A named analyst is the cheapest quality signal in this trade
What the Journal asks when a document arrives unsigned, and what the answers have been.
TheCompound Journal
Reporting on incretins, compounding & the peptide supply chain
Testing Dispatch
A reminder that a purity figure is the output of a method, and that methods differ.
A peptide content determination commissioned by the Journal on a 2 mg orforglipron vial from QSC has returned 86% of the labelled mass. Chromatographic purity on the same vial was above 97.3%. The two numbers measure different things and only one of them was on the certificate.
The Journal purchased 2600 vials from the same lot and had 18 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.
Havel Novotný, independent laboratory quality manager, 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."
QSC’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.
What the Journal asks when a document arrives unsigned, and what the answers have been.
A reminder that a purity figure is the output of a method, and that methods differ.
The supplier has not disputed the finding. It has not explained the gap either.
Follow the resin, not the catalogue.
The report states the gradient, the wavelength and the integration threshold, which is more than most.
The Journal does not treat a badge as evidence and states so wherever it reports one.