How to Read a Peptide COA: What Actually Matters

To read a peptide COA, check three numbers against the product claim: identity (is it the right compound), content (the actual milligrams), and purity (how clean). Confirm the lab is independent, verify the report at the lab's own source, and check the date and batch. No COA proves your specific vial.

A Certificate of Analysis, or COA, is the one document that separates a peptide you can trust from a number on a label. It is also where most of the industry quietly cuts corners, because almost nobody who buys peptides actually knows how to read one. Sellers know that, which is why "99% pure" gets splashed across every product page as if it settled the matter. It does not.

This is a plain-English walkthrough of what a COA really tells you, who actually does the testing that counts, and the one thing no COA can ever prove, no matter how clean it looks. None of it is complicated once someone explains it without the jargon.

What is a peptide COA?

A peptide COA (Certificate of Analysis) is a lab report on a peptide, ideally from an independent third-party testing lab rather than the manufacturer marking its own homework. It lists a set of measured values, and your job is to check that those values match what the product claims to be. Three of those values do most of the work.

Which three numbers matter most on a COA?

Identity, content and purity are the three numbers that matter most, and if you read nothing else on a COA, read these. Identity confirms it is the right compound, content confirms the milligram amount, and purity confirms how clean the peptide is. The rest of the COA is detail layered on top of those three.

Identity answers the most basic question: is this actually the compound you ordered? It confirms the vial contains, say, BPC-157 and not a different peptide or something close to it. Identity is usually established by mass spectrometry, a lab method that weighs molecules to confirm which compound is present, which measures the molecular weight and matches it to the expected peptide. If identity is wrong, nothing else on the page matters.

Content (sometimes called net content) is the actual milligram amount of peptide in the vial. This is the one people forget about, and it is where shortchanging happens. A vial labelled 10 mg that contains 8 mg is not "99% pure" in any meaningful sense to you, it is 20% short. Content tells you that you are getting the dose you paid for.

Purity is the percentage of the peptide that is the intended molecule rather than synthesis by-products or degraded fragments. It is measured by HPLC (high-performance liquid chromatography), a lab method that measures how pure a peptide is. A figure in the high 90s means a clean, well-made peptide.

Get those three lining up with the product claim, and the essentials are covered. Everything else on the COA is detail on top.

What does 99% purity mean for peptides?

For peptides, 99% purity means that of the peptide present, 99% is the correct molecule and only 1% is by-products. It does not mean 99% of the powder is active compound. Most of the visible powder is excipient added during freeze-drying, so the two claims are completely different, and sellers lean on the confusion.

Here is the thing the marketing relies on you not knowing.

Purity is not peptide versus filler. When you look at the powder or the little puck in the bottom of a vial, almost all of what you can see is excipient, usually mannitol or sucrose, added to protect the peptide while it is freeze-dried. The actual peptide is a tiny, often invisible amount. So "99% purity" does not mean "99% of the powder is the active compound". It means: of the peptide that is in there, 99% of it is the correct molecule and only 1% is by-products. Those are completely different claims, and sellers lean on the confusion.

No peptide is ever exactly 100% pure. Every synthesised compound carries some minor related substances. For context, official pharmaceutical guidelines for injectables allow up to around 12-13% total related substances. So a genuine 95-97% purity is not a second-rate product, it sits comfortably inside pharmaceutical-grade limits. Chasing a "99.9%" number on a label is often chasing a marketing figure, not a meaningful quality difference.

Why does dimer content matter more than purity for growth hormone?

For growth hormone and other large proteins, dimer content matters more than a flat purity percentage because these molecules naturally clump into dimers, and the meaningful measure is how much clean single-molecule monomer you have versus dimer. A high-quality growth hormone can read 96.6% purity with tightly controlled dimer content, while a simple "99% pure GH" claim ignores the number that actually matters.

For larger molecules like recombinant growth hormone (growth hormone made in engineered cells rather than chemically synthesised), a flat purity percentage can actually be misleading, and this is where a little knowledge pays off. These molecules naturally clump into dimers (two copies stuck together), and the meaningful quality measure is how much monomer (clean, single molecule) you have versus dimer, not a generic 99% claim. A growth hormone tested at, say, 96.6% with tightly controlled dimer content is a high-quality product, not a low-grade one. Anyone quoting you a simple "99% pure GH" is either not measuring what matters or hoping you will not ask.

What about sterility, endotoxin and heavy metals?

Sterility, endotoxin and heavy metals are the tests most COAs leave off, and the gap is worth understanding. Endotoxin is the one that matters most for anything injected, sterility is slow and often skipped, and heavy metals are rarely a real concern in peptides. Most COAs in this industry stop at identity, content and purity.

• Sterility is whether the product is free of living bacteria or mould. A proper sterility test is a 14-day process (you have to give anything present time to grow), which is why it is often skipped, it is slow and it costs money.
• Endotoxin testing looks for bacterial cell-wall fragments, which are inflammatory even when the bacteria themselves are dead. There is no single safe number; the limit depends on the dose and the body weight of whoever is using it. This is the test that matters most for anything injected, and it is the one the cheap end of the market almost never runs.
• Heavy metals get mentioned a lot, but they are not used in peptide synthesis and are rarely found at meaningful levels, so this is lower down the list of real-world concerns.

The honest caveat: when a seller says a peptide is "tested," that usually means identity, content and purity only, not sterility or endotoxin. That is not automatically a scandal, but it is worth knowing what the word does and does not cover.

What is Janoshik and why is it the gold standard?

Janoshik is an independent European analytical laboratory that has become the reference standard for third-party peptide and SARM testing, and three things make it the gold standard: it is independent (no stake in what it tests), it is comprehensive (it runs the tests that matter), and it is verifiable (every genuine report can be checked on Janoshik's own system). That verifiability is the part most people miss.

If you spend any time in this world, one lab name comes up again and again, and for good reason. Janoshik is an independent European analytical laboratory that has become the reference standard for third-party peptide and SARM (a separate class of research compounds) testing. When people talk about getting something "Jano tested," that is the lab they mean.

Three things make Janoshik the gold standard:

1. It is independent. It has no stake in what it is testing. It is not the seller grading their own work, which is exactly the conflict of interest that makes a manufacturer's in-house number worth so little.
2. It is comprehensive. It runs the tests that matter, HPLC purity, mass-spec identity, quantified content, and also offers endotoxin, sterility and heavy-metals testing.
3. It is verifiable. This is the part most people miss. Every genuine Janoshik report can be checked on Janoshik's own system, so a real result cannot be quietly faked or doctored after the fact.

A current, verifiable Janoshik COA is about the strongest quality signal a research peptide can carry. It is not the only good lab in the world, but it is the one the serious end of the industry treats as the benchmark, and it is the one worth knowing by name.

How can you spot a fake or meaningless COA?

To spot a fake or meaningless COA, verify it at the lab's own source using the report ID or QR code, never the PDF a seller emailed you. Then check that the three numbers match the product, check the date and batch, and be wary of suspiciously perfect figures with no by-product peaks shown. A PDF is easy to fake; a real COA is verifiable.

Before you trust one:

1. Verify it at the source. If a COA claims to be from Janoshik (or any lab), check the report on that lab's own verification system, using the report ID or QR code, not the PDF a seller emailed you. A genuine report checks out; a doctored one does not. This single step filters out most fakes.
2. Check the three numbers match the product. Identity matches the compound, content matches the labelled milligrams, purity matches the claim.
3. Check the date and batch. A COA from two years ago, or with no batch reference at all, tells you very little about what you are being sold today. Old and mismatched COAs are a favourite trick.
4. Be wary of suspiciously perfect numbers. A clean 96-98% with real by-product peaks shown is more believable than a flat "99.9%" with no detail.

Can a COA prove the exact vial in my hand?

No, a COA cannot prove the exact vial in your hand is what the certificate describes. A COA is a snapshot of a sample taken from a batch or production line, and testing consumes that sample, so by definition the tested vial is not the one you received. Your certificate is evidence about a batch or product line, not proof about your individual unit.

Here is the uncomfortable truth every honest vendor knows and most will not say out loud: a COA cannot confirm that the specific vial in your hand is what the certificate describes.

The certificate you hold can be months old, and there is simply nothing on it that ties it to the exact vial you are holding. That is the nature of the document, not a failure of any particular seller.

That does not make a COA worthless. It makes it something to weigh, with a grain of salt, alongside everything else you know, rather than a guarantee. Do your own research, read the document for what it actually is, and be honest with yourself about its limits.

So how does Primogen handle COAs and testing?

Primogen relies on reference COAs from suppliers it has vetted today, and shares them for exactly what they are: the supplier's own documents describing a product line, not tests Primogen commissioned and not your specific vial. Primogen does not currently run its own independent testing. Sending stocked products to Janoshik and publishing those results openly is on the roadmap as the company scales.

Follow that logic all the way down and you reach the real answer. Unless you are going to send your own vial to a lab like Janoshik yourself, you are placing a degree of trust in whoever you buy from. There is no way around it, and anyone who tells you their paperwork removes that trust entirely is selling you a feeling. The honest question is not "is there a COA," it is "do I trust this source, and are they straight with me about what they actually know."

So we will be straight about where Primogen stands today, and where we are going.

Right now, like the honest end of this market, Primogen relies on the suppliers we have vetted and on the reference COAs they provide. Those are the supplier's own documents describing the product line, not tests we commissioned and not your specific vial, and we share them for exactly what they are, no more. We do not currently run our own independent testing, and we are not going to pretend otherwise.

On our roadmap, as we scale, is our own independent testing: sending the products we stock to Janoshik ourselves and publishing those results openly. That own-batch testing is the standard we are building toward, and we would rather tell you plainly that it is a work in progress than dress up where we are today.

There is a real reason it is tied to scale, and we will own all of it, cost included. We are a new company growing quickly, and running full third-party testing across the entire lineup before we are buying at real volume would not be a sensible use of money yet. Cost is part of the honest picture at this stage, and we are not going to pretend otherwise. But it is not the main reason.

The bigger reason, though, is integrity, and it holds even if you set the money aside. Batch testing only means something if you can point to one batch and say, honestly, we bought this batch, we tested vials from it, and this is what you are getting. That only works when a single order genuinely is one batch. Buy small amounts, test one, then reorder more small amounts, and those reorders are effectively different batches from the supplier. A test of the first proves nothing about the next, so putting that certificate on the site would not actually prove the vial in your hand is the thing we tested. That is theatre, not quality assurance. So we would rather wait until our scale lets us test a batch and sell that same batch, and mean it. Doing it properly beats doing it for show.

And here is why that honesty matters. A lot of sellers will tell you "every batch is independently tested." It is almost always untrue. If it were true, they would show you the Janoshik COAs to prove it, because that is the entire point of testing. Most cannot. Some wave a single certificate, often old or from a different batch, and call it proof. The willingness to tell you what is not tested is usually a better signal of an honest source than any number on a glossy PDF.

And here is the truest thing on this page, the one we will say out loud even though it is not in our interest to: even once we are doing our own larger-batch Janoshik testing, nothing will hand you hard proof that the specific vial in your hand is the one that was tested. That is not a Primogen limitation, it is the nature of the thing. Short of you sending your own vial off yourself, no certificate from anyone closes that final gap. It always comes down to trust, your own due diligence, and whether enough dots connect and enough green flags line up for your own judgment. That is exactly why we want to do this with as much transparency as we possibly can. When proof of your individual vial is something nobody can truly give you, the only honest substitute is to show our work, tell you plainly what we do and do not know, and earn the trust rather than demand it.

What should I remember when reading a COA?

When reading a COA, remember the three numbers that matter, what a purity figure really means, and the limit no certificate can cross. Here is the short version.

• The three numbers that matter most are identity, content, purity. Read those first.
• "99% purity" is peptide-versus-by-products, not peptide-versus-filler, and 95-97% is genuinely good.
• For growth hormone, dimer content matters more than a flat percentage.
• Sterility and endotoxin are the tests most often skipped, and endotoxin is the one that matters most for injectables.
• Janoshik is the gold-standard independent lab, and a COA is only worth anything if you can verify it at the lab's source.
• No COA proves the exact vial in your hand, so unless you test it yourself, it comes down to trusting your source. Primogen trusts vetted suppliers and shares their reference COAs today, with our own Janoshik testing on the roadmap, published openly.

If you understand this much, you are already reading COAs more carefully than most of the market. New to all of this? Start with the beginner's guide to peptides, and see how to reconstitute and store once you have your vials.