MONOGRAPH No. 041
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🧪 Handling & Reference
Bacteriostatic 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.
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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.
RECONSTITUTION LIQUIDS COMPARED
| 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
1
Clean workspace with 70% IPA — let dry
Wet IPA does not disinfect. Allow 30 seconds to air-dry.
Wet IPA does not disinfect. Allow 30 seconds to air-dry.
2
Swab both vial tops — let dry
One fresh alcohol swab per vial. Both BAC water and peptide vial.
One fresh alcohol swab per vial. Both BAC water and peptide vial.
3
Never touch the needle tip
Handle syringes by the barrel only. Contaminated needle = contaminated vial.
Handle syringes by the barrel only. Contaminated needle = contaminated vial.
4
Add BAC water slowly down the glass wall
Never inject directly onto the cake. Swirl gently — do not shake.
Never inject directly onto the cake. Swirl gently — do not shake.
5
Store reconstituted vials at 2–8°C immediately
Refrigerate, do not freeze. Use within 4–6 weeks (vendor BUD).
Refrigerate, do not freeze. Use within 4–6 weeks (vendor BUD).
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Bacteriostatic water tracked from EU vendors.
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