Abstract: A detector apparatus supplies samples of gas or vapour to an ion mobility spectrometer (1) via a tube (2). The tube is made of fluorinated ethylene propylene selected to reduce adhesion of substances of interest to the tube, which may also be heated along its length further to reduce adhesion. The tube (2) is closely spaced from the inlet orifice (10) of the spectrometer 1 and opens into an enclosure (3) housing a fan (4), which draws gas and vapour through the tube. The tube (2) may be flexible and extend for some distance to enable sampling from locations remote from the spectrometer (1).

Abstract: An ion mobility spectrometer system includes two cells (1) and (2) driven by a drive unit (12) so that the cells operate at opposite polarities and are switched between different polarities either at regular intervals or in response to detection of a substance in one cell. Two reagents are supplied to both cells (1) and (2), one promoting detection of a substance in the positive mode and the other promoting detection of a substance in the negative mode so that there is no need to switch reagents when the polarity changes.

Abstract: An ion mobility spectrometer system comprising: an ion mobility detector; a gas/vapor circulating system for the ion mobility detector into which samples of gases and vapors of interest may be drawn for detection by the ion mobility spectrometer; the circulating system comprising an ion mobility cell, means for drying and/or cleaning the circulating gases/vapors in the circulating system, a dopant source, and means for causing circulation of the gases/vapors within the circulating system; in which the dopant source and the means for drying and/or cleaning the circulating gases/vapors are combined, whereby the need for a physically separate dopant source for the system is obviated. The dopant source material may be combined with the material for drying and or cleaning the circulating gases/vapors.

Abstract: An ion mobility spectrometer system comprising: an ion mobility detector; a gas/vapor circulating system for the ion mobility detector into which samples of gases and vapors of interest may be drawn for detection by the ion mobility spectrometer; the circulating system comprising an ion mobility cell, means for drying and/or cleaning the circulating gases/vapors in the circulating system, a dopant source, and means for causing circulation of the gases/vapors within the circulating system; in which the dopant source and the means for drying and/or cleaning the circulating gases/vapors are combined, whereby the need for a physically separate dopant source for the system is obviated. The dopant source material may be combined with the material for drying and or cleaning the circulating gases/vapors.