Glossary
Insulin Syringe Units (U-100)
U-100 syringe marks measure volume: 100 units fill 1 mL, so one unit is 0.01 mL. The peptide amount per unit depends only on your own reconstitution.
The scale on a U-100 insulin syringe was designed around insulin strength: U-100 insulin packs 100 international units into 1 mL, so the graduations go from 0 to 100 over one millilitre and every unit corresponds to 0.01 mL. Smaller 0.5 mL barrels keep 0.01 mL per graduation and simply stop at 50.
Units are volume marks
The essential point: a unit marks a volume and says nothing about how much peptide is present. The link between a mark and an amount held only for insulin, whose strength is fixed at 100 units in each millilitre. With any reconstituted research peptide, the amount contained in ten units depends solely on the concentration created during reconstitution. Worked case: dissolve 5 mg in 2 mL to get 2.5 mg/mL, and 10 units (0.10 mL) contain 250 mcg, i.e. 25 mcg per single unit. Reconstituting that vial with 1 mL of solvent doubles this to 50 mcg per unit.
For this reason, record the vial concentration on the label rather than a number of units. Choosing a syringe also means considering gauge and barrel volume — our range includes 1 mL syringes in 31G and 0.5 mL syringes in 29G, and the guide to picking a syringe explains the trade-offs.
Related terms
micrograms vs milligrams · luer-lock fittings · our syringe and vial range