Independent analysis puts a GL Biochem tirzepatide lot at 96.7%, against 95.9% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
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.
VendorInvestigate has released a batch of 9 analytical reports on research-grade mazdutide lots, including material from TFC and QST. Reported purities range across roughly 1.3 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.
The Journal purchased 4200 vials from the same lot and had 9 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.
Discrepancies of one to two percentage points between a supplier’s figure and an independent determination are common and usually explicable: a faster gradient resolves fewer impurities, a higher integration threshold discards more small peaks, and a wider solvent-front exclusion window removes early-eluting fragments from the calculation altogether. None of that is misconduct. All of it is invisible unless the method is disclosed.
"The useful thing in that report is not the percentage, it is the system suitability data," said Havel Novotný, independent laboratory quality manager. "It is the only part that tells you whether the percentage means anything."
TFC’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.
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
The physics of the drying cycle explains why some cakes are matte and full-volume and others are glassy discs, and why the difference is not cosmetic.
Documentation practice is the only part of vendor quality a buyer can assess before purchase.
Every certificate circulating in this market answers a question about molecules. Almost none answers a question about organisms, pyrogens, or the integrity of the seal.
The masking phenomenon known as low endotoxin recovery means a formulation can return a clean result while containing endotoxin the assay cannot see.
Chromatographic software does not integrate every fluctuation in the baseline. It applies a threshold, and the threshold changes the reported purity by amounts that matter…