PeptideCompareBacteriostatic water & sterile technique
Bacteriostatic water is not the same as sterile water, saline, or water for injection. Using the wrong reconstitution liquid is one of the most common handling mistakes. This guide explains what BAC water is and why it matters.
What is bacteriostatic water?
Bacteriostatic water is sterile water for injection containing 0.9% benzyl alcohol as a preservative. Benzyl alcohol inhibits bacterial growth — it does not kill bacteria already present, but prevents new bacteria from colonising the solution after the vial is opened. This makes it suitable for multi-dose vials: unlike plain sterile water, BAC water remains stable for research use after being punctured multiple times.
| LIQUID | PRESERVATIVE | MULTI-DOSE? | NOTES |
|---|---|---|---|
| BAC water | 0.9% benzyl alcohol | Yes | Standard for peptide reconstitution |
| Sterile WFI | None | Single-use | Use entire vial at once |
| 0.9% saline | None | Single-use | Acceptable alternative same session |
| Tap / distilled | None | Never | Not sterile — do not use |
5-step sterile technique
Wet IPA does not disinfect. Allow 30 seconds to air-dry.
One fresh alcohol swab per vial. Both BAC water and peptide vial.
Handle syringes by the barrel only. Contaminated needle = contaminated vial.
Never inject directly onto the cake. Swirl gently — do not shake.
Refrigerate, do not freeze. Use within 4–6 weeks (vendor BUD).
Potency retained over time
Each line is one storage condition: it starts at 100% and falls as potency is lost. Above the dashed 80% line the material is considered reliable — hover for exact values.
⚠ Modelled per compound from molecular structure — chain length, cyclisation, oxidation- and deamidation-prone residues and light sensitivity. Indicative only, not lab-measured per batch.