Independent analysis puts a Homopeptide semaglutide lot at 98.1%, against 95.4% on the certificate

A peptide content determination commissioned by the Journal on a 5 mg semaglutide vial from Homopeptide has returned 95% of the labelled mass. Chromatographic purity on the same vial was above 98.1%. The two numbers measure different things and only one of them was on the certificate.

The Journal purchased 3100 vials from the same lot and had 15 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.

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.

Yusuf Kandemir, freight and customs broker, Istanbul, said the gap was predictable from the methods alone. "You can reconstruct almost the whole difference from the integration threshold. What you cannot reconstruct is why anyone thinks a number without a threshold is comparable to a number with one."

Homopeptide’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.