What Is a Certificate of Analysis?
The document that says what is actually in the vial — issued per lot, by a lab with no stake in the sale.
01What a COA is
A certificate of analysis is a lab report for one specific batch of material. It states what was tested, by what method, and what the result was — typically identity (does the sample match the claimed compound) and purity (what fraction of the sample is that compound).
The word that matters most is specific. A COA is tied to a lot number. It is not a general specification that applies to every vial a supplier has ever shipped — it is a result for the batch in front of you.
02Why independence matters
A COA issued by the manufacturer testing its own product is a conflict of interest, not a fraud by default — but it removes the check that makes the document meaningful. An independent third-party laboratory, with no financial stake in the sale, has no reason to round a result favourably.
This is the single biggest differentiator between suppliers in this market. Ask who performed the test, not just whether one exists.
03What the numbers should show
Identity is usually confirmed by mass spectrometry, comparing the sample’s molecular weight against the expected value for the compound. Purity is usually reported by HPLC (high-performance liquid chromatography), as a percentage — industry practice for research peptides is ≥98%.
A rigorous panel adds tests unrelated to the peptide itself: endotoxin (bacterial contamination from the manufacturing process) and sterility, particularly relevant for anything reconstituted or handled in lab conditions.
04Red flags in a COA
Round numbers repeating across many products — every compound reading exactly 99.x% with no variation — is not how real chromatography behaves; real results scatter. A missing lot number means the certificate cannot be tied to the vial in hand. A test date that predates a supplier’s own product listing, or a lab that cannot be independently verified to exist, are both worth a direct question before ordering.
05FAQ
What is a certificate of analysis?
A lab report for one specific manufacturing lot, stating the identity and purity of that batch as measured by a named testing method.
Why does a COA need to be lot-specific?
Because manufacturing varies batch to batch. A general specification is a claim about the product line; a lot-specific COA is a measurement of the material actually in that vial.
Why does it matter who performs the test?
A manufacturer testing its own product has no external check on the result. An independent third-party laboratory has no financial stake in the outcome.
What purity level is standard for research peptides?
≥98% by HPLC is common industry practice, though the appropriate threshold depends on the intended use of the material.
Every Ethos Bio lot is analyzed by an independent third-party laboratory — HPLC purity and mass-spectrometry identity confirmation — with a batch-specific Certificate of Analysis supplied per lot.
How to read a COA — line by line → · What is a research peptide? → · Browse our certificates →