What Is Bacteriostatic Water?
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, a preservative that suppresses bacterial growth. That is what allows a reconstituted peptide vial to be entered more than once. Plain sterile water has no preservative, so it is intended for single use.
| Bacteriostatic water | Sterile water | |
|---|---|---|
| Contents | Sterile water + 0.9% benzyl alcohol | Sterile water only |
| Preservative | Yes (benzyl alcohol inhibits bacterial growth) | None |
| Vial use | Multi-use | Single use |
| Typical use in the lab | Reconstituting a vial used over several days | One-time reconstitution |
How Much Bacteriostatic Water to Add to a Peptide Vial
There is no single correct volume; pick one that gives a concentration that is easy to work with. Divide the peptide's milligrams by the water's millilitres. The chart covers the vial sizes researchers ask about most:
| Vial | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 5mg | 5 mg/mL | 2.5 mg/mL | 1.67 mg/mL |
| 10mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL |
| 15mg | 15 mg/mL | 7.5 mg/mL | 5 mg/mL |
| 20mg | 20 mg/mL | 10 mg/mL | 6.67 mg/mL |
| 30mg | 30 mg/mL | 15 mg/mL | 10 mg/mL |
| 50mg | 50 mg/mL | 25 mg/mL | 16.67 mg/mL |
| 80mg | 80 mg/mL | 40 mg/mL | 26.67 mg/mL |
A 10mg vial reconstituted with 2 mL of bacteriostatic water holds 10 ÷ 2 = 5 mg/mL. The same vial with 1 mL holds 10 mg/mL, and with 3 mL holds 3.33 mg/mL. For any other combination, use the reconstitution calculator.
How Much Bac Water for a 10mg Vial?
For a 10mg vial, 1 mL gives 10 mg/mL, 2 mL gives 5 mg/mL and 3 mL gives 3.33 mg/mL. 2 mL is a common choice because it produces a round 5 mg/mL figure. Evo Peptides' 10mg vials include BP-157, MT-1, MT-2, SLK and SMX.
How to Reconstitute a Lyophilized Peptide
- Let both vials reach room temperatureCold vials form condensation and are harder to mix.
- Wipe both stoppersUse an alcohol swab on each rubber stopper.
- Add the water slowly down the vial wallAim at the glass, not directly onto the powder.
- Swirl gently; do not shakeShaking can foam and damage some peptides.
- Label the vialWrite the concentration and reconstitution date.
- Refrigerate at 2–8 °CStore reconstituted vials cold and away from light.
Buying Bacteriostatic Water: Evo H2O
Evo H2O is bacteriostatic water with 0.9% benzyl alcohol, sold in 3 mL and 10 mL vials. The 10 mL size covers five vials at 2 mL each.
| Size | Price | Reconstitutes (at 2 mL per vial) |
|---|---|---|
| 3 mL | $6.95 | 1 vial |
| 10 mL | $19.95 | 5 vials |
| Test | Result |
|---|---|
| Identity | Benzyl alcohol confirmed |
| Assay | 99.90% |
| Endotoxin | 0.084 EU/mL |
How Long Does Reconstituted Peptide Last?
Stability depends on the peptide, but reconstituted vials should be refrigerated at 2–8 °C, protected from light, and used within weeks, not months. Multi-dose vials of bacteriostatic water are commonly discarded 28 days after first puncture. Peptide-by-peptide data is in the peptide storage guide.