Peptide Reconstitution Calculator

How peptide reconstitution is calculated

Reconstitution is the step where a lyophilised (freeze-dried) peptide is dissolved in a measured volume of bacteriostatic water so a precise amount can be drawn for research. The calculator uses three figures — the peptide mass in the vial, the volume of water added, and the dose you want to draw — to return everything you need to measure it on an insulin syringe.

The formula

• Concentration = total peptide (mcg) ÷ water volume (mL). A 5 mg vial reconstituted with 2 mL gives 5000 mcg ÷ 2 mL = 2500 mcg/mL.
• Volume to draw = desired dose (mcg) ÷ concentration (mcg/mL). For a 250 mcg dose at 2500 mcg/mL that is 0.1 mL.
• Units on the syringe = volume to draw (mL) × the syringe's units per mL. On a U-100 syringe, 0.1 mL is 10 units.
• Doses per vial = total peptide (mcg) ÷ desired dose (mcg).

A worked example

Take a 10 mg vial reconstituted with 2 mL of bacteriostatic water. The concentration is 10,000 mcg ÷ 2 mL = 5000 mcg/mL. To draw a 500 mcg research measurement you would draw 500 ÷ 5000 = 0.1 mL, which is 10 units on a U-100 insulin syringe, giving 20 measurements per vial.

Choosing a reconstitution volume

More water makes each unit on the syringe correspond to less peptide, which makes small measurements easier to draw accurately; less water concentrates the solution. Many researchers pick a water volume that makes the target dose land on a round number of units. Always confirm figures against the vial's certificate of analysis and store the reconstituted vial according to our storage guidance.