Mine Safety Appliances Company

Byron Lee Carnahan

Alexander Semenovich Tarassov

Charles W Pipich

Viktor Kouznetsov

Robert Eric Uber

John Michael Pertinarides

Generally, the present invention provides a device for heating the sample stream inlet of an ion mobility spectrometry (IMS) sensor. The heating device increases the temperature of the sample stream inlet surface to reduce the amount of time between adsorption and desorption taking place on the surface. This greatly improves the ability of the IMS sensor to follow rapidly changing analyte concentration levels. An alternate preferred embodiment of the present invention provides a flow smoothing device for decreasing the turbulence present in the fluid flow entering the IMS sensor's carrier stream inlet. This flow smoothing insert permits increasing the fluid flow rate entering the IMS sensor's carrier stream inlet to levels which maximize the IMS sensor's measurement sensitivity without causing mixing of the sample and carrier fluid stream flows.

Inlet heating device for ion mobility spectrometer

Generally, the present invention provides a recirculating filtration system for use with a transportable ion mobility spectrometer in gas chromatography applications. The transportable recirculating filtration system comprises a pump and a set of filters and flow sensors connected to an ion mobility spectrometry sensor having a gas chromatograph column at its inlet. The IMS sensor's outlet flow is cleaned by the filters and recirculated by the pump back into the IMS sensor as the carrier fluid stream flow. A portion of the IMS sensor's outlet flow equal to the amount of flow introduced into the sensor as the sample is exhausted from the filtration system to maintain a constant total flow volume through the system as the sample is being analyzed. Preferably, the multicapillary column is sealed to a heated transfer line leading to the sample stream inlet of the IMS sensor. The transfer line is preferably maintained at a temperature 10.degree. C.-40.degree. C. above that of the multicapillary column in order to ensure that analyte species will not adsorb on the walls of the transfer line instead of entering the sample stream inlet of the IMS sensor. The transfer line can be optionally configured with a flow smoothing insert to produce a laminar flow profile throughout the volume between the transfer line outlet end and the IMS sensor housing upon exit of the carrier flow stream from the flow smoothing insert.

Recirculating filtration system for use with a transportable ion

Generally, the present invention provides a recirculating filtration system for use with a transportable ion mobility spectrometer. One preferred embodiment of the transportable recirculating filtration system comprises a pump connected with a set of filters and flow sensors to an ion mobility spectrometry (IMS) sensor. The IMS sensor's outlet flow is cleaned by the filters and recirculated by the pump back into the IMS sensor as the carrier fluid stream flow. A portion of the IMS sensor's outlet flow equal to the amount of flow introduced into the sensor is exhausted from the filtration system to maintain a constant total flow volume through the system as the sample is being taken. An alternate preferred embodiment of the present invention provides a transportable recirculating filtration system for measuring an unknown concentration of a selected ionizable contaminant substance such as benzene present in a sample fluid stream in which other substances may coexist. The filtration system of the alternate preferred embodiment comprises a pump connected with a set of filters, flow sensors, and a plurality of valves to a device for introducing a controlled concentration of the selected ionizable contaminant into an ion mobility spectrometry (IMS) sensor. The unknown concentration is calculated using the Standard Addition Method. The alternate preferred embodiment of the present invention also provides a recirculating filtration system which can be used to calibrate the IMS sensor by establishing which ionogram structures result from the presence of a particular analyte in the sample stream. A known concentration of an analyte is introduced into the sample stream. The resulting ionogram is compared to an ionogram recorded with no contaminants present. By comparing these spectra, a correlation can be made between the positions of features in the ionogram and the analyte which gives rise to these features.

An ion mobility spectrometer having a housing with an analyzer positioned therein. The analyzer includes first and second longitudinally spaced apart electrodes which are preferably cylindrical in configuration. The space between the electrodes defines an analytical gap which is in communication with a source of carrier gas. An ionization source such as a .beta.-emitter or corona discharge is juxtaposed with the analytical gap and source of sample media and includes an ion aperture for ions to enter said gap. The spectrometer includes an ion detector for measuring ions. An electrical controller connected to the first and second electrodes for impressing a first direct potential and second periodic asymmetrical potential capable of creating a transverse electrical field therebetween during the flow of carrier gas in the analytical gap. Preferably, a third low voltage ripple potential is impressed in series with the first two potentials. A third electrode, normally the ionization source, for electrically migrating the ions formed by the source into the analytical gap is positioned proximate to the ion aperture.

Growing community of inventors

Pittsburgh, PA, United States of America

Byron Lee Carnahan