Reading a certificate · Lab Notes
How to read a certificate of analysis
The lab, the lot, the method beside the values, and what a missing result means.
A certificate of analysis is a record for a particular material, size, batch, and set of methods. It is not a blanket promise about every item in a catalog. Start at the top: identify the product code, the amount tested, the laboratory that performed the work, the report number, and the test date.
Next, find the sample or lot identification. The lot ties the result to a defined piece of inventory. If a certificate lists a batch such as 0726, that batch is the useful boundary of the result. A result without a product, size, batch, or method beside it is much harder to evaluate because you cannot tell what material it describes.
Read each value beside its method. HPLC may report an area percentage, while mass spectrometry may confirm an expected molecular mass. Those measurements answer different questions. Look for the stated specification, the result, and any pass or fail language; then check whether the method is described clearly enough to reproduce or interpret.
A missing result is information too. If sterility, endotoxin, residual solvent, or another test is not listed, do not infer that it passed. Banana Peppers labels products without a published certificate as “COA not currently available,” and sterility and endotoxin are not tested unless a certificate states it. The careful reading habit is simple: match the claim to the exact material, batch, date, and method that support it.