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 TFC dulaglutide lot at 95.8%, against 95.1% on the certificate

The report states the gradient, the wavelength and the integration threshold, which is more than most.

VendorInvestigate has released a batch of 19 analytical reports on research-grade dulaglutide lots, including material from TFC and KP. Reported purities range across roughly 2.4 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 16 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.

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.

"The figure is not wrong and neither is theirs," said Dr Emiko Tanabe, mass spectrometrist. "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."

TFC’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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