Researchers, laboratory managers and procurement
Supplier documentation review checklist
The specific requests that separate a supplier with a real documentation chain from one with a marketing asset — and how to read what comes back.
Updated 3 September 2026 · No sign-up required
Work top to bottom. A failure in the first group makes the rest of the checklist unnecessary, because there is no lot to attach any later answer to.
Record the answer you actually get, including “they did not respond”. The point of the exercise is a record you can compare across suppliers, not a verdict.
1. Lot-specific documentation
- Request the COA for the lot number physically printed on the container you received.A representative COA, a different lot, or a blank lot field are all the same answer.
- Confirm the lot number on the returned document matches the container.
- Check that the test date is consistent with the lot, and predates nothing that would have changed the material.
- If a batch-lookup portal exists, enter a lot number that should not exist. A real lookup returns nothing.
2. Who performed the analysis
- Is the testing laboratory named on the document?“Third-party tested” with no laboratory named is not a verifiable statement.
- Can the laboratory be contacted without going through the supplier?
- Does the laboratory publicly confirm it performs the specific analysis reported?
- Does the document say plainly whether the testing was in-house or independent?
3. Is the evidence interpretable
- Is the analytical method fully specified — column, mobile phase, gradient, detection wavelength?“HPLC” alone cannot be reproduced or compared between lots.
- Is the purity result accompanied by a chromatogram, not only a summary figure?
- Is identity supported by an observed mass compared against the expected mass, with charge states shown?
- Is net peptide content reported separately, if you are comparing material on a mass basis?Chromatographic purity and net peptide content are different numbers.
- Note explicitly which analyses were not performed. A report is silent on everything it did not test.
4. Claims to discount entirely
- A purity figure with no method, no lot and no chromatogram.
- “Pharmaceutical grade” or “lab grade”.Neither is a defined regulatory category for these materials.
- “GMP” with no facility, registration or auditor named.
- Accreditation logos on a supplier's own site with no register entry.Accreditation belongs to a laboratory and is verifiable on the accreditation body's public register.
- Review counts, testimonials and storefront polish.
5. Operational facts to establish
- Does the supplier synthesise, or resell material made elsewhere?
- Where does fulfilment actually happen, as distinct from where the company is registered?
- Are storage and shipping conditions stated, and do they match the material's stability requirements?
- Is pricing public, or quote-only?
- Is there a retention-sample policy, so a disputed lot can be re-tested against real material?
6. Record what you could not determine
- Mark unanswered fields as unknown rather than as a failure.Converting silence into a verdict is the most common error in supplier evaluation.
- Save a copy of each document as retrieved, with the date. Supplier-hosted files can change.