Reconstitution in the lab
Bacteriostatic Water for Peptides
Bacteriostatic water for peptides is the solvent that turns a lyophilised peptide into a solution in the lab. Its 0.9% benzyl alcohol lets the vial be opened several times within 28 days.
- 0.9%
- benzyl alcohol
- 3 mL
- per vial
- 28 days
- after first puncture
- 4.5–7.0
- pH range (USP)
Its role as a solvent
Research peptides usually arrive as a lyophilised powder, which is more stable for storage and transport. Before use in a protocol, the powder has to be dissolved.
Bacteriostatic water is the most common choice when the solution will be sampled several times. The benzyl alcohol keeps bacteria from growing in the vial between draws.
| Solvent | Typical lab use |
|---|---|
| Bacteriostatic water (0.9% benzyl alcohol) | Peptides that tolerate the preservative and will be sampled over several weeks |
| Sterile water | Alcohol-sensitive peptides, or a solution used in one step |
| Acetic acid 0.6% | Basic peptides that dissolve poorly in water alone |
Peptides sensitive to benzyl alcohol
Not every peptide tolerates benzyl alcohol. With some sequences and proteins it can cause aggregation or reduce activity.
The data sheet from the peptide supplier is the reference. If it recommends sterile water, a buffer or dilute acetic acid, follow it.
Where to buy
OXpeptides
Bac Water 3 mL
€10.90
- 3 mL glass vial, 0.9% benzyl alcohol
- Delivered in 4–6 working days, shipped from Europe
- Shipping €9.90, free on orders over €120
- 30-day returns, full refund
This water is sold and shipped by OXpeptides, from a warehouse in Europe.
Good handling practice
Peptides are fragile molecules, and rough handling can break them apart. A few habits protect the solution.
- Wipe both stoppers with 70% alcohol and let them dry.
- Let the liquid run down the inside wall of the vial, not onto the powder.
- Swirl gently until the powder has dissolved. Never shake.
- Label the vial with the opening date and its contents.
Storing the solution
Keep the reconstituted solution in the fridge at 2–8 °C, protected from light. Its stability depends on the peptide, so check the supplier data sheet.
The vial of bacteriostatic water itself must be used within 28 days of its first puncture. A 3 mL vial avoids keeping an opened bottle past that limit.
Common questions
Can you mix peptides with bacteriostatic water?
Yes, for most peptides it is the standard lab solvent. Some are sensitive to benzyl alcohol, so check the supplier data sheet first.
Should you shake a peptide vial after adding water?
No. Shaking can damage the peptide. Swirl the vial gently or let it stand until the powder has dissolved.
How long does a reconstituted peptide keep?
It depends on the peptide. Store the solution at 2–8 °C away from light and follow the stability data from the supplier.
Is sterile water better for peptides?
Only for peptides that react to benzyl alcohol, or when the solution is used in one step. Otherwise bacteriostatic water is more practical for repeated sampling.