Why summer is a documented quality problem in this trade
The route did not close because of a rule about peptides.
Testing Dispatch
PeptideMeter result on a Wuxi mazdutide lot lands 2.1 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
A peptide content determination commissioned by the Journal on a 5 mg mazdutide vial from GL Biochem has returned 94% of the labelled mass. Chromatographic purity on the same vial was above 97.1%. The two numbers measure different things and only one of them was on the certificate.
Content by elemental nitrogen determination returned 94% of the labelled nominal mass, which on a 5 mg vial corresponds to roughly 10.00 mg of peptide rather than the labelled figure. The remainder is accounted for by counter-ion, residual water and residual solvent, none of which is visible chromatographically.
Four independent services — PeptideMeter, VendorInvestigate, and the two others operating in this market — carry the analytical burden for a trade that has no release-testing obligation of its own. Each is paid by whoever submits the sample, which is usually the vendor. The Journal’s position is that a submitter-pays model is workable but that its incentive structure has to be stated whenever a result is quoted as verification.
"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Alastair Renshaw, pharmaceutical supply-chain consultant. "Purity is what you can afford. Content is what you need."
GL Biochem’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.
Related coverage
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Documentation practice is the only part of vendor quality a buyer can assess before purchase.
The submitted sample: the weakest link in the whole system
The condition on arrival is recorded by some services and not others, and it is one of the more informative lines in a report.
Everything a buyer assumes has been checked, ranked by whether it has
The absences are not concealment. They are the form the trade settled on, and no buyer has ever objected.
Nought point nine eight of a dalton: the modification that hides in plain sight
Deamidation adds 0.98 daltons. On a low-resolution instrument at incretin molecular weights, that is inside the noise.
Medutest result on a Hangzhou liraglutide lot lands 4.1 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.