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VendorCOA

How to read a peptide COA

A certificate of analysis (COA) is a lab's report on one sample. It is only as useful as three things: who tested it, what they measured, and whether it is the same batch as the vial in front of you.
Updated Oct 21, 2026 · 6 min read

Short answer: trust a COA when it names an independent lab, shows both an HPLC purity result with its chromatogram and a mass-spectrometry identity result, reports measured content in mg, and carries the same lot number printed on your vial. Missing any of those, treat it as marketing until an independent test says otherwise.

1. Who ran the test

Look for the lab's name, address and, ideally, its accreditation (ISO/IEC 17025 is the common standard). Labs frequently named on research-peptide COAs include Janoshik, Freedom Diagnostics, Vanguard Laboratory and Bioviridian. A COA from the company that made or distributed the raw powder is a supplier certificate. It describes their bulk batch, not the filled vial.

2. Purity: HPLC

High-performance liquid chromatography separates a sample into components. The purity figure is the main peak's share of the total detected area at the detection wavelength (often 214 or 220 nm for peptides). A real report includes the chromatogram, the trace with its peaks. Purity of 98% or more is the usual claim. Note what HPLC can't tell you: it measures how much of the sample is one compound, not which compound it is.

3. Identity: mass spectrometry

Mass spectrometry (LC-MS, ESI-MS or MALDI-MS) measures molecular mass and confirms the compound matches its expected mass. A COA with HPLC purity and no MS can describe a very pure sample of the wrong peptide.

4. Content: how many mg are actually in the vial

Quantity testing measures the mg present, usually reported as a number against the label (for example 10.3 mg found on a 10 mg label). Some COAs only say "conforms". That means the lab didn't publish a measurement, so the labelled amount, and any price per mg built on it, rests on the vendor's word.

5. Lot matching

Each production batch has a lot number. A lot-matched COA carries the same lot number printed on your vial's label. Many vendors publish one representative COA per product and send batch-specific COAs only on request. That is weaker: a test of a different batch says little about yours.

6. Other tests you may see

  • Endotoxin (USP <85>): bacterial endotoxin level.
  • Heavy metals (USP <232>): lead, arsenic, cadmium, mercury.
  • Sterility: whether microbes grow from the sample. Rarely shown for research vials.

Nine red flags

  1. No lab name or address. A COA should name the lab that ran the test. A vendor logo on a template is not a lab.
  2. The lab is the supplier. A certificate from the raw-material manufacturer or distributor tests their bulk powder, not the finished vial you buy.
  3. One COA for every size. If the same document covers 5 mg and 60 mg vials, it can't be lot-matched to both.
  4. No lot number, or a lot that isn't on your vial. Without a lot match you can't tell whether the test applies to what you hold.
  5. Dated before the product existed. A COA dated before the vendor's store or product launch may be a supplier's earlier batch.
  6. Purity but no identity test. HPLC tells you how pure a sample is, not what it is. Look for mass spectrometry (MS).
  7. "Conforms" instead of a number for content. If quantity isn't measured, the labelled mg per vial is unconfirmed.
  8. No chromatogram. A purity percentage with no trace behind it can't be checked.
  9. No way to verify. Good labs print a verification code or let you confirm a report with them directly.

Independent testing

A vendor's own COA is the vendor choosing what to show you. Independent results come from buying a vial on the open market and sending it to a lab. Finnrick runs a public database of such tests across many vendors, and community members commission tests from labs such as Janoshik. We link to those results on each vendor profile and count them in our score once at least five are on file.

See how each vendor's COAs stack up in the vendor directory.