Glossary
Certificate of analysis [COA]
TestingVerificationUpdated 2026-08-23
The short answerA certificate of analysis is a laboratory report for one specific production lot that establishes two things: identity, meaning the vial contains the compound named on the label, and purity, the percentage of the sample that is the target compound.
A certificate is only as good as its traceability. If the lot number on the report does not match the lot on the vial in your hand, it is a marketing document, not a certificate.
What a real certificate contains
- Lot or batch number matching the physical vial
- The issuing laboratory, independent of the seller, with contact details
- Analytical method named explicitly, typically LC‑MS for identity and HPLC for purity
- The chromatogram itself, not only a summary figure
- Test date and the sample it was drawn from
The three-step verification
- Match the lot number on the certificate to the lot printed on the vial.
- Confirm the laboratory is independent of the seller. A report on the seller’s own
letterhead is an in-house result, which is not the same thing and should be labeled as such.
- Look for the method and the trace. A table of percentages with no chromatogram cannot be
checked by anyone.
What a certificate does not tell you
Identity and purity are not sterility, endotoxin load, or residual solvent content. Those are
separate assays that most research supply is never subjected to. A supplier who implies a purity
certificate covers sterility is either confused or hoping you are.
Frequently asked questions
Does a COA prove a product is sterile?
No. A certificate of analysis establishes identity and purity. Sterility, endotoxin and residual solvents are separate assays. Most research supply is not sterility tested, and a supplier implying otherwise is misreading their own paperwork.
What if the lot number does not match?
Treat it as no certificate at all. A report reused across shipments tells you nothing about the vial you received.
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