How to Read a Peptide Certificate of Analysis (COA)

What a genuine peptide COA actually contains, third-party versus in-house testing, and the concrete red flags of a fake or unverifiable certificate.

Written bySebastian Hunter, Founder and EditorI'm a 42-year-old senior advisor and distance runner who came to peptides as a sceptic. I'm not a doctor: I read the research, run my own experiment and keep honest notes. Read full bio

Published September 22, 2026Updated October 3, 2026

The short version

A Certificate of Analysis, or COA, is a lab document meant to show what is in a vial and how pure it is. A genuine one names a real testing method and a real lab, and both can be checked. Many COAs circulating online cannot be checked at all: no method, no lab that answers, no lot number tying the paper to the product you received.

A real COA names a testing method, not just a purity percentage.
A lot or batch number is what ties the paper to the vial in your hand.
Third-party testing means the lab has no financial stake in the result.
If the issuing lab will not confirm the result when you contact it directly, the document is unverified.

A Certificate of Analysis, or COA, is the one piece of paper that stands between “trust us” and an actual laboratory measurement. For a peptide bought outside the FDA-approved drug supply, it is often the only quality evidence a buyer sees. Most people have never been shown what a genuine one should contain, which makes a fake one easy to pass off.

This page explains what a COA is, what it should say, and how to tell a real one from one that can’t be checked. It is general analytical-chemistry and consumer-protection information, not a claim about whether any specific peptide is safe or effective. My companion page on HPLC purity versus mass spectrometry identity covers what the two most common testing methods measure.

What a COA is

A COA is a document a laboratory issues after running specific analytical tests on a specific batch (also called a lot) of material. It does not cover the product line in general, or every vial that will ever ship under that name. It reports what was tested, which method was used, and what the lab found.

Batches matter because peptide production happens in batches. One batch can be cleaner or more consistent than another, from a raw material difference, a synthesis error, or a storage problem before testing. A COA for lot #A2201 tells you about lot #A2201. It does not automatically tell you about lot #A2305 shipped six months later, even if the seller reuses the same document for both.

The fields a genuine COA contains

A real COA is a structured lab report, not a marketing graphic. At minimum, it should name:

Peptide identity. The specific compound the batch was tested against: the name and, ideally, confirmation that the material matches that compound’s expected molecular structure, not just a label claim.
Batch or lot number. The production run the document covers. This lets you match the paper to the vial in your hand. A lab also uses it internally to find its own test record if you ask it to confirm the result.
Purity percentage, with the testing method named. A number on its own (“99% pure”) is not a measurement. A measurement names how the number was produced, most commonly HPLC (high-performance liquid chromatography). HPLC separates a sample into its component substances and measures how much of the total belongs to the main peak. Purity is covered in detail on my HPLC vs. mass spectrometry page.
Storage conditions the results apply to. Peptides degrade, depending on temperature, light and time. A COA that states results without the storage conditions they assumed describes a sample that may not resemble what showed up in your shipment.
Issuing laboratory name. Not a logo, not initials: a real, named laboratory that can be looked up and, in principle, contacted to confirm it issued the document.
Content or quantity, reported separately from purity. Purity describes what fraction of the detected material is one dominant substance. It does not state how much peptide, by weight, is in the vial. When the FDA reviewed certificates submitted for a peptide bulk substance, they listed identification, purity, related substances and content as separate, individually reported test results, not one combined figure. In that case, content meant counter-ion content. See the FDA briefing document on peptide bulk drug substances.

If any of these is missing, the document is incomplete, whatever the purity number on it claims.

Third-party testing vs. in-house testing, and why it matters

In-house testing means the company selling the product tested its own batch, using its own equipment or staff. Third-party testing means an independent laboratory, with no ownership stake in the seller and no financial interest in the result, performed the test.

Neither guarantees accuracy on its own. A poorly run third-party lab can still produce a bad result, and a well-equipped in-house lab can still produce an honest one. What third-party testing removes is one conflict of interest: the lab reporting the number is not the party whose revenue depends on that number looking good. That reduces the incentive to shade a result, but does not guarantee against one. A seller still chooses which third-party lab to use, and can choose not to publish a result it does not like. A published COA represents the batch and the test the seller chose to show you, not necessarily every batch or every test that was run.

Red flags

Signs a COA is not what it claims to be

Purity stated with no method named. “99% pure” with nothing describing how that figure was produced is a number, not a measurement.
No lot or batch number. A document that cannot be tied to the specific product you received could belong to any batch, including one that was never yours.
A lab that will not confirm the result when contacted directly. A real laboratory can generally tell you, given a lot number, whether it issued a matching certificate. Silence, evasiveness, or a lab that does not appear to exist when you look for it is a direct answer to the question you are actually asking.
A COA image with no verifiable lab name attached. A screenshot or PDF that reads as professional but names no traceable laboratory, or names one that cannot be located, has the look of evidence without the substance.
The same COA reused across multiple, differently dated listings. One certificate covering one batch should not be doing duty for every batch a seller ever ships.

Purity alone does not cover injectable-quality testing

A clean purity percentage answers one question. It does not tell you whether a batch is free of the contaminants that matter most for an injected product.

When the FDA reviewed certificates submitted for a peptide bulk substance, it made three points:

It treated sterility, bacterial endotoxin testing, and particulate matter as critical quality attributes for an injectable product, separate from identity and purity.
It noted certificates with no testing results at all for specified impurities, aggregates, microbial bioburden, or bacterial endotoxin levels.
It flagged residual solvents (leftover from synthesis) as a gap when no testing addressed them.

See the FDA briefing document on peptide bulk drug substances.

Endotoxin and sterility testing are standard attributes for any injectable product, not peptide-specific marketing language. A COA for an injected peptide that reports only purity, with no mention of endotoxin, bioburden or sterility testing, has not addressed a known category of risk. It has not necessarily hidden anything either, since many sellers do not run or disclose these tests. A buyer weighing risk should know the category exists and that a purity number does not cover it.

How to actually verify one

Treat verification as a small amount of due diligence, not a formality:

Check that the lot number on the COA matches the lot number on the vial or its packaging. If there is no lot number on either, there is nothing to match.
Identify the issuing laboratory and look it up independently. Use your own search, not a link the seller provided.
Contact the laboratory directly and ask it to confirm whether it issued a certificate for that lot number. A functioning lab can usually answer this in some form. One that goes quiet or cannot locate any record of the batch has told you something important.
Check that the testing method is actually named, and treat “purity” and “identity” as two separate questions. A method that establishes one does not automatically establish the other. See my page on HPLC vs. mass spectrometry for what each confirms.

None of this proves a product is safe or effective for any use. It only tells you whether the one document meant to back up a purity or identity claim can withstand being checked.

Common questions

What is a peptide certificate of analysis?

A certificate of analysis, or COA, is a document a laboratory issues after testing a specific batch of a product. For a peptide, it should report the analytical methods used, what they found about the identity and purity of that batch, and who did the testing. It describes the batch it was issued for, not the product line in general.

Does a COA prove a peptide is safe?

No. A COA is a snapshot of what a lab found when it tested one batch for specific attributes, usually purity and sometimes identity. It says nothing about whether the substance is safe to take, what a safe amount would be, or what happens with repeated use. Purity and safety are different questions, and a clean chromatogram answers only the first.

What is the difference between third-party and in-house testing?

In-house testing is done by the company that makes or sells the product, using its own laboratory and staff. Third-party testing is done by an independent laboratory with no ownership stake in the seller and no financial interest in the result. A seller can still choose which third-party lab to use and which results to publish, so independence reduces one conflict of interest, not every one.

What should I do if a COA has no lab name or the lab will not confirm results?

Treat the document as unverified. A real testing laboratory has a name, is generally locatable, and can typically confirm whether it issued a specific certificate for a specific lot number when contacted directly. A COA image with no traceable lab, or a lab that goes silent or evasive when asked to confirm a result, has not shown anything about the product.

Does a high purity percentage on a COA mean the vial contains the labelled peptide?

Not by itself. A purity percentage from a method like HPLC describes how much of whatever was measured is one dominant substance, relative to everything else that method detected. It does not confirm that the dominant substance is the peptide named on the label. Identity and purity are different determinations. A COA that reports only a purity number, with no method named for identity, has not answered the identity question at all.

How can you spot a fake peptide COA?

Check for the pieces a real one always has: a named testing method, a lot or batch number, a named laboratory, and stated storage conditions. A document missing any of these cannot be verified. Then try to verify it. Look up the laboratory independently of any link the seller gave you, and contact it directly to ask whether it issued a certificate for that lot number. A lab that cannot be found, or that will not confirm the result, is the clearest sign the document is not what it claims to be.

Is there one official COA for a specific peptide, such as retatrutide?

No. A COA covers one tested batch from one manufacturer, not a compound in general, so no single reference certificate exists for any peptide. Retatrutide is also not an FDA-approved drug, so no government agency issues or maintains an official certificate for it. Any COA offered for it applies only to the batch it names, from the source that tested it, and needs the same verification as any other.

Where can I get a COA for peptides?

From whoever tested the batch. That is usually the seller, who should be able to supply the COA for the lot number printed on your vial. I know of no central database of peptide COAs. Once you have one, look up the issuing laboratory yourself and ask it to confirm that it issued a certificate for that lot.

How do I get a COA for my product?

A laboratory issues a COA after testing a specific batch. Send a sample from that lot to a testing lab, ideally an independent one. Ask for a report that names the methods used, the identity and purity results, the lot number and the lab itself. It covers that batch only, not later ones.

References (1 sources)

Bibliographic detail is fetched from PubMed, not written by me - so a citation here cannot drift from the paper it names. Study design comes from PubMed's own tags rather than my judgement.

1.FDA briefing document for the Pharmacy Compounding Advisory Committee meeting, 23-24 July 2026 - evaluation of BPC-157-related bulk drug substances. Reviews submitted certificates of analysis and finds identity, purity, related-substance and counter-ion content reported as separate results, with gaps in sterility, endotoxin, and impurity testing.- US Food and Drug Administrationregulatory