Photodissociation for Ion Trap Mass Spectrometry

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The Analytical and Surface Chemistry program in the Division of Chemistry will support the research program of Prof. Jennifer Broadbelt of the University of Texas at Austin. Prof. Broadbelt's research program in the area of mass spectrometry will involve the use of both infrared and ultraviolet lasers for photo dissociation of ions in a quadrupole ion trap mass spectrometer, along with novel chemical derivatization methods to add chemical selectivity or enhance absorptivities of molecules. Upon irradiation of ions with infrared or ultraviolet photons, the ions absorb energy that leads to bond cleavages, resulting in formation of diagnostic fragment ions. These fragmentation patterns provide a "fingerprint" of the molecules, thus allowing confident identification of peptides and other biologically relevant molecules. The absorption of photons is essential for the success of this analytical method, and thus the absorptivity of molecules can be modulated by attaching different chemical groups, termed "chromophores", that enhance the absorption of photons. The objective of the study is to increase the photon absorption efficiencies of targeted analytes by appending chromophores via an array of derivatization strategies. Prof. Broadbelt and her students will append chemical groups to biomolecules that promote photoactivated reactions in the gas phase, such as the selective cleavage of polypeptide backbones in a site-specific, predictable manner upon photoactivation. The potential benefits of the proposed work to society at large include the training and education of future scientists, especially in the area of biological mass spectrometry, the development of innovative laser-based methods for structural characterization of biological molecules, and implementation of new ion activation strategies that are expected to be important in mass spectrometric analysis in many areas, ranging from proteomics to understanding the complexities of interactions of biological macromolecules.