What a COA Actually Proves, and What It Does Not

A certificate of analysis tells you what a lab measured for one sample on one day. It does not promise that the next vial in the same box matches, and it certainly does not promise that a different batch behaves the same way.

When you read a COA, start with identity. Before purity or dose mean anything, the lab has to confirm the molecule is what the label claims. Mass spectrometry answers that question. If a report skips identity and jumps straight to a purity number, treat the number with suspicion.

Next comes purity. A reverse phase HPLC trace separates the main compound from related impurities and shows each as a share of total area. A clean single peak is what you want. A cluster of smaller peaks beside the main one means the synthesis or storage left something behind.

Last is quantity. A vial labeled ten milligrams should contain close to ten milligrams. Underfilling is the most common and least discussed failure in this market, because it is invisible without a scale and a method. We publish measured content against label claim on every report so the gap is impossible to hide.