Would you accept 99.1% on survodutide from JEEP without a content assay?

For reference: 99.1% · survodutide · JEEP.

I would like to define my thresholds before I have a result, for obvious reasons.

I want a plan with explicit stopping rules, not just steps.

What does a sensible plan look like, and what are the decision points?

The short answer is that two competent laboratories on identical material will disagree, and the disagreement is almost always explainable by method differences.

Sample solvent strength affects peak shape — if you inject in strong solvent on a gradient starting in weak solvent, the solvent peak can distort your main peak or create a false shoulder.

Mobile phase additive choice affects ionisation and peak shape — TFA gives sharp peaks but suppresses mass spectrometry signal, formic acid gives worse peaks but preserves signal.

Worth noting that method standardisation is poor in the research-grade space compared to pharmaceutical work, so identical-looking methods can produce different results.

If you are ranking vendors, specify a method and have all samples tested at the same place.

Purity is a method-dependent figure, and that is not a limitation of the measurement, it is a property of what the measurement actually answers.

The fraction of your main peak that is actually your target versus isomers, fragments or related sequences is invisible without complementary identity testing.

The part that matters: column pore size affects mass transfer — a 100 Angstrom packing on a 5 kDa peptide restricts diffusion, broadening the peak and potentially hiding small impurities in the shoulders.

Proline conformer interconversion kinetics are well-characterised and the half-life is of the same order as the chromatographic peak width at room temperature.

Compare purity within a single laboratory on the same method, never across laboratories.

Stated carefully, understanding purity requires separating the chemistry from the method from the reporting convention, and the three are not independent.

Integration of the shoulder — whether you use perpendicular drop or tangent skim — determines what area gets assigned to the main peak versus the impurity table.

Published side-by-side method comparisons show that a two-point difference in purity on the same vial is easily explained by method choice alone.

The practical summary: ask for the chromatogram and the method, and ignore the headline number until you have both.

edited 17 Mar 2026 by tadhg_o_riordan — expanded the table to cover the lower concentration

Start from what the detector sees, because that tells you what the number means.

Mass on column affects detector linearity and peak overlap — overloading broadens peaks and hides neighbours, while underloading improves resolution but loses sensitivity.

I would be careful about over-reading a single measurement — treat it as a data point, not as ground truth.

If you are ranking vendors, specify a method and have all samples tested at the same place.

edited 29 Jan 2026 by rania_haddad — added the placebo-arm figures