A certificate of analysis (COA) is only as trustworthy as the structured data behind it. A single "99% pure" figure on a PDF tells you almost nothing. This guide walks through what a defensible, lot-level COA actually contains and how to read each section.

Identity before purity

Confirm the material is what the label claims before you trust any purity number. Look for an LC-MS identity result that reports the observed mass against the expected monoisotopic or average mass. If identity is not confirmed, the purity figure is meaningless.

Purity, with a method

A purity value must name its method — typically reverse-phase HPLC/UPLC with a stated detection wavelength. A bare percentage with no chromatogram and no method is a red flag. The chromatogram should show a clean main peak with the impurity profile within specification.

Lot traceability

The lot number on the COA must match the vial label and the catalog lot. Independent, third-party testing under ISO/IEC 17025 carries more weight than a supplier-provided document; the COA should state which it is and name the issuing laboratory and its accreditation.

What "structured" means

Prefer COAs that store each test as a discrete result — HPLC/UPLC purity, LC-MS identity, Karl Fischer water, net content — rather than a single summary line. Structured results let you verify each analytical claim independently. On this platform every displayed claim is backed by a recorded test.