Instrument Development: Development of Distance of Flight Mass Spectrometry Techniques for Chemical Measurement

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With this award, the Chemical Measurements and Imaging (CMI) Program in the Division of Chemistry is funding Drs. Steven Ray and Gary Hieftje at Indiana University to develop a group of chemical measurement techniques based on a new type of mass spectrometer, known as the distance-of-flight mass spectrometer (DOF-MS). The DOF-MS technique measures the distance each ion travels over a specified flight period to determine the ion mass-to-charge ratio (m/z). It offers many potential advantages, such as the determination of m/z for ions of very high mass, increased speed of measurement, improved dynamic range, adjustable and improved measurement resolution, and the subsequent collection of ions for follow-on analysis by other techniques. The applicability of a hybrid DOF-TOF MS instrument by the scientific community is expected to span across many fields, including bioanalytical chemistry, microbiology, the energy scieces and molecular biology. Drs. Ray and Hieftje are working with local mass spectrometry user facilities and Pacific Northwest National Laboratory (PNNL) to broaden the user basis and enhance the scientific impact of the new instrument being developed. Postdoctoral and graduate students involved in the research project experience valuable interdisciplinary training. Drs. Ray and Hieftje also are engaged in outreach activities by parterning with Rose-Hulman Institute of Technology, a local engineering-focused undergraduate institution, and a local K- 12 science education center to promote STEM student training and education.The goal of this project is the development of a set of chemical measurement strategies based on distance-of-flight mass spectrometry (DOF-MS). In this project, a combination of DOF-MS and TOF-MS is developed as a means to realize the benefits of both approaches in a single instrument. This DOF/TOF strategy may have the potential to significantly improve chromatographic MS detection with extremely wide dynamic range, fast temporal response, and wide coverage. Specifically, Drs. Ray and Hieftje couple the spatial segregation of DOF-MS to a novel type of charge-sensitive ion detector array known as a focal-plane camera (FPC) to simultaneously measure the ion currents observed at every spatially discrete detector element, thus detecting the m/z and abundance for each desired mass-to-charge ratio (m/z) with very wide dynamic range and excellent temporal registry. In addition, Dr. Ray and his collaborators are developing a Zoom-TOF-MS approach that uses the ion focusing strategies of DOF-MS with a TOF-MS setup to improve the mass resolving power of the instrument while requiring only minor functional and architectural changes. Zoom-TOF-MS provides enhanced resolution as well as increased temporal resolution of the mass analyzer, and improves the signal-to-noise ratio (S/N). The supported research activities could potentially provide an enabling new tool for a broad segment of the scientific community.