How to read a Certificate of Analysis

A Certificate of Analysis is the analytical record for a single manufactured lot. It is produced by an accredited laboratory after the batch is synthesized and lyophilized, and it travels with that lot for its entire life. Reading one well is the difference between trusting a number and verifying it.

Identity confirms the molecule is what the label says — typically by mass spectrometry, where the measured mass is compared against the theoretical mass of the target sequence. Purity is the proportion of the target relative to related impurities, measured by reverse-phase HPLC and reported at a fixed detection wavelength.

What each line means

Net content verifies the vial actually holds the stated mass within tolerance. Endotoxin, heavy metals, and sterility round out the panel — each a separate, independently reportable test. When all six pass, the lot is cleared for release.

The most important habit is matching the lot number on your vial to the COA you are reading. A COA for a different lot tells you nothing about the vial in your hand. Peptech ties every vial to its lot with a QR code so the match is unambiguous.

We don't ship until the data says pass — and the data is yours to read.