Why It Matters
A COA Is Only as Good as Its Provenance
A Certificate of Analysis (COA) is a lab report documenting a peptide batch's identity, purity, and impurity profile. It is not marketing collateral. When purchasing research-grade peptides, the COA is the single most important document you will review. Unfortunately, some suppliers publish generic or fabricated COAs. This guide explains how to distinguish authentic third-party analytical data from a template.
The Seven Markers
What Every Legitimate COA Must Contain
Named Testing Laboratory + Address
A real lab. Physical address. Contact phone or email. ISO 17025 accreditation is the gold standard. "Internal QC" is not a lab.
Unique Batch or Lot Number
This number must match the vial label. If the COA references a different lot than what shipped, ask why in writing.
Test Date + Analyst Name or ID
A dated report. Signed or initialed by the analyst. Reports without dates or attribution are red flags.
HPLC Purity with Chromatogram
Reverse-phase HPLC is standard. The report should include the chromatogram (the peak trace), retention time, peak area percent, and purity result. Purity as a bare number without the underlying trace is unverifiable.
Mass Spectrometry Confirmation
MS or LC-MS confirms molecular identity. The reported m/z (mass-to-charge ratio) must match the theoretical monoisotopic mass of the peptide within accepted tolerance (typically < 0.5 Da for peptides < 5 kDa).
Impurity & Solvent Panel
Residual TFA, residual solvents (ethanol, acetonitrile, DCM), water content, endotoxin (LAL test), and heavy metals. Not every peptide requires every test, but the panel appropriate to the compound must be present.
Match to Vial Label
Compound name, dose, batch number, and manufacture/expiration dates on the COA must match the vial. If they don't, the COA doesn't belong to the vial.
Red Flags
How to Spot a Fake or Templated COA
Generic Batch Number
"Lot 001" or "Batch A" reused across compounds. Every batch should have a unique alphanumeric ID.
Missing Chromatogram
Just a claim of "99.5% purity" with no visible peak trace. The trace is not optional.
Identical Values Across Batches
Real batches vary slightly (99.2%, 99.5%, 99.1%). If every batch shows "99.5% exactly," the report is a template.
No Lab Named
"Passed internal QC" is not a COA. Ask which lab performed the test and demand contact information.
Independent Verification
How to Confirm What the COA Says
If a COA looks legitimate but you want independent confirmation, you have two paths. First, contact the named testing lab directly and reference the batch number — reputable labs will confirm they generated the report (though they may not disclose results without client permission). Second, send a sub-sample of the vial to an ISO 17025 accredited third-party analytical lab and request a matched HPLC + MS panel. Costs range from $150-$400 per compound. This is the definitive test.
Sequence Labs practice: Every batch is tested by an ISO 17025 accredited lab. Full COAs (chromatogram + MS + impurity panel) are published in our COA library, indexed by batch number. Any customer can request independent re-testing at cost.
View COA LibraryVerify Any Sequence Labs Batch
Every batch we ship has a public COA. Enter your batch number in the COA library or contact us with the lot ID from your vial label — we will send the underlying analytical data.