Laboratory quality
Certificates of Analysis (CoAs)
What a CoA actually documents, why the document is not the same thing as the vial, and how to read one critically.
- Last updated:
- 2026-07-22
Overview
A Certificate of Analysis (CoA) is a report issued by a manufacturer or a third-party laboratory that summarises the analytical tests performed on a specific production batch. A typical peptide CoA includes identity confirmation (usually by mass spectrometry), purity (usually by HPLC), and sometimes water content, counter-ion identity, and appearance.
The CoA tells you what a lab technician measured, on a specific date, on a specific sample drawn from a specific batch. It is a snapshot of one part of one batch, described in one report.
Why it matters
A CoA is the most direct piece of evidence a research supplier can provide about a vial. Reading one well, and being clear about what it does and does not prove, is what separates informed evaluation from marketing consumption.
Key concepts
Batch identity
Every meaningful CoA identifies the batch (lot number, manufacturing date). If the batch number on the CoA does not match the batch number on the vial, the CoA is not evidence for that vial.
Test panel
CoAs vary widely in the tests they include. A CoA that reports only HPLC purity does not say anything about sterility, endotoxin, or the actual peptide mass in the vial.
Method disclosure
Well-drafted CoAs specify the analytical method (column, wavelength, mobile phase for HPLC; instrument for MS). This lets a technically fluent reader assess whether the method was appropriate to the claim.
Common misconceptions
- "A CoA proves purity." A CoA states a purity number under a specific method; it does not prove the vial is free of impurities the method could not detect.
- "A CoA proves sterility." Sterility is a separate test that most peptide CoAs do not include.
- "A CoA from a reputable third party is equivalent to regulatory approval." Third-party CoAs are strong evidence for what they test, but they are not evidence that the material is suitable for human use.
Practical interpretation
When a supplier publishes CoAs, match the batch number to your vial and read the test panel critically. When a supplier does not publish a CoA on request, that absence is itself information.
Limitations
Healthy Mango does not review or authenticate CoAs. Any CoA you receive from a research supplier is between you and that supplier.