1. Match the batch/lot number. The COA must show a batch or lot number that matches the one printed on your actual vial label. If the vendor can't produce a COA tied to your specific batch, that's a red flag.
2. Verify the testing lab is real. Look up the lab's name independently (not just a link the vendor gives you). Legitimate 3rd-party labs (e.g. Janoshik, MZ Biolabs) have their own websites and a track record — check if the report format matches what the lab actually publishes.
3. Check for inconsistent purity/mass results. Be suspicious of COAs claiming suspiciously round numbers (always exactly 99.9%) or no mass spec / HPLC chromatogram images included — real lab reports usually include the raw chromatogram, not just a summary number.
4. Cross-check the date. An old COA reused across many different batches is a major warning sign — testing should be batch-specific and reasonably recent.
5. Contact the lab directly if unsure. Many testing labs will confirm (without revealing private client info) whether a report ID is genuine. If a vendor discourages you from doing this, that's itself a red flag.
6. Watch for edited PDFs. Check document metadata/properties where possible — reports edited in image software or generic PDF editors (rather than exported directly from lab software) are a warning sign.
