Certificate of analysis (CoA)

A certificate of analysis is a document issued by a supplier, or by the laboratory acting for that supplier, that reports the measured test results for a named batch or lot of material against the specification you agreed with them. It describes one lot on one day, not the supplier's process in general.

A CoA usually carries the supplier and site name, the product name and code, the batch or lot number, the production or sample date, the parameters tested, the method used for each, the result, the specification limit it was measured against, and a signature or authorised name. Which parameters appear depends on the material. For a milk powder it might be moisture, fat, and a microbiological panel. For a spice it might be moisture, ash, and a screen for the contaminants that material is known for. For packaging it might be migration or dimensional results.

An example of how it lands in a plant. You buy milk powder against a spec that caps moisture and sets a limit for Enterobacteriaceae. Each delivery arrives with a CoA naming the lot, the sample date, the methods and the measured results, and the QA team files it against that supplier and that delivery. A year later an auditor picks a finished product batch, traces it back through your records to that lot, and asks to see the CoA. Either it is on file and in front of them within a minute, or the trail stops and a finding gets written up.

That is the practical difference between a CoA and most other paperwork in a supplier file. The CoA is the document an auditor reaches for when they want to test whether your traceability and your incoming goods checks actually meet in the middle.

A CoA is a supplier's statement of results. Holding one does not, on its own, tell you that the document is genuine, that the laboratory was accredited for the method used, that the sample tested came from the lot delivered, or that the parameters reported are the ones that matter for your product and process. Those are judgements the QA team makes, and a document tracking system does not make them for you.

It also does not behave like the annual documents beside it. An audit certificate has a printed expiry date, so it goes out of date on a day you can see coming. An allergen declaration goes stale quietly, when a supplier changes a recipe, a line or a site. A CoA does neither. It stays valid for the lot it describes forever, and it is simply absent for the lot that arrived this morning. Missing is the failure mode, not expired.

So a supplier programme has to handle two different problems at once: chase documents that expire on a date, and confirm that batch documents were received at all. Teams that run both on one spreadsheet tend to keep the dated ones tidy, because dates sort, and lose track of the batch ones, because nothing prompts.

• Specification. The agreed document setting the limits a CoA is measured against. Without a current spec, a CoA is a page of numbers with nothing to fail against.
• Allergen declaration. The supplier's statement on allergens present or handled at their site. Reviewed on change rather than reported per batch.
• Approved supplier list. The controlled register of suppliers you are permitted to buy from, and the documents each one owes you. A CoA is normally one of the required types on that list for raw material suppliers.
• Document control. The discipline of knowing which version of a document is current, where it is filed, and who last reviewed it. CoAs test it hardest because the volume is highest.
• Non-conformance. The finding raised when evidence cannot be produced. A missing CoA for a traced lot is a document control non-conformance before it is anything else.
• Corrective action, or CAPA. What you commit to after a finding, and what the auditor checks at the next visit.
• Unannounced audit. An audit with no scheduled date, which removes the week of catching up that most supplier files quietly depend on.

For the full list of what to ask each supplier for, see the sibling guide on what documents to collect from every food supplier. For how this fits a plant wide programme, see supplier compliance for food manufacturing plants.