A Certificate of Analysis — a COA — is the single most useful document a research-peptide supplier can give you. It is the lab record that says what a specific batch actually is and how pure it tested. Knowing how to read one is the difference between buying a verified research material and buying an unknown powder on trust.
This guide explains the fields on a COA, what good values look like, and the warning signs of an unreliable one. It is about reading documentation only — nothing here concerns the use of the material itself.
- A COA reports the lab test results for one specific batch of product.
- The fields that matter most: identity, batch number, date, the testing lab, HPLC purity and mass-spec identity.
- Good looks like: ≥99% HPLC purity, identity confirmed by mass spec, an independent named lab, and batch-specific dating.
- Biggest red flag: no independent lab named, or “email us for a COA” instead of published ones.
What a COA is
A Certificate of Analysis is a document produced by an analytical laboratory that records the test results for a particular batch of a product. The key word is batch: a COA is not a general statement about a product line, it corresponds to the specific lot a sample came from. A good COA can be matched to the batch number on the vial you receive.
The fields that matter
- Product identity — the compound name, and ideally its molecular formula or weight.
- Batch / lot number — should match the number printed on the vial you receive.
- Date — when the batch was tested; a COA should be dated.
- Testing laboratory — the name of the lab that ran the analysis (this is critical, see below).
- HPLC result — high-performance liquid chromatography, reported as a purity percentage.
- Mass spectrometry (MS) — confirms the molecule’s identity (that it is what it claims to be).
- Microbiological / appearance — sometimes included for completeness.
What good looks like
A strong COA shows a high HPLC purity — ≥96% is generally considered the floor for research material, and ≥99% is excellent — alongside a mass-spec result confirming the molecular identity. It names an independent, accredited laboratory rather than relying on “in-house” testing, and it is batch-specific and dated so it can be tied to the actual vial. Independent third-party labs that the research community recognises include names such as Janoshik, MZ Biolabs and Colmaric.
Red flags
- No independent lab named — or “tested in-house” with no third-party verification.
- “Email us for a COA” instead of openly published certificates — a widely recognised warning sign.
- No batch number, or a batch number that doesn’t match the vial.
- No date, or a COA reused across many different batches.
