What the quantity describes
The quantity printed on a vial (for example, a milligram figure) is the amount of material the vial is intended to contain. It is a statement of quantity, not of concentration or of any effect. For a lyophilised material, the same quantity can be reconstituted to different concentrations depending on how much diluent is added.
Quantity and concentration
Concentration links the quantity of material to the volume it is dissolved in. That is why the fill quantity is a starting point for laboratory calculations, and why a concentration calculator asks for both a material quantity and a diluent volume.
Reading the label together with documentation
The vial label states the quantity; specification documentation, where supplied, provides further detail. Values that are not stated should not be assumed.
Frequently asked questions
Does a bigger quantity mean a stronger material?
No. Quantity is how much material is present, not a measure of strength or effect.
How does fill quantity relate to concentration?
Concentration depends on both the quantity of material and the volume of diluent used to dissolve it.