A certificate of analysis (COA) is a report of test results for a sample from one production batch. Read carefully, it tells you what was measured, how, against what limits and by whom. Read carelessly, it can suggest far more than it shows.
This guide explains how to read one. It doesn't tell you whether any product is acceptable to use — a COA can't answer that, and neither can Peptade.
What is a certificate of analysis?
In pharmaceutical manufacturing, a COA goes with each batch of an ingredient. FDA's Q7 guidance on active pharmaceutical ingredients says certificates should be issued for each batch on request, and sets out what they should contain.
Even there, a COA isn't taken on trust. The same guidance tells manufacturers to run their own complete analyses at intervals, compare them with suppliers' certificates, and check the reliability of those certificates regularly.
Which fields does a thorough COA carry?
Q7's list makes a useful checklist. A thorough certificate carries:
For peptides, two tests do different jobs, and the next section explains why both matter: chromatography (HPLC) estimates purity, and mass spectrometry identifies molecules.
- The name of the material and, where appropriate, its grade.
- The batch (lot) number.
- The date of release, and an expiry or retest date.
- Each test performed, with its acceptance limits and the numerical results.
- A date and a signature from authorized quality-unit personnel.
- The name, address and phone number of the original manufacturer — and, if a repacker, agent or broker reissued the report, the laboratory that did the testing plus a reference to the original certificate.
Why isn't purity the same as identity?
Chromatography separates a mixture into its components; StatPearls notes that in pharmacology it's used to estimate the purity and potency of drugs. A high purity percentage says a sample is mostly one substance.
It doesn't say which substance. Mass spectrometry, which StatPearls describes as a technique used to identify and quantify analytes — peptides and proteins among them — answers that. A report with a purity figure but no identity result has told you the sample is mostly one thing, not what that thing is.
Numbers on paper can also be wrong. In a test-purchase study published in the Journal of Medical Internet Research, semaglutide vials from illegal online pharmacies claimed 99% purity on their labels; laboratory analysis measured purity between 7.7% and 14.37%, and found endotoxin in every sample.
Why does a COA describe a batch, not your vial?
A COA reports on a sample taken from one production run. Even a report issued exactly as stated can't show that your vial came from that batch, was filled and labeled correctly, stayed within its temperature range in transit and storage, or hasn't been opened or tampered with.
That makes the batch number the most important field for you: it's the only link between the document and the container in your hand. If the numbers don't match, the document isn't about your vial.
Why do fake or misleading COAs exist?
Because paperwork can travel separately from the product. FDA's review of poisonings from contaminated glycerin found that drug makers had relied on suppliers' COAs — often a copy on a distributor's letterhead rather than the original manufacturer's report — with the chain of custody unknown.
In the 2022–2023 incidents FDA describes in the same guidance, the appearance of one component's label and COA suggested the container's contents might differ from what both documents stated.
A COA can name a real laboratory and still not be that laboratory's report. Only the lab that issued it can confirm what it issued; if it offers a public report lookup, that's where to check.
What does Verify Your Compounds do — and not do?
Verify Your Compounds is a filing cabinet and a reading guide. It keeps COA documents against the compounds you track, shows what a document states, scans a QR code or barcode so you don't have to type it, puts the batch number from the document beside the one you type from your vial, shows a checklist of the fields a thorough report generally contains, and states whether the compound is FDA-approved, from FDA's public Drugs@FDA record.
The comparing is yours: the app records the answer you give and computes no match itself. The checklist is not a score — no grade, total or pass/fail. A scan records what the code contained; it doesn't identify the substance, doesn't retrieve or inspect a linked page, and forms no view about any seller.
Peptade does not test, verify, authenticate, validate, rate or certify any document, laboratory, batch, vendor or product. The feature's name describes what you do with your own documents, and PepBot won't assess a COA either. The regulatory status Peptade shows is about the compound, not your vial — it says nothing about what's inside the container or where it came from.
Key takeaways
- A COA reports tests on a sample from one batch — not on your vial.
- Check the fields FDA's Q7 guidance lists: material, batch, dates, tests with limits and results, signature, original manufacturer.
- Purity (HPLC) and identity (mass spectrometry) are different tests; a purity figure alone doesn't say what the substance is.
- Documents can be copied, reissued or wrong; only the issuing lab can confirm its report.
- Verify Your Compounds files and displays your documents; Peptade doesn't test or certify anything.
Sources
- FDA — Q7 Good Manufacturing Practice Guidance for Active Pharmaceutical Ingredients (ICH, 2016)
- FDA — Testing of Glycerin, Propylene Glycol, Maltitol Solution, Hydrogenated Starch Hydrolysate, Sorbitol Solution, and Other High-Risk Drug Components for Diethylene Glycol and Ethylene Glycol (guidance, 2023)
- StatPearls (NCBI Bookshelf) — Chromatography
- StatPearls (NCBI Bookshelf) — Mass Spectrometer
- Journal of Medical Internet Research — Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription: Market Surveillance, Content Analysis, and Product Purchase Evaluation Study (Ashraf et al., 2024)
Peptade is for tracking and education only. It is not medical advice, a diagnosis, or a prescription, and it does not tell you to take, start, stop or buy anything. See the Medical Disclaimer.