Independent analysis puts a QYB mazdutide lot at 95.3%, against 92.9% on the certificate

An independent purity determination on mazdutide material sold by QYB has returned 95.3%, a figure 3.6 percentage points below the number printed on the accompanying certificate. The analysis was performed by Medutest on a vial the Journal bought as an ordinary retail customer in May 2026 and posted unopened.

The Journal purchased 1000 vials from the same lot and had 11 of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

Four independent services — Medutest, PeptideMeter, and the two others operating in this market — carry the analytical burden for a trade that has no release-testing obligation of its own. Each is paid by whoever submits the sample, which is usually the vendor. The Journal’s position is that a submitter-pays model is workable but that its incentive structure has to be stated whenever a result is quoted as verification.

"The figure is not wrong and neither is theirs," said Havel Novotný, independent laboratory quality manager. "They are answers to two different questions and the trade has decided to pretend there is only one question. Print the gradient and the argument disappears."

QYB’s dossier has been updated with this determination and with the date of the request for comment. The dossier’s "what we could not verify" box records the questions still outstanding.