Characterization of\nAnticancer Drug Protomers Using\nElectrospray Ionization and Ion Mobility Spectrometry–Mass\nSpectrometry

We used electrospray ionization and ion mobility spectrometry–mass\nspectrometry to detect and characterize the three anticancer drugs\npalbociclib, copanlisib, and olaparib. Ion mobility–mass spectrometry\nand density functional theory revealed that these compounds generate\nisomers during ionization (protomers) due to the presence of multiple\nprotonation sites within their chemical structures. Our work has implications\nfor understanding the solution- and gas-phase chemistry of these molecules\nduring spray-based ionization processes.