Peptide Reconstitution Basics: Concentration, Draw Volume, and Units

Reconstitution math describes a lyophilized (freeze-dried) vial after a volume of water is added to it. Three figures follow from the amount in the vial, the water volume entered and an amount entered:

• Concentration: the vial amount divided by the water volume, in mg per mL.
• Draw volume: the amount entered divided by the concentration, in mL.
• Syringe units: the draw volume multiplied by the syringe scale's units per mL (U-100, U-40 or U-30).

The Peptide Reconstitution Calculator computes all three from the vial amount, the water volume and the amount entered. For how the water volume changes each figure, see water volume and concentration.

Worked example: one draw volume on three scales

These are illustrative round numbers, not amounts for any product.

Inputs: a vial of 10 mg, a water volume of 2 mL and an amount of 1 mg.

• 10 mg ÷ 2 mL computes to 5 mg/mL.
• An amount of 1 mg ÷ 5 mg/mL computes to 0.2 mL.
• On a U-100 scale, 0.2 mL × 100 units per mL computes to 20 units; on U-40, 0.2 mL × 40 computes to 8 units; on U-30, 0.2 mL × 30 computes to 6 units.

How the scale enters the arithmetic

Syringe scales are marked in units, not mL, and the units per mL differ by scale: 100 on U-100, 40 on U-40 and 30 on U-30. The same volume therefore reads as a different number of units on each scale, as in the example above. The mL figure is the same on every scale; only the unit reading changes.