Abstract: An apparatus comprising an ion selecting device; an individual ion counter device; and an interface device integral with the ion selecting device and downstream of an ion separating chamber of the ion selecting device. The interface device comprises a tagging particle generator and a tagging chamber. Sample gas containing ions of a selected mobility enters the tagging chamber from the ion selecting device and is exposed to uncharged neutral tagging particles from the tagging particle generator. The ions collide with the tagging particles to form a mixture of tagged ions and uncharged neutral tagging particles which is then separated in a tagged ions separator forming part of the individual ion counting device before the separated tagged ions are counted.

Abstract: The invention provides an apparatus for increasing a number concentration of molecules of an analyte of interest in real time from a sample gas flow containing ionised molecules of the analyte, aerosol particles and other molecules, the apparatus comprising: an ion-concentrating chamber having: an inlet for receiving the sample gas flow; an ion outlet; and at least one other outlet; the ion-concentrating chamber being connected or connectable to a gas flow generating and controlling device for establishing a gas flow velocity field within the ion-concentrating chamber to direct the aerosol particles and other molecules of the sample gas flow to the at least one other outlet; and one or more electrodes arranged in an axially spaced apart manner along the ion-concentrating chamber for creating an electric field within the ion-concentrating chamber to direct the ionised analyte molecules in the sample gas flow to the ion outlet, wherein the electrodes are configured such that an absolute value of the stren

Abstract: The invention provides a method and apparatus subjecting an analyte in an ion concentrating chamber to an electric and velocity field to concentrate analyte ions into a smaller space.

Abstract: An apparatus comprising an ion selecting device; an individual ion counter device; and an interface device integral with the ion selecting device and downstream of an ion separating chamber of the ion selecting device. The interface device comprises a tagging particle generator and a tagging chamber. Sample gas containing ions of a selected mobility enters the tagging chamber from the ion selecting device and is exposed to uncharged neutral tagging particles from the tagging particle generator. The ions collide with the tagging particles to form a mixture of tagged ions and uncharged neutral tagging particles which is then separated in a tagged ions separator forming part of the individual ion counting device before the separated tagged ions are counted.

Abstract: The invention provides a method for increasing the number concentration of molecules of an analyte of interest in real time from a sample gas flow containing the analyte and other molecules; the method comprising: (a) when the analyte molecules of interest in the sample gas flow are non-ionised or are not ionised to a desired extent, exposing the sample gas flow to an ionising entity to bring about formation of ions of the analyte and then passing the sample gas flow through an ion-concentrating chamber; or (b) when the analyte molecules of interest in the sample gas flow are already ionised, passing the sample gas flow through an ion-concentrating chamber without first exposing the sample gas flow to an ionising entity; whereby, in the ion-concentrating chamber, analyte ions and other molecules are subjected to an electric field and a velocity field such that analyte ions are concentrated by the combined effects of the electric field and velocity field into a smaller space; wherein the ion-concentrating c

Abstract: The invention provides a device for extracting a vaporizable analyte from a sample gas containing the analyte and unwanted aerosol particles; the device comprising a vapour extraction chamber (2), first (3) and second (4) inlets, and first (5) and second (6) outlets; the vapour extraction chamber (2) being provided with or being linked to a heat source for heating the vapour extraction chamber (2) to a desired temperature to facilitate vaporization of analyte present in the sample gas; the first (3) and second (4) inlets being linked to an upstream end of the vapour extraction chamber (2) and the first (5) and second (6) outlets being linked to a downstream end of the extraction chamber (2); the first inlet (3) allowing a sample of gas containing the analyte and unwanted aerosol particles to be introduced into the vapour extraction chamber (2); the second inlet (4) being connected or connectable to a clean gas supply that does not contain the analyte or unwanted aerosol particles; the device being configur

Abstract: The invention provides a method of separating and collecting ions of a predetermined ion mobility from a gaseous mixture of ions of different ion mobilities using a differential mobility analyser apparatus, wherein the differential mobility analyser apparatus comprises an ion-separation chamber having: (a) a sample gas flow inlet; (b) a focusing chamber, an opening at one end of which serves as the sample gas flow inlet through which sample gas can flow into the ion-separation chamber; (c) a sheath gas inlet connected or connectable to a supply of sheath gas; (d) a sheath gas outlet; (e) an ion outlet through which the ions of predetermined ion mobility can be collected; and (f) two or more electrodes arranged to provide an ion-separating electric field across the ion-separation chamber; wherein the focusing chamber is oriented at an angle of from 30° to 90° relative to a direction of flow of the sheath gas along the ion-separation chamber; and wherein a focusing zone is provided in the focusing chamber,