How to Verify a Peptide COA: Spot Fakes, Check Lab Reports, and Buy With Confidence

Two vendors. Different prices. Same COA. Same certificate ID, same lot number, same lab report.

This is not hypothetical. Users on r/labrats and analysts at VialAudit have documented the exact scenario: the COA was real, it just was not for the cheaper vendor's product. Both were selling tirzepatide with the same Janoshik report. But one batch was tested months earlier under different storage conditions.

A COA only certifies what was in that specific sample, at that specific time. Here is how to check if yours actually means something.

Start With the Batch Number

The batch number on the COA must match the batch number on your vial. If either is missing, stop. That is the first and most basic red flag.

Who Did the Testing?

Independent labs are identifiable and verifiable. The ones commonly used in the peptide industry:

Janoshik (Czech Republic). Each COA has a unique task key. Go to janoshik.com, use the verify tab, check the number. If the PDF does not have a verifiable key, it could be a copy.
Vanguard (Washington, US). ISO 17025 accredited. You can call them to confirm results.
Colmaric and Freedom Diagnostics. Both independent and verifiable.

If the COA says "in-house testing" with no named third-party lab, it is not third-party verification. It is a claim without evidence.

Read the Numbers, Not Just the Percentage

Real HPLC results have decimal variance: 98.74%, not 99.00% flat. A round number means someone typed it instead of measuring it.

A chromatogram tells you more than the purity number. One clean peak at the right retention time with no shoulders means clean product. A number without a chromatogram is incomplete.

The EMA's 2026 guideline recommends orthogonal purity methods because a single HPLC may not resolve coeluting impurity species. If the COA uses only one method, ask why.

What the Numbers Should Be

HPLC purity: 98%+ is good. 95-97% is acceptable. Below 95% is a red flag.
Mass spec: Must be on every COA. A vial can be 99% pure HPLC and still be the wrong compound. MS confirms identity.
Endotoxins: Under 1 EU/mg is ideal. Under 5 EU/mg is standard. Over 10 EU/mg is concerning.
Sterility: Pass or not tested.

The EMA guideline requires characterization of all related substances above 0.1%. That is the standard that legitimate manufacturers hold themselves to.

Why Your Vial Looks Empty

A 5mg or 10mg dose of lyophilized peptide is a dusting at the bottom of the vial. Some manufacturers add bulking agents (mannitol, trehalose) that make one vial look full and another look nearly empty. Go by the labeled mg amount and the COA, not by what your eyes see.

Testing Your Own Samples

Independent testing is cheap insurance. Single vial: skip unless the price makes it worth it. Medium batch ($300-$600): test one vial for identity and purity. Bulk order ($600+): almost always worth it.

Janoshik: ~$300 for identity + HPLC purity of a GLP-1 peptide. ~96 hours. Offers blind testing.
Vanguard: ISO/IEC 17025:2017 accredited. Level 1 testing from $250. 5-8 business days.
Freedom Diagnostics: Domestic US testing, public COA portal.

Check FDA Warning Letters

Search the vendor's name at fda.gov in the warning letters section. Takes five minutes. In 2025-2026, the FDA sent warning letters to Gram Peptides, Prime Peptides, Xcel Research, Summit Research, USApeptide.com, Pink Pony Peptides. The pattern is consistent: "research use only" labels combined with therapeutic marketing. If the marketing makes human-use claims, the FDA considers the product an unapproved drug regardless of the label.

The Shared COA Problem

Multiple vendors with the same COA does not automatically mean fraud. A manufacturer tests one batch and multiple resellers buy from it. But if Vendor A sells at $80/vial and Vendor B uses the same COA at $40/vial, the COA has no connection to the cheaper product. It only certifies what was in that original sample, not what ended up in your vial.

Red Flags Summary

No batch number. "Internal testing." No chromatogram. Round purity numbers. Vendor not independently searchable. Sells syringes and bac water alongside peptides. Makes therapeutic claims under "research only" labeling. Any one of these is cause to walk.