Reliable Detection of Chemical Warfare Agents Using High Kinetic Energy Ion Mobility Spectrometry
C. Schäfer, Maria Allers, Moritz Hitzemann, Alexander Nitschke, Tim Kobelt, Max Mörtel, Stefanie Schröder, Arne Ficks, Stefan Zimmermann
Abstract
High Resolution Image Download MS PowerPoint Slide High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) ionize and separate ions at reduced pressures of 10–40 mbar and over a wide range of reduced electric field strengths E / N of up to 120 Td. Their reduced operating pressure is distinct from that of conventional drift tube ion mobility spectrometers that operate at ambient pressure for trace compound detection. High E / N can lead to a field-induced fragmentation pattern that provides more specific structural information about the analytes. In addition, operation at high E / N values adds the field dependence of ion mobility as an additional separation dimension to low-field ion mobility, making interfering compounds less likely to cause a false positive alarm. In this work, we study the chemical warfare agents tabun (GA), sarin (GB), soman (GD), cyclosarin (GF) and sulfur mustard (HD) in a HiKE-IMS at variable E / N in both the reaction and the drift region. The results show that varying E / N can lead to specific fragmentation patterns at high E / N values combined with molecular signals at low E / N . Compared to the operation at a single E / N value in the drift region, the variation of E / N in the drift region also provides the analyte-specific field dependence of ion mobility as additional information. The accumulated data establish a unique fingerprint for each analyte that allows for reliable detection of chemical warfare agents even in the presence of interfering compounds with similar low-field ion mobilities, thus reducing false positives.