How to Read a Peptide Certificate of Analysis (COA)

A Certificate of Analysis (COA) is the single most important document in research-peptide supply. It is the lab's written record of what a specific batch actually contains — and it is the only thing that separates a verifiable supplier from a marketing claim. If a supplier cannot show you a batch-specific COA from an independent laboratory, you have no way of knowing what is in the vial.

What a COA measures

A complete peptide COA reports several distinct things. Each answers a different question:

• Identity — is this actually the peptide it claims to be? Confirmed by mass spectrometry (the measured molecular weight should match the theoretical weight of the sequence).
• Purity — what percentage of the material is the target peptide, versus related impurities, truncated sequences, or residual synthesis reagents? Measured by HPLC (high-performance liquid chromatography) and reported as a percentage of total peak area.
• Batch / lot number — ties the certificate to one specific production run. A COA with no batch number is effectively meaningless.
• Test date and laboratory — when the analysis was performed and by whom. An independent third-party lab is far stronger evidence than an in-house result.

How to read the purity figure

Purity is reported as area-under-the-curve from the HPLC trace. A result of "≥ 99%" means the target peptide accounts for 99% or more of the detected material. For research applications, higher purity means fewer confounding variables — impurities can interfere with experimental results in ways that are difficult to control for.

Be wary of a purity claim printed only on a product page with no accompanying chromatogram. The chromatogram — the actual graph — is where purity is proven. A number on its own can be typed by anyone.

Verifying a COA is genuine

The strongest verification is a batch number you can check against the laboratory's own records. This is why we publish every batch's COA before the product is listed and let you look up any vial by its batch number on our Lab Results page. The batch on your vial should match the batch on the published certificate, and the laboratory named should be reachable and independent.

Red flags:

• No batch number, or the same COA reused across every product
• Purity claimed but no chromatogram shown
• An "independent" lab that cannot be found or contacted
• A test date years old, or missing entirely

Why this matters more in peptides than almost anywhere else

Research peptides are difficult to evaluate by eye — a vial of lyophilised powder tells you nothing about what it contains. The category has a long history of mislabelled and under-strength product. A published, batch-specific, independent COA is the mechanism that makes quality checkable rather than merely claimed. It is the reason we test every batch through an independent laboratory and publish the result before anything ships.

All products are supplied strictly for laboratory research use only. Not for human or animal consumption.