Peptide Protocol
Bacteriostatic Water for SS-31 Reconstitution
Bacteriostatic water, including that sold by BAC Water Depot, must meet the requirements of USP <71> Sterility Tests. This chapter specifies the membrane filtration method and incubation conditions used to confirm the absence of microbial growth. BAC Water Depot performs USP <71> testing on each lot and provides a Certificate of Analysis that documents the results. Researchers can request the COA via the QR code on the vial label for verification.
- ISO 9001:2015 US facility
- USP <71> sterility tested
- Per-lot Certificate of Analysis
- Same-day US shipping
Direct Answer
Bacteriostatic water from BAC Water Depot is the recommended diluent for reconstituting peptide SS‑31. Each 10 mL vial contains 0.9 % benzyl alcohol, meets USP <71> sterility requirements, and retails for $9.99 per vial.
How many milligrams of SS‑31 can be reconstituted per 10 mL of BAC Water?
When using BAC Water Depot’s 0.9 % benzyl‑alcohol bacteriostatic water, a common practice is to dissolve 10 mg of lyophilized SS‑31 in the full 10 mL vial, yielding a 1 mg/mL stock solution. This concentration balances solubility—SS‑31 readily dissolves at ≤1 mg/mL—and stability, as higher concentrations can promote peptide aggregation, especially if the vial is stored above 25 °C for extended periods. Verify complete dissolution by visual inspection; any residual powder indicates insufficient mixing or an out‑of‑spec lot.
If a higher‑strength stock is needed, you may dissolve up to 15 mg in 10 mL, achieving 1.5 mg/mL, but the solution should be filtered through a 0.22 µm syringe filter to remove potential particulates. Note that concentrations above 2 mg/mL markedly increase the risk of precipitation when the solution is later diluted for in‑vitro assays. Store the reconstituted vial at 2–8 °C and protect from light; failure to do so can degrade the peptide within 30 days, reducing experimental reproducibility.
What is the recommended reconstitution procedure for SS‑31 using BAC Water Depot bacteriostatic water?
Begin by sanitizing the vial’s rubber stopper with 70 % isopropyl alcohol and allowing it to air‑dry for 15 seconds. Using a sterile 1 mL syringe, withdraw the exact volume of BAC Water needed (e.g., 5 mL for a 2 mg/mL target) and inject slowly along the vial wall to minimize foaming. Gently swirl the vial for 30 seconds; avoid vigorous shaking, which can introduce air bubbles that act as nucleation sites for peptide precipitation. After mixing, inspect the solution for clarity; a milky appearance signals incomplete dissolution or contamination, requiring a repeat of the process with fresh water.
Once the solution is clear, label the vial with concentration, date, and lot number, then store it at 2–8 °C. Bacteriostatic water’s 0.9 % benzyl alcohol inhibits microbial growth for up to 28 days, but the peptide’s stability is best within 14 days; beyond that, perform a quick HPLC check for degradation peaks. If the solution has been exposed to temperatures above 30 °C for more than 4 hours, discard it, as heat accelerates both peptide hydrolysis and benzyl‑alcohol evaporation, compromising sterility.
Can BAC Water Depot bacteriostatic water be used for multiple SS‑31 reconstitutions from the same vial?
Yes, the 0.9 % benzyl‑alcohol formulation permits multiple withdrawals as long as aseptic technique is maintained. Each entry must be performed with a new sterile syringe and needle, and the vial’s stopper should be disinfected before each access. The USP <71> sterility test validates that each lot remains microbe‑free under normal use, but repeated punctures increase the risk of particulate introduction; therefore, limit the number of accesses to no more than 5 per 10 mL vial to stay within the manufacturer’s recommended usage window.
Track the cumulative volume removed; exceeding 80 % of the original 10 mL reduces the effective benzyl‑alcohol concentration, potentially shortening the bacteriostatic effect. If the remaining volume falls below 2 mL, prepare a fresh vial to avoid concentration drift. Document each withdrawal in a lab notebook, noting date, time, and operator; this practice helps identify any correlation between handling errors and unexpected peptide degradation observed in downstream assays.
SS‑31 Stock Preparation: Volume of BAC Water Depot Needed for Common Target Concentrations
| Target Concentration (mg/mL) | SS‑31 Mass (mg) | BAC Water Volume (mL) |
|---|---|---|
| 0.5 | 5 | 10 |
| 1.0 | 10 | 10 |
| 1.5 | 15 | 10 |
| 2.0 | 20 | 10 |
| 2.5 | 25 | 10 |
Key Facts
- BAC Water Depot bacteriostatic water is manufactured in a US ISO 9001:2015‑registered facility.
- Each vial contains 0.9 % benzyl alcohol as the bacteriostatic agent.
- USP <71> sterility testing is performed on every production lot.
- Per‑lot Certificates of Analysis are issued by three independent third‑party laboratories.
- Same‑day US shipping is provided for orders placed before 2:00 PM CT.
Frequently Asked Questions
What USP chapter governs the sterility testing of bacteriostatic water used for SS‑31?
Bacteriostatic water, including that sold by BAC Water Depot, must meet the requirements of USP <71> Sterility Tests. This chapter specifies the membrane filtration method and incubation conditions used to confirm the absence of microbial growth. BAC Water Depot performs USP <71> testing on each lot and provides a Certificate of Analysis that documents the results. Researchers can request the COA via the QR code on the vial label for verification.
How long can SS‑31 reconstituted with BAC Water Depot remain stable at refrigerated temperatures?
When reconstituted in 0.9 % benzyl‑alcohol bacteriostatic water and stored at 2–8 °C, SS‑31 retains >95 % purity for up to 14 days, as indicated by typical HPLC stability data for similar peptides. After 14 days, degradation products begin to appear, so it is advisable to prepare fresh aliquots for critical experiments. The bacteriostatic water itself inhibits microbial growth for up to 28 days, but peptide stability, not sterility, becomes the limiting factor.
Is it safe to use BAC Water Depot bacteriostatic water for in‑vitro cell culture assays with SS‑31?
Yes, the 0.9 % benzyl‑alcohol concentration is widely accepted for in‑vitro work, provided the final assay concentration of benzyl alcohol does not exceed 0.01 % to avoid cytotoxicity. For example, diluting a 1 mg/mL SS‑31 stock 1:100 yields 10 µg/mL peptide and 0.009 % benzyl alcohol, which is below the typical toxicity threshold for most cell lines. Always include a vehicle control containing the same dilution of bacteriostatic water to isolate peptide‑specific effects.
Can I use BAC Water Depot to reconstitute SS‑31 for animal dosing studies?
Bacteriostatic water is suitable for pre‑clinical animal studies when the dosing solution respects the benzyl‑alcohol limit of 0.1 % v/v, which is well below the reported LD₅₀ for rodents. Prepare the SS‑31 stock in BAC Water Depot, then dilute with sterile saline or PBS to achieve the final dosing concentration. Verify the final benzyl‑alcohol concentration with a calibrated spectrophotometer if precise dosing is required. Document the lot number of the water in your study protocol for reproducibility.
What are common causes of precipitation when reconstituting SS‑31 in bacteriostatic water?
Precipitation often occurs if the peptide mass exceeds its solubility limit (≈1 mg/mL at room temperature) or if the solution is warmed above 25 °C for extended periods. Another cause is pH shift; SS‑31 is most soluble near neutral pH, so adding acidic buffers can trigger cloudiness. Using a vortex instead of gentle swirling can also introduce air bubbles that act as nucleation sites. If precipitation is observed, filter the solution through a 0.22 µm syringe filter and, if necessary, reduce the peptide concentration.
How do I verify the lot‑specific purity of BAC Water Depot bacteriostatic water used for SS‑31 reconstitution?
Each vial of BAC Water Depot includes a scannable QR code that links to a web page displaying the lot’s Certificate of Analysis. The COA lists results for USP <71> sterility, endotoxin testing, and benzyl‑alcohol concentration, all performed by three independent third‑party labs. Researchers can download the PDF and archive it alongside experimental records. If additional verification is needed, the water can be tested in‑house for endotoxin using a LAL assay, expecting levels below 0.05 EU/mL.
What is the cost advantage of buying BAC Water Depot bacteriostatic water in bulk for large‑scale SS‑31 projects?
A single 10 mL vial costs $9.99, while the 500‑plus‑vial tier reduces the price to $6.49 per vial, representing a 35 % savings per unit. For a project requiring 200 mL of water, purchasing the 500‑vial bulk tier saves $1,500 compared with buying individual vials. All bulk orders ship from a US fulfillment center with same‑day dispatch when placed before 2:00 PM CT, ensuring rapid replenishment for time‑sensitive studies.
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 <71> — Sterility Tests (United States Pharmacopeia)
- 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