A motivation of our research is to make inroads in the daunting task of chemical analysis of the brain’s composition and temporal changes. We introduced a new soft ionization process for use in mass spectrometry (MS), termed laserspray ionization (LSI), which demonstrates intriguing advantages of speed of analysis, high spatial resolution for imaging, mass range extension, and improved fragmentation common with multiply-charged ions. Multiply-charged protein ions are readily sequenced by electron transfer dissociation (ETD) providing a new means of chemical sequencing directly from surfaces. Interfacing with ion mobility spectrometry (IMS) adds a useful additional separation of gas-phase ions from mixtures, where conventional liquid chromatography (LC) approaches are not applicable, permitting powerful deconvolution of sample complexity, even with identical masses (isomers), directly from surfaces. Structural information is obtained by cross-section analyses of the folding transitions of lysozyme, a protein associated with neurodegenerative diseases. We have extended LSI to high vacuum time-of-flight (TOF) mass spectrometers and determined that ionization requires desolvation of the charged clusters. We show applied examples, in which conventional MALDI failed while LSI produced the desired results providing a molecular view of the endogenous and exogenous chemical composition. Fundamentals are discussed for these new ionization processes requiring as little as the solvent used to dissolve the analyte to produce intact gaseous protein ions.

Laserspray ionization mass spectrometry: Fundamentals, instrumentation, and imaging applications

255th National Meeting (2018)

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