Janoshik result on a Qingdao semaglutide lot lands 3.7 points below the supplier’s figure

Janoshik has published a purity determination of 95.6% on a 20 mg vial of semaglutide supplied by Homopeptide, against a figure of 93.6% on the certificate that accompanied the vial. The sample was submitted by the Journal in June 2026 as part of a continuing programme of arm’s-length purchasing, and the vendor was told before the order was placed that any result would be published.

Content by elemental nitrogen determination returned 93% of the labelled nominal mass, which on a 20 mg vial corresponds to roughly 7.63 mg of peptide rather than the labelled figure. The remainder is accounted for by counter-ion, residual water and residual solvent, none of which is visible chromatographically.

The Journal purchased 4300 vials from the same lot and had 23 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.

Batch variance rather than vendor quality is the recurring finding of this programme. Across the 23 determinations the Journal has commissioned to date, within-vendor spread has been wider than between-vendor spread for two thirds of the companies tracked, which is an argument against rating any supplier on a single number.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Sinéad Corrigan, patient advocate and former trial participant. "Purity is what you can afford. Content is what you need."

Homopeptide’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.