How to Reconstitute Research Peptides — UK Guide
Every lyophilised research peptide needs reconstitution with bacteriostatic water before it can be used in research. This guide walks through the process, the maths, and the common pitfalls — for Retatrutide, Semaglutide, Tirzepatide and any other peptide in our catalogue.
What you'll need
- Lyophilised peptide vial
- Bacteriostatic water 10ml
- 1ml insulin syringe (U-100 markings)
- Alcohol swabs
- Refrigerator for storage
Step-by-step
- Wipe both vial stoppers with an alcohol swab and let dry.
- Draw your chosen volume of bacteriostatic water (e.g. 2ml) into the syringe.
- Insert the needle into the peptide vial at an angle and inject the water slowly down the side wall — never aim straight at the powder.
- Remove the syringe and gently swirl the vial. Do not shake.
- Wait for the powder to dissolve fully into a clear solution.
- Label the vial with the date of reconstitution and store at 2–8°C.
Reconstitution table (1ml / 100 unit insulin syringe)
On a standard U-100 insulin syringe, 100 units = 1ml and 10 units = 0.1ml. Pick the row that matches your vial strength and how much bacteriostatic water you've added.
| Vial | Bac water | Per 1 unit | Per 10 units (0.1ml) | Units for 1mg |
|---|---|---|---|---|
| 5mg | 1ml | 50 mcg | 500 mcg | 20 |
| 10mg | 1ml | 100 mcg | 1 mg | 10 |
| 10mg | 2ml | 50 mcg | 500 mcg | 20 |
| 15mg | 1ml | 150 mcg | 1.5 mg | ~7 |
| 15mg | 2ml | 75 mcg | 750 mcg | ~13 |
| 20mg | 1ml | 200 mcg | 2 mg | 5 |
| 20mg | 2ml | 100 mcg | 1 mg | 10 |
| 30mg | 2ml | 150 mcg | 1.5 mg | ~7 |
| 30mg | 3ml | 100 mcg | 1 mg | 10 |
| 40mg | 2ml | 200 mcg | 2 mg | 5 |
| 40mg | 4ml | 100 mcg | 1 mg | 10 |
Example: a 15mg vial in 2ml of bacteriostatic water gives 75mcg per unit — so a 0.5mg research dose = ~7 units, and a 1mg dose = ~13 units on the U-100 scale.
Working out doses
Reconstitution maths is simple but easy to get wrong. Use our free peptide reconstitution calculator — enter your vial mg, the volume of bacteriostatic water added and your target dose, and it returns the exact syringe units to draw.
Storage rules
- Lyophilised (unmixed): stable long-term in a freezer, months at fridge temperature.
- Reconstituted: 2–8°C in the fridge, use within 28 days.
- Keep out of direct light. Avoid repeated freeze-thaw cycles.
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View full shopFrequently asked questions
How much bacteriostatic water do I add?
Common volumes are 1ml, 2ml, 3ml or 4ml depending on the vial strength and the dose units you want per syringe mark. Use our peptide calculator for an exact figure for any peptide.
How long does reconstituted peptide last?
Once reconstituted with bacteriostatic water, peptides should be stored at 2–8°C (refrigerated) and used within 28 days. The benzyl alcohol in bac water acts as a preservative.
Can I use sterile water instead of bacteriostatic water?
Sterile water has no preservative — it should only be used for single-use reconstitution. For multi-use vials, bacteriostatic water (which contains 0.9% benzyl alcohol) is the correct choice.
What syringe should I use?
Insulin syringes (typically 1ml / 100 unit U-100 markings) are standard for research peptide work because the unit graduations make small-volume measurement straightforward.
Why does my vial fizz when I add water?
If you add water too forcefully you can denature the peptide. Always run the bacteriostatic water slowly down the inside wall of the vial and gently swirl — never shake.
Disclaimer: All products sold by Peptides UK 4U are for laboratory and research purposes only. They are not intended for human or animal consumption, diagnosis, treatment or prevention of any disease.