Abstract: The invention concerns an ion trap, including a first ring-shaped end cap electrode and a second ring-shaped end cap electrode, between which is formed a ring-shaped ion storage cell, as well as a plurality of radially inner disk-shaped ring electrodes and a plurality of radially outer disk-shaped ring electrodes, which delimit the ring-shaped ion storage cell. The invention also relates to a mass spectrometer that has such an ion trap as well as a control device that is designed to actuate the disk-shaped ring electrodes and the end cap electrodes for the storage, selection, excitation and/or detection of ions in the ring-shaped ion storage cell.

Abstract: Methods for generation of shape data for a set of electronic designs include inputting a set of shape data, where the set of shape data represents a set of shapes for a device fabrication process. A convolutional neural network is used on the set of shape data to determine a set of generated shape data, where the convolutional neural network comprises a generator trained with a pre-determined set of discriminators. The set of generated shape data comprises a scanning electron microscope (SEM) image.

Abstract: An ion guide defining a guide axis receives ions. The ion guide applies a potential profile that includes a pseudopotential well to the ions using an ion control field. The ion control field includes a component for restraining movement of the ions normal to the guide axis and a component for controlling the movement of the ions parallel to the guide axis. The ion guide sequentially injects the ions with the same ion energy and in decreasing order of m/z value into an ELIT aligned along an ELIT axis to focus the ions irrespective of m/z value at the same location on the ELIT axis within the ELIT at the same time by varying a magnitude of the pseudopotential well. The ELIT can trap the focused ions using in-trap potential lift or mirror-switching ion capture.

Abstract: A mass spectrometer system (10) is provided in which the voltage controller (12) can have separate first and second high-voltage control circuits (34, 40) which are physically disconnected from and at different ground planes to one another. Communication between the first and second high-voltage control circuits (34, 40) is enabled via an interface circuit (30) and one or more wireless, preferably radio-frequency, communicators (38, 44, 46, 48).

Abstract: In an inductively coupled plasma-mass spectrometry (ICP-MS) system, ions are transmitted into a collision/reaction cell. A DC potential is applied at an exit of the cell at a first magnitude to generate a DC potential barrier effective to prevent the ions from exiting the cell. The DC potential barrier is maintained during a confinement period to perform an interaction. After the confinement period, analyte ions or product ions are transmitted to a mass spectrometer by switching the exit DC potential to a second magnitude effective to allow the analyte ions or product ions to pass through the cell exit as a pulse. The analyte ions or product ions are then counted during a measurement period. The interaction may be ion-molecule reactions or ion-molecule collisions.

Abstract: The mass spectrometer includes an ionizer, a mass separator, a detection device, a storage, and a controller. The detection device includes a detector and an electron introducer. The electrons from the electron introducer are introduced into the detector. In addition to an analysis operation, the mass spectrometer performs an operation to determine a voltage applied to the detector. At this point, electrons are introduced from the electron introducer to the detector. In the case that a detection value from the detector is less than a threshold, the controller can determine that a defect such as aging is generated in the detector.

Abstract: The present application relates to an ion transmission device, more particularly, to a device and method for generating, storing and transmitting positive and negative ions. The device includes a wire electrode, a perforated insulating board, a tensioning device, an axial field electrode and an ion source for providing ions. The generated positive and negative ions are respectively stored on two ends of a cavity by the device; and the positive or negative ions are led out as needed. The utilization efficiency of positive and negative ions, as well as sensitivity, are greatly improved by the device.

Abstract: Provided is a mass spectrometric method including steps of transporting ions generated in an ion source 2 to a mass spectrometer section 4 through an ion optical system 3 having a plurality of ion lenses 31, 32 and 33, and detecting the ions after performing mass separation of the ions. The method further includes steps of: adjusting a voltage applied to a first ion lens 33 which is one of the ion lenses 31, 32 and 33 so that the detection sensitivity for an ion having a predetermined mass-to-charge ratio satisfies a previously specified requirement; and applying, to a second ion lens 32 which is one of the ion lenses 31, 32 and 33 except the first ion lens 33, a voltage at which a change in the ion detection sensitivity with respect to the voltage applied to the second ion lens 33 is within a previously specified range.

Abstract: A method of manufacturing a device for manipulating charged particles using an axial electric field as they travel along a longitudinal axis of the device is disclosed. The method comprises providing first electrodes of different lengths, supplying different voltages to these electrodes and arranging grounded electrodes between the first electrodes in order to form the desired axial potential profile.

Abstract: A mass analyser comprises a pair of electrode arrays. Each array has a set of focusing electrodes which are supplied, in use, with voltage to create an electrostatic field in a space between the electrode arrays causing ions to undergo periodic, oscillatory motion in the space, ions passing between electrodes of the sets of focusing electrodes and being repeatedly focused at a center plane, mid-way between the electrode arrays. At least one electrode of each set of focusing electrodes has an electrode surface closer to the center plane than the electrode surfaces of other electrodes of the same set. The analyzer may be an ion trap mass analyser or a multi-turn ToF mass analyzer.

Abstract: There is provided an analyzing apparatus including an irradiation unit irradiating a first point with a laser, a convergence unit causing an analysis target to converge at the first point, and a unit analyzing a sample gas including a substance that has been irradiated with the laser at the first point using an ion mobility sensor. One example of the convergence unit includes a unit causing the analysis target to be captured in a carrier substance in a liquid state; and a discharging unit discharging the carrier substance including the analysis target to the first point.

Abstract: The present disclosure provides a new tandem mass spectrometer and methods of using the same for analyzing charged particles. The differentially pumped dual linear quadrupole ion trap mass spectrometer of the present disclose includes a combination of two linear quadrupole (LQIT) mass spectrometers with differentially pumped vacuum chambers.

Abstract: The present invention provides a radio frequency (RF) power supply in a mass spectrometer. The power supply provides an RF signal to electrodes of a storage device to create a trapping field. The RF field is usually collapsed prior to ion ejection. In an illustrative embodiment the RF power supply includes a RF signal supply; a coil arranged to receive the signal provided by the RF signal supply and to provide an output RF signal for supply to electrodes of an ion storage device; and a shunt including a switch operative to switch between a first open position and a second closed position in which the shunt shorts the coil output.

Abstract: Apparatus and methods are provided that enable the interaction of low energy electrons and positrons with sample ions to facilitate electron capture dissociation (EGO) and positron capture dissociation (PGO), respectively, within multipole ion guide structures.

Abstract: Provided are methods for determining the amount of reverse T3 in a sample using mass spectrometry. The methods generally involve ionizing reverse T3 in a sample and detecting and quantifying the amount of the ion to determine the amount of reverse T3 in the sample.

Abstract: An atmospheric pressure (AP) interface for a spectrometer includes wall for separating an ionization chamber from a reduced-pressure region of the spectrometer, an ion inlet defining an ion path from the ionization chamber to the reduced-pressure region, and a passage defining a gas path from the ionization chamber to a gas outlet external to the reduced-pressure region. The passage may have a greater gas conductance than the ion inlet such that most gas into the passage and not the ion inlet. The interface device is configured for applying a static electric field effective for focusing ions in the ionization chamber preferentially into the ion inlet.

Abstract: A mass or mass to charge ratio selective ion trap is disclosed having an increased charge storage capacity. A RF voltage acts to confine ions in a first (y) direction within the ion trap. A DC voltage and/or an RF voltage acts to confine ions in a second (x) direction within the ion trap. A quadratic DC potential well acts to confine ions in a third (z) direction within the ion trap. Ions are excited in the third (z) direction and are caused to be mass or mass to charge ratio selectively ejected in the third (z) direction.

Abstract: A novel scanning method of a mass spectrometer apparatus is introduced so as to relate by simple time shifts, rather than time dilations, the component signal (“peak”) from each ion even to an arbitrary reference signal produced by a desired homogeneous population of ions. Such a method and system, as introduced herein, is enabled in a novel fashion by scanning exponentially the RF and DC voltages on a quadrupole mass filter versus time while maintaining the RF and DC in constant proportion to each other. In such a novel mode of operation, ion intensity as a function of time is the convolution of a fixed peak shape response with the underlying (unknown) distribution of discrete mass-to-charge ratios (mass spectrum). As a result, the mass distribution can be reconstructed by deconvolution, producing a mass spectrum with enhanced sensitivity and mass resolving power.

Abstract: A method and an apparatus are described to improve the separation capacity of an ion analyzer incorporating at least two stages of ion mobility analysis. The new invention utilizes possible use of different mixtures of gases and dopants in each stage, control over different concentrations of gases and dopants in each stage, and allowance of passage of the selected ions from one stage to the next while avoiding the mixing of the gases and dopants among stages. The new invention also includes a method to reduce the time required to identify the physical properties in a set of ion filters where at least one of the filters is a scannable ion mobility analyzer. The present invention also includes how to provide a set of scannable ion mobility analyzers operating in series, wherein each stage can be operated as a filter, or allowing for the passage of all ions.

Abstract: An apparatus and method are provided for analyzing samples of molecules. The apparatus comprises a mass analysis system including a differential mobility spectrometer, which includes at least three filter electrodes defining two ion flow paths where the filter electrodes generate electric fields for passing through selected portions of the sample ions based on the mobility characteristics of the sample ions. The differential mobility spectrometer also includes a voltage source that provides DC and RF voltages to at least one of the filter electrodes to generate the electric field, a first and a second ion inlet that receive sample ions, and an ion outlet that outputs the selected portion of the sample ions. A mass spectrometer receives some or all of the selected portion of the sample ions.

Abstract: Provided are methods for determining the amount of reverse T3 in a sample using mass spectrometry. The methods generally involve ionizing reverse T3 in a sample and detecting and quantifying the amount of the ion to determine the amount of reverse T3 in the sample.

Abstract: A miniature electrode apparatus is disclosed for trapping charged particles, the apparatus including, along a longitudinal direction: a first end cap electrode; a central electrode having an aperture; and a second end cap electrode. The aperture is elongated in the lateral plane and extends through the central electrode along the longitudinal direction and the central electrode surrounds the aperture in a lateral plane perpendicular to the longitudinal direction to define a transverse cavity for trapping charged particles.

Abstract: A mass spectrometer having a multi-stage differential pumping system with an ion lens provided in a partition wall separating a second intermediate vacuum chamber and a third intermediate vacuum chamber, the incircle radii of ion guides and the size of the opening of the ion lens are determined so that the circumferential edge of the opening is located outside the circumferential surface of a virtual tubular body straightly connecting the incircle at the rear edge of the second ion guide in the front stage and the incircle at the front edge of the third ion guide in the rear stage. Although the ion lens is located in between, the radio-frequency electric field created by the second ion guide can be effectively connected to the radio-frequency electric field created by the third ion guide through the opening of the ion lens.

Abstract: An ion trap is provided between a collision cell and a time-of-flight mass separator. During a time period in which precursor ions derived from the same compound are selected with a quadrupole mass filter, a collision energy is changed from one to another. Various product ions that are produced by dissociation respectively under collision energies of the plurality of stages and precursor ions that are not dissociated are temporarily trapped in the ion trap, and are ejected in a packet form in the state where these ions are mixed, and are introduced into the time-of-flight mass separator 6 to be subjected to a mass spectrometry. Thereby, in a data processing unit, one MS/MS spectrum in which product ions produced in various dissociation modes under various CID conditions appear is created.

Abstract: An ion trap includes a containment region for containing ions, and a plurality of electrodes positioned on a regular polyhedral structure encompassing the containment region. An electrode is positioned on each vertex of the encompassing structure and at least one of the polygonal surfaces includes additional electrodes configured to form a plurality of quadrupoles on the surface. Alternating RF voltage is applied to the plurality of electrodes, so that directly neighboring electrodes are of equal amplitude and opposite polarity at any point in time. This configuration on the polyhedral structure forms a potential barrier for repelling the ions from each of the regular polygonal surfaces and containing them in the trap. Mass selective filters can be formed from the quadrupoles for parallel mass analysis in different m/z windows. Application of a small DC potential to a plate electrode outside the quadrupoles preferentially depletes single charged ions for enhanced signal-to-noise analysis.

Abstract: The invention provides a method of producing a mass spectrum, comprising: obtaining a transient from the oscillation of ions in a mass analyser; Fourier transforming the transient to obtain a complex spectrum having a real component and an imaginary component; and calculating an enhanced spectrum which comprises a combination of (i) and (ii) wherein (i) comprises a Positive spectrum; and (ii) comprises an Absorption spectrum. Also provided are an apparatus for producing a mass spectrum suitable for carrying out the method as well as a method of determining a phase correction for a complex spectrum obtained by Fourier transformation from a detected transient obtained from a mass analyser.

Abstract: An ion trap device is disclosed. The device includes a series of electrodes that define an ion flow path. A radio frequency (RF) field is applied to the series of electrodes such that each electrode is phase shifted approximately 180 degrees from an adjacent electrode. A DC voltage is superimposed with the RF field to create a DC gradient to drive ions in the direction of the gradient. A second RF field or DC voltage is applied to selectively trap and release the ions from the device. Further, the device may be gridless and utilized at high pressure.

Abstract: An ion mobility separator or spectrometer is disclosed comprising an inner cylinder and an outer cylinder defining an annular volume through which ions are transmitted. Spiral electrodes a-f are arranged on a surface of the inner cylinder and/or on a surface of the outer cylinder. A first device is arranged and adapted to maintain a DC electric field or a pseudo-potential force which acts to urge ions from a first end of the ion mobility separator or spectrometer to a second end of the ion mobility separator or spectrometer. A second device is arranged and adapted to apply one or more transient DC voltages to the spiral electrodes in order to urge ions towards the first end of the ion mobility separator or spectrometer. The net effect is to extend the effective path length of the ion mobility separator.

Abstract: A glass ceramic including an alkali metal earth oxide, e.g. SrO suitable for overmolding a RF component provides a good RF response and good mechanical robustness. Specifically, SrO reduces the flow temperature of the ceramic while maintaining the RF and mechanical performance. The resulting glass formulation contains 10-50 mol % SrO, 5-30 mol % Al2O3, and 20-60 mol % B2O3.

Abstract: An electrode changeover switch which switches the connection state of electrodes is provided in the wiring path between eight electrodes through, arranged rotation-symmetrically about ion optical axis, and voltage generation switch which generates square wave high voltage ±V. When switch is switched as shown in the drawing, two circumferentially adjacent rod electrodes are connected to form one set, a square wave voltage of opposite phase is applied to circumferentially adjacent sets, and an effectively quadrupole electric field is formed. When switch is switched, a square wave voltage of opposite phase is applied to circumferentially adjacent rod electrodes and an octupole electric field is formed. In this way, by switching the switch according to the mass range, etc., it becomes possible to rapidly switch the number of poles of a multipole electric field and to suitably transport ions.

Abstract: An ion mobility spectrometer has an inlet for an analyte substance opening into an ionization region that produces ions of the substance. Parallel grid electrodes extend laterally across the ion flow path and apply an electric field to the ions that is switchable between a relatively low magnitude alternating field that varies in magnitude over multiple periods and an asymmetric alternating field of sufficiently high magnitude to cause differential mobility effects. A collector collects the passed ions, and an indication of the nature of the analyte substance is produced from the collected ions passed during both the low and high field intervals. Also disclosed is the application of a substantially alternating field between the electrodes, which field varies between a low value and a higher value over a time exceeding that of the alternating period.

Abstract: A method of dissociating ions in a multipole ion guide is disclosed. A stream of charged ions is supplied to the ion guide. A main RF field is applied to the ion guide to confine the ions through the ion guide. An excitation RF field is applied to one pair of rods of the ion guide. The ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions. The multipole ion guide is, but not limited to, a quadrupole, a hexapole, and an octopole.

Abstract: In one embodiment, a mass spectrometer includes an RF drive circuit for generating RF signals, a quadrupole mass filter, and a fixed connection assembly for delivering RF signals from the RF drive circuit to the quadrupole mass filter, the fixed connection assembly representing the entire delivery path of RF signals from the RF drive circuit to the quadrupole mass filter. By avoiding flexible components such as a freestanding wires or flexible circuit boards, the need for retuning when parts are removed or disturbed for testing or servicing is reduced, and a modular instrument in which components and connections are standardized and therefore interchangeable is realized.

Abstract: Described herein are methods and systems related to the use of the pre-existing ion injection pathway of a mass spectrometer to perform beam-type collision-activated dissociation, as well as other dissociation methods. Following injection and selection of a particular ion type or population, that population can be fragmented using the pre-existing ion injection pathway or inlet of a mass spectrometer. This is achieved by transmitting the ions back along the ion injection pathway. As the ions pass into the higher pressure regions located in or near the atmospheric pressure inlet, the ions are fragmented and then trapped. Following fragmentation and trapping, the ions can either be re-injected into the primary ion selection device or sent on to a secondary mass analyzer.

Abstract: Provided are a controller and a control method for improving signal performance of an ion cyclotron resonance mass spectrometer. The controller and control method apply electric signals for causing ions injected into an ion trap of the ion cyclotron resonance mass spectrometer to be injected to the center of the trap as close as possible to trap electrodes, and adjust biased ion motion by appropriately adjusting signals of trap electrodes for causing the injected ions to make ion motion, thereby improving the fidelity of ion signals. The control method for improving signal performance of an ion cyclotron resonance mass spectrometer includes an ion position adjustment process and an ion signal detection process.

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: A mass spectrometry method that corrects the effects from space charge and that achieves both sensitivity and a dynamic range. The mass axis of the mass spectrum is corrected based on the counts of ions accumulated within the ion trap at the point in time each ion was extracted.

Abstract: In an ion cyclotron resonance cell, which is enclosed at its ends by electrode structure elements with DC voltages of alternating polarity, longitudinal electrodes are divided so that the ICR measurement cell between the electrode structure elements consists of at least three sections. An excitation of ion cyclotron motions can be performed by applying additional trapping voltages to longitudinal electrodes located closest to the electrode structure elements and introducing ions into the center set of longitudinal electrodes. The ions are then excited into cyclotron orbits by applying radiofrequency excitation pulses to at least two rows of longitudinal electrodes to produce orbiting ion clouds. Subsequently, the additional trapping voltages are removed and an ion-attracting DC voltage is superimposed on the DC voltages. Ions excited to circular orbits can be detected using detection electrodes in the outer ICR cell sections.

Abstract: A mass spectrometer operating according to the iso-tach principle in which a mass filter accelerates ions to nominally equal velocities irrespective of their mass-to-charge ratios. The mass spectrometer is provided with an improved detector based on an electrostatic lens arrangement made of a concave lens followed in the beam path by a convex lens. These lenses deflect ions away from the beam axis by a distance from the beam axis that is inversely proportional to their mass-to-charge ratios. The mass-to-charge ratio of the ions can then be determined by a suitable detector array, such as a multi-channel plate placed in the beam path. This provides a compact and sensitive instrument.

Abstract: Apparatus and methods are provided that enable the interaction of low energy electrons and positrons with sample ions to facilitate electron capture dissociation (EGO) and positron capture dissociation (PGO), respectively, within multipole ion guide structures. The apparatus and methods described herein allow EGO (and PCO) to be performed within multipole ion guides, either alone, or in combination with conventional ion fragmentation methods.

Abstract: A mass spectrometer having a resolution improved by introducing ions into a mass spectrometry part with a high efficiency is provided with a small-sized, simple configuration. The mass spectrometer includes an opening/closing mechanism provided between a sample introducing piping part for introducing a sample into the mass spectrometry part and the mass spectrometry part to conduct gas introduction intermittently and control sample passage. The mass spectrometer further includes a pump mechanism to evacuate a high pressure side of the sample introducing piping part, that is, an opposite side of the opening/closing mechanism to the mass spectrometry part to have a pressure in a range of 100 to 10,000 Pa.

Abstract: An object of the present invention is to provide means for solving troubles. Examples of the troubles include sensitivity degradation and resolution degradation of a mass spectrometer, which are caused by an axis deviation of a component, particularly at least one orifice located between an ion source and a detector, to decrease the number of ions reaching the detector, and a variation in performance caused by exchange of components such as the orifice. For example, the invention has the following configuration in order to solve the troubles. A mass spectrometer includes: an ion source; a detector that detects an ion; an orifice and a mass separator that are disposed between the ion source and the detector; and an axis adjusting mechanism that adjusts axis positions of the orifice and/or the mass separator such that an opening of the orifice and/or an incident port of the mass separator is disposed on a line connecting the ion source and an incident port of the detector.

Abstract: Provided are methods for determining the amount of reverse T3 in a sample using mass spectrometry. The methods generally involve ionizing reverse T3 in a sample and detecting and quantifying the amount of the ion to determine the amount of reverse T3 in the sample.

Abstract: An ion trap includes a trap exit at which an ion energy adjusting device is located. The adjusting device may be configured for focusing a beam of ions ejected from the trap, reducing the energy distribution of the ions, and/or reducing the average kinetic energy of the ions. The adjusting device may include lenses to which RF and/or DC voltages are applied.

Abstract: In an ion cyclotron resonance mass spectrometer ions are excited into cyclotron orbits by an alternating current excitation signal having a nonlinear function of the excitation frequency vs. time in a “chirp.” Such an excitation signal produces transients which have no pronounced beats, even if mixtures of many ion species, all having the same mass differences, are present. The dynamic measuring range for the image currents can thus be better utilized. In particular, sum spectra of specified quality can be generated from a significantly smaller number of individual transients, and thus in a significantly shorter measuring time.

Abstract: An ion transfer arrangement for transporting ions between higher and lower pressure regions of the mass spectrometer comprises an ion transfer conduit 60. The conduit 60 has an inlet opening towards a relatively high pressure chamber 40 and an outlet 70 opening towards a relatively low pressure chamber. The conduit 60 also has at least one side wall surrounding an ion transfer channel 115. The side wall includes a plurality of apertures 140 formed in the longitudinal direction of the side wall so as to permit a flow of gas from within the ion transfer channel 115 to a lower pressure region outside of the side wall of the conduit 60.

Abstract: An ion trap includes a containment region for containing ions, and a plurality of electrodes positioned on a regular polyhedral structure encompassing the containment region. An electrode is positioned on each vertex of the encompassing structure and at least one of the polygonal surfaces includes additional electrodes configured to form a plurality of quadrupoles on the surface. Alternating RF voltage is applied to the plurality of electrodes, so that directly neighboring electrodes are of equal amplitude and opposite polarity at any point in time. This configuration on the polyhedral structure forms a potential barrier for repelling the ions from each of the regular polygonal surfaces and containing them in the trap. Mass selective filters can be formed from the quadrupoles for parallel mass analysis in different m/z windows. Application of a small DC potential to a plate electrode outside the quadrupoles preferentially depletes single charged ions for enhanced signal-to-noise analysis.

Abstract: An ion trap for a mass spectrometer is disclosed. The ion trap includes a ring electrode and first and second electrodes which are arranged on opposite sides of the ring electrode. The ring electrode and the first and second electrodes are configured to generate an electric field based on the received RF signal. The first electrode defines a first aperture and the second electrode defines a second aperture, the first aperture and the second aperture being asymmetric relative to each other and configured to generate a hexapole field.

Abstract: The present invention relates to the analytical electronics used to identify compositions and structures of substances, in particular, to the analyzers comprising at least one mass-spectrometer (MS) and may be applied in such fields as medicine, biology, gas and oil industry, metallurgy, energy, geochemistry, hydrology, ecology. Technical result provides the increase in MS resolution, gain in sensitivity, precision and measurement rates of substances compositions and structures concurrently with enhancement of analyzer functional capabilities, downsizing and mass reduction. In claimed invention the ion flux generation and its guiding are performed in off-axis single-flow mode; parallel multi-stage mode; through use of three-dimensional field with mean meridian surface including without limitation three-dimensional reflecting and dual-zoned reflecting modes or by method of multi-reflection arrays. Devices to implement the claimed method are embodied.

Abstract: Provided is a quadrupole mass spectrometer including direct-current voltage sources having response characteristics which ensure that the response time of the direct-current voltage will be shorter than the period of time required for an ion having the highest mass-to-charge ratio (m/z) among the ions introduced into a quadrupole mass filter to pass through this filter. Main rod electrodes and pre-rod electrodes are connected to each other via primary differentiation circuits. Thus, in the transient state of the voltage change due to the switching of the mass-to-charge ratio, among the ions entering the quadrupole mass filter, ions having low m/z values can be removed by a pre-electrode unit, and ions having high m/z values can be removed by a main electrode unit. Accordingly, a large amount of ions can be prevented from passing through the filter and entering an ion detector.