Two gradients, one sample, two purities
A shallow gradient resolves impurities that a steep one runs into the parent peak. Both methods are legitimate; only one of them can see the small stuff.
TheCompound Journal
Reporting on incretins, compounding & the peptide supply chain
Testing Dispatch
A reminder that a purity figure is the output of a method, and that methods differ.
Janoshik has published a purity determination of 96.6% on a 20 mg vial of orforglipron supplied by QST, against a figure of 94.6% on the certificate that accompanied the vial. The sample was submitted by the Journal in April 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.
The Journal purchased 4200 vials from the same lot and had 24 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.
Reported figures across the set were: highest 96.6%, lowest 94.6%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 24 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.
Batch variance rather than vendor quality is the recurring finding of this programme. Across the 24 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 Havel Novotný, independent laboratory quality manager. "Purity is what you can afford. Content is what you need."
QST’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.
A shallow gradient resolves impurities that a steep one runs into the parent peak. Both methods are legitimate; only one of them can see the small stuff.
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
Reported from the analysis, not from a warning notice.
Reported from the analysis, not from a warning notice.
Calibration drift is real, unremarkable, and the reason serious laboratories run internal standards.
Every degradation pathway accelerates by orders of magnitude on reconstitution, because the solvent that lyophilisation removed is the reagent most of them need.