Quality Assurance
How HPLC Measures Benzyl Alcohol in Bacteriostatic Water
The net content indicates the measured concentration of benzyl alcohol in the water, expressed as a percentage weight/volume. This figure is derived from an HPLC-UV assay that quantifies benzyl alcohol against certified standards. If the reported value falls outside the accepted range, the lot is not released for distribution.
- ISO 9001:2015 US facility
- USP <85> endotoxin tested
- Per-lot Certificate of Analysis
- Same-day US shipping
Direct Answer
BAC Water Depot’s bacteriostatic water is quantified for benzyl alcohol by HPLC‑UV, which reports a net content of 0.9 % w/v per lot’s Certificate of Analysis. Purity is verified at ≥ 98 % by the same HPLC method and the product ships same‑day from Dallas for orders placed before 2:00 PM CT.
How does HPLC‑UV determine benzyl alcohol content in bacteriostatic water?
The HPLC‑UV method separates benzyl alcohol from the aqueous matrix using a reverse‑phase C18 column with a mobile phase of 60 % water and 40 % acetonitrile, buffered to pH 3.0 with phosphoric acid. A UV detector set at 210 nm measures peak area, which is compared to a calibration curve prepared from certified benzyl‑alcohol standards (0.5 %–1.5 % w/v). The assay’s limit of quantitation is 0.05 % w/v, ensuring the label claim of 0.9 % w/v is accurately verified for each lot.
Method validation includes repeatability (≤ 2 % RSD) and specificity, confirming that no excipient peaks interfere with the benzyl-alcohol signal. A common failure mode is column fouling from repeated injections of unfiltered samples, which can shift retention time and inflate the apparent concentration. Each sample is filtered before injection, and the column is regenerated after a set number of injections. The independent third-party lab documents these validation parameters on the lot’s CoA.
What are the acceptance criteria for benzyl alcohol net content in the CoA?
For example, a lot may report 0.88 % w/v, which is within the acceptable range (0.85–0.95 %). The CoA also includes the purity result from HPLC-UV (≥ 98 %) and a chromatogram showing a single, well-resolved benzyl-alcohol peak with a retention time of 3.2 ± 0.1 minutes. Any result outside these limits triggers a lot-rejection and re-analysis before release.
If the net content falls below the lower limit, the lot is flagged for investigation, often due to incomplete mixing during vial filling. In practice, the manufacturer adjusts the mixing time and verifies homogeneity by sampling multiple vials from the same lot. The independent laboratory repeats the assay on a second vial to confirm the anomaly before a final decision. All accepted lots carry a QR‑code linking directly to the published CoA at bacwaterdepot.com/coa/<lot-number>.
Can HPLC‑UV detect degradation products of benzyl alcohol in bacteriostatic water?
The validated HPLC‑UV method includes a forced‑degradation study that monitors for known benzyl‑alcohol breakdown products such as benzoic acid and benzaldehyde. These degradants elute at distinct retention times (≈ 4.5 min for benzoic acid, ≈ 5.1 min for benzaldehyde) and are detected at 254 nm. The method’s limit of detection for each degradant is 0.01 % w/v, allowing the laboratory to confirm that no significant degradation has occurred during storage. The CoA reports “No detectable degradants” when peak areas are below the reporting threshold.
A frequent source of false-positive degradant peaks is the use of acidic mobile phases that can generate artefacts from column bleed. To mitigate this, the lab employs a silica-based guard column and verifies baseline stability before each batch run. This rigorous approach ensures that the 0.9 % w/v benzyl-alcohol remains chemically intact throughout the product’s shelf life.
Typical HPLC‑UV assay results for BAC Water Depot bacteriostatic water (per lot)
| Lot | Benzyl Alcohol Net Content (% w/v) | Purity (% by HPLC‑UV) | Degradants Detected | pH (reported) |
|---|---|---|---|---|
| 2023‑A01 | 0.89 | 99.1 | None | 5.2 |
| 2023‑B07 | 0.91 | 98.7 | None | 4.8 |
| 2024‑C03 | 0.90 | 99.3 | None | 5.0 |
| 2024‑D12 | 0.88 | 98.9 | None | 4.9 |
Key Facts
- BAC Water Depot bacteriostatic water contains 0.9 % w/v benzyl alcohol as a preservative.
- Purity of the water is verified at ≥ 98 % by HPLC‑UV on each lot.
- Each lot’s Certificate of Analysis is generated by an independent third‑party laboratory and accessed via a QR code.
- Unopened vials store at controlled room temperature 15–30 °C, no refrigeration and no cold‑chain shipping.
- Once punctured, vials should be refrigerated at 2–8 °C and discarded after 28 days.
Frequently Asked Questions
What does the benzyl alcohol net content mean on a bacteriostatic water CoA?
The net content indicates the measured concentration of benzyl alcohol in the water, expressed as a percentage weight/volume. This figure is derived from an HPLC-UV assay that quantifies benzyl alcohol against certified standards. If the reported value falls outside the accepted range, the lot is not released for distribution.
How is purity defined for bacteriostatic water in the HPLC assay?
Purity refers to the proportion of the water that is free of impurities, measured by the area of the benzyl‑alcohol peak relative to the total chromatographic signal. BAC Water Depot requires a purity of at least 98 % as determined by HPLC‑UV at 210 nm. The assay also confirms that no extraneous peaks exceed the detection limit of 0.01 % w/v. The purity result is listed on the lot’s CoA alongside the benzyl‑alcohol net content.
Can I rely on the HPLC‑UV benzyl alcohol assay for quantitative research work?
Yes. The HPLC‑UV method used by the independent laboratory provides a limit of quantitation of 0.05 % w/v and a repeatability of ≤ 2 % relative standard deviation. These performance characteristics make the assay suitable for quantitative research that requires precise knowledge of preservative concentration. Researchers should still verify the assay’s suitability for any specialized analytical protocol.
What is the typical price for a single vial of BAC Water Depot bacteriostatic water?
A single 10 mL vial of BAC Water Depot bacteriostatic water is priced at $9.99. Bulk pricing reduces the cost per vial, for example a 25‑pack is $174.99, which works out to $6.99 per vial. All prices are listed on the website and include the same independent CoA documentation for each lot.
How long can I store punctured bacteriostatic water before it must be discarded?
After a vial is punctured, it should be refrigerated at 2–8 °C and used within 28 days. This recommendation is based on the preservative efficacy of the 0.9 % benzyl alcohol and the microbial analysis performed on each lot. The expiration date printed on the label and the CoA provides the final discard point for unopened vials.
Where can I buy BAC Water Depot bacteriostatic water for peptide research?
BAC Water Depot sells research‑use‑only bacteriostatic water directly through its website. Orders placed before 2:00 PM CT Monday–Friday ship the same business day from Dallas, TX via USPS Priority Mail (1–3 business days). Free standard shipping is offered on orders over $250 up to 100 vials, making it a convenient source for researchers needing reliable, ISO‑registered product.
Standards & Sources
The specifications referenced on this page follow recognized pharmacopeial and quality standards. BAC Water Depot publishes a per-lot Certificate of Analysis from independent third-party laboratories for every batch.
- USP <85> — Bacterial Endotoxins Test (LAL method)
- ISO 9001:2015 — Quality Management Systems certification
- Benzyl alcohol 0.9% w/v — the bacteriostatic preservative standard for multi-dose vials