Janoshik result on a Changsha tirzepatide lot lands 0.8 points above the supplier’s stated figure

Janoshik has published a purity determination of 98.5% on a 30 mg vial of tirzepatide supplied by JEEP, against a figure of 96.0% on the certificate that accompanied the vial. The sample was submitted by the Journal in February 2026 as part of a continuing programme of arm’s-length purchasing, and the vendor was told before the order was placed that any result would be published.

Content by elemental nitrogen determination returned 96% of the labelled nominal mass, which on a 30 mg vial corresponds to roughly 5.25 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.

Reported figures across the set were: highest 98.5%, lowest 96.0%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 21 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 — Janoshik, Medutest, 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.

Marek Doležal, analytical chemist and former QC laboratory manager, thought the split-sample design was the useful part. "A single result on a single vial is an anecdote with a decimal point. Pairs from one lot to two laboratories is the cheapest experiment that answers a real question."

JEEP’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.