PeptideMeter result on a Xianning semaglutide lot lands 4.4 points above the supplier’s stated figure

A peptide content determination commissioned by the Journal on a 2 mg semaglutide vial from WXT has returned 97% of the labelled mass, the balance being the counter-ion and residual water that every lyophilised salt carries. Chromatographic purity on the same vial was above 98.8%. The two numbers measure different things, and this is one of the few certificates in the trade to print both.

Reported figures across the set were: highest 98.8%, lowest 95.6%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 14 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

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.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Havel Novotný, independent laboratory quality manager. "Purity is what you can afford. Content is what you need."

WXT’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.