How to Read a Peptide Certificate of Analysis (COA)

A Certificate of Analysis (COA) is a lab report showing that a specific batch of a compound was tested. Knowing how to read one is the fastest way to judge a research peptide supplier.

The key sections

• Compound and amount — the peptide name and labeled quantity (for example, 10 mg).
• Lot or batch number — ties the report to one production batch. It should match your vial label.
• Purity (HPLC) — High-Performance Liquid Chromatography separates the sample into components. Purity is the share of the main peak; research-grade peptides are commonly reported at 98–99%+.
• Identity (Mass spectrometry) — confirms the molecule's measured mass matches the expected mass of the peptide, so you know it is the right compound, not just a pure one.
• Testing lab and date — who ran the test and when.

Purity is not identity

A sample can be very "pure" and still be the wrong molecule. That is why HPLC purity and mass-spec identity work best together.

Red flags

• No lot number, or a lot number that never changes across years
• Missing lab name or test date
• Purity shown without any method listed
• Reports that cannot be tied to the product you received

Where to find ours

We publish available reports on our Lab results page, and each product page links its COA when we have one.