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During the last year, the principles and predictive tools for this analyzer have been advanced beyond the nominal understanding considered heretofore acceptable for specialized uses of IMS. The importance and need for these advances reside in the creation of automated intelligence (to minimize the need for human resources) and in the formation of tools for the identification of chemicals not previously characterized by IMS. In our findings, IMS spectra were found to arise from considerations both of proton affinities in the initial event of ion creation and of ion stabilities in the non-equilibrium, uni-polar drift region. Aliphatic amines were systematically explored and kinetic measurements were made on ion stabilities and used in modeling the origins of ion mobility spectra. Neural networks were used to explore an existing data base and results revealed hitherto unknown properties of ion mobility spectra.

Drift tubes barely the size of a quarter coin have been created and shown to provide analytical performance for detecting volatile organic compounds (VOCs) in air with sensitivity and selectivity comparable to larger analyzers in ion mobility spectrometry (IMS). These new micro-scale drift tubes have been operated under high field radio frequency (RF) regimes so that ion shutters and aperture grids could be removed from the drift tube. This advance also allowed the prototype units to be made with a planar design using manufacturing methods suitable for mass production and low cost. Ion characterization and separation with an RF-IMS drift tube are based upon differential mobilities, of gas phase ions, between high field and low field limits. Analytical measurement performance for a VOCs in air are shown and discussed.