Independent analysis puts a TFC mazdutide lot at 98.4%, against 95.9% on the certificate

VendorInvestigate has published a purity determination of 98.4% on a 10 mg vial of mazdutide supplied by TFC, against a figure of 95.9% on the certificate that accompanied the vial. The sample was submitted by the Journal in September 2024 as part of a continuing programme of arm’s-length purchasing, and the vendor was told before the order was placed that any result would be published.

The Journal purchased 9 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.

Content by elemental nitrogen determination returned 97% of the labelled nominal mass, which on a 10 mg vial corresponds to roughly 13.80 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.

Batch variance rather than vendor quality is the recurring finding of this programme. Across the 7 determinations the Journal has commissioned to date, within-vendor spread has been wider than between-vendor spread for two thirds of the companies tracked, which is an argument against rating any supplier on a single number.

Dr Sirichai Boonmee, peptide chemist, Chulalongkorn University, thought the split-sample design was the useful part. "A single result on a single vial is an anecdote with a decimal point. Pairs from one lot to two laboratories is the cheapest experiment that answers a real question."

TFC’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.