What the four services actually offer, test by test
We asked all four services what they can determine, on what timescale, at what price, and under what accreditation. The answers are printed in full.
Testing Dispatch
PeptideMeter result on a Wuxi cagrilintide lot lands 2.5 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
A peptide content determination commissioned by the Journal on a 10 mg cagrilintide vial from JEEP has returned 94% of the labelled mass. Chromatographic purity on the same vial was above 95.9%. The two numbers measure different things and only one of them was on the certificate.
Reported figures across the set were: highest 95.9%, lowest 93.0%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 7 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.
Discrepancies of one to two percentage points between a supplier’s figure and an independent determination are common and usually explicable: a faster gradient resolves fewer impurities, a higher integration threshold discards more small peaks, and a wider solvent-front exclusion window removes early-eluting fragments from the calculation altogether. None of that is misconduct. All of it is invisible unless the method is disclosed.
"The useful thing in that report is not the percentage, it is the system suitability data," said Rowena Ashcombe, community pharmacist and diabetes educator. "It is the only part that tells you whether the percentage means anything."
JEEP’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.
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