Independent analysis puts a GL Biochem semaglutide lot at 97.8%, against 94.6% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
TheCompound Journal
Reporting on incretins, compounding & the peptide supply chain
Testing Dispatch
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Two laboratories analysing vials from the same cagrilintide lot have returned figures 4.0 percentage points apart. VendorInvestigate reported 98.3%; Medutest reported a lower number on a shallower gradient with a tighter integration threshold. Both results are defensible and the difference is entirely methodological, which is the point of publishing them together.
Reported figures across the set were: highest 98.3%, lowest 94.3%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 15 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.
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 figure is not wrong and neither is theirs," said Sinéad Corrigan, patient advocate and former trial participant. "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."
FGP’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.
A reminder that a purity figure is the output of a method, and that methods differ.
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
The supplier has not disputed the finding. It has not explained the gap either.
Documentation practice is the only part of vendor quality a buyer can assess before purchase.
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
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