The short answer
A certificate of analysis (COA) describes tests performed on a sample. To judge its relevance, match the product and batch, identify the laboratory, check the methods and see what was actually measured. A purity percentage alone is not evidence of clinical safety, sterility or a product licence.
Start with the sample and batch
Check whether the report refers to raw material, a finished product or a sample supplied by the seller. Those are not automatically equivalent. A report may be authentic but still fail to describe the item currently offered.
Record the batch or lot identifier, sample description, report number, test date and supplier. Look for a way to verify the report directly with the named laboratory. A screenshot with a removed header or an undated badge provides less traceability than a complete report.
Different tests answer different questions
The following distinctions help you ask informed questions. They are not a protocol for carrying out laboratory tests or deciding whether a product is safe to use.
| Result | Question it addresses | What it does not establish alone |
|---|---|---|
| Identity | Is the measured material consistent with the stated compound? | Suitability for a patient or cosmetic use |
| Chromatographic purity | How the detected components compare under a specific method | That the entire contents are the stated active material |
| Quantity / assay | How much specified material was measured | The correct amount for any individual |
| Microbiological testing | Which organisms or microbial properties were assessed | All other chemical and clinical risks |
| Batch and stability records | Which lot and storage conditions the evidence covers | A licence or an effectiveness claim |
Why “99% pure” is not a complete quality statement
A reported percentage has to be read with its method, detection limits and sample preparation. It does not tell you everything that was absent, and it should not be converted into a “99% safe” claim. Two reports using different methods may not support a meaningful ranking.
A vendor-wide average can also hide variation between products and batches. For a useful comparison, retain the individual results and the dates instead of replacing them with a single unexplained score.
A practical evidence record
Use a small evidence table for each product you are investigating. “Not provided” is a valid entry; it makes an uncertainty visible rather than turning it into an assumed pass.
- Full product name, formula or specification, and intended use.
- Batch identifier on the product and on the report.
- Who selected the sample and who commissioned the test.
- Laboratory name and an independent contact or report-verification route.
- Methods, results, units and any stated limits or qualifications.
- Which safety questions were not tested.
- Date checked and any unanswered questions sent to the supplier.
Keep analytical quality separate from healthcare decisions
A sound analytical report can make a supplier’s documentation easier to audit. It cannot decide whether a person needs treatment or whether a particular use is appropriate. For a medicine, clinical evidence and the regulated supply pathway remain separate requirements.
For a finished face serum, also check the full ingredient label and directions. For a food supplement, inspect allergens and serving information. If a seller supplies only a raw-material report, ask for the information relevant to the finished product instead of assuming it is covered.
Sources: GOV.UK: consumer products and cosmetics · GPhC: staying safe when getting treatment online
Common questions
Is a COA the same as independent product certification?
No. A COA records sample test results. Independence, sample selection, batch relevance and the scope of testing must be checked separately.
Can a COA prove halal status?
A chemical COA does not establish ingredient provenance, processing controls or halal certification. Those need separate documentation.
Is a missing test the same as a failed test?
No. Missing evidence and a test failure are different findings. Neither should be silently converted into a verified pass.
Sources & editorial note
AI-assisted editorial research prepared for Sanara Health on 8 September 2026. This page has not been clinically reviewed and does not provide a personal treatment recommendation. Product and regulatory information can change.