Reading a certificate of analysis
The fields that matter on a COA, and the ones that signal a document worth questioning.
Lot traceability
The lot code on the certificate must match the code printed on the vial. A certificate without a lot reference documents nothing in particular.
Who signed it
An independent laboratory, a release date and a named method carry more weight than an unattributed purity claim on a product page.
The supporting data
Look for the chromatogram and mass spectrum, not just a summary table. The raw trace is where peak shape, shoulders and baseline noise become visible.