PeptideMeter result on a Guangzhou exenatide lot lands 4.3 points below the supplier’s figure

PeptideMeter has released a batch of 9 analytical reports on research-grade exenatide lots, including material from SSA and MKM. Reported purities range across roughly 4.3 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.

Content by elemental nitrogen determination returned 97% of the labelled nominal mass, which on a 2 mg vial corresponds to roughly 9.54 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.

The wider context is that material sold for research use carries no regulatory release specification in any jurisdiction the Journal has examined. A certificate is a commercial document, not a compliance one, and its content is whatever the issuer chooses to put on it. That is the gap independent testing fills, and it fills it imperfectly.

Sinéad Corrigan, patient advocate and former trial participant, was more cautious. "One lot tells you about one lot. I would not draw a conclusion about a company from a single determination, and I would not let a company draw one either."

SSA’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.