Bacteriostatic Water: A Reconstitution Reference

Reconstitution is a small step that carries outsized risk. Rushing it introduces contamination, denatures peptide, or produces a solution at the wrong concentration, and all three problems surface later as unexplained variability.

Bacteriostatic vs. sterile water

Sterile water contains no preservative and is intended for single use. Bacteriostatic water contains a small percentage of benzyl alcohol, which inhibits bacterial growth and makes multi-draw use from a single vial practical over a longer window. For laboratory work involving repeated aliquots from the same reconstituted vial, bacteriostatic water is the common choice.

Calculating your volume

Concentration is simply peptide mass divided by diluent volume. A 10 mg vial reconstituted with 2 mL of bacteriostatic water yields 5 mg per mL. Reconstituting the same vial with 1 mL yields 10 mg per mL. Decide the concentration your protocol calls for before you open anything, and write it on the vial afterward.

Technique

• Let the vial reach room temperature before adding diluent.
• Wipe both stoppers with an alcohol prep pad and allow them to dry.
• Angle the needle so the stream runs down the inner wall of the vial rather than jetting directly onto the peptide cake.
• Do not shake. Swirl gently, or let the vial rest until the cake dissolves on its own.
• Inspect the solution, it should be clear and free of particulates.

After reconstitution

Refrigerate the vial, keep it out of light, and record the date. Most reconstituted research peptides are used within a matter of weeks; the specific window depends on the compound and the storage condition.

This reference is provided for laboratory and research purposes only. Products are not for human or animal consumption.