Independent analysis puts a QYB mazdutide lot at 95.1%, against 91.4% on the certificate

Medutest has published a purity determination of 95.1% on a 5 mg vial of mazdutide supplied by QYB, against a figure of 91.4% on the certificate that accompanied the vial. The sample was submitted by the Journal in July 2024 as part of a continuing programme of arm’s-length purchasing, and the vendor was told before the order was placed that any result would be published.

The Journal purchased 11 vials from the same lot at retail and had four 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.

The Journal purchased 11 vials from the same lot at retail and had four 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.

The wider context is that material sold for research use carries no regulatory release specification in any jurisdiction the Journal has examined. A certificate is a commercial document, not a compliance one, and its content is whatever the issuer chooses to put on it. That is the gap independent testing fills, and it fills it imperfectly.

"The gap that matters is not between the two laboratories, it is between either of them and the certificate," said Lorcan Feeney, analytical services director at an independent laboratory. "One of those documents states a method. Compare like with like and most of this disappears."

QYB’s dossier has been updated with this determination and with the company’s response to it. The dossier’s ordering box records the lead times, the minimum quantities and what a buyer should ask for at the point of order.