TFC names the synthesis and fill sites behind its catalogue
Documentation practice is the only part of vendor quality a buyer can assess before purchase.
Testing Dispatch
Independent analysis puts a Homopeptide tirzepatide lot at 99.3%, against 95.3% on the certificate
The result is unremarkable. What the report states alongside it is not.
An independent purity determination on tirzepatide material sold by Homopeptide has returned 99.3%, a figure 3.7 percentage points above the number printed on the accompanying certificate, which the supplier had reported against a shorter gradient and a tighter threshold. The analysis was performed by VendorInvestigate on a vial the Journal bought as an ordinary retail customer in November 2024 and posted unopened.
The Journal purchased 19 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 95% of the labelled nominal mass, which on a 15 mg vial corresponds to roughly 14.46 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 — VendorInvestigate, Medutest, 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.
"The gap that matters is not between the two laboratories, it is between either of them and the certificate," said Marek Doležal, analytical chemist and former QC laboratory manager. "One of those documents states a method. Compare like with like and most of this disappears."Homopeptide’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.
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