A certificate of analysis (COA) is a laboratory report: it records the sample tested, the methods used, and the measurements reported. You do not need to recognize every instrument name to begin checking one. Start with the lot code, then read each test separately.
Check these four things first
- Match the lot. Find the lot code on the vial or order record and look it up on Lab results. Check that the product and lot correspond to the report.
- Identify the laboratory. Look for its name, report number, and testing date. Check who submitted the sample, if listed.
- Read the tests individually. Identity, purity, content, endotoxin, and sterility answer different questions. A reported pass for one does not cover the others.
- Verify at the source. Follow the laboratory verification link, where provided, and compare the report number, lot, and figures. If there is no working link, use the laboratory's independently published contact details.
What each test tells you
| Test or field | What to look for | What it does not establish |
|---|---|---|
| Identity, often mass spectrometry (MS or LC-MS) | The laboratory's identity finding, observed molecular mass, and comparison with the expected material. | A mass match alone does not establish every detail of a molecular structure or the quantity in a vial. |
| Purity by high-performance liquid chromatography (HPLC) | The reported percentage, the method, and the chromatogram when provided. | A chromatographic percentage is not automatically the percentage of the vial's total mass that is peptide. |
| Content or quantity | A separately reported amount, its units, and the method used to measure it. | A label quantity alone is not a laboratory measurement. |
| Endotoxin | Whether the test was performed, its units, and any reporting limit. | An endotoxin measurement does not establish sterility. |
| Sterility | Whether the report lists a sterility test and its finding under that method. | A sterility finding does not cover identity, purity, or all possible contaminants. |
HPLC separates components under a particular method. An area percentage compares the integrated signal of a peak with the other included signals; the detector and method determine what is measured. Read it alongside identity testing and any separate content assay. See What HPLC purity does and does not tell you for more detail.
For identity testing, use the laboratory's stated interpretation and acceptance criteria. Do not infer identity from one mass number alone. See Identity testing by mass spectrometry.
Read an untested field literally
Not tested means the report provides no measurement for that test. It is neither a pass nor a failure. A blank field is also not evidence of a pass; ask for clarification.
For example, a report with identity and HPLC purity findings but no endotoxin or sterility testing supports only the listed identity and purity findings. It cannot answer the missing questions.
A figure reported as less than a threshold is bounded by the method's reporting limit. It does not mean zero. Keep the unit with the figure when comparing reports.
Check the report details
Look for the sample or lot identifier, compound name, test and report dates, methods, units, laboratory name, report number, and authorized reviewer where provided. Some reports list a separate sample identifier; there should be a clear connection to the lot offered for sale.
If a report names the client or submitting party, read that too. A manufacturer-submitted sample and a sample submitted by the seller have different sampling histories. Do not assume the seller collected the sample unless the record says so.
The number of decimal places is not a test of authenticity. Laboratories use different reporting and rounding conventions. Verify the report with the laboratory rather than judging its typography or how precise a number looks.
If something does not match
A mismatched lot code, missing method, unclear unit, or unavailable verification record needs clarification. Keep the report number and lot code, then contact us. For questions about a laboratory's measurement, check with the laboratory named on the report.
These gaps do not automatically prove that a report is false. They do limit what you can confirm from it.
What a COA cannot tell you
A COA describes the sample examined by the methods listed at the time of testing. It does not mean every vial was individually tested, and it does not establish safety or suitability for use in people or animals. A certificate is not regulatory approval.
All products on this site are for laboratory research use only. Read the Research use policy before ordering, or find a lot certificate to use this checklist with a published record.
Have a vial or lot code to check?
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