Independent analysis puts a Homopeptide retatrutide lot at 98.9%, against 98.1% on the certificate

An independent purity determination on retatrutide material sold by Homopeptide has returned 98.9%, a figure 3.9 percentage points below the number printed on the accompanying certificate. The analysis was performed by Medutest on a vial the Journal bought as an ordinary retail customer in May 2025 and posted unopened.

Content by elemental nitrogen determination returned 90% of the labelled nominal mass, which on a 30 mg vial corresponds to roughly 12.02 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 22 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.

"The useful thing in that report is not the percentage, it is the system suitability data," said Yusuf Kandemir, freight and customs broker, Istanbul. "It is the only part that tells you whether the percentage means anything."

Homopeptide’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.