PeptideMeter result on a Wuhan mazdutide lot lands 2.3 points below the supplier’s figure

An independent purity determination on mazdutide material sold by SWB has returned 95.6%, a figure 2.3 percentage points below the number printed on the accompanying certificate. The analysis was performed by PeptideMeter on a vial the Journal bought as an ordinary retail customer in March 2026 and posted unopened.

Content by elemental nitrogen determination returned 93% of the labelled nominal mass, which on a 5 mg vial corresponds to roughly 6.67 mg of peptide rather than the labelled figure. The remainder is accounted for by counter-ion, residual water and residual solvent, none of which is visible chromatographically.

Discrepancies of one to two percentage points between a supplier’s figure and an independent determination are common and usually explicable: a faster gradient resolves fewer impurities, a higher integration threshold discards more small peaks, and a wider solvent-front exclusion window removes early-eluting fragments from the calculation altogether. None of that is misconduct. All of it is invisible unless the method is disclosed.

"The useful thing in that report is not the percentage, it is the system suitability data," said Sinéad Corrigan, patient advocate and former trial participant. "It is the only part that tells you whether the percentage means anything."

SWB’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.