How do I reconstitute a lyophilized peptide?

Reconstituting a peptide means dissolving the freeze-dried powder in bacteriostatic water (BAC water). Use a clean syringe to draw 1–2 mL of BAC water and inject it slowly down the side of the vial. Never inject directly onto the powder. Gently swirl — do not shake. Store at 2–8°C after reconstitution.

What is bacteriostatic water and why is it used?

Bacteriostatic water (BAC water) is sterile water containing 0.9% benzyl alcohol. The benzyl alcohol prevents bacterial growth, making the reconstituted peptide solution stable for multi-use research over weeks. Standard sterile water has no preservative and must be used immediately.

How many units should I draw on an insulin syringe?

On a U-100 insulin syringe, 100 units = 1 mL. To find your syringe units: divide your desired dose (mcg) by the concentration (mcg/mL), then multiply by 100. Example: 250 mcg ÷ 2500 mcg/mL × 100 = 10 units. Use this calculator to compute it automatically.

How much bacteriostatic water should I add to a 5mg peptide vial?

For a 5mg (5000 mcg) peptide vial, adding 2 mL of BAC water gives a concentration of 2500 mcg/mL — a common working concentration. For smaller doses (under 100 mcg), add 2.5 mL to get 2000 mcg/mL, making the injection volume easier to measure precisely.

How long does a reconstituted peptide last?

A peptide reconstituted in bacteriostatic water is typically stable for 2–4 weeks when stored refrigerated at 2–8°C and protected from light. Lyophilized (freeze-dried) peptides stored at −20°C maintain stability for 1–2 years. Once reconstituted, do not refreeze.

Research Tool

Peptide Reconstitution
& Dosage Calculator

Enter your vial size, bacteriostatic water volume, and desired dose. Instantly see concentration, injection volume, and the exact units to draw on a U-100 insulin syringe.

Calculator Inputs

Quick-fill a peptide preset:

Reconstitution

Peptide Vial Size (mg)

The amount printed on the vial label (e.g. 5mg, 10mg)

Bacteriostatic Water Added (mL)

How much sterile bacteriostatic water you'll inject into the vial

Dosage

Desired Dose (mcg)

Your target dose in micrograms (1mg = 1000mcg)

Syringe Type

Most insulin syringes are U-100 (100 units = 1mL)

Results

Concentration — mcg / mL

Amount of peptide per 1mL of solution

Injection Volume — mL per dose

Volume to draw for your desired dose

Syringe Units to Draw — units on syringe

Fill to this number on the barrel

Total Doses per Vial — doses

Full doses at your chosen amount

Enter your values and press Calculate

How to Read a U-100 Insulin Syringe

The numbers on the barrel are "units." On a U-100 syringe, 100 units = 1mL — the most common syringe type used in peptide research.

Find the unit markings

Each line on the barrel is units. Major marks at 10, 20, 30… up to 100. Minor marks every 2 units.

Draw to the correct line

Pull the plunger until the bottom of the rubber stopper aligns with your target unit number.

Units ≠ mg ≠ mcg

Units measure volume, not mass. The calculator converts your mcg dose to units based on concentration.

Small dose = tiny volume

250mcg at 2500mcg/mL = 10 units. If under 5 units, add more BAC water to make measuring easier.

Cart

Peptide Reconstitution
& Dosage Calculator

Calculator Inputs

Results

Draw to this line on your syringe

How this was calculated

How to Read a U-100 Insulin Syringe

Find the unit markings

Draw to the correct line

Units ≠ mg ≠ mcg

Small dose = tiny volume

Peptide Reconstitution& Dosage Calculator

Calculator Inputs

Results

Draw to this line on your syringe

How this was calculated

How to Read a U-100 Insulin Syringe

Find the unit markings

Draw to the correct line

Units ≠ mg ≠ mcg

Small dose = tiny volume

Peptide Reconstitution
& Dosage Calculator