High-Performance Liquid Chromatography (HPLC) is the gold standard for determining peptide purity. Understanding how it works helps researchers interpret COA results.
How HPLC Works
A sample is dissolved and injected into a column. Different molecules travel through the column at different rates based on their chemical properties. A detector measures the amount of each component as it elutes, producing a chromatogram—a graph of signal versus time.
Reading a Chromatogram
- Peaks: Each peak represents a compound. The main peak is the target peptide.
- Purity %: Calculated as (area of main peak ÷ total area of all peaks) × 100.
- Impurities: Smaller peaks indicate byproducts, degradation products, or related compounds.
What Good Results Look Like
- A single dominant peak for the target peptide
- Purity ≥99%
- Minimal or no significant impurity peaks
- Clean baseline between peaks
HPLC does not confirm identity—that requires mass spectrometry. Together, HPLC and MS provide comprehensive quality assurance.