Independent analysis puts a SWB dulaglutide lot at 98.6%, against 96.9% on the certificate

An independent purity determination on dulaglutide material sold by SWB has returned 98.6%, a figure 2.1 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 September 2025 and posted unopened.

The Journal purchased 8 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 93% of the labelled nominal mass, which on a 5 mg vial corresponds to roughly 10.14 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.

The wider context is that material sold for research use carries no regulatory release specification in any jurisdiction the Journal has examined. A certificate is a commercial document, not a compliance one, and its content is whatever the issuer chooses to put on it. That is the gap independent testing fills, and it fills it imperfectly.

"The gap that matters is not between the two laboratories, it is between either of them and the certificate," said Dr Emiko Tanabe, mass spectrometrist. "One of those documents states a method. Compare like with like and most of this disappears."

SWB’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.