Separating And Identifying Site-Specific Isomeric Amino Acids In GLP-1 Receptor Agonists On The Cyclic™ IMS P20 Mass Spectrometer

By Dale Cooper Shepherd, Isabella Jones, and Emma Marsden-Edwards

Peptide isomers that share the same mass and co-elute during chromatography can remain hidden in conventional LC-MS workflows, complicating impurity analysis for GLP-1 receptor agonists. For liraglutide, identifying these low-abundance variants is especially important because subtle structural changes may influence stability and biological activity. This application note presents a site-specific characterization workflow using the Waters Cyclic IMS P20 Mass Spectrometer. Multiple passes through the cyclic mobility device provide the resolving power needed to separate otherwise indistinguishable isomers. Pre-IMS fragmentation and product ion-level mobility analysis, supported by Wideband Enhancement, then help localize structural differences within the peptide sequence.

See how advanced ion mobility can strengthen confidence in the identification and characterization of challenging isomeric impurities.