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 98% of the labelled mass, the balance being the counter-ion and residual water that every lyophilised salt carries. Chromatographic purity on the same vial was above 96.3%. The two numbers measure different things, and this is one of the few certificates in the trade to print both.

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.

Content by elemental nitrogen determination returned 98% 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.

"The figure is not wrong and neither is theirs," said Lorcan Feeney, analytical services director at an independent laboratory. "They are answers to two different questions and the trade has decided to pretend there is only one question. Print the gradient and the argument disappears."

QST’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.