Certificates of Analysis & Verification

Published August 21, 2026 · Artemis Labs

Research Buyer FAQ › Certificates of Analysis & Verification

A Certificate of Analysis, or COA, is the lab report for one batch of material. It says what the batch is, how pure it is, who tested it, and when. This page shows what a real one contains, how a forged one gives itself away, and what a COA does not cover.

How this page was built. The checks below are things a buyer can do without lab access. Facts about FDA letters and vendor closures come from the public record listed under References.

How do I know if a peptide COA is real or fake?

Compare the document against the vial and against itself — a forged COA almost always breaks in more than one place. Start with the batch number. The lot printed on the COA has to match the lot printed on the vial label. If the COA has no lot at all, or the lot is a round number like 001, you are probably looking at a marketing sample rather than a batch report.

Then look for the raw evidence. A real report shows the chromatogram and the mass spectrum as pictures, not just a number typed into a table. Faked reports tend to reuse one trace across several products, or print the same purity figure — 99.2%, say — on every compound in a catalog. Real batches vary. Finally, check that the report names the lab and the test date, and that the date comes before your order.

One more thing worth saying plainly: a PDF is easy to edit. A COA is evidence, not proof. It earns its weight when the lab is named, the batch is traceable, and the numbers move from batch to batch the way real measurements do.

What is a Certificate of Analysis for peptides?

It is the batch-specific lab report that states what the material is and how pure it is. A COA is tied to one production lot, not to a product line. It records the tests that were run, the results, the method, the date, and the lab. Our longer walk-through of the document, section by section, is the guide to reading a peptide Certificate of Analysis.

What information has to be on a COA?

At minimum: the compound name, the lot or batch number, the test date, the methods used, the results, and the name of the lab. For a synthetic peptide that means an identity test and a purity test — usually mass spectrometry for identity and HPLC for purity — with the observed value shown next to the expected value. A document with results but no methods is not a COA. The field-by-field version is in the guide to reading a peptide Certificate of Analysis.

What does a peptide COA look like?

One or two pages laid out like a lab report, in four parts. A header identifies the compound and the batch: compound name, lot number, test date, and the lab. A results table lists each test beside its outcome — an HPLC purity percentage, and a mass-spectrometry line showing the observed mass next to the expected mass for the sequence. The raw evidence follows: the chromatogram (the HPLC trace with its peaks) and the mass spectrum, shown as images rather than summarised as numbers. Last comes the lab’s identification, often with an analyst signature. A document missing the images, the lot number or the methods is a summary, not a COA. How forgeries give themselves away is covered in how to spot a forged Certificate of Analysis.

What is the difference between a third-party COA and an in-house one?

A third-party COA is written by a lab that does not work for the seller. An in-house COA is written by the seller’s own quality team. Both can be honest and both can be careful. The difference is who carries the cost of being wrong. An outside lab has no commercial reason to round a number up.

In-house data is normal and useful for day-to-day quality control. It is not a substitute for outside verification when a purity figure is being used to sell something. If a vendor will not say which of the two you are holding, that itself is the answer. For our own catalog, the manufacturer performs periodic quality testing on production batches — and every check on this page applies to us the same way it applies to anyone.

Why is there no batch number on my vial?

Because the vendor either did not run a batch-level test or did not carry the number through to the label — and neither is good. The batch number is the thread that ties the vial in your hand to a specific lab report. Without it, a COA cannot be matched to anything. A vial with no lot marking cannot be verified at all, no matter how good the paperwork looks.

Artemis Labs does not currently publish batch documents or operate a lot-lookup page; the manufacturer performs periodic quality testing on production batches. Measured against the standard this page teaches, that is an honest gap on our side, and it is named again below.

Do I get a COA with every vial?

No. Artemis Labs does not currently issue batch documents with orders, and we would rather say that plainly than hand you a piece of paper we cannot stand behind. The manufacturer performs periodic quality testing on production batches — that is the whole claim, stated at its honest size. If independent, batch-matched documentation ever becomes something we can publish and defend, this page will announce it first. Every item in the Artemis Labs catalog is supplied for laboratory research use only.

What does “third-party tested” actually mean?

It means an outside lab, not the seller, ran the test. That is the whole claim — and it is narrower than it sounds. The phrase says nothing about which tests were run, how often, or on what. A vendor can truthfully say “third-party tested” after sending one sample to one lab one time, years ago.

So the useful follow-up questions are: tested for what, and how often? Identity and purity are different tests and answer different questions. A batch tested for identity alone has not been checked for purity. When you see the phrase, look past it to the COA and check the lot number, the method and the date.

How much does third-party peptide testing cost?

Enough to show up in the price of the vial. An independent lab charges per sample and per method, and charges again for every new lot — an HPLC purity run and a mass-spectrometry identity check are separate line items, so a vendor testing every batch of every compound is paying for testing continuously, not once. No single dollar figure is printed here because lab price lists vary with the methods ordered and the turnaround time, and a quoted number would go stale; the structure of the cost is the point. It is also the honest explanation for part of the price gap between tested and untested product: a seller who skips per-lot testing removes a recurring cost, which is covered under why some peptides are so much cheaper than others.

Can I test peptide purity myself?

Not quantitatively. Visual inspection catches gross problems only — a wet or collapsed cake, a missing lot number, a fill that changes from vial to vial in the same order. Those checks are worth doing, but none of them produces a purity number. A purity percentage comes from HPLC and an identity confirmation from mass spectrometry, and those are instruments analytical laboratories run, not things a home bench can reproduce. What a buyer can do is commission the measurement: independent analytical labs accept mailed-in samples and return a report for a fee, and that class of service is the strongest verification available to someone outside a lab, because it does not pass through the vendor at all. What such a report should contain — and the limits of what any lab report can show — is covered in what “third-party tested” actually means.

Can I see the COA before I buy?

No — there is no document to see, before or after purchase, and this page will keep saying so until that changes rather than point you at a demonstration PDF and let it stand in for the real thing. What you can do today is apply every check in this section to any vendor’s paperwork, ours included: ask who ran the test, what was tested, and how the document ties to the lot in your hand.

Who actually tests your peptides?

The manufacturer performs periodic quality testing on production batches. That is the whole answer, and it is deliberately smaller than the answer most vendors give: we do not commission independent testing ourselves, we do not hold batch documents, and we are not going to describe an arrangement we cannot show you. If that changes — if independent, batch-matched testing becomes something we pay for and can document — this page will say so, name the lab, and publish what it found. Until then, weigh this answer the way this page teaches you to weigh any vendor’s: as an unverified statement from the seller.

Can I trust a vendor that will not show COAs?

No, and you do not need a further reason. A batch report is the cheapest thing a real vendor can produce. Refusing to show one is not a policy; it is an answer. The wider set of checks — testing, documentation, citations, counter-evidence, and what the vendor sells alongside the peptides — is laid out in the peptide supplier evaluation checklist.

What does a COA not tell you?

Quite a lot, and vendors rarely volunteer the list. A standard peptide COA covers identity and purity. It does not cover sterility. It does not cover endotoxin. It usually does not report water content, residual solvents, or the counterion left over from purification, unless those tests are named on the document.

That matters for one reason above all: research-use-only material is not sterile-filled, and a purity figure does not imply that it is. A COA is a chemistry document. It says what the molecule is and how much of the sample is that molecule. It does not certify anything beyond what its own methods measured, and we would rather write that down than let the document seem to say more than it does.

What is a chromatogram and how do you read one?

A chromatogram is the picture an HPLC run produces — a flat line with peaks rising out of it. Each peak is something that came off the column at a given time. The tall peak is your peptide; small peaks beside it are everything else. Purity is the area of the main peak as a share of the total area. The step-by-step reading is in our explainer on HPLC and mass-spectrometry verification.

What does mass spec check that HPLC does not?

Identity. HPLC tells you how much of the sample is one substance; it does not tell you which substance. Mass spectrometry weighs the molecule and compares the measured mass with the expected mass for that sequence. Run alone, HPLC can certify the wrong compound at 99%.

The pairing is not academic. Hannappel and colleagues re-examined a long-used thymosin preparation by high-resolution mass spectrometry in 2018 and reported a composition different from the one assumed for decades (PMID 30063862). Identity testing is what catches that. Both methods are covered in HPLC and mass-spectrometry verification.

This page is one section of the full Artemis Labs research-buyer FAQ.

References

  1. Hannappel E, et al. “Thymosin fraction 5 re-evaluated after 35 years by high-resolution mass spectrometry.” Expert Opin Biol Ther. 2018;18(sup1):199–203. PMID 30063862 · doi:10.1080/14712598.2018.1474196
  2. Yoshida K, et al. “Impurity profiling of synthetic cyclic peptides based on orthogonality between hydrophilic-interaction and reversed-phase liquid chromatography.” J Chromatogr A. 2025;1745:465748. PMID 39922152 · doi:10.1016/j.chroma.2025.465748
  3. US FDA — Warning Letters database. fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters