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.
"Ask for the suitability summary before you argue about the percentage," said Dr Beatriz Sarmiento, clinical pharmacologist, Universidad de Navarra. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."FGP’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.
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 confirmed the determination and supplied the method behind its own figure inside a week.
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.
Storage instructions in this market are close to uniform and almost never accompanied by the study that would justify them. Uniformity is a sign of convention, not of…