How is peptide purity tested and why does it matter?

Peptide purity is primarily tested using High-Performance Liquid Chromatography (HPLC) and mass spectrometry. HPLC separates peptides based on their molecular properties to identify and quantify impurities, while mass spectrometry confirms the exact molecular weight and can detect modifications or contaminants. Testing is critical because impure peptides may contain truncated sequences, synthesis byproducts, or contaminants that could affect research reliability or safety outcomes.