Anyone reviewing supplier documentation
COA field-by-field audit sheet
Every field on a certificate of analysis, what it establishes, and what its absence means — in the order that determines whether the rest of the document can be read at all.
Updated 3 September 2026 · No sign-up required
Read a COA in this order. If any of the first four fields is missing or unresolvable, stop — the remaining numbers cannot be interpreted, however impressive they look.
Load-bearing fields
- Lot / batch identifier present and matching the container.Without it, the result cannot be tied to any specific product.
- Test date and report date present.Establishes when the material was in the stated condition.
- Testing laboratory named and independently contactable.An unnamed laboratory cannot be asked to confirm its own report.
- Analytical method stated in full.A bare percentage with no method is a claim, not a measurement.
Result fields
- Purity result, with the basis it is a percentage of.Almost always chromatographic area percent — a ratio of detector response, not of mass.
- Identity confirmation with an observed value, not just “conforms”.Purity without identity is compatible with a pure and entirely wrong substance.
- Net peptide content, if the material is being compared by mass.Counterion and water routinely account for a substantial share of dry mass.
- Chromatogram or spectrum included, so the summary can be checked against raw output.
Independent properties — only true if actually tested
- Bacterial endotoxin result, against a stated limit.
- Sterility result.Nothing else on the document implies it.
- Water content, by Karl Fischer titration.
- Counterion content, by ion chromatography.
- Residual solvents.
Failure patterns
- One representative COA republished for every order.
- An internal result presented as third-party verification.
- A method named but not specified.
- An image of a document with no retrievable original and no laboratory contact.