Abstract: A method of operating an IMS cell, the method including obtaining first ion mobility spectrometry (IMS) data indicating the time of flight of ions through a drift gas of an IMS drift chamber, identifying, in the first IMS data, a reference feature associated with a selected group of ions; providing a dose of water vapour into the IMS cell to shift the reference feature to a selected time interval; and controlling dosing of water vapour into the drift gas based on second IMS data obtained using the IMS drift chamber to keep the reference feature within the selected time interval.

Abstract: The present disclosure relates to a process for facilitating the identification of target chemicals which may be detected by means of an ion mobility spectrometer and a system for implementing the same. In an aspect of the disclosure, there is provided a process for determining the ratio of CI? to CI?.OOH reactant ion species formed in a pentachloroethane doped ion mobility spectrometer operating in negative mode, said process comprising: i) introducing a sample comprising or consisting essentially of isoflurane into a pentachloroethane doped ion mobility spectrometer; ii) collecting data relevant to the detection of two isoflurane monomer ions formed following reaction with CI? and CI?.OOH reactant ion species present in the pentachloroethane doped ion mobility spectrometer; and iii) determining the ratio of CI? to CI?.OOH reactant ion species formed in the pentachloroethane doped ion mobility spectrometer based on an evaluation of the data collected.

Abstract: The present disclosure relates to a process for facilitating the identification of target chemicals which may be detected by means of an ion mobility spectrometer and a system for implementing the same. In an aspect of the disclosure, there is provided a process for determining the ratio of CI? to CI?.OOH reactant ion species formed in a pentachloroethane doped ion mobility spectrometer operating in negative mode, said process comprising: i) introducing a sample comprising or consisting essentially of isoflurane into a pentachloroethane doped ion mobility spectrometer; ii) collecting data relevant to the detection of two isoflurane monomer ions formed following reaction with CI? and CI?.OOH reactant ion species present in the pentachloroethane doped ion mobility spectrometer; and iii) determining the ratio of CI? to CI?.OOH reactant ion species formed in the pentachloroethane doped ion mobility spectrometer based on an evaluation of the data collected.

Abstract: A detection system has several conventional computers (1, 2, 3) with one or two IMS detectors (20, 21) mounted in their PCI slots (18, 19). The sieve packs (26, 27) of the detectors (20, 21) may be mounted outside the detector casing itself and within the computer housing (10) so that they can be larger, to extend time between replacement. Power supply and a part at least of the processing of the detectors (20, 21) is provided by the computers (1, 2, 3). The computers (1, 2, 3) are connected in a network system so that an indication of detection of hazardous substances can be provided at a remote location.

Abstract: An ion mobility spectrometer comprises an ion mobility cell (10) into which molecules of a sample to be analysed are introduced. The ion mobility cell (10) is doped with ions produced by a corona discharge ionisation source (40). In one mode of operation, the corona discharge ionisation source (40) operates to produce a continual dopant stream, and in a second mode of operation, the corona discharge ionisation source (40) produces dopant ions selectively. In the non-continuous mode of operation, the ion mobility cell (10) may be doped with chemical dopant ions instead, switching between the two dopant regimes being accomplished very rapidly. The ion mobility spectrometer is particularly suitable for the detection of explosive compounds and narcotics, the ion mobility spectrum of explosives doped with ions from the corona discharge ionisation source differing from the ion mobility spectrum of such explosive compounds doped with chemical dopants.

Abstract: A corona discharge ionization source, for use for example with an ion mobility spectrometer, comprises an adjustable corona point electrode (20) which is held transversely within a cylindrical target electrode (14). A corona discharge is produced by a constant or pulsed potential difference between the two electrodes. In alternative embodiments, there may be a further corona discharge electrode (58), providing additional control, and also an annular counterelectrode (60) surrounding the further point electrode (58).