Janoshik result on a Qingdao semaglutide lot lands 3.7 points above the supplier’s stated 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 97% 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 11 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.

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 Marek Doležal, analytical chemist and former QC laboratory manager. "Purity is what you can afford. Content is what you need."

Homopeptide’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.