How to read a certificate of analysis

A certificate of analysis (COA) is the record of the tests run on one production lot. Before a vial is used, it is worth spending two minutes with that document.

Start with the lot number

The lot number printed on the vial label must match the one on the certificate. If it doesn't, the results describe different material.

Purity and identity

HPLC purity shows how much of the detected material is the target peptide. Mass spectrometry confirms that the main peak really is the expected sequence. Read the two together: a high purity figure for the wrong molecule is of no use.

Contaminant screens

Endotoxin (LAL) and, where listed, heavy-metal and sterility results tell you about substances a purity test can't see. Check each result against the specification limit printed next to it.

Who tested it, and when

A useful certificate names the laboratory, its accreditation and the test date. Keep a copy with your experiment records.

For research use only. Not for human or veterinary use.