PeptideMeter result on a Zhuhai mazdutide lot lands 2.7 points above the supplier’s stated figure

An independent purity determination on mazdutide material sold by JEEP has returned 98.8%, a figure 2.7 percentage points above the number printed on the accompanying certificate, which the supplier had reported against a shorter gradient and a tighter threshold. The analysis was performed by PeptideMeter on a vial the Journal bought as an ordinary retail customer in February 2025 and posted unopened.

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 4 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

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 4 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

Batch variance rather than vendor quality is the recurring finding of this programme. Across the 4 determinations the Journal has commissioned to date, within-vendor spread has been wider than between-vendor spread for two thirds of the companies tracked, which is an argument against rating any supplier on a single number.

Dr Wenjun Xie, process chemist and peptide manufacturing consultant, said the gap was predictable from the methods alone. "You can reconstruct almost the whole difference from the integration threshold. What you cannot reconstruct is why anyone thinks a number without a threshold is comparable to a number with one."

JEEP’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.