Adapted from the Jike Bio source article, How to Read a Peptide Certificate of Analysis (COA). The original is retained in the site archive. This is a document review guide, not a test result for a particular batch or a claim that displayed products have received independent testing.
Match the product and batch first
Compare the product name, identifier and batch number with the package label, order and accompanying records. Review the test date, report version, issuing organization and any applicable storage or retest information. Ask for an explanation if an identifier is missing or inconsistent. Keep the original report and the clarification together; a report for a similar product is not a substitute.
Read results in their method context
Check the method name, sample identification, units and stated basis for evaluating each result. Establish whether the reported scope addresses the requirements agreed for the research project. If a document supplies a number without sufficient context, ask about the associated plot, integration approach and supporting records. Results obtained using different methods or conditions should not be treated as interchangeable without reviewing that context.
Review chromatograms critically
- Match the sample or batch identifier on the plot to the report.
- Look for readable axes, retention time information and an explanation of integration.
- Ask the issuing laboratory about additional peaks, shoulders or questions concerning peak shape and baseline treatment.
- Clarify how the reported purity metric is defined and what the method covers.
A chromatogram supports interpretation of an analytical result within its stated scope. A dominant peak or an area percentage does not, by itself, establish the complete sequence or show that every possible component has been measured.
Understand the limits of mass information
Read the expected and observed values together with the report's interpretation of the signals and its stated evaluation criteria. Do not infer the complete amino acid sequence or every modification position from a single peak. Multiple signals also require context; ask the issuing laboratory how the method, sample and project requirements affect their interpretation rather than deciding acceptance from appearance alone.
Record a traceable review
Document which report version was reviewed, which material it covers, what was checked and what remains unresolved. A report applies only to the samples or batches within its identification and scope. A sample COA on a website demonstrates document structure, not the quality of an unrelated delivery. Base receipt, handling and use decisions on matching batch records and the relevant institutional procedures.