What a split-sample exercise can establish, and what it cannot
Two years ago we ran an anonymised version of this comparison and promised a named one. This is it, with every method printed in full.
Testing Dispatch
PeptideMeter result on a Hong Kong mazdutide lot lands 2.6 points above the supplier’s stated figure
The result is unremarkable. What the report states alongside it is not.
An independent purity determination on mazdutide material sold by Homopeptide has returned 98.6%, a figure 2.6 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 July 2025 and posted unopened.
Reported figures across the set were: highest 98.6%, lowest 94.7%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 8 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 98.6%, lowest 94.7%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 8 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.
Four independent services — PeptideMeter, VendorInvestigate, 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.
Havel Novotný, independent laboratory quality manager, 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."
Homopeptide’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.
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We split six vials four ways and posted them
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VendorInvestigate result on a Zhuhai survodutide lot lands 4.2 points above the supplier’s stated figure
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Janoshik result on a Zhuhai tirzepatide lot lands 2.5 points above the supplier’s stated figure
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