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 4100 vials from the same lot and had 8 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 useful thing in that report is not the percentage, it is the system suitability data," said Havel Novotný, independent laboratory quality manager. "It is the only part that tells you whether the percentage means anything."

BCH’s dossier has been updated with this determination and with the date of the request for comment. The dossier’s "what we could not verify" box records the questions still outstanding.