Independent analysis puts a BCH tirzepatide lot at 98.3%, against 94.9% on the certificate

PeptideMeter has released a batch of 8 analytical reports on research-grade tirzepatide lots, including material from BCH and JEEP. Reported purities range across roughly 2.1 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 20 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 98.3%, lowest 94.9%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 8 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.

"The gap that matters is not between the two laboratories, it is between either of them and the certificate," said Lorcan Feeney, analytical services director at an independent laboratory. "One of those documents states a method. Compare like with like and most of this disappears."

BCH’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.