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: A method for analyzing a structure of a substance of interest uses triple-quadrupole mass spectrometry (TQ-MS), and allows for acquisition of MSn information from data resulting from the TQ-MS measurement. The method includes (a) performing a measurement of triple quadrupole mass spectrometry with respect to the substance of interest while varying a value of CID energy; (b) at given values of CID energy, calculating percentages of precursor ion contents to a total ion content, and percentages of product ion contents to the total ion content; (c) extracting values of the percentages of product ion contents to the total ion content, wherein said values are values of the percentages of product ion contents at the respective values of CID energy; and (d) calculating sums of all combinations of the values of the percentages of product ion contents to the total ion content extracted in step (c).

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: In order to enable the mass spectroscope to reduce the operation load of the adjustment of the amplitude difference, and to reduce the increase in power consumption caused by the difference between the resonance frequency and the drive frequency, the resonance circuit unit of the ion trap section is configured to control the amplitude difference adjustment section of the resonance circuit unit to adjust that the amplitude difference between the high-voltage RF signals decreases, and controls the frequency synchronizing section of the resonance circuit unit to adjust that the resonance frequency of the resonance circuit is aligned with the drive frequency of the RF signal source, on the basis of the information about the amplitude difference between the high-voltage RF signals and the resonance frequency of the resonance circuit unit, which have been measured by a resonance frequency/amplitude difference measuring unit.

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: Selective ionization at atmospheric or near atmospheric pressure of a sample diluted in air is provided in multiple steps. Initially, components of air and/or other gas are ionized to generate reactive ions. The reactive ions are then filtered using a high frequency filter to yield selected reactive ions. Thereafter, the selected reactive ions are reacted with sample molecules of a sample being analyzed in a charge transfer process. Depending on the properties of the sample molecules, the filter may select some reactive ions to enter the sample zone and block others entirely thus controlling ion chemistry and charge transfer yields in the sample zone. The described system is directed to controlling ions at the ion source level, using a high frequency filter technique, in connection with subsequent analysis. The method generates the ions of choice for subsequent analysis in such platforms as ion mobility and differential mobility spectrometers.

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: An ion trap comprises substantially elongate electrodes 10, 20 some of which are curved along their axis of elongation and which define a trapping volume between them. The sectional area of this trapping volume towards the extremities of the trap in the direction of elongation is different to the sectional area away from its extremities (eg towards the middle of the trap). In a preferred embodiment, the trap has a plurality of elongate electrodes, wherein opposed electrodes have different radii of curvature so that the trap splays towards its extremities. Thereby, a wider mass range of ions can be trapped and ejected, a higher space charge capacity (for a given trap length) is provided, and sharper ion beam focussing on ejection is possible.

Abstract: A collision cell is disclosed that provides ion activation in various selective modes. Ion activation is performed inside selected segments of a segmented quadrupole that provides maximum optimum capture and collection of fragmentation products. The invention provides collisional cooling of precursor ions as well as product fragments and further allows effective transmission of ions through a high pressure interface into a coupled mass analysis instrument.

Abstract: This mass spectrometer is provided with an ion guide (37) having a multipole rod electrode (1), a power source unit (5) for applying voltage to the multipole rod electrode, and a control unit for controlling the power source unit, said mass spectrometer being characterised by the multipole rod electrode having a rod electrode divided into a plurality of segmented rods (2A-1, 2A-2, 2B-1, 2B-2, 2C-1, 2C-2, 2D-1, 2D-2) at mutually different positions in the axial direction. Thus enabled is low-cost, high-throughput analysis.

Abstract: A method and apparatus are described herein for the interface of an ion mobility spectrometer (IMS) to a mass spectrometer (MS) that utilizes collisional focusing, through internal modification. Commercial standalone IMS instrumentation cannot be combined in tandem with a commercially available MS that utilizes collisional focusing due to the physics of the differentially pumped interface of the MS being an unsuitable environment for an IMS measurement. The invention provides for transfer of the ion beam from the IMS to the MS without distortion of the chemical species or temporal profile due to large scale collisions in the differentially pumped interface, by increasing the electric field strength between the orifice and skimmer, and decreasing the pressure in the differentially pumped interface, thereby reducing the number of background gas collisions encountered by the ion beam during transit from the IMS to the MS.

Abstract: A mass spectrometer is disclosed comprising a device which is operable in a first mode of operation to separate ions temporally according to their ion mobility by applying a continuous axial electric field. The device is also operable in a second mode of operation wherein ions are separated temporally according to the their mass to charge ratio by pulsing an applied axial electric field ON and OFF.

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: A method and apparatus for transmitting ions in a mass spectrometer from an ion source to a mass analyzer extracts analyte ions from the ion source in such a manner that the number of extracted analyte ions is maximized. The ions are then transmitted through an ion guide to the mass analyzer. The ion guide is filled with an interaction gas and its operating parameters are adjusted so that, as the ions pass through the ion guide, the analyte ion energy distribution width is narrowed and the analyte ions are collimated within the ion guide to improve the resolution and sensitivity of the mass analyzer.

Abstract: An ion trap mass spectrometer with high sensitivity for detection in the high mass-to-charge ratio is provided. with separate measurement of square-wave voltages on the positive and negative electrode sides applied to a ring electrode in rectifying circuits and smoothing the measured voltages in integrating circuits, respectively, the areas of square-wave voltages on the positive and negative electrode sides are replaced with the peak values h1 and h2 of DC signals, respectively. A comparator circuit outputs the difference of said peak values as the error signal ?, and variable delay circuits adjust the amount of delay of control signals so that the error signal ? becomes zero. This changes the relative phase relation between control signals on the positive and negative electrode sides that turn on and off the switches, and renders the duty ratio of square-wave voltages nearly 50%.

Abstract: An ion trap mass spectrometer and methods for obtaining a mass spectrum of ions by step scanning the driving frequency in frequency increments over a bandwidth, wherein for each step a specific frequency is held for a fixed number of complete cycles, wherein each specific frequency is changed continuously to the frequency in the next step, and wherein each specific frequency in each step starts at phase zero position.

Abstract: There is provided of an on mobility spectrometer for separating ions according to their on mobility comprising, in various aspects: a drift tube having therein a drift space and in the drift space at least two on separation paths of different lengths: a straight drift tube having therein a helical ion separation path; a helical on separation path surrounding an axially extending inner electrode assembly; and a drift tube for separating ions according to their ion mobility wherein a rotating arcuate electric field is applied in operation to separate ions having an ion mobility such that their rotational velocity in the drift tube is matched to the rotational velocity of the rotating arcuate electric field. Various methods for separating ions according to their on mobility are also provided.

Abstract: As a control parameter given to a direct-current (DC) voltage generator which generates a DC voltage for ion selection, a “mass-related offset” for allowing an adjustment of the offset for each mass-to-charge ratio is provided in addition to the “gain” and “common offset” which respectively determine the gradient and position of a scan line drawn on a stability diagram during a mass-scan operation. In an automatic adjustment operation using a standard sample, under the control of an automatic regulator, the “gain” and “common offset” are initially set, after which the “mass-related offset” for each mass-to-charge ratio is determined so that the mass-resolving power will be substantially uniform, and these data are stored in a control data memory. In an analysis of a sample of interest, a quadrupole voltage controller controls the DC voltage generator and a radio-frequency (RF) voltage generator according to the control parameters read from the memory.

Abstract: The present invention relates to a device for measuring glow discharge spectrometry in pulsed mode, which includes an RF electric field generator in pulsed mode, a discharge lamp, an impedance matching device for transferring the electric power supplied by the generator to the discharge lamp and a mass spectrometer suitable for measuring at least one signal representative of an ionised plasma species. According to the invention, the device includes a measurement system suitable for measuring a signal representative of the impedance mismatch ?? between the generator and the discharge lamp, said measurement system including a fast acquisition system, synchronized with the pulses and suitable for supplying the impedance matching device with a signal representing the impedance mismatch ?? for at least one part of said pulses. The device enables continuous impedance adaptation.

Abstract: A multipole rod assembly, such as used as mass analyzer, is fabricated using rods adhesively attached to shoes, which are then attached to isolation rings. A fixture is used in conjunction with precision-made spacers to precisely assemble the ion mass analyzer. The rods and shoes can be made of metal, while the isolation rings are preferably made of insulator, such as ceramic. The shoes and isolation rings need not be made to high precision, as the spacer ensures high accuracy in alignment and symmetry of the rods. Consequently, the rods are the only precision machined parts in the ion mass analyzer assembly.

Abstract: The present invention concerns a method of detecting the antifungal cyclic hexapeptides Pneumocandin B0 and/or Pneumocandin C0 specific fragment is/are detected using MS in negative mode.

Abstract: A method and sensor for monitoring chemical species in a gas flow are described. An ionized sample of gas is passed through a flow channel, with a DC electric field applied transverse to the longitudinal axis of the channel. Any electric current produced by the ion flow is measured, with variations in the current being indicative of a change in composition of the gas flow. In certain embodiments, the DC field may be varied over time, to sweep the field voltage. The detected current against field voltage graph may be taken as a profile of a particular gas composition. Variations in the profile again are indicative of a change in gas composition.

Abstract: The apparatus introduces a second adjustable resonant point in a QMS at a frequency that is close to a multiple of the fundamental frequency by adjusting driving point impedance characteristics of the QMS. The apparatus measures the first and second resonant point of the QMS to account for changes in the operational characteristics of the QMS.

Abstract: An ion trap mass analyzer is disclosed comprising a segmented rod set. Ions are trapped radially within the mass analyzer by a radial pseudo-potential well. The ions are also confined axially within a quadratic axial potential well. An AC voltage or potential is applied to the electrodes comprising the ion trap mass analyzer in order to excite parametrically ions within the ion trap.

Abstract: A mass analyser is provided comprising a plurality of electrodes having apertures through which ions are transmitted. A plurality of pseudo-potential corrugations are created along the axis of the mass analyser. The amplitude or depth of the pseudo-potential corrugations is inversely proportional to the mass to charge ratio of an ion. Transient DC voltages are applied to the electrodes in order to urge ions along the length of the mass analyser. 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 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.

Abstract: An ion guide that transports ions from an ion source at generally a high-pressure level to a mass analyzer at generally a low-pressure level has a plurality of identical electrodes fabricated with protruding elements that forming an ion tunnel or an ion funnel, when the electrodes are assembled around a common longitudinal axis. The protruding elements allow the generation of the radio frequency field necessary to radially confine ions. Each electrode may be machined from a solid block of conductive material, such as metal. The disclosed arrangement greatly simplifies the manufacturing process, reducing cost, and improving robustness and reliability of the ion guide itself.

Abstract: An ion collision cell is fabricated by four semi-circular profile elements, all of which are attach to the same reference plate. Consequently, all four elements remain aligned to the same reference plate. The four elements form a semi-circular channel with a semi-circular quad electrodes. The quad electrodes receive electrical potential to form the field required to focus and maintain the ions at the center of the channel. semi-circular insulators are provided on all sides of the channel so as to seal the channel over its length from the interior of the mass spectrometer.

Abstract: A mass spectrometer is disclosed comprising a first storage ion trap arranged upstream of a high performance analytical ion trap. According to an embodiment ions are simultaneously scanned from both the first and second ion trap. At any instant in time the quantity of charge present within the second ion trap is limited or restricted so that the second ion trap does not suffer from space charge saturation effects and hence the performance of the second ion trap is not degraded.

Abstract: A mass spectrometry (MS) method which includes generating in a vicinity of the quadrupole ion trap hydrogen molecules, directing at least part of the hydrogen molecules into the quadrupole ion trap cell, applying AC and DC voltages to quadrupole ion trap cell electrodes to create a combined AC/DC trapping field, placing sample ions inside the quadrupole ion trap cell, cooling at least part of said ions using said hydrogen molecules as a buffer gas, changing the combined AC/DC trapping field to eject the ions from the quadrupole ion trap cell, and detecting the ejected ions.

Abstract: A portable mass spectrometer having an atmospheric pressure interface for introducing ions generated at ambient pressure gas conditions into a vacuum of the mass spectrometer. The mass spectrometer has a vacuum chamber having at least one vacuum section and at least one gas inlet for directing the ambient pressure gas including the ions into the at least one vacuum section. The at least one gas inlet has a gas passage channel of a length L and a limiting cross section S with a ratio of L/S being less than 20,000 cm?1. The mass spectrometer has a radio frequency (RF) ion guide in the at least one vacuum section positioned for collecting the ions from the at least one gas inlet and transmitting the ions further to a mass analyzer for analyzing the ions transmitted from the ion guide.

Abstract: An ion mobility spectrometer has a reaction region separated from a drift region by an electrostatic gate. A doping circuit supplies a dopant to the reaction region but the drift region is undoped. Two high field ion modifiers are located one after the other in the drift region. One ion modifier can be turned on to remove dopant adducts from the admitted ions, or both ion modifiers can be turned on so that the ions are also fragmented. In this way, several different responses can be produced to provide additional information about the nature of the analyte substance and distinguish it from interferents.

Abstract: Described herein are methods and systems which enable a unique platform for analyte quantitation. The methods and systems relate to determining the amount of interference in a precursor ion isolation window resulting from an impurity. Once the level of impurity is determined, several methods can be employed to reduce the amount of interference in a subsequent MS/MS spectrum. The methods and systems described herein enable increased quantitation accuracy while maintaining high levels of throughput.

Abstract: In an embodiment, a collision cell comprises rods each having a first end and a second end remote from the first end; an inductor connected between adjacent pairs of rods; and means for applying a radio frequency (RF) voltage between adjacent pairs of rods. The RF voltage creates a multipole field in a region between the rods; and means for applying a direct current (DC) voltage drop along a length of each of the rods.

Abstract: An ion-mobility analyser is disclosed comprising a plurality of axially segmented upper electrodes, a plurality of axially segmented lower electrodes, a first plurality of axially segmented intermediate electrodes and a second plurality of axially segmented intermediate electrodes which together define an ion pathway. An asymmetric voltage waveform is applied to the upper electrodes and a DC compensating voltage is applied to the lower electrodes in order to separate ions in a vertical radial direction according to their rate of change of ion mobility with electric field strength. At the same time, a DC axial voltage gradient is maintained along the axial length of the analyser in order to separate ions axially according to their ion mobility.

Abstract: A new pulsed multiple reaction monitoring process and system are disclosed that uses a pulsed ion injection mode for use in conjunction with triple-quadrupole instruments. The pulsed injection mode approach reduces background ion noise at the detector, increases amplitude of the ion signal, and includes a unity duty cycle that provides a significant sensitivity increase for reliable quantitation of proteins/peptides present at attomole levels in highly complex biological mixtures.

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

Abstract: The invention relates to measuring cells and measuring methods in oscillation mass spectrometers in which clouds of the same species of ion oscillate harmonically in a potential well in a longitudinal direction, decoupled from their motion transverse to this direction. A frequency analysis of the longitudinal oscillations of these ion clouds, which is carried out by a Fourier analysis of the induced image currents between two detection electrodes, leads to frequency spectra of the ions and hence to mass spectra. The position of the ion trajectories relative to the detection electrodes and the design of the measuring cells in the oscillation mass spectrometers is used to generate large proportions of harmonics in the image currents, and evaluate the frequency signals of the harmonics.

Abstract: An ion guide is disclosed wherein an axial DC voltage barrier is created at the exit of the ion guide. A primary RF voltage is applied to the electrodes in order to confine ions radially within the ion guide. A supplemental RF voltage is also applied to the electrodes. The supplemental RF voltage has a greater axial repeat length than that of the primary RF voltage. The amplitude of the supplemental RF voltage is increased with time causing ions to become unstable and gain sufficient axial kinetic energy such that the ions overcome the axial DC voltage barrier. Ions emerge axially from the ion guide in mass to charge ratio order.

Abstract: An apparatus and a method for trapping charged particles and performing controlled interactions between them are provided. The apparatus includes a substrate and RF electrodes and dedicated DC electrodes arranged on the substrate and configured to generate a trapping potential for trapping the charged particles above the substrate. The RF and dedicated DC electrodes include at least one RF trapping electrode configured to be driven with an RF voltage for contributing to the trapping potential, an array of two or more trapping site DC electrodes configured to be biased with a DC voltage for contributing to the trapping potential, and a first individually drivable RF control electrode arranged between a first pair out of the two or more trapping site DC electrodes.

Abstract: A mass spectrometer is disclosed comprising a device which is operable in a first mode of operation to separate ions temporally according to their ion mobility by applying a continuous axial electric field. The device is also operable in a second mode of operation wherein ions are separated temporally according to the their mass to charge ratio by pulsing an applied axial electric field ON and OFF.

Abstract: A mass spectrometer is disclosed comprising a quadrupole rod set ion trap wherein a potential field is created at the exit of the ion trap which decreases with increasing radius in one radial direction. Ions within the ion trap 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.

Abstract: The present invention generally relates to mass spectrometry and related techniques, and in some cases, to determining single species using mass spectrometry. In certain instances, polymers such as DNA or RNA can also be sequenced. Certain embodiments of the invention relate to passing a polymer, such as DNA, RNA, a protein, a polypeptide, a polysaccharide, etc., through a pore and cleaving the polymer in sequence. For instance, the polymer may be cleaved using a laser or an electric field. In some embodiments, a property of at least one subunit of a polymer is determined using mass spectrometry. In some embodiments, a single ion (which may be a subunit of a polymer, or an ion based on another species) can be isolated in a mass spectrometer and a signal generated from the single ion.

Abstract: In a first-stage intermediate vacuum chamber, cluster ions causing a background noise are dominantly formed in area (A), while fragment ions are dominantly generated in area (B). Taking this fact into account, in an in-source CID analysis mode, a DC voltage higher than that applied to a skimmer is applied to a first ion guide so as to create an accelerating electric field in area (B), whereby the ions are sufficiently energized to promote the fragmentation. When the in-source CID is not performed, a DC voltage higher than that applied to the first ion guide is applied to the exit end of a desolvation tube so as to create an accelerating electric field only in area (A) without creating such a field in area (B), whereby both the formation of the cluster ions and the generation of the fragment ions are suppressed, so that a high-quality chromatogram can be obtained.

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: 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: 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: An ion-ion reaction cell is provided comprising a plurality of electrodes (1) forming an ion guide (2). One or more transient DC voltage waves (8, 9) are applied to the electrodes (2). Reagent anions and analyte cations are arranged to undergo ion-ion reactions within the reaction cell and the resulting fragment ions which are formed within the reaction cell are then subsequently translated out of the reaction cell by means of one or more transient DC voltage waves (8, 9).

Abstract: A ion mobility-based analyzer system including a first ion mobility-based filter for passing selected ions through a time-varying field where the time-varying field being compensated by an adjustable compensation setting. The analyzer also includes a second ion mobility-based filter for receiving a first portion of ions from the first ion mobility-based filter. The second ion mobility-based filter includes a voltage gradient for separating ions of the first portion of ions where the ions have associated retention times based on their times of flight through the voltage gradient. The second ion mobility-based filter includes a detector for detecting the ions at their retention times. The analyzer system further includes a display that displays the detected ions in a plot relating the retention times of the ions in the second ion mobility-based filter with compensation settings of the first ion mobility-based filter.

Abstract: A Time of Flight mass analyser is disclosed wherein the time period between successive orthogonal acceleration pulses is less than the time of flight of ions having the maximum mass to charge ratio of interest. As a result, some ions are subject to wrap-around and will appear in a subsequent mass spectrum. Mass spectra obtained at two different sampling rates may be compared and mass peaks relating to ions which have and have not been subject to wrap-around may be identified.

Abstract: Analyte ions are analyzed first by field asymmetric ion mobility spectrometry (FAIMS) before being analyzed by a mass analyzer. Analyte ions are produced at near atmospheric pressure and transferred via a dielectric capillary into the vacuum system of the mass analyzer. While passing through the capillary, the ions are analyzed by FAIMS via electrodes on the interior wall of the capillary. Improved ion transmission is achieved by providing smooth geometric transitions between the channel in FAIMS analyzer and the channel in the remainder of the capillary.