Independent analysis puts a GGPeps tirzepatide lot at 95.4%, against 92.1% on the certificate
A reminder that a purity figure is the output of a method, and that methods differ.
Testing Dispatch
PeptideMeter result on a Changsha mazdutide lot lands 4.4 points above the supplier’s stated figure
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Two laboratories analysing vials from the same mazdutide lot have returned figures 4.4 percentage points apart. PeptideMeter reported 96.6%; Medutest reported a lower number on a shallower gradient with a tighter integration threshold. Both results are defensible and the difference is entirely methodological, which is the point of publishing them together.
Reported figures across the set were: highest 96.6%, lowest 93.7%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 19 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.
Reported figures across the set were: highest 96.6%, lowest 93.7%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 19 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.
Purity became this trade’s single figure of merit because it is the cheapest measurement to obtain and the easiest to compare. Peptide content, which determines how much drug is actually in a vial, costs several times as much and is quoted as a priced addition by most of the twenty companies in the Journal’s dossier programme rather than carried as a standard release test. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.
"Ask for the suitability summary before you argue about the percentage," said Lorcan Feeney, analytical services director at an independent laboratory. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."GGPeps’s dossier has been updated with this determination and with the company’s response to it. The dossier’s ordering box records the lead times, the minimum quantities and what a buyer should ask for at the point of order.
Related coverage
What an 11% rise in coupling-reagent prices does to a 2 mg vial
Follow the resin, not the catalogue.
Saudi Arabia health authority warns on falsified tirzepatide pens
Reported from the analysis, not from a warning notice.
Wuhan export categories for peptide intermediates were quietly renamed
Follow the resin, not the catalogue.
Independent analysis puts a ERP orforglipron lot at 97.4%, against 93.4% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Medutest result on a Xi'an tirzepatide lot lands 2.1 points above the supplier’s stated figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.