COA reading

How to read a peptide COA

By The Merit Research Team

A peptide COA has seven key fields. Start with the compound name, lot number, and purity percentage — then check the testing method (HPLC-MS is stronger than HPLC alone), the test date, and the issuing lab's contact information. The lot number is the only field that ties the COA to the specific stock you're receiving.

The seven fields of a COA

Compound name

Should match the peptide you ordered — e.g. "BPC-157," "Semaglutide," "TB-500 (Thymosin Beta-4)." Some labs use CAS numbers alongside common names. Confirm the listed compound matches what you expected. A COA for "TB4 fragment" may or may not correspond to the specific lot you have — clarify with the vendor.

Lot or batch number

The identifier that connects a COA to a specific production run. Match this against your order invoice or the vial label. A COA with no lot number can't be tied to any specific batch — it's evidence of general testing practice, but not a certificate for the product you received.

Test date

The date the sample was tested. COAs age — Merit Verified applies an age-decay to how much older COAs count in a vendor's Merit Score. A COA from 18+ months ago for a product the vendor actively stocks is a yellow flag: either the same old lot is still being sold, or new batches aren't being tested.

Testing method

The analytical technique used — typically HPLC or HPLC-MS. HPLC measures purity by separating sample components. HPLC-MS additionally confirms molecular identity via mass spectrometry, making it more definitive. A COA without a listed method is closer to a purity claim than a COA. Some documents also list the instrument model and serial number — a harder detail to fabricate.

Purity percentage

The fraction of the sample confirmed to be the target compound. Quality research peptides typically show ≥98% purity on a well-run HPLC. Values consistently at exactly 99.9% or 100.0% across multiple documents are a mild red flag — real analytical results have natural variation. Note that purity measures identity and concentration, not safety: it doesn't screen for solvents, heavy metals, or microbial contamination.

Lab identity and contact information

The lab's name, address, and contact information should be on the document. This is the starting point for verification — search the lab name independently to confirm it exists outside the vendor's website. For Janoshik COAs, the document will include a test ID that can be verified on Janoshik's public portal.

Chromatogram (if present)

A chromatogram is the visual trace produced by HPLC — a graph showing the detector signal over time, with peaks corresponding to each component in the sample. Its presence on a COA is meaningful: a fabricator would need to generate plausible instrument data to include it. Its absence doesn't indicate fraud, but its presence is evidence of a real run.

What a COA can and cannot tell you

A COA certifies a tested lot — not your specific vial. Match the lot number on the COA to your order. Lots are produced in batches; your vial is part of a lot, not individually tested. If you can confirm the lot number matches, you have meaningful evidence. If you can't, the COA is still useful as evidence of a vendor's testing habits but isn't a certificate for what you received.

Purity is not safety. A 99% purity result measures the peptide's identity and concentration. It doesn't screen for residual solvents, heavy metals, endotoxins, or microbial contamination — separate tests that most vendors don't commission. No COA you're likely to receive covers all of these.

An old COA may not reflect current stock. Vendors change suppliers, reformulate lots, and exhaust old inventory. A COA from 2022 for a product a vendor is actively selling in 2025 raises the question of whether the tested lot is still what's being shipped. Ask the vendor which lot your order ships from.

Browse indexed COAs How to spot a fake COA

Frequently asked questions

What is a good purity percentage on a peptide COA?

Quality research peptides typically show ≥98% purity via HPLC. Some high-grade compounds hit 99%+. Values below 95% are a red flag — either the lot is degraded, the testing is poor, or the compound has significant impurities. Purity measures identity and concentration, not safety; even a 99% purity COA doesn't screen for solvents, metals, or contamination.

How do I read a Janoshik COA?

A Janoshik COA typically includes a test ID in the header, the compound name, lot identifier, test date, HPLC method details, measured purity percentage, and the Janoshik lab contact information. The most important check: enter the test ID into Janoshik's public COA lookup to confirm the document is genuine — fabricated documents claiming Janoshik provenance won't return a match there.

What is a lot number on a peptide COA?

A lot number (also called batch number) identifies a specific production run. It links the COA to a particular batch of the compound — not to the entire catalog of that peptide the vendor has ever sold. To use a COA as actual verification, you need to confirm the lot number on the COA matches the lot number of the product you're receiving. Ask the vendor which lot your order ships from.

Where can I find COAs for peptide vendors?

Merit Verified indexes COAs from public sources and independent aggregators across 100+ vendors. Search any vendor or peptide in the Merit Verified directory to see COAs on file, which labs issued them, and when. Individual vendors should also be able to provide COAs directly on request, or link to COAs from the testing lab.

What does "HPLC-MS" mean on a COA, and why is it better than just HPLC?

HPLC-MS combines High-Performance Liquid Chromatography (which measures purity) with mass spectrometry (which confirms molecular identity). HPLC alone tells you the fraction of the sample that elutes at the expected retention time — it doesn't independently confirm the molecule is what you expect. Mass spec adds that identity confirmation, making HPLC-MS a stronger overall certificate than HPLC alone.

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