Certificate of analysis (COA)

A certificate of analysis is a laboratory’s test report for one batch of a product, usually covering identity, purity, and content. The document describes only the sample tested; it does not prove that the vial in your hand came from that batch, matches the sample, or remained unchanged afterward.

What is a certificate of analysis?

A certificate of analysis, shortened to COA, records which sample or batch was tested, which specifications applied, and what the laboratory found. The COA meaning is narrower than “this product is good”: it is a dated report of defined tests, not a blanket approval of a seller, product line, or future batch.

FDA’s manufacturing guidance says an authentic COA for an active ingredient should identify the batch, list the tests, limits, and numerical results, and name the original manufacturer. The issuer may be the manufacturer’s quality unit, a repacker, or another laboratory. “COA” does not automatically mean independent third-party testing.

What does a peptide COA prove?

A peptide COA can support three separate claims about the tested sample: identity asks whether the expected peptide was present; purity asks how much detected material was the target rather than related impurities; content asks how much peptide was actually measured. One result cannot quietly stand in for the other two.

For a COA peptide example, take BPC-157. A report tied to a submitted BPC-157 batch can describe that sample’s identity, purity, and content. The report says nothing direct about a vial with a different batch number, or a matching label whose contents were never part of the submitted sample.

What does a COA not prove?

A COA does not prove that the seller shipped the tested material, that every vial in the batch is identical, or that unlisted tests passed. A genuine report can be recycled for another batch; a file can also be edited after the laboratory issues it. FDA documented altered COAs in a 2025 warning letter, including failing results changed to passing results.

The paper is only as strong as the sampling, method, and issuer behind it. In one independent evaluation of 98 synthetic research peptides, every supplier COA claimed at least 95% purity, but the researchers’ own testing found only 43 met that specification. That is why third-party testing for peptides is a stronger evidence layer, not a magic seal.

Where should you go next?

A certificate of analysis is the document; judging whether one is credible is a separate task. The step-by-step checks belong in how to read a peptide COA. For the wider quality picture—including batch matching, test independence, and what paperwork cannot establish—use the guide to spotting quality peptides or return to the peptide reference.