RUI: Development of Next-Generation Drift-Time Ion Mobility Spectrometry through the Application of Pulsed Ionization and Voltage Sweep Methodologies

Whitworth University, Spokane WA

Investigators

Abstract

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Eric Davis and his group at Whitworth University are working to improve the capabilities of ion mobility spectrometry (IMS), a chemical measurement technique commonly used in security and military applications for the detection of explosives, narcotics, and chemical warfare agents. The Davis group seeks to expand the usefulness of IMS by improving its ability to separate complex, real-world mixtures rapidly. The research is primarily performed by Whitworth undergraduate students under the supervision of Professor Davis. Through collaboration with Brian H. Clowers at Washington State University, Dr. Davis' students are exposed to the graduate school environment, helping to better prepare them to pursue graduate studies. Research opportunities also expand into the local community of analytical chemists within the greater Spokane, WA area, bringing together industrial and academic chemists for the mutual benefit of students and the community. Prior efforts in creating voltage sweep (VS) IMS separations have utilized either stepped-potential or multiplexed VS methods that do not attain the high-resolution or high-speed separations required for many IMS applications. Utilization of printed circuit board-based IMS cells (with minimal circuit tracing to reduce capacitance) and application of high voltage amplifiers (capable of 500 V/ms slew rates) enable single-run VSIMS methods which can provide significant improvements in IMS resolution and peak capacity. Parasitic losses of ions through the gating process under low-field conditions can be mitigated through use of pulsed ionization sources and elimination of the ion gate. Primary aims are to (1) develop a single-run VSIMS method using high voltage amplifiers to allow high resolution, high peak capacity IMS separations; (2) evaluate the utility of pulsed ionization sources with both IMS and mass spectrometry (MS) with respect to ion formation, kinetics, and speciation; and (3) utilize pulsed sources in IMS separations to avoid gate depletion effects under low-field voltage sweep conditions. 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.