Abstract: In a mass spectrometer with an electrostatic ion trap, the electrostatic ion trap has an outer electrode with an ion-repelling electric potential applied to it and a plurality of inner electrodes with ion-attracting potentials applied to each inner electrode. The outer electrode and the inner electrodes are shaped and arranged in such a way that a harmonic electric potential is formed in one spatial direction and, perpendicular to this spatial direction, an electric potential is formed in which ions move in stable, radial trajectories.

Abstract: An ion mobility spectrometer has two drift chambers and a common, doped reaction region. Each drift chamber includes an ion modifier, such as one that fragments the doped ions by a high electrical field. One of the drift chambers is doped and the other is undoped. In this way, the dopant adducts are removed by the modification process but then recombine with dopant only in the doped chamber so that different outputs are produced by the two drift chambers.

Abstract: A two-dimensional radial-ejection ion trap is constructed from four apertured electrodes having inwardly facing hyperbolic surfaces, with each electrode being spaced from the centerline by a distance r that is greater than the hyperbolic radius r0 defined by the hyperbolic surfaces. This geometry produces a balanced symmetrical trapping field that has a negligible octopole field component and a relatively large dodecapole or icosapolar field component. In one specific implementation, the ion trap is selectably operable as a quadrupole mass filter by applying a filtering DC voltage to the electrodes.

Abstract: An ion cell having an axis includes a sheath of individual electrodes that extends along the axis and defines an internal volume. Adjacent individual electrodes are electrically insulated from each other. The individual electrodes each receive a DC potential and RF voltage. At least some of the individual electrodes have a width that varies in the axial direction such that an electrical effect on an axis potential varies along the axis of the ion cell.

Abstract: Ions obtained through EI process from a first gas are subjected to mass analysis to obtain ion intensities which are stored in a first file, and ions obtained through soft ionization process from a second gas having same concentration of components as that of the first gas are subjected to mass analysis to obtain ion intensities which stored in a second file, and molecular weights are determined based on parent ions from soft ionization measurement data. A mass spectrum corresponding to the determined molecular weight is read out based on an NIST database, and the ion intensity data stored in the first file and the read out NIST data are compared with each other, and component molecules of the first gas are determined based on the comparison results. Qualitative analysis of mixed gas can be conducted in real time with high accuracy by making effective use of the measurement data of both mass analysis based on EI process and mass analysis based on soft ionization process.

Abstract: An ion guide or mass analyser is disclosed comprising a plurality of electrodes having apertures through which ions are transmitted in use. A pseudo-potential barrier is created at the exit of the ion guide or mass analyser. The amplitude or depth of the pseudo-potential barrier is inversely proportional to the mass to charge ratio of an ion. One or more transient DC voltages are applied to the electrodes of the ion guide or mass analyser in order to urge ions along the length of the ion guides or mass analyser. The amplitude of the transient DC voltage applied to the electrode may be increased with time so that ions are caused to be emitted from the ion guide or mass analyser in reverse order of their mass to charge ratio.

Abstract: Methods and systems are provided for detecting analytes in a gas phase sample. An ion mobility spectrometer is provided for detecting analytes having an excess amount of dopant in its separation region. In an embodiment, the dopant is added directly to the separation region, such as with a drift gas or by diffusion, thereby providing excess dopant that dominates subsequent cluster formation and maintenance. Excess dopant in the separation region minimizes or reduces interfering signals associated with unwanted substances, such as water vapor, that are introduced to the IMS. In an aspect, the invention provides IMS systems and methods having increased sensitivity and reliability for analyte detection.

Abstract: A radio-frequency ion guide (20) for converging ions by a radio-frequency electric field and simultaneously transporting the ions into the subsequent stage is composed of eight rod electrodes (21 through 28) arranged in such a manner as to surround an ion optical axis (C). Each of the rod electrodes (21 through 28) is disposed at a tilt with respect to the ion optical axis (C) so that the radius r2 of the inscribed circle (29b) at the end face of the ion exit side is larger than the radius r1 of the inscribed circle (29a) at the end face of the ion injection side. Accordingly, the gradient of the magnitude or depth of the pseudopotential is formed in the ion's traveling direction in the space surrounded by the rod electrodes (21 through 28). Ions are accelerated in accordance with this gradient. Therefore, even in the case where the gas pressure is relatively high and ions have many chances to collide with gas, it is possible to moderate the ions' slowdown and prevent the ions' delay and stop.

Abstract: A mass spectrometer is disclosed comprising an ion guide (1) or ion mobility spectrometer having helical, toroidal, part-toroidal, hemitoroidal, semitoroidal or spiral ion guiding region (4). The ion guide (1) may comprise a tube made from a leaky dielectric wherein an RF voltage is applied to outer electrodes in order to confine ions radially within the ion guide (1). A DC voltage is applied to a resistive inner layer in order to urge ions along the ion guide (1). Alternatively, the ion guide may comprise a plurality of electrodes each having an aperture through which ions are transmitted.

Abstract: A radio frequency (RF) drive system and method for driving the ion trap or mass filter of a mass spectrometer has a programmable RF frequency source coupled to a RF gain stage. The RF gain stage is transformer coupled to a tank circuit formed with the ion trap or mass filter. The power of the RF gain stage driving the ion trap or mass filter is measured using a sensing circuit and a power circuit. A feedback value is generated by the power circuit that is used to adjust the RF frequency source. The frequency of the RF frequency source is adjusted until the power of the RF gain stage is at a minimum level. The frequency value setting the minimum power is used to operate the RF drive system at the resonance frequency of the tank circuit formed with the transformer secondary inductance and the ion trap or mass filter capacitance.

Abstract: A solution is supposed to be created with a method for generating positively and/or negatively ionized gas analytes for gas analysis in an ion mobility spectrometer or in a mass spectrometer, with which method the gas analyte can be ionized without the restrictions of previous ionization methods for gas analysis in an ion mobility spectrometer or in a mass spectrometer, forming positive and/or negative ions. This is achieved in that the positive and/or negative gas ions are generated by means of a plasma, which is brought about by means of a dielectrically inhibited discharge, whereby the dielectrically inhibited discharge is produced in that a noble gas is passed in through a capillary made of a dielectric material, whereby an alternating voltage is applied by means of two electrically insulated electrodes disposed on the capillary adjacent to the exit region of the capillary, and the gas analyte is passed to the exit region outside of the capillary.

Abstract: A two-dimensional substantially quadrupole field is provided. The field comprises a quadrupole harmonic of amplitude A2 and an octopole harmonic of amplitude A4, wherein A4 is greater than 0.01% of A2, A4 is less than 5% of A2, and, for any other higher order harmonic with amplitude An present in the field, n being any integer greater than 2 except 4, A4 is greater than ten times An.

Abstract: A high field asymmetric waveform ion mobility spectrometry (FAIMS) comprises an electrical power supply electrically connected to at least one of the FAIMS electrodes and operable to as to apply a periodic asymmetric square-wave waveform voltage to at least one of the electrodes so as to selectively transmit a type of ion in and through a FAIMS analyzer region to an ion outlet, wherein the electrical power supply is operable so as to vary a time duration of pulses of the asymmetric square-wave waveform so as to control the type of ion selectively transmitted, an efficiency of said selective transmission or the ability to prevent transmission of a different type of ions in and through said analyzer region to the ion outlet.

Abstract: A mass analyser (2) is provided comprising a plurality of electrodes having apertures through which ions are transmitted in use. A plurality of pseudo-potential corrugations are created along the axis of the mass ((analyser 2). The amplitude or depth of the pseudo-potential corrugations is inversely proportional to the mass to charge ratio of an ion. One or more transient DC voltages are applied to the electrodes of the mass analyser (2) in order to urge ions along the length of the mass analyser (2). The amplitude of the transient DC voltages applied to the electrodes is increased with time and ions are caused to be emitted from the mass analyser (2) in reverse order of their mass to charge ratio. Two AC or RF voltages are applied to the electrodes. The first AC or RF voltage is arranged to provide optimal pseudo-potential corrugations whilst the second AC? or RF voltage is arranged to provide optimal radial confinement of ions within the mass analyser (2).

Abstract: The mass spectrometer is characterized in that a linear ion trap, that consists of electrodes for mass-selective discharge, is provided with a mechanism that excites ions in a first direction that is perpendicular to the rod axes and a mechanism that simultaneously generates an electric field on the axes in a second direction that is perpendicular to the axial direction and the first direction in order to generate an electric field on the central axis. Highly efficient, high-speed scanning can be achieved using this configuration.

Abstract: An MS/MS spectrometric analysis method obtains throughput and mass resolving power of precursor ions. In a mass spectrometer, ions, which are introduced and accumulated in an ion trap unit, are resonance-extracted mass-selectively. A profile of precursor ions at the m/z axis of the ion trap and a profile at the mass analyzer portion, which performs mass analysis of the ions extracted from a collision induced dissociation portion, is obtained by performing a measurement when the injection energy to the collision induced dissociation portion is low, and when the injection energy to the collision induced dissociation portion is high. The profile at the m/z axis of the ion trap of the obtained two-dimensional spectrum is substituted with the profile at the m/z axis of the mass analyzer portion. In this way, the m/z of both the precursor ions and the fragment ions can be determined with high mass resolving power.

Abstract: The present invention pertains to a method for determining an analyte substance or analyte substance mixture of ammonia and/or N-methyl-2-pyrrolidone as a component of a gas in the presence of a dopant mixture by means of an ion mobility spectrometer and to a corresponding ion mobility spectrometer.

Abstract: A distance-of-flight mass spectrometer (DOF-MS) imparts constant momentum acceleration to ions in an ion source and uses an ion mirror to enhance energy focusing. Embodiments of DOF-MS with ion mirror are shown. Further, a method of compensating for the dispersion of initial ion position and velocity in the ion source is discussed.

Abstract: A method of introducing ions into an ion trap and an ion storage apparatus are described. Introduction means are used to introduce first ions into an ion trap through an entrance aperture to the ion trap. An operating condition of the introduction means is adjusted to cause second ions, of different polarity to the first ions to be introduced into the ion trap through the same entrance aperture.

Abstract: The invention herein generally relates to non-destructive, high order harmonic ion motion image current detection. In certain embodiments, ion motion corresponding to high order harmonic frequencies, instead of the secular frequencies, is detected using image current detection with a constant excitation applied to the waveform signal.

Abstract: This invention provides a method of aligning sets of cylindrical electrodes in the geometry of a miniature quadrupole electrostatic lens, which can act as a mass filter in a quadrupole mass spectrometer. The electrodes are mounted in pairs on microfabricated supports, which are formed from conducting parts on an insulating substrate. Complete segmentation of the conducting parts provides low capacitative coupling between co-planar cylindrical electrodes, and allows incorporation of a Brubaker prefilter to improve sensitivity at a given mass resolution. A complete quadrupole is constructed from two such supports, which are spaced apart by further conducting spacers. The spacers are continued around the electrodes to provide a conducting screen.

Abstract: An ion guide chamber comprising a gas-tight elongate chamber, at least one first electrode for generating a field for transporting ions along the elongate chamber and at least one second electrode for generating a field for focusing ions within the elongate chamber. The elongate chamber, e. g. constituted by a glass tube, comprises a resistive structure extending substantially along a main axis of the chamber, whereas the first electrode is constituted by the resistive structure. Furthermore, the second electrode is arranged outside the elongate chamber. Having the RF electrodes arranged outside the vacuum chamber, provides a mechanically simple solution as well as insuring that contamination of the RF electrodes to the analyte gas cannot occur. This allows for a cost-saving design of the RF electrodes and with the corresponding voltages outside the chamber, preferably at atmospheric pressure or high vacuum, avoids discharges within the tube.

Abstract: A mass spectrometer is disclosed comprising a FAIMS device comprising two parallel electrodes (9a, 9b) in series with an ion mobility separator (12) forming part of a mass spectrometer. Ions are separated in the FAIMS device (9a, 9b) according to their rate of change of ion mobility with electric field strength. The ions which are onwardly transmitted from the FAIMS device (9a, 9b) are then passed to an ion separator device (12) comprising a plurality of electrodes (12) and an optional ion trapping region (33). Ions are radially confined with the ion separator by application of an AC or RF voltage to the electrodes (12) and ions are separated according to their ion mobility by applying an axial DC voltage gradient which may remain constant as a function of time or which may vary with time.

Abstract: An ion guide includes multiple stages. An electric field within each stage guides ions along a guide axis. Within each stage, amplitude and frequency, and resolving potential of the electric field may be independently varied. The geometry of the rods maintains a similarly shaped field from stage to stage, allowing efficient guidance of the ions along the axis. In particular, each rod segment of the ith of stage has a cross sectional radius ri, and a central axis located a distance Ri+ri from the guide axis. The ratio ri/Ri and is substantially constant along the guide axis, thereby preserving the shape of the field.

Abstract: During the structural analysis of a protein or peptide by tandem mass spectroscopy, a peptide ion derived from a protein that has already been measured and that is expressed in great quantities is avoided as a tandem mass spectroscopy target. A peptide derived from a minute amount of protein, which has heretofore been difficult to analyze, can be automatically determined as a tandem mass spectroscopy target within the real time of measurement. Data concerning a protein that has already been measured and a peptide derived from the protein is automatically stored in an internal database. The stored data is collated with measured data with high accuracy to determine an isotope peak. In this way, the process of selecting a peptide peak that has not been measured as the target for the next tandem analysis can be performed within the real time of measurement and a redundant measurement of peptides derived from the same protein can be avoided.

Abstract: A method of mass spectroscopy according to example embodiments may include injecting ions into a Penning trap and exciting the ions into cyclotron and/or magnetron motions. The cyclotron motions and magnetron motions may be converted to one another with external radio frequency signals. The ions may be ejected from the Penning trap onto a position sensitive charged particle detector to determine the phases and amplitudes of the motions. Ion cyclotron resonance frequencies may be determined based on the phases and amplitudes of the motions of the ejected ions.

Abstract: 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.

Abstract: A superconducting magnet configuration (4; 14) for generating a homogeneous magnetic field B0 in an examination volume (4b), has an interior radial superconducting main field coil (1) which is disposed rotationally symmetrically about an axis (z-axis) and an oppositely driven coaxial radially exterior superconducting shielding coil (2) is characterized in that the magnet configuration (4; 14) consists of the main field coil (1), the shielding coil (2), a ferromagnetic field formation device (3; 18) and a ferromagnetic shielding body (AK), wherein the ferromagnetic field formation device (3; 18) is located at the radially inside of the main field coil (1) and the ferromagnetic shielding device (AK) surrounds the main field coil (1) and the shielding coil (2) in a radial and axial direction, the main field coil (1) consisting of an unstructured solenoid coil or of several radially nested unstructured solenoid coils (15, 16) which are driven in the same direction, the axial extent Labs of the shielding coil (2)

Abstract: In a scan measurement in which a mass scan is repeated across a predetermined mass range, when a voltage is returned from a termination voltage of one scan to an initiation voltage for the next scan, an undershoot or other drawbacks occur to destabilize the voltage value. Therefore, an appropriate waiting time is required. Conventionally, this waiting time has been set to be constant regardless of the analysis conditions. On the other hand, in the quadrupole mass spectrometer according to the present invention, the mass difference ?M between the scan termination mass and the scan initiation mass is computed based on the specified mass range, and a different settling time is set in accordance with this mass difference. When the mass difference ?M is small and hence requires only a short voltage stabilization time, a relatively short settling time is set. This shortens the cycle period of the mass scan, which increases the temporal resolution.

Abstract: A device for improved transportation and focusing of ions in a low vacuum or atmospheric-pressure region of a mass spectrometer is constructed from one or more electro-dynamic or electrostatic focusing lenses that is/are coupled to the first electrode of a stacked ring ion guide (SRIG) to which oscillatory (e.g., radio-frequency) voltages are applied. Such configurations as disclosed herein, minimizes deleterious field effects and/or repositioning problems of desired ion transfer instruments that utilize such stacked ring ion guides by generally configuring the outlet end of the ion transfer device to a desired position within the electro-dynamic or electro-static focusing lens(es).

Abstract: In conventional mass spectrometers, if ions are converged by a radio-frequency electric field under the condition of relatively high gas pressure, the ions are decelerated and are delayed, or stagnated in an extreme case, to cause a decrease in the detection sensitivity or an appearance of a ghost peak. By contrast, in the mass spectrometer according to the present invention, lens electrodes 40 comprises four plate-shaped electrodes 41a through 41d, which are radially arranged around the ion optical axis C at intervals of 90 degrees from each other; the four electrodes placed in the plane being approximately perpendicular to the ion optical axis C form a group, and a plurality of the groups are arranged along the ion optical axis C direction at approximately even intervals. The radio-frequency voltages each applied to each of any pair of electrodes adjacent along the direction of the ion optical axis C have a given amount of phase shift.

Abstract: The invention relates generally to ion mobility based systems, methods and devices for analyzing samples and, more particularly, to sample pre-separation and amplification.

Abstract: A collision/reaction cell for a mass spectrometer includes an RF multipole having electrodes that are shaped and positioned such that the value of the radial spacing r0 increases from the inlet to the outlet end. The longitudinally increasing r0 improves transmission of relatively low-m/z product ions relative to a conventional collision/reaction cell design.

Abstract: A tandem linear ion trap and time-of-flight mass spectrometer, where the ion trap has a straight central axis orthogonal to the flight path of the mass spectrometer. The ion trap comprises a set of electrodes, (401, 403, 402, 404) at least one of the electrodes has a slit for ejecting ions towards the mass spectrometer; a set of DC voltage supplies (+V, ?V, V1, V2) to provide discrete DC levels and a number of fast electronic switches (409) for connecting/disconnecting the DC supplies to at least two of the electrodes; a neutral gas filling the ion trap and a digital controller to provide a switching procedure of ion trapping, manipulation with ions, cooling and including a state at which all ions are ejected from the ion trap towards the mass spectrometer.

Abstract: A method of aligning sets of cylindrical electrodes in the geometry of a miniature quadrupole electrostatic lens, which can act as a mass filter in a quadrupole mass spectrometer is provided. The electrodes are mounted in pairs on microfabricated supports, which are formed from conducting parts on an insulating substrate. Complete segmentation of the conducting parts provides low capacitative coupling between co-planar cylindrical electrodes, and allows incorporation of a Brubaker prefilter to improve sensitivity at a given mass resolution. A complete quadrupole is constructed from two such supports, which are spaced apart by further conducting spacers. The spacers are continued around the electrodes to provide a conducting screen.

Abstract: The mobility of mass-selected ions in gases is measured at pressures of a few hectopascal by selecting the ions under investigation in a quadrupole filter according to their mass-to-charge ratio m/z, measuring their mobility in a drift region at a pressure of a few hundred Pascal under the influence of a DC electric field and then filtering the measured ions by means of a quadrupole field in order to eliminate, or detect changes in, the mass-to-charge ratio. Several embodiments for the drift region are disclosed, in which the ions are kept in the axis of the drift region by RF fields. As these drift regions can also be utilized for a collision-induced decomposition of the ions, the device can additionally be used as a so-called triple quadrupole mass spectrometer.

Abstract: In accordance with an aspect of an embodiment of the present invention, there is provided a method for fragmenting ions in an ion trap of a mass spectrometer.

Abstract: The invention relates to mass spectrometers in which ion clouds are stored in two spatial directions by radial forces while oscillating largely harmonically at a mass-specific frequency in a third spatial direction perpendicular to the other two, in a potential minimum, the shape of which is as close to a parabola as possible. Analysis of the oscillation frequencies of these ion clouds, preferably by a Fourier analysis, leads via a frequency spectrum to a mass spectrum. The frequency spectrum is analyzed to identify false signals in the frequency spectrum as harmonics and eliminating them where necessary.

Abstract: A system and method for trapping a charged particle is disclosed. A time-varying periodic multipole electric potential is generated in a trapping volume. A charged particle under the influence of the multipole electric field is confined to the trapping volume. A three electrode configuration giving rise to a 3D Paul trap and a four planar electrode configuration giving rise to a 2D Paul trap are disclosed.

Abstract: This invention relates to mass spectrometry that includes ion trapping in at least one of the stages of mass analysis. In particular, although not exclusively, this invention relates to tandem mass spectrometry where precursor ions and fragment ions are analysed. A method of mass spectrometry is provided comprising the sequential steps of: accumulating in an ion store a sample of one type of ions to be analysed; accumulating in the ion store a sample of another type of ions to be analysed; and mass analysing the combined samples of the ions; wherein the method comprises accumulating the sample of the one type of ions and/or the sample of another type of ions to achieve a target number of ions based on the results of a previous measurement of the respective type of ions.

Abstract: A compact, low-cost, and simple ion trap capable of operating at a low vacuum level is provided along with technology for utilizing that ion trap to perform mass spectroscopy and analyzing ion mobility without a drop in measurement accuracy. Ions are trapped in a one dimensional potential formed by a potential comprised of a direct current voltage and a potential comprised of an alternating current voltage. The trapped ions are made to collide with an electrode by changing at least the applied direct current voltage or alternating current voltage, and are detected as an electrical current value.

Abstract: A method for calibrating an ion trap mass spectrometer is disclosed. The method includes establishing an optimal phase and amplitude-m/z relationship by acquiring peak quality data at varying values of amplitude and 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: In a three-dimensional Paul RF ion trap at least one of the ring electrode and end cap electrodes is structured to produce a high capture efficiency for analyte ions introduced into the trap. The electrode structuring may be produced by an electrode surface profile having edges or protrusions, resulting in a scattering reflection of the introduced ions. Alternatively, at least one electrode may be formed by physically separate electrode components. In one embodiment, the trap can be switched between operating as a linear ion trap with good capture efficiency and operating as a three-dimensional ion trap with good ion reaction conditions.

Abstract: A method for differential mobility separation of ions using digital-drive based high voltage fast switching electronics. The digital waveform delivered to the spectrometer is characterized by at least two substantially rectangular pulses of different amplitude and polarity. The control circuitry allows for waveform frequency, duty cycle and pulse amplitudes to be varied independently. Balanced as well as unbalanced asymmetric waveforms can be designed for optimum differential mobility separation of ions. The digital drive is designed for differential mobility spectrometers including parallel plate and segmented plate multipoles of planar symmetry, as well as multipoles of cylindrical symmetry, which may optionally be arranged in series. The use of the digital drive establishes alternating electric fields during which the displacement as a result of ion oscillation is determined by mobility coefficients.

Abstract: A combined rf-only/FAIMS apparatus is disclosed for use in mass spectrometry and other applications. The disclosed apparatus includes a plurality of curved electrodes arranged around a central ion transmission channel. FAIMS functionality is removed electronically when not desired by application of radio frequency (rf) waveforms to the curved electrodes.

Abstract: A method for the mass-selective transport of ions, especially in a mass spectrometer, comprises the steps movement of the ions on a movement path on which a plurality of electrodes are arranged, and loading the electrodes with pulse-shaped acceleration voltages under the effect of which the ions experience a mass-dependent change of speed, wherein the electrodes are loaded with the pulse-shaped acceleration voltages such t at target ions with a pre-determined target mass are accelerated along the movement path Furthermore, an ion conductor for mass-selective transport of ions, especially in a mass spectrometer, is described.

Abstract: A method for reducing the energy spread of ions over a specific and limited mass to charge ratio range is disclosed, along with an ion deceleration arrangement for implementing such a method. An electric field, having an electric field strength E is generated by a deceleration electrode arrangement (250). Ions of a specific and limited mass to charge ratio range, but having a spread of energies, are directed into the decelerating electric field generated by the deceleration electrode arrangement (250). The decelerating electric field is then removed, once substantially all of the ions of the specific mass to charge ratio range have entered the decelerating electric field. By matching the electric field strength E to the energy spread of the ions upon entry into the electric field, the energy spread of the said ions is reduced. Preferred embodiments of the invention employ energy dispersion upstream of the ion deceleration arrangement.

Abstract: Disclosed are ion cyclotron resonance (ICR) cells and other ion-trapping cells with plural groups of multiple trapping electrodes for shaping (e.g., flattening) the radial electric field within the ICR cell. Also disclosed are methods for controlling the electric field to diminish effects of de-phasing. The diminished effects are achieved by decreasing space-charge contributions by increasing the length of the ion-oscillation path along the z-axis of the ICR cell. The methods and devices enhance the time-domain signal of a Fourier-transform ion-cyclotron resonance mass spectrometer (FTICR-MS) and provide enhanced resolution and accuracy of mass measurements.

Abstract: A method for fast and accurate recognition of species contained in trace amounts in complex mixtures such as ambient air or biological fluids is taught based on the use in tandem of one or several differential mobility analyzers (DMAs) and possibly also a mass spectrometer (MS), all arranged in series. The two DMAs operate in different regions of the ion drag versus drift velocity curve (for instance, linear versus nonlinear regions), hence separating according to more than one independently discriminating parameters of the ion. Very high discrimination can be achieved even with a single stage of mass spectrometric separation by selecting a narrow range of ions with the DMA, and analyzing them in the MS, first without fragmentation, and then with fragmentation. This process does not require necessarily a tandem MS when fragmentation takes place in the inlet region of the MS.

Abstract: Disclosed is an electrode structure for a drift tube in IMS comprising a ring electrode, for each of two surfaces of the ring electrode, at least a part adjacent to the inner radius is formed into a cone, and the angles formed between the cones and the axis of the ring electrode are different from each other. The electrode structure of the present invention can alleviate, even eliminate, the accumulation of space charges in the drift tube. Such structure is particularly suitable when the electric field in the drift tube is low in strength or a great number of ions pass through. Meanwhile, the structure allows a significant decrease in the size of the outer radius of the electrode, while the inner radius remains constant. In this way, it is possible to effectively reduce the outline size of the drift tube and thus make the IMS compact.