What a Certificate of Analysis actually tells you
6 min read · Updated September 2026 · MY PEPTIDES Research Team
Key facts
A Certificate of Analysis (COA) is the document that spells out what is actually in the vial. For research peptides it is the single most important piece of supporting data, because without it purity and identity are nothing more than claims. A COA worth its name is batch-specific and usually reports HPLC purity, where high-performance liquid chromatography measures how much of the sample is the target peptide (say 99%+) versus impurities; a mass-spectrometry result showing the measured molecular weight matches the expected sequence, and therefore the right peptide; and identity details such as the compound name, batch or lot number and test date. To read one, confirm the batch number matches the vial you received, look for a specific HPLC purity figure rather than a vague statement, and check that the mass-spectrometry result lines up with the expected molecular weight. Treat any supplier that cannot produce a batch-specific COA on request with caution. Our compounds are synthesized in our own UK laboratory, and every US batch is verified in a US laboratory before it ships, so the certificate that travels with a US order reflects a test on that lot. The products referenced here are supplied for in-vitro laboratory research use only and have not been evaluated by the FDA.
A Certificate of Analysis (COA) is the document that spells out what is actually in the vial. For research peptides it is the single most important piece of supporting data, because without it, purity and identity are just claims. A vendor can print any number on a label. A COA is the evidence behind the number, tied to a specific batch, produced by an analytical method, and dated.
For laboratory research only. The products referenced here are supplied for in-vitro laboratory research only. They are not for human or veterinary use, they have not been evaluated by the FDA, and nothing here is dosing or medical advice.
What a COA actually is
A Certificate of Analysis is a per-batch test record. It is not a marketing sheet and it is not a generic product spec that reads the same for every lot. A real COA answers two questions about the material in front of you: is this the right compound, and how pure is it. Everything else on the page exists to tie those two answers to the exact vial you received, which is why the batch or lot number matters as much as the purity figure.
Because peptide material varies from synthesis to synthesis, a certificate that is not batch-specific tells you very little. Two lots of the same peptide can differ in purity, and the whole point of the document is to report the lot you actually hold, not an average or an aspiration.
What a COA confirms
A COA worth its name is batch-specific and usually reports:
- HPLC purity. High-performance liquid chromatography separates the sample into its components and measures how much of it is the target peptide (say 99%+) versus impurities and truncated sequences. This is the headline purity figure.
- Mass spectrometry. This confirms the measured molecular weight matches the weight expected from the sequence, which is how you know it is the right peptide and not a similar one.
- Identity and batch details. The compound name, the batch or lot number, and the test date, so the certificate can be tied to a specific vial at a specific point in time.
Some certificates add appearance, water content, or acetate content. Those are useful extras, but the two that carry the weight are purity by HPLC and identity by mass spectrometry.
What HPLC and mass spectrometry each measure
These two tests answer different questions, and a certificate needs both. HPLC tells you how much of the sample is the peptide you wanted, expressed as a percentage of the total. A high HPLC figure with no identity test still leaves open the possibility that the material is a pure something-else.
Mass spectrometry tells you what the peptide is by measuring its molecular weight. A matching mass is strong evidence the sequence is correct, but a mass result on its own says nothing about how much impurity rides along with it. Purity without identity, or identity without purity, is half a certificate. Together they establish that the vial holds the intended compound at the stated purity.
How to read one
- Confirm the batch number on the certificate matches the batch printed on the vial you received. If they do not match, the document describes different material.
- Look for a specific HPLC purity figure (for example 99.1%), not a vague statement like "high purity" or a blanket "99%+" stamped across every product.
- Check that the mass-spectrometry result lines up with the expected molecular weight for the sequence.
- Confirm the certificate is dated, since peptide material is not stable indefinitely and an undated COA cannot place a lot in its life.
- Treat any supplier that cannot produce a batch-specific COA on request with caution.
What a COA is not
A COA is proof of composition, not of safety or approval. It confirms what is in the vial and how pure it is. It does not make the compound a medicine, it is not clearance to use the material in people or animals, and it is not an FDA sign-off. Research peptides that ship with a clean certificate are still supplied strictly for in-vitro laboratory research.
A few things should also raise an eyebrow: a certificate with no method named, a purity figure with no chromatogram or number behind it, a document that cannot be tied to your batch, or a single generic PDF reused for every lot. Any of those means the certificate is decoration rather than evidence.
Our US batches and the COA that ships with them
Every order we ship in the United States arrives with its batch-specific Certificate of Analysis, and many product pages link the document straight from the page so you can read it before you buy. Recent certificates also sit in our COA library.
The provenance behind that document is worth stating plainly: every compound is synthesized in our own UK laboratory rather than imported and repackaged, and each US batch is verified in a US laboratory before it ships. The certificate that travels with a US order therefore reflects a test on that lot, not a generic sheet. The vials are supplied pre-mixed as solutions, HPLC-verified, dispatched cold-chain from the warehouse that serves the United States with tracked delivery next business day, priced in US dollars, and stored refrigerated at 2-8°C on arrival.
Why it matters
Research is only as sound as what goes into it. A verified 99%+ pure peptide means you can pin your experimental results on the compound itself rather than on impurities, a truncated sequence, or the wrong molecule entirely. When a result cannot be reproduced, the starting material is one of the first places to look, and a batch COA is what lets you rule it in or out. Browse the catalog, and see how to store research peptides once your vials arrive.
Related reading
BPC-157
Available now from MY PEPTIDES — 99%+ purity, COA with every order, fast US shipping.
Frequently asked questions
- What is a Certificate of Analysis?
- A batch-specific document confirming the purity (by HPLC) and identity (by mass spectrometry) of a given peptide. Every order we ship comes with one. For research use only.
- Are your peptides third-party tested?
- Every product ships with a Certificate of Analysis that includes HPLC purity data and mass-spectrometry confirmation of identity. Our compounds are synthesized in our own UK laboratory, and each US batch is verified in a US laboratory before it ships.
- Does every US order come with a COA?
- Yes. Every order we ship in the United States arrives with its batch-specific Certificate of Analysis, and recent certificates are also published in our COA library so you can review the format before ordering.
- Does a COA mean the peptide is FDA-approved?
- No. A Certificate of Analysis confirms what is in the vial and how pure it is. It is not an FDA approval and does not make the compound a medicine. The material is supplied strictly for in-vitro laboratory research and has not been evaluated by the FDA.
- What should I check first on a COA?
- Match the batch number on the certificate to the batch on your vial, then look for a specific HPLC purity figure and a mass-spectrometry result that matches the expected molecular weight. A dated, batch-specific certificate with a named method is the standard to hold a supplier to.