Quality Control
Peptide Purity
Definition
Peptide purity refers to the percentage of the target peptide present in a sample relative to all peptide-related species, as determined by HPLC analysis. Research-grade peptides are typically >95% pure, while pharmaceutical-grade exceeds 99%. Impurities can include deletion sequences (missing one or more amino acids), truncated sequences, oxidized forms, and racemized products. Higher purity is critical for research reproducibility, as impurities can introduce confounding variables. Purity should not be confused with peptide content, which measures the peptide fraction versus non-peptide components like water, salts, and counter-ions.