How to Request a COA from a Supplier: What to Expect

Why the wording of the request matters

A Certificate of Analysis is a traceability record tied to one production run, not a marketing asset. Asking for one means asking whether an independent, accredited laboratory tested a defined batch and whether the result meets a stated specification. The question "Can I see your COA?" can be answered with almost any sheet that carries a purity figure, so the useful requests are narrower.

A request that names the lot, the issuing laboratory and the raw data can only be satisfied in full by someone holding genuine third-party results. Send it in writing, by email or ticket, so there is a record of what was asked and what came back.

What the request should name

The lot, not a sample document

A generic certificate reports testing from some earlier run. It says nothing about a particular vial. A batch-specific certificate carries a lot number, and that number has to match the one on the label. If the lot is not yet known, ask which lot the document refers to.

Example wording

"Could you send the Certificate of Analysis for lot [number], including the issuing laboratory's name, the HPLC chromatogram and the LC-MS spectrum?"

The laboratory

Who signed the certificate matters as much as the figures. A producer's in-house QC is the producer grading its own work. A third-party laboratory accredited to ISO/IEC 17025 works under audited procedures with validated equipment and has no commercial stake in the outcome. A plain question about the issuing lab and its accreditation is enough, and a producer holding genuine third-party data answers it without fuss.

The raw charts

A purity percentage is easy to type. The HPLC chromatogram shows the peaks, so you can see whether significant impurities sit beside the main compound. The LC-MS spectrum shows the measured mass and confirms identity, which matters because structural analogues can have similar purity profiles and different masses. Both belong in the PDF or as attachments. Numbers without charts are assertions.

Reading the response

Stalling is informative, and it follows a few recognisable patterns.

"The COA is proprietary." A certificate is a quality document, not a trade secret. Calling a test result proprietary suggests it does not exist in the form described.

"Documents are shared only after payment." Quality records that can be seen only after a transaction cannot inform it. Routine batch testing does not work this way.

"Available on request." That is the request. Restate it in writing and cite the lot.

No reply after two follow-ups. Keep a note of what was asked and what arrived. The gap in documentation is the finding.

Check the reply against the label

The last check takes about half a minute. Read the lot number on the vial or outer packaging, then find the lot field on the certificate. They must match exactly, with no transposed characters. A mismatch means the document was issued for a different batch. It does not prove the material is poor, only that you have no evidence about it.

What a complete response looks like

A full reply contains a lot number matching the assigned batch, the issuing laboratory by name, an HPLC purity figure with the chromatogram, LC-MS identity with the measured mass, and often water content by Karl Fischer and endotoxin by LAL. Each figure traces back to the named lab and lot. A one-page PDF with complete data from a named independent lab is worth more than a branded multi-page document with no chart and no laboratory.

Red flags in the response

No lot number. An issuing lab that is the same entity as the seller. A percentage with no chromatogram or spectrum. A report dated years before the stated production date. Any one of these means there is not yet a verifiable batch-specific certificate.

Reference points: ILAC on laboratory accreditation (ISO/IEC 17025) · WHO quality guidance. Information only. Updated November 2026.