Capabilities and limitations of ion mobility spectrometry for field screening applications

The objective of this review is to provide an overview of the capabilities and limitations of ion mobility spectrometry (IMS) as it pertains to field screening. The first section of the review provides a description of the instrument and its operation along with examples of its primary advantages of simplicity, selectivity, and sensitivity. IMS is a simple and potentially inexpensive analytical technique with tunably variable selectivity of response, especially for polar organic compounds, and with sensitivity on the order of 0.1 ppb for most vapor-phase compounds. The second section describes the history of IMS as a field-portable technique and discusses some of the difficulties experienced in this capacity. Problems in IMS include competitive ion/molecule reactions, low resolution, a limited dynamic response range, ease of contamination, long residence times in the spectrometer, and concentration-dependent response characteristics. Some of these problems have been solved, while others await further developments in IMS before they cease to limit the utility of IMS in reliable field-portable instruments. Finally, future developments which are needed in Order for IMS to reach its full capacity in portable instruments far field monitoring are discussed. These future developments include non-time-of-flight instruments, high-temperature operation, and nonradioactive ionization sources. (C) 1997 John Wiley & Sons, Inc.