How to read a peptide certificate of analysis (COA)

A certificate of analysis (COA) is a lab report saying what was found when a specific batch of a peptide was tested. A useful one shows the batch number, a purity figure from HPLC, an identity check from mass spectrometry, the testing lab and a date, but even a good COA cannot prove that the vial in your hand is what the paper says.

Most research peptides are unlicensed, so no regulator is checking the product before it reaches you. A COA is one of the few pieces of evidence you can look at. It is worth knowing what it can and cannot tell you. This is general information, not medical advice.

What a COA is meant to show

In plain terms, a COA should answer three questions about one batch:

1. Is it the right molecule? (identity)
2. How much of the powder is that molecule? (purity)
3. Who says so, and which batch does it apply to? (traceability)

HPLC: the purity number

HPLC (high-performance liquid chromatography) separates the components of a sample and shows them as peaks on a graph. The main peak is your peptide. Smaller peaks are impurities such as truncated chains, leftovers from synthesis, or degradation products.

What to look for

• A purity percentage, often calculated as the main peak's area divided by the total area. Reports for research-grade peptides commonly quote figures in the high 90s
• The chromatogram itself, not just a number. You want to see a dominant main peak and a flat baseline
• The detection wavelength and method (often 214 or 220 nm for peptides). It does not need to make sense to you, but it should be there
• A sample ID or batch number printed on the chromatogram

Mass spectrometry: the identity check

Mass spec (MS) measures the molecular weight of what is in the sample. For a given peptide, the expected mass is known from its amino-acid sequence. If the measured value matches the expected one, within a small tolerance, that supports the claim that it is the right compound.

• The report should state the expected (theoretical) mass and the observed mass
• Peptides often show as multiple charged ions, so you may see several peaks. A lab should explain which matches
• If a COA lists a purity figure but no identity data at all, that is a gap. You know it is clean-ish, but not what it is

For example, a COA for BPC-157 or TB-500 should show masses consistent with that specific peptide, not just a generic "peptide" label. If you are not sure what the number should be, a reputable source will have it published, or you can check the reference mass for that sequence.

Batch numbers and traceability

A batch number links the paper to the product. Check that:

• The batch number on the COA matches the batch number on your vial label
• The product name and strength match (a COA for a 5 mg vial of something is not a COA for your 10 mg vial)
• There is a test date and a lab name and contact details
• The same batch number is not being reused across clearly different products or months

If your vial has no batch number, the COA cannot be linked to it and is mostly decoration.

Third-party vs vendor-issued COAs

A COA issued by the seller's own lab is better than nothing, but it is the seller marking its own homework. An independent third-party lab has no stake in the sale and is more credible, though not infallible.

• Independent labs usually have a name, address, accreditation details and a way to verify the report
• Some labs offer a verification code or an online lookup, so you can confirm the report is real
• Be wary of reports that look like the vendor's own template, with their logo and no lab details
• Some people pay for their own independent testing of a vial. That is the strongest check available, and it only applies to that vial

What a COA cannot tell you

• Whether your vial is the tested batch. Paper can be copied, and a good batch can be followed by a bad one
• How many mg are in it. Unless the report includes quantitative content testing, you do not know
• Sterility and endotoxins. Standard HPLC and MS tests do not show whether a product is sterile or free from bacterial endotoxins. Those need separate tests, and they matter for anything injected
• Whether it is safe or effective. A pure peptide can still have no good human evidence behind it. Many, such as BPC-157, are backed mostly by animal data
• Whether the sample sent to the lab was representative. A vendor can send the lab their best vial

Red flags

• No batch number, or one that does not match your vial
• A purity figure and nothing else: no chromatogram, no mass spec, no lab name
• Identical-looking COAs for different products, or a screenshot rather than a document
• Perfect 100% or suspiciously round numbers on every batch
• A lab you cannot find, or contact details that do not work
• Missing or crude edits: mismatched fonts, misaligned logos, different dates
• The seller will not tell you where the testing was done
• COAs for big-name drugs such as semaglutide, tirzepatide or retatrutide that name only a purity and no identity data. These are popular targets for counterfeits and mislabelled product

A short checklist

1. Does the batch number on the COA match your vial?
2. Is there both a purity (HPLC) and an identity (MS) result?
3. Is the lab named and independent, and can the report be verified?
4. Is the tested product the same compound and strength as your vial?
5. Is the test recent and from the same batch window as your purchase?

For general ways to reduce risk, see safer use.

Bottom line

A COA is a useful screening tool, not a guarantee. Treat a complete, verifiable, batch-matched report from an independent lab as modestly reassuring, and treat a vague or generic one as no reassurance at all. Nothing on paper replaces the risks that come with unlicensed products.