Abstract: A method for analyzing a mixture of components includes forming precursor ions from the components, alternately causing the precursor ions to pass to and to by-pass a fragmentation device, to form product ions from the precursor ions that pass to the device and to form substantially fewer product ions from precursor ions that by-pass the device, and obtaining mass spectra from product ions received from the device and from precursor ions that by-passed the device. An apparatus for analyzing a sample includes an ion source for forming precursor ions from the components of the sample, a fragmentation device for forming product ions from the precursor ions, a by-pass device disposed upstream of the fragmentation device for switchable by-pass of the fragmentation device, and a mass analyzer.

Abstract: In an RF ion trap, analyte ions are fragmented by applying a moderately high RF storage voltage to the trap. The ions are then excited via dipolar excitation, and after a short time, the ions are forced into a resting state, again using dipolar excitation. The RF storage voltage is then rapidly reduced to a low value thereby making it possible to store small fragment ions produced by ergodic decompositions that occur subsequent to the reduction of the RF storage voltage.

Abstract: A method of plasma particle simulation capable of preventing solution divergence. A space within a housing chamber of a plasma processing apparatus is divided into a plurality of cells. A weighting factor corresponding to the number of plasma particles represented by a superparticle is set in each of the divided cells. Superparticles are set in each of the divided cells using plasma particles contained in the divided cell and the set weighting factor. The behavior of the superparticles in each of the divided cells is calculated. The weighting factor becomes smaller as the divided cell is located closer to a solid wall surface of the housing chamber.

Abstract: A multipole ion guide comprises rods disposed about an axis, each of the rods having a first end and a second end remote from the first end. Each of the rods is disposed at a respective greater distance from the axis at the first end than at the second end. The multipole ion guide comprises means for applying a radio frequency (RF) voltage between adjacent pairs of rods, wherein 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. A mass spectroscopy system is also disclosed.

Abstract: In a method for exciting a precursor ion in an ion trap, the ion is trapped in a nonlinear trapping field that includes a quadrupolar field and a multipole field. The quadrupolar field is generated by applying a radio-frequency (RF) trapping voltage to the ion trap at a trapping amplitude and trapping frequency. A supplemental alternating-current (AC) voltage is applied to the ion trap at a supplemental amplitude and supplemental frequency. The supplemental amplitude is low enough to prevent ejection of the ion from the ion trap, and the supplemental frequency differs from the secular frequency of the ion by an offset amount. One or more operating parameters of the ion trap are adjusted, such that the ion absorbs energy from the supplemental field sufficient to undergo collision-induced dissociation (CID) without being in resonance with the supplemental field.

Abstract: A Q-pole type mass spectrometer can be used under a high-pressure atmosphere of more than 0.1 Pa. The Q-pole type mass spectrometer can analyze the mass of gas molecules continuously, and can separate mass properly even if an ion is injected at high speed in order to reduce the influence of an end electric field near an end face (fringing) of the Q-pole. The motion of the ions to be measured in the diameter direction is independent of the motion of ions in the axial direction within the Q-pole region of the Q-pole type mass spectrometer. In the Q-pole type mass spectrometer installed in a reduced pressure atmosphere, the motion of ions to be measured in the axial direction advancing from an ion source toward a collector, is controlled within the Q-pole region so as to separate the mass of the ions to be measured by Coulomb force generated by a quadrupole high-frequency electric field in the diameter direction.

Abstract: In various embodiments the present teachings provide high-voltage, asymmetric-waveform power supplies useful for, e.g., differential mobility spectrometry. In various embodiments, provided are high-voltage, asymmetric-waveform power supplies for high-field asymmetric waveform ion mass spectrometers having field values greater than about 5,000 volts cm?1 and varying in time at rates greater than about 600 kilohertz (KHz).

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

Abstract: An improved ion optical lens designed to increase the amount of ion current delivered into a multi-pole ion detector or transfer device, such as quadrupole mass analyzer, an ion guide, collision cell, etc. A device and method is disclosed that utilizes a tubular entrance lens to introduce ions into or sample ions at a field-free or near field-free region disposed at the junction of two sets of multi-pole assemblies operating with radio frequency potentials shifted 180 degrees out of phase with respect to each other. The method is useful for increasing the transport of ions into as they enter into or exit out of a multi-pole mass analyzer, such as a quadrupole mass analyzer, an ion guide, collision cell, etc.

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

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

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

Abstract: A method for analyzing a sample comprising the steps of: generating ions from the sample within an ionization chamber at substantially atmospheric pressure; entraining the ions in a background gas; transferring the background gas and entrained ions to an evacuated chamber of a mass spectrometer system using an ion transfer tube having an inlet end and an outlet end, wherein a portion of the ion transfer tube adjacent to the outlet end comprises an inner diameter that is greater than an inner diameter of an adjoining portion of the ion transfer tube; and analyzing the ions using a mass analyzer of the mass spectrometer system.

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

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

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

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

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

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

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

Abstract: A device for transporting and focusing ions in a low vacuum or atmospheric-pressure region of a mass spectrometer is constructed from a plurality of longitudinally spaced apart electrodes to which oscillatory (e.g., radio-frequency) voltages are applied. In order to create a tapered field that focuses ions to a narrow beam near the device exit, the inter-electrode spacing or the oscillatory voltage amplitude is increased in the direction of ion travel.

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

Abstract: The present invention discloses an mixed signal RF drive electronics board that offers small, low power, reliable, and customizable method for driving and generating mass spectra from a mass spectrometer, and for control of other functions such as electron ionizer, ion focusing, single-ion detection, multi-channel data accumulation and, if desired, front-end interfaces such as pumps, valves, heaters, and columns.

Abstract: One or more methods for determination and/or deconvolution of complex mass spectra, using quadrupole ion trap mass spectrometry.

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

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

Abstract: A variable duty cycle ion source assembly is coupled to a continuous beam mass spectrometer. The duty cycle can be adjusted based on previous scan data or real time sampling of ion intensities during mass analysis. This provides the ability to dynamically control the total number of ions formed, mass analyzed and detected for each ion mass of interest. A reflection mechanism that provides a variable duty cycle, enables electrons to be reflected through an ion volume multiple times before atoms or molecules are ionized in the ion volume, thereby providing for dynamic control of the ion population.

Abstract: A quadrupole ion trap includes a switch 3 for switching a trapping voltage between discrete voltage levels VH, VL. This creates a digital trapping field for trapping precursor ions and product ions in a trapping region of the ion trap. A gating voltage is applied to a gate electrode 12 to control injection of source electrons into the ion trap. Application of the gating voltage is synchronised with the switching so that electrons are injected into the trapping region while the trapping voltage is at a selected one of the voltage levels and can reach the trapping region with a kinetic energy suitable for electron capture dissociation to take place.

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

Abstract: The present invention relates to a new method for identifying polypeptides by deducing the amino acid sequence of the carboxy and amino termini by a mass spectrometer analysis. The method comprises the steps of dissociating highly charged peptide precursor ions (e.g., z>4) using electron transfer dissociation inducing anions followed by removal of those reagents and introduction of a second, proton transfer inducing anion type. The second PTR reaction duration is adjusted to convert the ETD products to primarily the +1 charge-state to reduce the highly charged c and z-type fragments, producing an m/z spectrum containing a series of c and z-type fragment ions that are easily interpreted to reveal the sequence of the amino and carboxy terminus, respectively.

Abstract: A method of obtaining a mass spectrum of elements in a sample is disclosed. Sample precursor ions having a mass to charge ratio M/Z are generated, and fragmented at a dissociation site, so as to produce fragment ions of mass to charge ratio m/z. The fragment ions are guided into an ion trap of the electrostatic or “Orbitrap” type, the fragment ions entering the trap in groups dependent upon the precursor ions M/Z. The mass to charge ratio of each group is determined from the axial movement of ions in the trap. The electric field in the trap is distorted. Ions of the same m/z, that are derived from different pre-cursor ions, are then separated, because the electric field distortion causes the axial movement to become dependent upon factors other than m/z alone.

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

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

Abstract: The invention relates to instruments for storing ions in more than one ion storage device and to the use of the storage bank thus created. The ion storage bank includes several storage cells configured as RF multipole rod systems, where the cells contain damping gas and are arranged in parallel. Each pair of pole rods is used jointly by two immediately adjacent storage cells such that the ions collected can be transported from one storage cell to the next by briefly applying DC or AC voltages to individual pairs of pole rods. The ions can thus be transported to storage cells in which they are fragmented or reactively modified, or from which they can be fed to other spectrometers. In particular, a circular arrangement of the storage cells on a virtual cylindrical surface makes it possible to accumulatively fill the storage cells with ions of specific fractions from temporally sequenced separation runs.

Abstract: The invention relates generally to ion mobility based systems, methods and devices for analyzing samples and, more particularly, to sample detection using multiple detection and analytical techniques in combination.

Abstract: An ion mobility spectrometer is described having an ion filter in the form of at least one ion channel having a plurality of electrodes. A time-varying electric potential applied to the conductive layers allows the filler to selectively admit ion species. The electric potential has a drive and a transverse component, and in preferred embodiments each of the electrodes is involved in generating a component of both the drive and transverse fields. The device may be used without a drift gas flow, Microfabrication techniques are described for producing microscale spectrometers, as are various uses of the spectrometer.

Abstract: A method of separating ions includes providing a FAIMS analyzer region for separating ions, the FAIMS analyzer region in fluid communication with an ionization source and with an ion detecting device. The method further includes affecting a gas composition within a first portion of the FAIMS analyzer region to be different from a gas composition within a second portion of the FAIMS analyzer region. The establishment of a gas composition gradient within the FAIMS analyzer region enhances ion focusing and ion transport efficiency.

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

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

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

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

Abstract: A mass spectrometer is disclosed comprising a mass selective ion trap or mass analyser (4) arranged upstream of an ion guide (6). Ions are scanned out of the mass selective ion trap or mass analyser (4) and are received in one or more axial potential wells created or formed within the ion guide (6). One or more transient DC voltages or potentials are preferably applied to the ion guide (6) in order to create a plurality of axial potential wells which are translated along the length of the ion guide (6). Ions are released in packets from the exit of the ion guide (6) and are orthogonally accelerated into a drift or flight region of an orthogonal acceleration Time of Flight mass analyser (13) with a relatively high duty cycle.

Abstract: Methods of separating ionized particles comprise the step of providing a particle separator comprising a housing, and an electric field disposed inside the housing. The electric field defines a magnitude E (volt/cm) which increases the farther ionized particles travel within the housing. The method further includes delivering a gas flow, wherein the gas flow defines a velocity, Vgas, and delivering ionized particles into the housing, wherein the ionized particles define a mobility value, K (cm2/volt*sec). The product of the mobility value K and the electric field magnitude E define a mobility velocity for the ionized particles, Vmob (cm/sec)=K*E. The method also includes stopping the ionized particles at a location where Vmob is equal and opposite Vgas.

Abstract: This invention relates to a method of operating a charged particle trap in which ions undergo multiple reflections back and forth and/or follow a closed orbit around, usually, a set of electrodes. The invention allows high-performance isolation of multiple ion species for subsequent detection or fragmentation by deflecting ions out of the ion trap according to a timing scheme calculated with reference to the ions' periods of oscillation within the ion trap.

Abstract: Auxiliary electrodes for creating drag fields may be provided as arrays of finger electrodes on thin substrates such as printed circuit board material for insertion between main RF electrodes of a multipole. A progressive range of voltages can be applied along lengths of the auxiliary electrodes by implementing a voltage divider that utilizes static resisters interconnecting individual finger electrodes of the arrays. Dynamic voltage variations may be applied to individual finger electrodes or to groups of the finger electrodes.

Abstract: A system and method are disclosed that provide up to complete transmission of ions between coupled stages with low effective ion losses. A novel “interfaceless” electrospray ionization system is further described that operates the electrospray at a reduced pressure such that standard electrospray sample solutions can be directly sprayed into an electrodynamic ion funnel which provides ion focusing and transmission of ions into a mass analyzer.

Abstract: A matrix assisted laser desorption/ionization (MALDI) method and related system for analyzing high molecular weight analytes includes the steps of providing at least one matrix-containing particle inside an ion trap, wherein at least one high molecular weight analyte molecule is provided within the matrix-containing particle, and MALDI on the high molecular weight particle while within the ion trap. A laser power used for ionization is sufficient to completely vaporize the particle and form at least one high molecular weight analyte ion, but is low enough to avoid fragmenting the high molecular weight analyte ion. The high molecular weight analyte ion is extracted out from the ion trap, and is then analyzed using a detector. The detector is preferably a pyrolyzing and ionizing detector.

Abstract: An inductively coupled plasma mass spectrometer comprises a control device 70 for collectively controlling each of the following factors: the amount of liquid drops in the aerosol that is to be supplied to a plasma torch 20, the flow rate of carrier gases 76A and 76B in this aerosol, the RF output of a high-frequency power source 80, and the distance Z between plasma torch 20 and sampling interface 15 and 16.

Abstract: The current invention facilitates the construction of a compact high performance quadrupole mass analyzer which has the operational characteristics of a modern research grade system and the ergonomic and cost structure of a moderate benchtop system. A multipole field device is physically located within the windings of the RF resonant circuit. By combining the space consumed by the RF windings and its housing and the space consumed by the multipole field device and its vacuum housing, the overall size of the resultant mass spectrometer is reduced.

Abstract: A method for analyzing ions includes providing a desolvation chamber in communication with an analytical gap of a FAIMS analyzer, via an ion inlet orifice. A flow of ions is introduced into the desolvation chamber along a flow path that is toward the ion inlet orifice and into the analytical gap of the FAIMS analyzer. A flow of a desolvation gas is provided into the desolvation chamber via a first gas inlet, such that a portion of the flow of the desolvation gas is counter-current to the flow of ions. A flow of a carrier gas is provided separately via a second gas inlet, which is defined downstream relative to the desolvation chamber. In particular, the composition of the carrier gas is different than the composition of the desolvation gas. Accordingly, the flow of the carrier gas is provided substantially into the analytical gap for transporting ions along a path between the ion inlet orifice and an ion outlet orifice of the analytical gap.