How to Read a Certificate of Analysis — What to Look For

A Certificate of Analysis is supposed to be your guarantee that a research peptide is what the vendor claims it is — the right compound, at the stated purity, without contaminants. In practice, COAs range from rigorous independent laboratory documentation to documents that are essentially worthless as quality verification.

Knowing the difference is one of the most practical skills in peptide research. This guide walks through exactly what a legitimate COA contains, which laboratories are credible, how to verify a COA is real, and the red flags that should make you walk away from a vendor entirely. The vendor enforcement article covers the 2025-2026 closures that made this more important than ever — multiple closures were preceded by third-party testing revealing quality failures that vendors' own documentation had not surfaced.

Why COAs matter — the quality problem in plain numbers

Independent testing across the grey-market peptide space has documented purity levels ranging from 60 to 85% at some vendors — well below the 98%+ required for pharmaceutical-grade compounds.

What this means practically: if you source a BPC-157 vial labeled as 5mg from a vendor whose actual purity is 70%, you are receiving approximately 3.5mg of the active compound and 1.5mg of unknown impurities. At consistent dosing, this means your research results are unreliable because the dosing is inaccurate. At worst, the impurities themselves create unknown safety risks.

This is not a hypothetical. Finnrick Analytics documented that Peptide Sciences — the industry's largest vendor, generating $7.4 million in monthly sales — tested at failing grades on multiple compounds including retatrutide, where counterfeit detection was flagged across 37 samples. This was a vendor whose customers assumed they were buying quality.

A COA from a credible, independent laboratory is the primary tool for verifying you are not in this situation.

The three legitimate labs — know these names

There are three laboratories that appear consistently in legitimate, credible peptide COA documentation. Knowing these names is the starting point for evaluating any vendor.

Janoshik Analytical

Based in the Czech Republic. Janoshik is the most commonly cited independent peptide testing laboratory in the research community. Provides HPLC purity testing and mass spectrometry identity confirmation. The key feature that makes Janoshik verification meaningful: every test result is assigned a unique task number that can be verified directly on Janoshik's own website at janoshik.com. If a vendor provides a Janoshik COA, you can enter the task number on Janoshik's site and see the original result. This makes Janoshik-verified COAs genuinely verifiable in a way that matters.

MZ Biolabs

US-based analytical laboratory. Provides similar HPLC and mass spectrometry testing to Janoshik. MZ Biolabs results can be verified through their own verification portal. A well-regarded option particularly among US-based vendors because of domestic testing and faster turnaround.

Colmaric Analyticals

A third legitimate option that appears in credible vendor documentation. Less commonly cited than Janoshik or MZ Biolabs but an accepted independent testing source.

If a vendor's COA comes from any lab other than these three — or from a lab with an unfamiliar name — that is not automatically a red flag, but it warrants additional investigation. Look up the lab independently. Verify it is a real, accredited analytical laboratory with a verifiable web presence separate from the vendor.

What a legitimate COA actually contains

A COA is a document, not just a number. Here is what a legitimate third-party COA includes — and what each element tells you.

The compound name and molecular formula

The document should clearly state what compound was tested, including its full chemical name and molecular formula. For BPC-157, this is the 15-amino acid sequence with the molecular weight of 1,419.55 Daltons. The compound identification should match exactly what was labeled on the product.

The batch or lot number

Every legitimate COA is batch-specific. It documents the results for a specific production run — not a generic test that applies to all product indefinitely. The batch number on the COA should match the batch number on the vial you receive. If a vendor provides a COA without a batch number, or if the batch number on the COA does not match your vial, the COA is not verifying what you actually received.

HPLC purity result

HPLC stands for High-Performance Liquid Chromatography. It is the standard method for measuring purity — what percentage of what is in the vial is actually the compound you are looking for, versus other molecules. The minimum acceptable purity for research-grade peptides is 98%. A legitimate COA will state the purity as a specific percentage with the testing methodology described.

Mass spectrometry identity confirmation

HPLC tells you how pure something is. Mass spectrometry tells you what it actually is. A compound could be 99% pure — but if it is the wrong compound, purity is irrelevant. Mass spectrometry identifies the molecular weight of what was tested and confirms it matches the expected compound. This is particularly important for newer, more complex compounds like retatrutide where counterfeiting has been documented.

High-quality COAs include both HPLC purity and mass spectrometry identity. COAs with only HPLC are better than no COA — but a COA with both tests is the genuine gold standard.

Endotoxin testing

Endotoxins are bacterial cell wall components that cause inflammatory responses when injected. A peptide can be 99% pure and still cause serious injection-site reactions or systemic inflammation if endotoxin levels are high. Endotoxin testing (expressed as EU/mg — endotoxin units per milligram) is standard for pharmaceutical-grade injectable compounds and should appear on a legitimate COA for any injectable peptide.

Many grey-market vendor COAs do not include endotoxin testing. This is a meaningful gap for anyone researching injectable compounds.

Date of testing

COAs should be dated. A COA dated two years ago does not tell you about the current batch. Legitimate vendors test each production batch and the COA date should correspond to the production timeframe of what you are receiving.

How to verify a COA is real — the Janoshik method

For COAs from Janoshik Analytical, verification is straightforward and you should always do it.

Step 1: Find the task number on the COA document. It will appear as a unique identifier, typically in the format of a number that Janoshik assigned when the test was submitted.

Step 2: Go to janoshik.com and navigate to their results search or verification page.

Step 3: Enter the task number. The original Janoshik result will display — the actual data from the laboratory, unmodified by the vendor.

Step 4: Compare what is shown on Janoshik's site to what appears on the vendor's COA document. If they match, the COA is verified. If they do not match — or if the task number returns no result — the COA may have been fabricated.

This verification step takes two minutes. It is the most powerful tool available for confirming a vendor is providing legitimate documentation rather than a professionally formatted but meaningless document.

For MZ Biolabs COAs, the same verification logic applies through their own verification system.

Red flags — walk away from any vendor showing these

In-house testing only

If a vendor's COA is labeled as tested by their own internal quality control laboratory — rather than an independent third party — it is essentially the vendor grading their own homework. They have complete control over what gets reported. In-house testing is not a substitute for independent verification.

No batch number

A COA without a specific batch or lot number is not documenting a specific production run. It may be a single historical test applied across all products indefinitely. You have no way to verify that the vial you received was part of the tested batch.

COA "available on request"

If a vendor requires you to contact customer support to receive a COA, rather than linking it directly on the product page, that is a transparency red flag. Legitimate vendors who have nothing to hide make their COAs publicly accessible. The extra friction of "request a COA" can indicate reluctance to have documentation available for scrutiny.

HPLC only with no mass spectrometry

Purity testing without identity confirmation means you know the vial contains something at a given purity — but not definitively that the something is the compound labeled. For established compounds like BPC-157 this is a smaller concern than for newer compounds. For GLP-1 analogs and other high-value compounds where counterfeiting is documented, mass spectrometry identity confirmation is non-negotiable.

Pricing significantly below market rate

BPC-157 at $10-15 for a 5mg vial when credible vendors charge $35-55 per 5mg is not a deal. The math of legitimate peptide synthesis, third-party testing, and cold-chain shipping does not support those economics. If a price looks too good to be true in this market, it is almost always reflecting a quality shortcut somewhere — lower purity, no real testing, or an entirely different compound being sold under the label.

No verifiable business information

A physical address, a registered business entity, and a real contact email are baseline legitimacy signals. Vendors with only a contact form and no verifiable business information have no accountability if something goes wrong.

The ThePeptide.expert Price Index and vendor verification

Our Price Index tracks 16 verified, currently operating vendors — all with publicly accessible third-party COA documentation. When Nazish on our team verifies prices monthly, COA status and lab name are part of what gets recorded and displayed.

This does not mean every product from every listed vendor has been independently tested by ThePeptide.expert. It means we have verified that these vendors make COA documentation accessible, operate under a consistent third-party testing policy, and have operated for 12+ months with community track records. It is a baseline filter, not a guarantee.

Ultimately, verifying the specific COA for the specific product you are considering remains your responsibility as a researcher. This guide gives you the tools to do that in five minutes for any Janoshik or MZ Biolabs-documented product. If you're new to any of this, start with our are peptides legal explainer.