HPLC Purity — A Research Reference
How HPLC measures peptide purity, what ≥99% means in practice, and how to read an HPLC trace on a Certificate of Analysis.
What HPLC measures
High-Performance Liquid Chromatography separates the components of a sample as they pass through a column. The output is a chromatogram in which the area under each peak is proportional to the abundance of that component. For a research peptide, the largest peak ideally represents the target compound, with negligible side peaks.
The ≥99% convention
Research-grade peptides are typically expected to meet ≥99% HPLC purity by area. The remaining <1% is composed of synthesis-related side products and trace solvents.
What to look for on a COA
- A labeled chromatogram tied to a specific lot number.
- A numeric purity result (e.g., "99.2% by HPLC area").
- The analytical column, mobile phase, and detection wavelength.
- Test date close to the lot manufacturing date.