Purity

Purity is the proportion of a sample that is the target compound rather than impurities, byproducts, or residual reagents. It is most commonly measured by HPLC and expressed as a percentage of total peak area.

In research, purity sets a ceiling on data quality: if a sample’s actual contents differ from its label, any work using it is compromised before it begins. This is why a per-batch purity figure — backed by the raw chromatogram — matters more than a brand claim.