Abstract: The present invention provides a novel approach for reliably and accurately detecting and identifying airborne particles. This is done by providing a novel system which incorporates electrostatic concentrators and/or ion mobility separators with Raman, IR, UV, XRF, LIF and LIBS spectroscopy and/or other spectroscopic techniques.

Abstract: An ion trap mass spectrometry system adapted for portability and related method includes an ion source for generating ions from a sample to be analyzed, and a resistive drift tube coupled to an output of the ion source for receiving the ions injected therein. The resistive drift tube decelerates the ions to provide cooled ions having a mean translational kinetic energy of less than 5 keV. A miniature ion trap or trap array, such having apertures <1 mm, is coupled to an output of the resistive drift tube for trapping the cooled ions. A spectrometer is coupled to the miniature ion trap for analyzing the cooled ions.

Abstract: A technique is disclosed for conducting collision induced dissociation (CID) in a quadrupole ion trap (QIT) having higher order field components. In order to compensate for the shift in the frequency of motion with amplitude of the excited ions arising from the influence of higher-order field components, the amplitude of the RF voltages applied to the QIT is monotonically varied during the excitation period to prolong the condition of resonance, resulting in higher average kinetic energies of the excited ions. Thus, higher fragmentation efficiencies may be obtained, or a targeted level of fragmentation may be achieved in less time relative to conventional CID.

Abstract: A method and apparatus for identification of activating ions by collisions is described. The method uses a plurality of linear ion taps and a plurality of sources of ions and a mass measuring device. A first source is operated to dispense first ions into first trap, where the ions may be kinetically cooled. A second source is operated to dispense second ions into the first trap, where the first and the second ions are stored. Ions in the first trap are ejected so as to enter a second trap, where the ions are stored prior to mass spectrometry. The apparatus may use quadrupole rods to form the ion traps, and the voltage and pressure differences between the first and second traps are controllable values.

Abstract: A device (6) for separating ions according to differences in their ion mobility as a function of electric field strength is disclosed. The device (6) comprises an upper electrode (7a), a lower electrode (7b) and a plurality of intermediate electrodes (8). An asymmetric voltage waveform is applied to the upper electrode (7a) and a DC compensating voltage is applied to the lower electrode (7b).

Abstract: A mass spectrometer is disclosed comprising an ion mobility spectrometer or separator (4) and an ion guide (6) arranged downstream of the ion mobility spectrometer or separator (4). A plurality of axial potential wells are created in the ion guide (6) so that ions received from the ion mobility spectrometer or separator (4) become confined in separate axial potential wells. The potential wells maintain the fidelity and/or composition of ions received from the ion mobility spectrometer or separator (4). The potential wells are translated along the length of the ion guide (6).

Abstract: Systems and methods of the invention include a branched radio frequency multipole configured to act, for example, as an ion guide. The branched radio frequency multipole comprises multiple ion channels through which ions can be alternatively directed. The branched radio frequency multipole is configured to control which of the multiple ion channels ions are directed, through the application of appropriate potentials.

Abstract: To analyze glycans and peptide sequences without liberating glycans from glycosylated peptides, a glycan structure is analyzed through negative-ion CID, in which sialic acid and fucose are resistant to elimination, and a peptide sequence is analyzed through positive-ion ECD.

Abstract: This invention describes an electrode structure formed from a plurality of individual electrodes, the individual electrodes being provided on separate submounts, the submounts being coupled to one another using kinematic ball mounts. Such a structure may be configured as a RF ion guide, mass filter or ion trap.

Abstract: A linear trap having high ejection efficiency and low ejection energy is realized. In a mass spectrometer in which ions generated by an ion source are introduced to a quadrupole rod structure applied with RF voltage and ejected from the quadrupole rod structure so as to be detected by a detection mechanism, a mass dependent potential is formed in the axial direction of the quadrupole rod structure and ions are ejected mass selectively from the vicinity of a minimum point of the potential, the mass dependent potential being formed by applying electrostatic voltage and RF voltage to an insertion electrode inserted in the quadrupole rods.

Abstract: A method of transmitting ions along an analyzer region between closely spaced electrodes is disclosed. The method includes providing an analyzer region for transmitting ions, the analyzer region in fluid communication with an ionization source and with an ion detecting device. The method further includes affecting a pressure within at least one portion of the analyzer region, to differ from the pressure within another part of the analyzer region, and providing an electric field that is synchronized with the pressure differences to focus the ions.

Abstract: In a liquid chromatograph mass spectrometer having an ionization interface capable of simultaneously performing ionization operations by ESI and APCI, a spray nozzle 22 for spraying a liquid sample given form a liquid chromatograph section as charged droplets, and a corona discharger 25 for ionizing mobile phase solvent molecules are placed in the same ionization chamber 21. The same voltages are applied to both the spray nozzle and the corona discharger from a single high-voltage power supply 41. The electrical power's value of the heater 27 of the heated dry gas supplier for drying the charged droplets generated in the spray nozzle 22 are set to be suitable for the ionization according to APCI. Consequently, the labor for the circuit design and the number of the parts are reduced. At the same time, the parameter setting items for the user are decreased, which leads to enhanced operability.

Abstract: A mass spectrometer is disclosed comprising a quadrupole rod set ion trap (2, 3) wherein a potential field is created at the exit of the ion trap (4, 5) which decreases with increasing radius in one radial direction. Ions within the ion trap (2, 3) are mass selectively excited in a radial direction. Ions which have been excited in the radial direction experience a potential field which no longer confines the ions axially within the ion trap but which instead acts to extract the ions and hence causes the ions to be ejected axially from the ion trap (2, 3).

Abstract: An apparatus including a plurality of electrodes defining a trapping chamber of an ion trap, wherein at least one of the electrodes is a transparent electrode having at least a portion that is both optically transparent and electrically conductive; a controller connected to the plurality of electrodes, wherein the controller includes a memory containing computer readable instructions which, when executed, cause the controller to send control signals to the plurality of electrodes so that: the plurality of electrodes produce and maintain a trapping field in the trapping chamber, and the plurality of electrodes change the trapping field so that ions of a predetermined mass in the trapping chamber are selectively moved; and an optical detector oriented so that the portion of the transparent electrode that is both optically transparent and electrically conductive is between the optical detector and the trapping chamber.

Abstract: A method for calibrating an ion trap mass spectrometer is disclosed. The method includes steps of identifying a phase (defined by the RF trapping and resonant ejection voltages) that optimizes peak characteristics, and then determining, for each of a plurality of calibrant ions, an optimal resonant ejection voltage amplitude when the ion trap is operated at the identified phase. The resonant ejection voltage applied to the electrodes of the ion trap may then be controlled during analytical scans in accordance with the established relationship between m/z and resonant ejection voltage amplitude.

Abstract: A mass spectrometer that is switchable to operate as a linear trap or as a mass filter, and attaining both high ejection efficiency when operated as a linear trap and high mass resolving power when operated as a mass filter. A mass spectrometer includes an ion source for ionizing a sample, a linear trap quadrupole rod lens supplied with ionized ions, a trap electrode for forming a potential to trap the supplied ions between one end of the quadrupole lens and the other end, a control unit to regulate the trap lens voltage, and a mass analyzer or detector to detect ions ejected from the linear trap, and characterized in switching between an operation where the supplied ions are trapped in a section quadrupole rod lens and ejected by the controller unit regulating the trap electrode voltage; and an operation where ions are selective passed through according to their mass.

Abstract: An ion mobility spectrometer or other ion apparatus has two or three grid electrodes 51 and 52; 151 to 153; 106 and 107; 106? and 107? extending laterally of the ion flowpath. An asymmetric waveform with a dc compensating voltage is applied between the electrodes to produce a field parallel to the ion flow path that affects ions differently according to their field-dependent mobility. This filters or delays different ions selectively in their passage to an ion detector 11, 111, 111 to facilitate discrimination between ions that would otherwise produce a similar output.

Abstract: A mass spectrometer introducing ions produced at an ion source, and including quadrupole rods which have an inlet and an outlet and to which a radio-frequency voltage is applied, the mass spectrometer, i.e., a mass spectrometry device implemented by a linear trap which exhibits high ejection efficiency, high mass resolution, and low ejection energy, executes the following steps: Trapping at least part of the ions by a trap potential generated on the central axis of a quadrupole field, oscillating part of the trapped ions in an intermediate direction between the mutually-adjacent quadrupole rods, ejecting the oscillated ions by an extraction field, and detecting the ejected ions or introducing the ejected ions into another detection process.

Abstract: Apparatus and methods are provided for trapping, manipulation and transferring ions along RF and DC potential surfaces and through RF ion guides potential wells are formed near RF-field generating surfaces due to the overlap of the radio-frequency (RF) fields and electrostatic fields created by static potentials applied to surrounding electrodes. Ions can be constrained and accumulated over time in such wells During confinement, ions may be subjected to various processes, such as accumulation, fragmentation, collisional cooling, focusing, mass-to-charge filtering, spatial separation ion mobility and chemical interactions, leading to improved performance in subsequent processing and analysis steps, such as mass analysis. Alternatively, the motion of ions may be better manipulated during confinement to improve the efficiency of their transport to specific locations, such as an entrance aperture into vacuum from atmospheric pressure or into a subsequent vacuum stage.

Abstract: A method for analyzing data from a mass spectrometer comprising obtaining calibrated continuum spectral data by processing raw spectral data; obtaining library spectral data which has been processed to form calibrated library data; and performing a least squares fit, preferably using matrix operations (equation 1), between the calibrated continuum spectral data and the calibrated library data to determine concentrations of components in a sample which generated the raw spectral data. A mass spectrometer system (FIG. 1) that operates in accordance with the method, a data library of transformed mass spectra, and a method for producing the data library.

Abstract: An ion cyclotron spectrometer may include a vacuum chamber that extends at least along a z-axis and means for producing a magnetic field within the vacuum chamber so that a magnetic field vector is generally parallel to the z-axis. The ion cyclotron spectrometer may also include means for producing a trapping electric field within the vacuum chamber that includes at least a first section that induces a first magnetron effect that increases a cyclotron frequency of an ion and at least a second section that induces a second magnetron effect that decreases the cyclotron frequency of an ion. The cyclotron frequency changes induced by the first and second magnetron effects substantially cancel one another so that an ion traversing the at least first and second sections will experience no net change in cyclotron frequency.

Abstract: The present invention is a device to restrict the sampling of analyte ions and neutral molecules from surfaces with mass spectrometry and thereby sample from a defined area or volume. In various embodiments of the present invention, a tube is used to sample ions formed with a defined spatial resolution from desorption ionization at or near atmospheric pressures. In an embodiment of the present invention, electrostatic fields are used to direct ions to either individual tubes or a plurality of tubes positioned in close proximity to the surface of the sample being analyzed. In an embodiment of the present invention, wide diameter sampling tubes can be used in combination with a vacuum inlet to draw ions and neutrals into the spectrometer for analysis. In an embodiment of the present invention, wide diameter sampling tubes in combination with electrostatic fields improve the efficiency of ion collection.

Abstract: A table (21) for relating an appropriate DC bias voltage to each of a plurality of selectable scan speeds is stored beforehand in an auto-tuning data memory section (20). In an auto-tuning operation, a controller (10) determines the DC bias voltage corresponding to each scan speed by referring to the table (21) and fixes the output of an ion-drawing voltage generator (13) at that voltage. Subsequently, while changing the voltages applied to relevant sections such as an ion optical system (2), the controller (10) finds voltage conditions under which the detection signal is maximized. The conditions thus found are stored in an auto-tuning result data (22). In an analysis of a target sample, a DC bias voltage corresponding to a scan speed specified by an operator is obtained from the DC bias voltage table (21), and the optimal conditions for this voltage are obtained from the auto-tuning result data (22). Based on these items of information, conditions for the scan measurement are determined.

Abstract: This invention relates generally to multi-reflection electrostatic systems, and more particularly to improvements in and relating to the Orbitrap electrostatic ion trap. A method of operating an electrostatic ion trapping device having an array of electrodes operable to mimic a single electrode is proposed, the method comprising determining three or more different voltages that, when applied to respective electrodes of the plurality of electrodes, generate an electrostatic trapping field that approximates the field that would be generated by applying a voltage to the single electrode, and applying the three or more so determined voltages to the respective electrodes. Further improvements lie in measuring a plurality of features from peaks with different intensities from one or more collected mass spectra to derive characteristics, and using the measured characteristics to improve the voltages to be applied to the plurality of electrodes.

Abstract: In a mass spectrometer in which a high ion dissociation efficiency is possible, inserted electrodes are arranged with a form divided into two or more in the axial direction of the ion trap, an electric static harmonic potential is formed from a DC voltage applied to the inserted electrodes, and with an Supplemental AC voltage applied, ions in the ion trap are oscillated between the divided inserted electrodes in the axial direction of the ion trap by resonance excitation, and the ion with a mass/charge ratio within a specific range is mass-selectively dissociated. Thus, a high ion dissociation efficiency is realized by the use of ion trap of the present invention.

Abstract: A method of analyzing ions is provided having a first ion guide with first and second ends and introducing a first group of ions and a second group of ions of opposite polarity into the first ion guide, and applying an RF voltage potential to the first ion guide for confining the first and second groups of ions radially within the first ion guide. A first trapping barrier is provided to the first end of the first ion guide for trapping the first group of ions within the first ion guide and a second trapping barrier is provided to the second end of the first ion guide for trapping the second group of ions within the first ion guide and an axial field is provided for pushing the first group of ions toward the first trapping barrier and pushing the second group of ions toward the second trapping barrier.

Abstract: A mass analyzer system includes an ion inlet that receives a flow of ions, a multi-mode ion controller that controls some or all of the ions, and a multi-mode mass analyzer, in communication with the ion controller, that performs at least one of analyzing and controlling some or all of the ions. The system also includes a detector, in communication with the multi-mode mass analyzer, that detects some or all of the ions and a processor that controls the operation of at least one of the multi-mode ion controller and the multimode mass analyzer.

Abstract: A method and apparatus of combining two independent multipoles in an interlaced fashion to form a resultant multipole structure is introduced. Such an arrangement enables ions from two separate sources to be merged along a predetermined longitudinal direction but also enables in the reverse path, predetermined portions of ions from a single source to be directed along one or more ion channel paths to also enable, for example, simultaneous collection by a Time of Flight (TOF) mass analyzer and an ion trap.

Abstract: A novel instrument and method for TOF/TOF mass spectrometry is offered. A spiral trajectory time-of-flight mass spectrometer satisfies the spatial focusing conditions for the direction of flight and a direction orthogonal to the direction of flight whenever ions make a turn in the spiral trajectory. An ion gate for selecting precursor ions is placed in the spiral trajectory of the spiral trajectory time-of-flight mass spectrometer. Electric sectors are placed downstream of the ion gate.

Abstract: In a tandem mass spectrometer using a collision cell for ion fragmentation, the upper limit of the collision energy required for collision induced dissociation (CID) can be extended without reaching or going beyond the upper electrical discharge limit of the system components. The present teachings describe a method of lifting the potential energy of ions to a predetermined level sufficient for CID fragmentation while satisfying a discharge free condition. The present teaching also describes a method of lifting the potential energy of the fragment ions after CID fragmentation so that the product ions have sufficient energy for mass analysis.

Abstract: In a linear ion trap in which an essentially quadrupole RF electrical field is generated between at least four rod-shaped electrodes, ions may be mass-selectively ejected orthogonally to the axis. An aspect of the invention comprises compensating for field irregularities along the axis of a linear ion trap, which result, at different ejection locations, in the ejection of ions of the same masses at slightly different times, by of measuring the ions that are ejected at the different ejection locations using a number of separate detectors, and correcting, after a mass calibration of each of the mass spectra, the time shifts of the various location-dependent mass spectra during their addition to a combined spectrum.

Abstract: An ion detector includes collision surfaces for converting both positively and negatively charged ions into emitted secondary electrons. Secondary electrons may be detected using an electron detector, than may, for example include an electron multiplier. Conveniently, secondary electrons (or electrons emitted by the multiplier) may be detected using an electron pulse counter.

Abstract: This invention relates to a mass spectrometer including a reaction cell and to a method of using such a mass spectrometer. In particular, although not exclusively, this invention relates to a tandem mass spectrometer and to tandem mass spectrometry. The invention provides a method of mass spectrometry using a mass spectrometer having a longitudinal axis, comprising guiding ions to travel along the longitudinal axis of the mass spectrometer in a forwards direction to pass through an intermediate ion store and then to enter a reaction cell, to process the ions within the reaction cell, to eject the processed ions to travel back along the longitudinal axis to enter the intermediate ion store once more, and to eject one or more pulses of the processed ions in an off-axis direction to a mass analyser.

Abstract: The methods described herein generally relate to characterization of large analytes, such as biomolecules, by molecular mass analysis. Specifically, the methods are directed to molecular mass analysis of singly- or multiply-charged ions by selective ion filtering carried out by a digital thresholding process.

Abstract: A coaxial hybrid ion trap that uses two substantially planar opposing plates to generate electrical focusing fields that simultaneously generate at least two different types or shapes of trapping regions, wherein a first trapping region is a quadrupole trapping region disposed coaxially with respect to the opposing plates, and wherein a second trapping region is a toroidal ion trap having a toroidal trapping region that is simultaneously created around the quadrupole trapping region.

Abstract: A method for multiplexed analysis using ion mobility spectrometer in which the effectiveness and efficiency of the multiplexed method is optimized by automatically adjusting rates of passage of analyte materials through an IMS drift tube during operation of the system. This automatic adjustment is performed by the IMS instrument itself after determining the appropriate levels of adjustment according to the method of the present invention. In one example, the adjustment of the rates of passage for these materials is determined by quantifying the total number of analyte molecules delivered to the ion trap in a preselected period of time, comparing this number to the charge capacity of the ion trap, selecting a gate opening sequence; and implementing the selected gate opening sequence to obtain a preselected rate of analytes within said IMS drift tube.

Abstract: While applying a square wave voltage to the ion electrode (21) so that ions already captured in the ion trap (20) do not disperse, the timing of irradiating a laser light for ion generation is controlled in such a manner that ions reach the ion inlet (25) at a predetermined timing of a cycle of the voltage. In the case of a positive ion (cation) for example, the timing of laser light irradiation is adjusted in such a manner that the target ions reach the ion inlet (25) in the low level period of a cycle of the square wave voltage. By injecting ions in addition to the ions already captured in the ion trap (20) in this manner, the amount of ions can be increased, and by performing a mass separation and detection after that, the signal intensity in one mass analysis can be increased. Accordingly, by decreasing the number of repetitions of the mass analysis for summing up mass profiles, the measuring time can be shortened.

Abstract: An electrostatic trap such as an orbitrap is disclosed, with an electrode structure. An electrostatic trapping field of the form U?(r,?,z) is generated to trap ions within the trap so that they undergo isochronous oscillations. The trapping field U?(r, ?,z) is the result of a perturbation W to an ideal field U(r, ?,z) which, for example, is hyperlogarithmic in the case of an orbitrap. The perturbation W may be introduced in various ways, such as by distorting the geometry of the trap so that it no longer follows an equipotential of the ideal field U(r, ?,z), or by adding a distortion field (either electric or magnetic). The magnitude of the perturbation is such that at least some of the trapped ions have an absolute phase spread of more than zero but less than about 2? radians over an ion detection period Tm.

Abstract: The present invention is a device to restrict the sampling of analyte ions and neutral molecules from surfaces with mass spectrometry and thereby sample from a defined area or volume. In various embodiments of the present invention, a tube is used to sample ions formed with a defined spatial resolution from desorption ionization at or near atmospheric pressures. In an embodiment of the present invention, electrostatic fields are used to direct ions to either individual tubes or a plurality of tubes positioned in close proximity to the surface of the sample being analyzed. In an embodiment of the present invention, wide diameter sampling tubes can be used in combination with a vacuum inlet to draw ions and neutrals into the spectrometer for analysis. In an embodiment of the present invention, wide diameter sampling tubes in combination with electrostatic fields improve the efficiency of ion collection.

Abstract: In a linear ion trap ions of both positive and negative polarities are stored simultaneously for fragmentation reactions caused by electron transfer dissociation (ETD). The ion trap comprises a plurality of parallel pole rods or stacked rings and the ions are stored by applying two phases of a first RF voltage to the pole rods or stacked rings in alternation, thereby radially confining both positive and negative ions. A second, single-phase RF voltage is applied to all the pole rods or stacked rings in common and creates a pseudopotential barrier at the ends of the linear ion trap that acts axially on ions of both polarities in order to maintain the ions in the trap.

Abstract: A mass spectrometer system and a method of operating a mass spectrometer are provided. An RF field is produced between the plurality of rods to radially confine the ions in the rod set. The RF field has a resolving DC component field. The resolving DC component field is varied along at least a portion of a length of the rod set to provide a DC axial force acting on the ions.

Abstract: A method of processing ions in a quadrupole rod set is provided, comprising a) establishing and maintaining a two-dimensional substantially quadrupole field having a quadrupole harmonic with amplitude A2 and a selected higher order harmonic with amplitude Am radially confining ions having Mathieu parameters a and q within a stability region defined in terms of the Mathieu parameters a and q; c) adding an auxiliary excitation field to transform the stability region into a plurality of smaller stability islands defined in terms of the Mathieu parameters a and q; and, d) adjusting the two-dimensional substantially quadrupole field to place ions within a selected range of mass-to-charge ratios within a selected stability island in the plurality of stability islands.

Abstract: The present invention is a device to restrict the sampling of analyte ions and neutral molecules from surfaces with mass spectrometry and thereby sample from a defined area or volume. In various embodiments of the present invention, a tube is used to sample ions formed with a defined spatial resolution from desorption ionization at or near atmospheric pressures. In an embodiment of the present invention, electrostatic fields are used to direct ions to either individual tubes or a plurality of tubes positioned in close proximity to the surface of the sample being analyzed. In an embodiment of the present invention, wide diameter sampling tubes can be used in combination with a vacuum inlet to draw ions and neutrals into the spectrometer for analysis. In an embodiment of the present invention, wide diameter sampling tubes in combination with electrostatic fields improve the efficiency of ion collection.

Abstract: Disclosed is apparatus and method for improving the signal by changing the voltage applied to an analyzing trap of a high resolving power Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer. More specifically, after the ion activation, a voltage different from that of a trap electrode is applied to an additional electrode in the center of the trap electrode, and the voltage is maintained until the end of a detection cycle. Applying the above method, the stability of the ions confined in a trap is more increased, and therefore, the detected time domain signal is being lengthened. The lengthened time domain signal results in an increase of the frequency or an improvement of the resolving power and the sensitivity of the mass-to-charge domain signal.

Abstract: A mass spectrometer is disclosed comprising a quadrupole rod set ion guide or mass filter device. Broadband frequency-signals (13, 14, 15) having a plurality of frequency notches (16a; 16b; 16c) are applied sequentially to the rods of the quadrupole rod set. The notched broadband frequency signals (16a, 16b, 16c) cause undesired ions to be resonantly or parametrically ejected from the ion guide. The resulting ion signals are deconvoluted to provide a mass spectrum.

Abstract: A method of controlling ion parking in an ion trap includes generating a trapping field for trapping cations and anions, and applying a tailored waveform during a period when ion/ion reactions occur to park first generation product ions with m/z values that differ from those of a cation and an anion in selected m/z regions. In particular, the tailored waveform inhibits simultaneously the reactions of ions of disparate m/z ratios.

Abstract: Disclosed is a quadrupole mass spectrometer, which is capable of, during an SIM measurement, maximally reducing a settling time-period necessary for an operation of changing an input voltage to a quadrupole mass filter in a staircase pattern, and preventing unwanted ions from excessively entering a detector during a course of changing between a plurality of mass values. Under a condition that a response speed of a DC voltage U to be applied to quadrupole electrodes is less than that of an amplitude of a high-frequency voltage V, a control section 10 is operable to rearrange the mass values in descending order of mass value, and an optimal settling-time calculation sub-section 101 is operable to determine a settling time-period for each of the mass values, based on a mass-value difference and a post-change mass value.

Abstract: An electrostatic ion trap confines ions of different mass to charge ratios and kinetic energies within an anharmonic potential well. The ion trap is also provided with a small amplitude AC drive that excites confined ions. The mass dependent amplitudes of oscillation of the confined ions are increased as their energies increase, due to an autoresonance between the AC drive frequency and the natural oscillation frequencies of the ions, until the oscillation amplitudes of the ions exceed the physical dimensions of the trap, or the ions fragment or undergo any other physical or chemical transformation.

Abstract: A dual ion trap mass analyzer includes adjacently positioned first and second two-dimensional ion traps respectively maintained at relatively high and low pressures. Functions favoring high pressure (cooling and fragmentation) may be performed in the first trap, and functions favoring low pressure (isolation and analytical scanning) may be performed in the second trap. Ions may be transferred between the first and second trap through a plate lens having a small aperture that presents a pumping restriction and allows different pressures to be maintained in the two traps. The differential-pressure environment of the dual ion trap mass analyzer facilitates the use of high-resolution analytical scan modes without sacrificing ion capture and fragmentation efficiencies.

Abstract: A method of operating a mass spectrometer having an elongated rod set and a set of auxiliary electrodes is provided, the rod set having an entrance end and an exit end and a longitudinal axis. The method comprises a) admitting ions into the entrance end of the rod set; b) trapping at least some of the ions in the rod set by producing a barrier field at an exit member adjacent to the exit end of the rod set and by producing an RF field between the rods of the rod set; and, c) providing an auxiliary AC excitement voltage to the set of auxiliary electrodes to energize a first group of ions of a selected mass to charge.