Peptides 101: Understanding HPLC Purity, Lyophilization, and Mass Spectrometry

Ensuring rigorous purity in peptide synthesis is foundational for reproducible scientific results. When sourcing research compounds, understanding the analytical metrics on a Certificate of Analysis (COA) is vital. ### HPLC (High-Performance Liquid Chromatography)HPLC purity measures the percentage of the target peptide peak relative to all UV-absorbing impurities. For demanding in vitro and in vivo assays, a purity threshold of ≥99.0% is standard to eliminate confounding bioactivity from truncated sequences or deletion peptides. ### Mass Spectrometry (LC-MS)Liquid chromatography-mass spectrometry confirms the molecular weight of the synthesized compound. Discrepancies between theoretical and experimental mass indicate sequence errors or incomplete deprotection during solid-phase peptide synthesis (SPPS).