Independent analysis puts a WWB semaglutide lot at 96.9%, against 93.3% on the certificate

An independent purity determination on semaglutide material sold by WWB has returned 96.9%, a figure 1.8 percentage points above the number printed on the accompanying certificate, which the supplier had reported against a shorter gradient and a tighter threshold. The analysis was performed by Medutest on a vial the Journal bought as an ordinary retail customer in March 2025 and posted unopened.

Content by elemental nitrogen determination returned 94% of the labelled nominal mass, which on a 30 mg vial corresponds to roughly 13.14 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.

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.

Marek Doležal, analytical chemist and former QC laboratory manager, wanted the wavelength printed. "A method reading at 280 nanometres cannot see a fragment that has lost its aromatic residue. That is not a failure of the laboratory, it is a fact about the question they were asked."

WWB’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.