How to Read a Certificate of Analysis
What a real COA should contain, what to look for in HPLC and mass spec data, and how to spot a sloppy or misleading one.
Last updated: 19 April 2026
What a COA should show
A useful certificate of analysis identifies the compound, lists the testing methods used, presents the actual chromatograms and spectra, and shows purity figures alongside method-specific limits of detection.
Reading the HPLC trace
High-performance liquid chromatography separates compounds by their interaction with a stationary phase. A clean main peak with no significant secondary peaks is a quality signal.
Watch for: very narrow integration windows that hide impurities, missing axis labels, and reports that quote a purity number without showing the trace.
Reading the mass spectrum
Mass spectrometry confirms the molecular weight matches the expected peptide. The reported mass should match the theoretical mass within instrument tolerance.
Red flags
No raw data. Logo without a lab name. Generic 99%+ purity claims with no methodology. Same COA reused across batches.