Bacteriostatic Water

Bacteriostatic Water

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative. The preservative is what separates it from plain sterile water: it suppresses bacterial growth in the vial, so a reconstituted peptide can be drawn from more than once instead of being made up fresh each time.

1. 1What it is for

   It is the standard diluent for reconstituting lyophilised research peptides. The freeze-dried powder is dissolved by adding the water slowly down the inside wall of the vial, then swirling — never shaking — until it is clear. How much to add depends on the concentration you are working to; the reconstitution calculator works it out for you.

2. 2The 28-day window

   Once a bacteriostatic water vial is first punctured, the accepted working life is 28 days refrigerated. That is a property of the preservative, not of the peptide in it — a reconstituted peptide has its own, usually shorter, stability. Date the vial when you first pierce the stopper.

3. 3Handling

   Store unopened vials at room temperature, away from light. Wipe the stopper with an alcohol swab before every draw. Do not use a vial that is cloudy, discoloured or past its printed expiry, and do not decant it into another container.