Pulsed Ionization Source for Ion Mobility Spectrometers
12-G00261-1114-1209.pdf (185 KB)
the way is a miniature ion mobility spectrometer (IMS) that uses a pulsed corona ionization source. This detector has demonstrated both high sensitivity and high resolution without the drawbacks of other systems.
Ion mobility spectrometry is an important method for detecting drugs, explosives, volatile organic compounds, and chemical warfare agents. Miniaturization has enabled field-deployable spectrometers for security applications. However, miniaturization typically leads to a loss of specificity because as the ion drift channel is reduced in size, it becomes increasingly difficult to achieve diffusion-limited resolution. In addition, the radioactive ion sources used in many IMSs present potential safety and hazardous waste disposal issues. Other ionization sources such as lasers or ultraviolet light have also been found unsuitable for miniature IMSs because of their size.DescriptionThe ORNL device consists of a nickel corona electrode ion source; a miniature IMS drift channel composed of a stack of electrodes, insulating spacers, and miniature resistors; a pulse generator coupled with a high voltage pulse amplifier; and a detector. A high voltage pulse is applied to the corona electrode, generating ions in the vicinity of the electrode tip through field-induced ionization. The pulse also serves as the start signal for ion mobility measurements. After the pulse, the ions so created move in the drift field and are separated according to their mobilities in the carrier gas. High sensitivity is maintained because the ions generated by this technology are highly concentrated.
The pulsed corona ionization source can be used with a variety of detection devices, including miniature gas chromatographs, but it is especially well suited for coupling with ORNL’s family of miniature IMSs and micro ion trap spectrometers. One such system, which uses ORNL’s patented miniature ion traps arranged in a two-dimensional array, can be placed before the electrode stack in the corona electrode system to increase storage capacity, improve resolution, and provide even greater sensitivity.Benefits
- Speed, high sensitivity, and high resolution
- Flexibility (can be coupled with all types of IMS detectors)
- Amenable to microfabrication techniques
- Could be interfaced with other miniature analytical instruments
- No hazardous wastes or related safety concerns
Applications and Industries
- Detecting drugs, explosives, or chemical warfare agents in the field (e.g., at ports and airports)
- Field-deployable hand-held detectors
- Stack sampling
- Direct sampling of the atmosphere and airborne particles
- Detecting diseases, proteins, and other biomolecules
- Detecting metabolites in blood
- Protein characterization
- Quality assurance
Jun Xu, J. Michael Ramsey, and William B. Whitten. Pulsed Discharge Ionization Source for Miniature Ion Mobility Spectrometers, U.S. Patent US 6,822,225 B2, issued November 23, 2004.Patents and Patent Applications
|Title and Abstract||
Pulsed discharge ionization source for miniature ion mobility spectrometers
A method and apparatus is disclosed for flowing a sample gas and a reactant gas (38, 43) past a corona discharge electrode (26) situated at a first location in an ion drift chamber (24), applying a pulsed voltage waveform comprising a varying pulse component and a dc bias component to the corona discharge electrode (26) to cause a corona which in turn produces ions from the sample gas and the reactant gas, applying a dc bias to the ion drift chamber (24) to cause the ions to drift to a second location (25) in the ion drift chamber (24), detecting the ions at the second location (25) in the drift chamber (24), and timing the period for the ions to drift from the corona discharge electrode to the selected location in the drift chamber.
|Oak Ridge National Laboratory||11/23/2004
Ion trap array-based systems and methods for chemical analysis
An ion trap-based system for chemical analysis includes an ion trap array. The ion trap array includes a plurality of ion traps arranged in a 2-dimensional array for initially confining ions. Each of the ion traps comprise a central electrode having an aperture, a first and second insulator each having an aperture sandwiching the central electrode, and first and second end cap electrodes each having an aperture sandwiching the first and second insulator. A structure for simultaneously directing a plurality of different species of ions out from the ion traps is provided. A spectrometer including a detector receives and identifies the ions. The trap array can be used with spectrometers including time-of-flight mass spectrometers and ion mobility spectrometers.
|Oak Ridge National Laboratory||08/23/2005
|Technology ID||Development Stage||Availability||Published||Last Updated|
|UT-B IDs 200201114, 200201209-PFTT||Development||Available||08/21/2012||08/21/2012|