HPLC purity

High-performance liquid chromatography (HPLC) is the industry standard for measuring peptide purity. A peptide labelled as ≥99% HPLC purity has been analysed on a calibrated HPLC system, typically using a reverse-phase C18 column with a UV detector at 214 nm or 220 nm. Each peak in the chromatogram represents a distinct molecular species; the area under the target peak, expressed as a percentage of the total peak area, is the purity figure. For research peptides, ≥99% is the practical ceiling — values reported above this should still be reviewed alongside the mass spectrometry trace to confirm the species is actually the intended sequence.