Understanding HPLC identity & purity testing

High-Performance Liquid Chromatography (HPLC) separates the components of a sample as they pass through a column at different rates. The resulting chromatogram shows peaks that correspond to the compounds present.

For a research reference material, HPLC is used two ways: to confirm the main peak corresponds to the expected compound (identity), and to measure how much of the total signal that peak represents (identity purity).

Identity answers 'is this the compound on the label?' — often confirmed with mass spectrometry alongside HPLC.

Purity answers 'how much of the sample is that compound?' — reported as a percentage against a defined threshold. A higher figure means fewer co-eluting or unrelated peaks.

Reproducible work depends on knowing your inputs. A documented identity and purity result removes guesswork about what is in the vial and at what level, so results can be attributed to the experiment rather than to an uncharacterized input.