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

Janoshik result on a Nantong mazdutide lot lands 0.9 points above the supplier’s stated figure

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

Janoshik has released a batch of 15 analytical reports on research-grade mazdutide lots, including material from GGPeps and JEEP. Reported purities range across roughly 0.9 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.

Content by elemental nitrogen determination returned 94% of the labelled nominal mass, which on a 10 mg vial corresponds to roughly 14.92 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.

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.

"Ask for the suitability summary before you argue about the percentage," said Dr Beatriz Sarmiento, clinical pharmacologist, Universidad de Navarra. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."

GGPeps’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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