Janoshik result on a Nantong exenatide lot lands 3.1 points above the supplier’s stated figure

An independent purity determination on exenatide material sold by QST has returned 99.2%, a figure 3.1 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 Janoshik on a vial the Journal bought as an ordinary retail customer in June 2024 and posted unopened.

Reported figures across the set were: highest 99.2%, lowest 97.0%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 7 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

Discrepancies of one to two percentage points between a supplier’s figure and an independent determination are common and usually explicable: a faster gradient resolves fewer impurities, a higher integration threshold discards more small peaks, and a wider solvent-front exclusion window removes early-eluting fragments from the calculation altogether. None of that is misconduct. All of it is invisible unless the method is disclosed.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Lorcan Feeney, analytical services director at an independent laboratory. "Purity is what you can afford. Content is what you need."

QST’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.