How to verify a peptide certificate of analysis

A certificate of analysis (COA) is only useful if it describes the lot you are buying and was issued by a lab that actually ran the test. Work through these checks before you rely on one.

1. Confirm the lab exists and issued the report

• Look up the lab independently. Do not use a link supplied only by the seller.
• Use the report's task number, accession number or verification key on the lab's own site.
• If the lab cannot confirm the report, treat it as unverified.

2. Match the report to your lot

• The lot or batch number on the COA should match the vial label.
• The client name should be the supplier you are buying from, not an unnamed upstream factory.
• The test date should be recent relative to the batch.

3. Read the actual results

• Identity: mass spectrometry should show the expected mass for the sequence.
• Purity: HPLC purity with a chromatogram, not just a number.
• Net content: if listed, from amino acid or nitrogen analysis. Otherwise estimate it with the net content calculator.
• Safety tests: endotoxin, sterility and heavy metals matter for cell work and are often missing.

4. Warning signs

• Identical chromatograms on reports for different lots or different peptides.
• Purity of exactly 99.9% on every product.
• Reports with no lab address, accreditation or signatory.
• Image-only COAs with edited fonts or misaligned text.