Reference
Reading a Certificate of Analysis
Purity, identity, batch linkage: the fields that matter and how to interpret them.
16 July 2026 · 5 min
A Certificate of Analysis is only useful if you know what to look for. Most of a COA is boilerplate. Three fields carry the weight.
Identity
Look for the analytical method and both masses. A credible identity section names the technique, typically mass spectrometry, and shows the measured mass against the theoretical mass of the compound. If a certificate asserts identity without showing a measurement, it is a claim rather than a result.
Purity
Purity should state the method, the main-peak percentage, and how impurities were quantified. HPLC is the standard.
Be alert to how the number is framed. "99 percent" with no method attached means little. A purity figure is a measurement under specific conditions, and the conditions belong on the document.
Batch linkage
This is the field most often skipped and the one that decides whether the other two mean anything.
The batch number on the certificate must match the batch number printed on the product you received. A certificate without that linkage describes some material the seller once tested, not the material in front of you. It is the difference between evidence and marketing.
Independence
Finally, check who ran the analysis. A laboratory with no commercial relationship to the seller has no stake in the result. An in-house number may well be accurate, but it cannot be verified from outside.
We keep a certificate on file for every lot we release, filed under the batch number printed on the pen. Ask for it and we will send it.
> For laboratory and research use only. Not for human or animal consumption.
All articles are for informational and research purposes only. Products are sold strictly for in-vitro research use. Nothing here is medical advice.
