Peptide Fundamentals · 6 min read · March 4, 2026
Reading a Certificate of Analysis
A field guide to the four documents that matter — and the one that does not.
Dr. Mira Halden
Chief Scientific Officer
The four documents
A complete Certificate of Analysis is really four artifacts under one cover sheet: the HPLC chromatogram, the mass-spectrometry confirmation, the appearance and solubility panel, and the batch metadata (lot number, synthesis date, analyst signature).
Each answers a different question. The chromatogram answers 'what else is in the vial.' The mass spec answers 'is the main peak actually the molecule we think it is.' The appearance panel answers 'does it look right.' The metadata answers 'can we trace it.'
Red flags
A CoA without a batch number cannot be traced. A CoA without an analyst signature or laboratory name cannot be audited. A CoA with only a summary and no raw data — no chromatogram image, no MS trace — is a summary document, not a certificate.
The most common shortcut is a CoA that reports only one method. HPLC alone tells you about the peak shape; MS alone tells you about the mass. Neither is sufficient on its own.
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