What is a peptide Certificate of Analysis?

The short version

A Certificate of Analysis (COA) is a document issued after a sample of material has been analysed. It states what was tested, which analytical methods were used, what the instrument reported, and which batch the sample was drawn from.

A COA is evidence about one batch at one point in time. It is not a general statement about a compound, a supplier or a product line, and it carries no meaning beyond the batch identifier printed on it.

What a peptide COA normally contains

Certificates vary between laboratories, but a usable peptide COA generally carries the following fields.

• Compound or product identity — the name of the material analysed, and often the sequence or molecular formula.
• Batch or lot number — the identifier that ties the certificate to a specific production run.
• Date of analysis — when the sample was tested, not when the document was printed.
• Analytical methods — for peptides, typically HPLC for purity and mass spectrometry for identity.
• Results — the reported purity figure and the observed versus expected mass.
• Issuing party — the laboratory or manufacturer that performed the analysis and signed the document.
• Chromatogram and spectrum — the underlying instrument output, where the issuer includes it.

Batch-specific versus generic certificates

The single most useful thing to check on a certificate is whether it is tied to a batch. A document that names a compound but no batch number cannot be matched to the vial in front of you, so it tells you nothing verifiable about that vial.

A generic certificate is sometimes reused across many production runs. That may still be an honest document about the original run it describes, but it stops being evidence the moment it is applied to different material.

Supplier certificates and independent certificates

A supplier or manufacturer certificate is issued by the party that produced the material. An independent certificate is issued by an analytical laboratory with no commercial interest in the result.

Both are legitimate document types and they answer slightly different questions. A manufacturer certificate describes what the producer measured at release. An independent certificate describes what a separate party measured on a sample of the material as supplied.

How certificates work on this site

Where a certificate has been issued for a batch we hold, it is published against the relevant product and is searchable by product, strength or batch number in the certificate library. Certificate type — supplier or independent — is labelled on each record.

Where no certificate exists for current stock, the product page says so rather than displaying an unrelated document. Absence of a certificate on a product page means we do not hold one for that batch, not that a document exists elsewhere.