Microwave-Enhanced Ionization Techniques for Mass Spectrometry

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Steven Ray and his research group at the State University of New York at Buffalo are working to improve the capabilities of mass spectrometry (MS) – an important tool for chemical analysis. In particular, the Ray group is developing a new strategy that uses highly-focused microwave radiation to enhance and control the initial step in MS analysis – formation of charged particles (ions) from samples of interest. If successful, this research could have broad scientific impact, on the most important modern methods utilized in mass spectrometry, including electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) MS methods. Dr. Ray is also creating undergraduate analytical chemistry laboratory experiments that use simple microwave-assisted techniques to demonstrate green analytical chemistry and bioanalytical methodologies. In this project, Steven Ray and his research team will work to exploit finely tuned microwave radiation to refine ionization methods in mass spectrometry. Microwave radiation at the 2.45 GHz frequency, say, can influence charge-carrying molecules by direct dielectric heating, which achieves energy transfer in ways different from conventional conductive heat transfer. In MS applications, microwave dipole polarization and ionic conduction can facilitate droplet desolvation processes associated with ESI-MS, as well as formation of free gas-phase ions in MALDI-MS. Microwave radiation also can accelerate charge separation and volatilization by impacting the rates of ionization reactions, and can accelerate enzyme-mediated proteolytic reactions used in bioanalytical mass spectrometry. Specialized waveguide structures are being modeled by computer simulation and constructed to focus microwaves into well-defined ionization volumes, where energy transfer can be measured, controlled, and modulated. Insight into how microwaves influence the mechanism of ion formation is being exploited to improve extant ionization sources. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.