How to Read a Certificate of Analysis (COA)

A Certificate of Analysis (COA) is the document a testing laboratory issues after it has analysed a sample from a specific batch. For anyone running laboratory work, it is the quickest way to confirm that the material on the bench matches what the paperwork says.

The header: who tested what, and when

The top of a COA identifies the testing laboratory, the date of analysis, a unique test or report number and the sample identifier. The sample identifier should match the batch or lot number printed on the vial label. If the two do not match, the COA does not describe the material you have.

Identity

Identity testing confirms the compound is what it claims to be. This is usually done by mass spectrometry, which compares the measured molecular mass against the expected value. A result reported as a match, or within a small tolerance, is what you want to see.

Purity

Purity is normally measured by HPLC (high-performance liquid chromatography) and expressed as a percentage of the main peak relative to everything detected. A figure such as 99.1% means 99.1% of the detected signal belongs to the target compound.

Quantity or content

Some reports also state the measured amount of material per vial. This helps confirm that fill weights are consistent from vial to vial.

How to verify a COA

• Check that the batch number on the report matches the label.
• Look for a verification link or code from the testing lab and open it on the lab’s own website.
• Confirm the test date is recent enough to be relevant to the batch.

Every batch we stock has its reports published on our Lab Results page, with links that open directly on the independent lab’s site.

All materials are supplied strictly for laboratory research use only and are not for human or animal consumption.