Ion-mobility spectrometry as a fast monitor of chemical composition

Ion-mobility spectrometry (IMS) has been known best for screening explosives at airports, detecting chemical agents for the military, and monitoring stack gas emissions in industry. These have been supplemented by applications for determining the accumulation of impurities in gas switches for hydroelectric generating stations and for measuring the levels of volatile organic compounds in the life-supporting atmosphere of the International Space Station. An enlarged scope of applications for this fast method has become possible through advances in miniaturization of drift tubes and new methods for characterizing ions. Also, ion sources of broad importance, such as electrospray ionization, have been added to drift tubes at ambient pressure. Finally, the ion chemistry, which long made IMS a sensitive and selective sensor but also frustrated attempts to rationalize response, has been explored and clarified. New methods for introducing structural content into mobility spectra mean that mobility spectrometers can be general analytical measurement devices and can provide rapid analysis of samples spanning the range of vapor pressures and chemical classes. This article presents selected recent developments in IMS with emphasis on speed of measurement or on uses for which no other method has been convenient or economical. (C) 2002 Published by Elsevier Science B.V. All rights reserved.