How to Read a Certificate of Analysis (COA)

A Certificate of Analysis, or COA, is the document that accompanies a peptide batch and reports the actual test results for that specific lot, rather than a general product specification. Knowing how to read one is a basic but useful skill for anyone working with research compounds.

Most COAs start with identifying information: the compound name, batch or lot number, manufacture date, and sometimes an expiration or retest date. This section confirms that the certificate belongs to the exact vial in hand, since results can vary slightly between batches.

The purity section usually reports results from HPLC and sometimes mass spectrometry, showing a percentage purity figure alongside the method used to obtain it. A COA may also include an identity confirmation, verifying that the molecule tested matches the expected peptide sequence rather than a similar compound.

What to look for: match the batch number on the COA to the label on the vial, check that the purity method is disclosed rather than just a bare percentage, and confirm the document is specific to the lot you received rather than a generic template.

At Zurich BioGenix, a COA is generated for every batch we sell, and copies are available on request so researchers can verify results before starting an experiment. All products remain intended for laboratory research only.