Independent analysis puts a GGPeps retatrutide lot at 95.3%, against 92.8% on the certificate

Janoshik has released a batch of 7 analytical reports on research-grade retatrutide lots, including material from GGPeps and FGP. Reported purities range across roughly 2.1 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.

The Journal purchased 4200 vials from the same lot and had 7 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 89% of the labelled nominal mass, which on a 20 mg vial corresponds to roughly 7.19 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.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Lorcan Feeney, analytical services director at an independent laboratory. "Purity is what you can afford. Content is what you need."

GGPeps’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.