Janoshik result on a Chengdu cagrilintide lot lands 1.8 points below the supplier’s figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
Testing Dispatch
Independent analysis puts a WXT semaglutide lot at 98.0%, against 95.7% on the certificate
The result is unremarkable. What the report omits is not.
PeptideMeter has released a batch of 10 analytical reports on research-grade semaglutide lots, including material from WXT and CPC. Reported purities range across roughly 1.6 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 1800 vials from the same lot and had 10 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.
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."
WXT’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.
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