Independent analysis puts a QST survodutide lot at 96.3%, against 95.4% on the certificate

A peptide content determination commissioned by the Journal on a 15 mg survodutide vial from QST has returned 95% of the labelled mass. Chromatographic purity on the same vial was above 96.3%. The two numbers measure different things and only one of them was on the certificate.

The Journal purchased 3500 vials from the same lot and had 3 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.

Content by elemental nitrogen determination returned 95% of the labelled nominal mass, which on a 15 mg vial corresponds to roughly 9.76 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.

Four independent services — PeptideMeter, VendorInvestigate, and the two others operating in this market — carry the analytical burden for a trade that has no release-testing obligation of its own. Each is paid by whoever submits the sample, which is usually the vendor. The Journal’s position is that a submitter-pays model is workable but that its incentive structure has to be stated whenever a result is quoted as verification.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Havel Novotný, independent laboratory quality manager. "Purity is what you can afford. Content is what you need."

QST’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.