exhaust the vial within the 28-day post-puncture stability window.
Does PX1 Research provide lot-specific Certificates of Analysis (COA) for 5ml bac water?
Yes. Every batch of 5ml bac water supplied by PX1 Research includes a downloadable, lot-traceable COA verifying HPLC/GC preservative concentration, USP sterility, and endotoxin parameters.
All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.