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 should be identifiable and verifiable. Examples of testing providers are listed below; confirm their current accreditation, scope, and verification process directly.

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.

We built a free COA Spec Checker Chrome extension that pulls the spec table out of a COA PDF so claimed and measured values sit side by side. It speeds up reading, not verification. Still match the batch number and check with the lab directly.

Read the Numbers, Not Just the Percentage

A rounded result deserves scrutiny, but rounding alone does not prove that a result was fabricated. Review the method, chromatogram, sample identity, and laboratory verification process together.

A chromatogram provides context for a reported purity result, but one peak does not by itself establish identity, purity, or suitability. Request the chromatogram, method details, and an identity test when evaluating a batch.

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

There is no universal purity threshold for every peptide, intended use, or regulatory stage. Ask which specification applies, which method produced the result, and whether identity, content, water, residual solvents, endotoxins, bioburden, or sterility testing is relevant to the intended use. HPLC purity alone does not establish identity.

Applicable reporting, identification, and qualification thresholds depend on the product, method, intended use, and governing specification. Use the applicable regulatory guidance rather than treating one percentage as a universal purchasing rule.

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 may be appropriate when supplier documentation is incomplete, the order is material to your work, or the risk of an incorrect identity or impurity profile is high. Choose the sample size and test panel with a qualified laboratory.

Fees, test panels, accreditation scope, and turnaround times change. Request a current quote and confirm that the laboratory's methods are suitable for the material and intended use.

Check FDA Warning Letters

Search the vendor's legal name and relevant trade names in the FDA warning-letter database. Read the specific letter and its date rather than relying on a third-party summary. Product labels do not determine compliance by themselves; regulators may consider the product, claims, intended use, and overall marketing context.

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, unverifiable testing, missing analytical context, an unsearchable legal entity, or therapeutic marketing under research-use labeling should trigger additional review. None of these signals alone proves that a product is fraudulent.