How to Read a COA. And Catch a Fake One.
By Justin Ragazzine, Founder, Pure Chain Aminos
A number on a PDF is not a test result
Independent testing in 2026 has made one thing clear: the gap between what a label says and what is in the vial is wide, and the Certificate of Analysis is the only document standing between the two. Most buyers never open it. Most who do stop at the purity percentage.
What a COA is, and is not
A Certificate of Analysis is a laboratory’s report on one specific lot of material. It is not a manufacturer’s promise, not a product description, and not a template. If it does not name the lot, the lab, the method and the date, it is a marketing image with a percentage on it.
Three questions a COA has to answer
- Is it what it says it is? Identity, confirmed by mass spectrometry against the expected molecular weight.
- How much of it is the compound? Purity by HPLC, plus net peptide content, which is a different number and usually a lower one.
- Is it safe to handle in a laboratory setting? Endotoxin, sterility and, where relevant, heavy metals and residual solvents.
The one-sentence version. A real COA lets you call the lab and ask about the lot. A fake one gives you nothing to call.
Anatomy of a complete Certificate of Analysis
| Field | What it should show | Why it matters |
|---|---|---|
| Lot / batch number | Matches the number printed on the vial you received | Without it, the COA describes some other material |
| Issuing laboratory | Named lab, address, accreditation (ISO/IEC 17025 or CLIA), analyst or task ID | The only field you can independently verify |
| Identity (MS) | Observed mass vs. theoretical mass, within instrument tolerance | Proves the compound is the compound |
| Purity (HPLC) | Chromatogram with the main peak area as a percentage, method and column noted | The headline number, but only for what dissolved and eluted |
| Net peptide content / quantity | Milligrams of actual peptide in the vial, not gross weight | A “10 mg” vial can be 6 mg of peptide plus counter-ion and water – or 19 mg |
| Counter-ion (TFA / acetate) | Salt form and residual level | Affects net content and in-vitro behavior |
| Endotoxin (LAL / rFC) | EU/mg or EU/vial against a stated limit | Bacterial contamination is invisible to HPLC |
| Sterility | Pass/fail by a named method (e.g., USP <71>) | Also invisible to purity testing |
| Date of analysis | Specific date, plausibly after manufacture and before sale | A COA older than the product line is a template |
| Vial photograph | Image of the tested vial with visible lot label | Ties the paper to the physical batch |
Purity is not quantity. 99% purity means 99% of what the instrument saw was the target peptide. It says nothing about how many milligrams are in the vial. The Australian sample was both nearly double the labeled mass and 16.6% pure. You need both numbers, from the same lot.
Seven signs a COA was never issued by a lab
- No lot number, or a lot number that does not match the vial. The most common failure. One generic certificate reused across every batch of a product is not a certificate; it is a graphic.
- The laboratory is unnamed, or named but unfindable. Search the lab. It should have its own website, an address, and an accreditation you can look up. “Tested by a US lab” is not a lab.
- A purity percentage with no chromatogram. HPLC produces a trace. A COA that reports 99.4% with no peak, no retention time and no method was typed, not measured.
- Identity claimed without a mass. Mass spectrometry reports an observed molecular weight. If the certificate says “identity: confirmed” with no number, nothing was confirmed.
- Suspiciously perfect numbers. Real instruments produce 98.7%, 99.13%, 1,012.6 Da. A page of round 99.9% results across every field, every lot, every product is the signature of a template.
- Endotoxin and sterility missing entirely. Purity-only COAs are cheaper to obtain and skip the two contamination tests that matter most for handling.
- The date makes no sense. A COA dated before the product launched, years old, or identical across dozens of lots, was not generated per batch.
The Finnrick lesson. On the independent index, vendor pass rates for the same compound run from the low 90s to well under 50%. Almost every one of those vendors publishes a COA. The paper is not the test; the independent re-test is.
How to verify a COA in five minutes
- Match the lot. Compare the lot number on the certificate to the label on the vial. No match, stop here.
- Find the lab. Search the laboratory named on the COA. Confirm it exists, find its accreditation, and note its contact details.
- Verify with the lab, not the vendor. Some labs (Janoshik is the best-known example) publish a lookup where a task number and key confirm the certificate was issued by them. Others will confirm by email. If a lab cannot or will not confirm, treat the COA as unverified.
- Read the mass. Compare the observed molecular weight on the MS result to the theoretical weight for the compound. They should agree within the instrument’s stated tolerance.
- Read the purity method. HPLC with a named column, gradient and detection wavelength. Look at the chromatogram: one dominant peak, small impurity peaks, nothing hidden.
- Find the quantity. Net peptide content or assayed mass per vial. If only gross weight is given, the label mass is unverified.
- Check contamination results. Endotoxin in EU/mg or EU/vial against a limit; sterility pass by a named method.
- Look for the vial. A photograph of the tested vial with a legible lot label ties the certificate to the batch.
- Cross-check the vendor on an independent index. Finnrick and similar registries publish pass rates by vendor and compound. Self-published COAs plus a strong independent record is the pattern to look for.
What a good result looks like. Lot matches, lab confirms, mass agrees, chromatogram is clean, net content is stated, endotoxin and sterility pass, the vial photo is legible, and the vendor’s independent pass rate is high. Anything less is a claim, not a certificate.
How Pure Chain Aminos tests, and why we photograph the vial
We built our quality process around the checklist in this guide, because we wanted a buyer to be able to run it on us and have nothing come up empty.
Every batch through one independent lab
Every batch is tested through Freedom Diagnostics Lab, an independent CLIA-certified laboratory, for identity by mass spectrometry and purity by HPLC, with the additional panels for that lot reported on the same certificate. The COA carries the lot number, the method, the date and the lab’s identification, and it is published on the product page for that lot.
The vial in the picture is the vial that was tested
Each COA includes a photograph of the sampled vial with its lot label legible. It is a small thing that closes the biggest gap in the category: the gap between a document and a physical batch.
GMP synthesis in U.S.-registered facilities
Solid-phase peptide synthesis in U.S.-registered GMP facilities, lyophilized and sealed under controlled conditions, shipped domestically the same day on orders placed before noon Pacific.
What we are still working on
Two things a rigorous buyer would notice. First, we are adding our products to independent testing indices so our results sit next to everyone else’s, not just on our own site. Second, we are moving to a lot-lookup page where any certificate can be pulled by number without finding the product first. We would rather say so than pretend the process is finished.
Run the checklist on us. Pick any product at purechainaminos.com, open the COA, and work through the verification steps above. If anything fails, email support@purechainaminos.com and we will answer with the lab’s confirmation or a correction.
Frequently asked questions
Sources
- Finnrick, retatrutide product page and vendor index, finnrick.com
- ABC News (Australia), “Double-strength retatrutide peptide sparks warning,” June 27, 2026
- Janoshik Analytical, public certificate verification, janoshik.com
- USP General Chapters <61>, <71>, <85> – microbial, sterility and bacterial endotoxin test methods
For research and laboratory use only. Not for human consumption, veterinary use, or medical applications. Nothing in this article is medical, dosing, or legal advice.
Related reading: 7 red flags when buying research peptides online and why “99% pure” isn’t the whole story.
Browse: full research compound catalog and guides.
Related: HPLC vs mass spectrometry on a peptide COA and how to store lyophilized research peptides.
