Independent analysis puts a GL Biochem tirzepatide lot at 99.2%, against 95.8% on the certificate

Janoshik has released a batch of 14 analytical reports on research-grade tirzepatide lots, including material from GL Biochem and BCH. Reported purities range across roughly 2.2 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 1400 vials from the same lot and had 14 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.

Purity became this trade’s single figure of merit because it is the cheapest measurement to obtain and the easiest to compare. Peptide content, which determines how much drug is actually in a vial, costs several times as much and is not offered as a standard release test by any of the twenty companies in the Journal’s dossier programme. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.

"The figure is not wrong and neither is theirs," said Yusuf Kandemir, freight and customs broker, Istanbul. "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."

GL Biochem’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.