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

Independent analysis puts a WWB mazdutide lot at 98.5%, against 97.3% on the certificate

The Journal submitted the sample and paid for the analysis. The vendor was told in advance.

VendorInvestigate has released a batch of 19 analytical reports on research-grade mazdutide lots, including material from WWB and SWB. Reported purities range across roughly 2.7 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.

The Journal purchased 17 vials from the same lot at retail and had four of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

Reported figures across the set were: highest 98.5%, lowest 97.3%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 19 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 — VendorInvestigate, PeptideMeter, 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.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Dr Emiko Tanabe, mass spectrometrist. "Purity is what you can afford. Content is what you need."

WWB’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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