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 93% 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 97.3%. The two numbers measure different things, and this is one of the few certificates in the trade to print both.
The Journal purchased 13 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.
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 Sirichai Boonmee, peptide chemist, Chulalongkorn University. "One of those documents states a method. Compare like with like and most of this disappears."QSC’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.
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 confirmed the determination and supplied the method behind its own figure inside a week.
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.