Vol. 3, No. 6 — June 2026Independent since 2024

TheCompound Journal

Reporting on incretins, compounding & the peptide supply chain

A monthly journal of record.
30 issues · 32 contributors
Not medical advice. We sell nothing.

Testing Dispatch

VendorInvestigate result on a Guangzhou retatrutide lot lands 3.9 points above the supplier’s stated figure

The result is unremarkable. What the report states alongside it is not.

An independent purity determination on retatrutide material sold by KP has returned 97.1%, a figure 3.9 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 VendorInvestigate on a vial the Journal bought as an ordinary retail customer in November 2024 and posted unopened.

Reported figures across the set were: highest 97.1%, lowest 93.6%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 9 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 97.1%, lowest 93.6%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 9 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

Purity became this trade’s single figure of merit because it is the cheapest measurement to obtain and the easiest to compare. Peptide content, which determines how much drug is actually in a vial, costs several times as much and is quoted as a priced addition by most of the twenty companies in the Journal’s dossier programme rather than carried as a standard release test. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.

"The figure is not wrong and neither is theirs," said Dr Sirichai Boonmee, peptide chemist, Chulalongkorn University. "They are answers to two different questions and the trade has decided to pretend there is only one question. Print the gradient and the argument disappears."

KP’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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