The record, lot by lot.
Each lot is sent to an outside analytical laboratory for identity and purity analysis before it is listed, and the certificate is filed under the lot number printed on the vial. It is published exactly as the laboratory issued it, never summarised and never averaged across the catalogue, and the lot certificate ships with every order.
Proof over promises.
That's the whole standard. Every lot carries an outside lab's certificate. Find your batch, read the lot, check the figures. Then decide.