Bacteriostatic Water for Peptide Reconstitution: What Researchers Need to Know

Bacteriostatic water (BAC water) is the standard solvent used to reconstitute lyophilized research peptides. It looks identical to sterile water, but the difference matters for research integrity.

What makes it “bacteriostatic”?

Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth in a multi-use vial. This allows a single vial to be drawn from multiple times over its usable window without the same contamination risk as plain sterile water, which is intended for single use only.

How much do you need?

The right volume depends on the peptide’s mass and the target concentration for your research protocol. Under-diluting concentrates the peptide; over-diluting wastes material across more draws. Peptryn’s Peptide Reconstitution Calculator converts peptide mass and target dose into an exact BAC water volume and draw amount.

Reconstitution steps

Inject BAC water slowly down the inside wall of the vial rather than directly onto the lyophilized powder, then gently swirl — do not shake — until fully dissolved. Shaking can denature the peptide structure.

Storage after reconstitution

Once reconstituted, store at 2–8°C and use within the timeframe specified for that peptide (commonly 28 days). Avoid repeated freeze-thaw cycles, which degrade peptide integrity over time.

Peptryn’s BAC Water

Peptryn’s Bacteriostatic Water is research-grade, sterile, and sized for peptide reconstitution. Pair it with our Peptide Calculator to get exact draw volumes for any vial.

For laboratory research use only. Not for human consumption, self-administration, or veterinary use.