Purity vs Identity vs Quantity

Purity, identity and quantity answer different analytical questions.

Purity describes the relative composition observed under a selected chromatographic method.

Identity asks whether the principal signal is consistent with the claimed compound.

Quantity, assay or fill amount asks how much of a substance is present.

A high chromatographic purity result does not automatically prove correct fill quantity, sterility, endotoxin absence, absence of every possible contaminant, biological activity, safety, or human suitability.