Handling and measurement
Concentration
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How much material sits in a given amount of liquid, usually written as milligrams per millilitre. It is a ratio, so it needs both numbers to exist at all. A vial of powder has no concentration until liquid goes in; at that moment the quantity printed on the label and the volume you added together fix it. As an illustration of the arithmetic only, 5 mg of powder dissolved in 2 mL gives 2.5 mg in every millilitre.
Why it matters here
Concentration is the bridge between a mark on a syringe and an amount of material. Without it a syringe reading is a volume and nothing more. It is also the number nobody else can supply for you, because it depends entirely on how much liquid you personally added to your own vial.
What it is not
The figure printed on the vial is the total quantity inside, not the concentration. A label reading 5 mg means the whole vial holds 5 mg however much water you later add, so two vials with identical labels can end up at completely different concentrations, and a concentration copied from someone else's vial does not describe yours.
Also called
- concentration
- strength
- mg/ml
- mg per ml
- mcg/ml
- how strong
- dilution
Strength is the everyday word for the same idea and mg/mL is how it is written. People also speak of a vial being dosed at a concentration, which merges two different things: concentration is a property of the liquid in the glass and says nothing about any amount taken from it.
Compounds carrying this term
None on file yet. This term is in the controlled vocabulary but no compound record currently uses it — which is a statement about our coverage, not about the term.