KP 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
VendorInvestigate result on a Zhuhai retatrutide lot lands 1.8 points above the supplier’s stated figure
A reminder that a purity figure is the output of a method, and that methods differ.
VendorInvestigate has published a purity determination of 98.3% on a 10 mg vial of retatrutide supplied by SSA, against a figure of 96.0% on the certificate that accompanied the vial. The sample was submitted by the Journal in January 2026 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.
Content by elemental nitrogen determination returned 95% of the labelled nominal mass, which on a 10 mg vial corresponds to roughly 7.40 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.
Content by elemental nitrogen determination returned 95% of the labelled nominal mass, which on a 10 mg vial corresponds to roughly 7.40 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.
Purity became this trade’s single figure of merit because it is the cheapest measurement to obtain and the easiest to compare. Peptide content, which determines how much drug is actually in a vial, costs several times as much and is quoted as a priced addition by most of the twenty companies in the Journal’s dossier programme rather than carried as a standard release test. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.
"Ask for the suitability summary before you argue about the percentage," said Dr Wenjun Xie, process chemist and peptide manufacturing consultant. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."SSA’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.
Related coverage
Independent analysis puts a FGP liraglutide lot at 95.7%, against 95.0% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
What a 32% rise in coupling-reagent prices does to a 20 mg vial
Follow the resin, not the catalogue.
What Medutest can tell you about a vial by weighing its water
Water is a reactant in hydrolysis, a plasticiser that mobilises the amorphous matrix, and a carrier for everything else. All three matter.
Independent analysis puts a FGP retatrutide lot at 97.1%, against 95.4% on the certificate
The result is unremarkable. What the report states alongside it is not.
What the paperwork is for, and who it was designed to protect
The header identifies the batch, the table records the tests, and the footer says who is answerable. Two of the three are usually incomplete.