50 results about "Differential mobility analyzer" patented technology

A multi-stage differential mobility analyzer (MDMA) for aerosol measurements includes a first electrode or grid including at least one inlet or injection slit for receiving an aerosol including charged particles for analysis. A second electrode or grid is spaced apart from the first electrode. The second electrode has at least one sampling outlet disposed at a plurality different distances along its length. A volume between the first and the second electrode or grid between the inlet or injection slit and a distal one of the plurality of sampling outlets forms a classifying region, the first and second electrodes for charging to suitable potentials to create an electric field within the classifying region. At least one inlet or injection slit in the second electrode receives a sheath gas flow into an upstream end of the classifying region, wherein each sampling outlet functions as an independent DMA stage and classifies different size ranges of charged particles based on electric mobility simultaneously.

Improvements are provided in the detection of atmospheric vapors by ionizing them near ambient pressure, and analyzing them as ions. Lowest detection limits of parts per quadrillion (ppq) concentrations are enabled by a combination of improvements, including the use of a filter to remove occasional intense signal from explosive particles. Several sources of chemical background are identified and solutions for their reduction or elimination are presented. Gains in response time may be achieved by operating at elevated temperature. When the ionizer is an electrospray source, the use of high boiling point solvents is indicated. An increased selectivity is achieved by operating a differential mobility analyzer (DMA) in series with a mass spectrometer. However, ppq sensitivities require various improvements in the DMA system including a special coupling to the ionizer, controlling the temperature in the DMA pump circuit, avoidance of induction on the DMA electrodes from heating devices, etc.

Prior work on differential mobility analysis (DMA) combined with mass spectrometry (MS) has shown how to couple the output of the DMA with the inlet of an atmospheric pressure ionization mass spectrometer (APCI-MS). However, the conventional ion inlet to an APCI-MS is a round orifice, while conventional DMA geometries make use of elongated slits. The coupling of two systems with such different symmetries limits considerably the resolutions attainable by the DMA in a DMA-MS combination below the value of the DMA alone. The purpose of this invention is to overcome this limitation in the case of a parallel plate DMA. One solution involves use of an elongated rather than a circular MS sampling hole, with the long dimension of the MS inlet hole aligned with that of the DMA slit. Another involves use of a more elongated orifice in the DMA exit and a more circular hole on the MS inlet, the two being connected either through a short transfer conduit or through an ion guide. The DMAs described can also be coupled profitably to detectors and analyzers other than mass spectrometers.

In order to provide a differential mobility analyzer and the like that allows (i) easy increase of an upper limit of particle size of charged particle which can be classified and (ii) analysis of charged particles whose particle size is variable, a DMA (Differential Mobility Analyzer) includes: a classification tank in which an inlet electrode having an inlet slit, an intermediate electrode having a slit, and an outlet electrode having an outlet slit are arranged in sequence in such a manner that adjacent electrodes are disposed opposing each other at predetermined intervals; a gas supply section supplying the classification tank with sheath gas; and a voltage generator applying a predetermined voltage between the electrodes disposed opposing each other, the classification tank including a first classification section and a second classification section each formed by the electrodes disposed opposing each other, and the gas supply section controlling a flow rate of the sheath gas to be supplied to the classification tank individually per first classification section and second classification section.

Prior work on differential mobility analysis (DMA) combined with mass spectrometry (MS) has shown how to couple the output of a planar DMA with the atmospheric pressure inlet of an atmospheric pressure ionization mass spectrometer (APCI-MS). However, because the ion inlet to APCI-MS instruments is a round orifice, while conventional DMA geometries make use of elongated slits, the coupling of both has attained less resolving power or tolerated a smaller sample flow rate than a DMA alone. The present invention overcomes these limitations with an axial DMA of cylindrical symmetry using more than two electrodes. The configuration is related to that previously proposed by Labowsky and Fernández de la. Mora (2004, 2006), where ions with a critical electrical mobility are brought into the symmetry axis of the DMA. Ions with this critical mobility are now optimally transmitted into the MS, with much higher resolution than possible in planar DMAs. In a preferred embodiment of this DMA facilitating DMA-MS coupling, one DMA electrode intersecting the symmetry axis is relatively planar.

Distributed non-charged particles having a desired particle diameter are introduced into a chamber. A photoionizer in which a soft X-ray power is adjustable is attached to the chamber, to charge the particles within the chamber. The power level of the soft X-ray is adjusted by a controller so as to produce singly charged particles. The charged particles are then introduced into a differential mobility analyzer for classification, thus producing monodisperse standard particles having particle diameter of 0.1 to 1.0 μm.

One aspect of the present invention is to extract multiple ionic species in a FAIMS into one or more IMS drift tubes simultaneously. By adjusting FAIMS operational parameters, ions in FAIMS are detected on IMS detectors through separation in FAIMS and/or separation and collection in the IMS. This method provides a continuous separation of specific ions from an ion swarm by employing a high-field differential mobility analyzer (FAIMS) with a plurality of orthogonal transitions paths spaced incrementally along the electrodes which allow additional separation by a conventional IMS drift tube. The components of the sample can be collected or detected.

The present invention consists of a differential mobility analyzer (DMA) intended for achieving the electric field conditions necessary so that it has an component opposite to the drag flow. This electric field component opposite to the drag flow causes the main electric field to be not perpendicular to the velocity field of the drag flow but oblique. Under these conditions, it is possible to increase the resolution of the device, thus reducing the threshold of errors in the detection of the type particle injected in the analyzer. This invention is characterized by the arrangement and nature of the electrodes intended for obtaining the oblique electric field. The invention also comprises the use of this analyzer as part of a device which comprises it, giving rise to an assembly combining the efficiency of the analyzer of the state of the art with the high resolution of the analyzer of the invention.

A new instrument for electrical-mobility based size segregation of particles at high resolution is described. The instrument called the high-flow dual-channel differential mobility analyzer (HD-DMA) comprises of five flows: a polydisperse aerosol flow, a clean sheath flow, two monodisperse sample flows and a residual excess flow. High resolution measurements are possible because of the large sheath flowrates that are permissible in this instrument.

A differential mobility analyzer (DMA) for separating charged particles or ions suspended in a gas and a method of using the DMA for separating such particles. The invention includes various means for increasing the resolution of the DMA by stabilizing the laminar flow within the DMA and by allowing unusually large flow velocities.