PeptideMeter result on a Guangzhou exenatide lot lands 4.3 points above the supplier’s stated 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 99% 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.

"Ask for the suitability summary before you argue about the percentage," said Havel Novotný, independent laboratory quality manager. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."

SSA’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.