Varian Associates, Inc.

Varian, Inc.

Agilent Technologies, Inc.

Other

Gregory J Wells

Roger C Tong

Mingda Wang

Charles K Huston

Peter P Yee

Steven D Schachterle

Barbara A Bolton

Edward G Marquette

Frank Londry

Eugen F Mesaros

Richard K Simon

Tho V Thieu

Edward Marquette

August Specht

Raymond E March

Gregory R Ott

John R Berg

Minada Wang

Marvin A Ruport

Adolph Bohnstedt

Joseph G Lisko

Jonathan Parrish

Rong-Qiang Liu

Karen Milkiewicz

Jason Burke

Gulzar Ahmed

Bruce Dorsey

Ming You

Tao Guo

Daming Feng

In a mass spectrometer, a dual stage axial extraction field is applied to transport ions from an accumulator to a detector cell. Ions of a same mass may be transported to the detector cell or a point axially preceding the detector cell at the same time. This may be done by selecting the relative strengths of a first axial electric field applied to the accumulator and a second axial electric field applied to a shutter located at an exit end of the accumulator. This may also be done by selecting relative axial lengths of the accumulator, shutter, and an ion guide located at an exit end of the shutter. A dual stage decelerating field may also be applied to slow ions down prior to and after entering the detector cell.

Methods and apparatus for filling an ion detector cell

A sample is ionized by chemical ionization by flowing the sample and a reagent gas into an ion source at a pressure below 0.1 Torr. While maintaining the ion source at a pressure below 0.1 Torr, the reagent gas is ionized in the ion source by electron ionization to produce reagent ions. The sample is reacted with the reagent ions at a pressure below 0.1 Torr to produce product ions of the sample. The product ions are transmitted into an ion trap for mass analysis.

Low-pressure electron ionization and chemical ionization for mass spectrometry

An electron capture dissociation apparatus comprises ion guide electrodes, an electron emitter, and an electron control device. The ion guide electrodes are arranged along a central axis and spaced circumferentially to circumscribe an interior space extending along the central axis. The electron emitter is disposed outside the interior space. The electron control device is configured for focusing an electron beam from the electron emitter toward the central axis, along a radial electron beam direction between two of the ion guide electrodes, and for decelerating the electron beam in a DC decelerating field of adjustable voltage potential directed along the electron beam direction.

Electron capture dissociation apparatus and related methods

An electron source includes a first electrode, a second electrode, a thermionic element interposed between and electrically isolated from the first electrode and the second electrode, and a guard electrode interposed between and electrically isolated from the first electrode and the second electrode. The thermionic element and the guard electrode may be at substantially the same voltage. Another electron source includes a first electrode, a second electrode, a thermionic element interposed between and electrically isolated from the first electrode and the second electrode, and a thermal expansion component interposed between and electrically isolated from the first electrode and the second electrode. The thermal expansion component may be heated to cause expansion. The heating may be cycled to cause alternating expansion and contraction.

Electron source for ionization with leakage current suppression

A method for controlling charge flux into a charge accumulation device includes determining a charge accumulation time during which charges are to be accumulated in the charge accumulation device, measuring a charge flux of a first ion beam produced from an ion source, determining a target number of charges to be accumulated in the charge accumulation device during the charge accumulation time based on the measured charge flux and, based on the determined target number of charges, modulating a second ion beam produced from the ion source to cause the target number of charges from the second ion beam to be accumulated in the charge accumulation device during the charge accumulation time. An ion processing device is configured for controlling the charge flux. An ion beam modulator modulates the ion beam.

Charge control for ionic charge accumulation devices

An electrode for use in a device such as an ion trap has an axial length extending generally in the direction of a central axis from a first axial end to a second axial end, and an inside surface. The inside surface includes a surface profile that is uniform from the first axial end to the second axial end, or at least is uniform for a uniform section length along the axial direction. The electrode may include an elongated surface feature such as a groove that extends for at least the uniform section length. An aperture may communicate with the groove. The electrode may be axially segmented into regions. Gaps between the regions may be oriented at an angle relative to a plane orthogonal to the central axis. The electrode may be one of several electrodes arranged as an electrode structure coaxially disposed about an elongated interior space.

Two-dimensional electrode constructions for ion processing

An electrode structure for manipulating ions includes a main electrode and a compensation electrode. An outer surface of the main electrode includes a curved section that includes an apex. An aperture is generally disposed at the apex and extends along a radial center line from the outer surface through a thickness of the main electrode. The compensation electrode is disposed at the radial center line and at a tangent line tangent to the apex. Another electrode structure includes a plurality of main electrodes defining an interior space, and one or more compensation electrodes disposed in the interior space. RF signals may be applied to the main electrodes and to the compensation electrode.

Compensating for field imperfections in linear ion processing apparatus

Methods for applying an RF field in a two-dimensional electrode structure include applying RF voltages to one or more main electrodes and compensation electrodes. The voltages on the one or more compensation electrodes may be adjusted to be proportional to the voltages on the main electrodes. The adjustment(s) may be done to optimize the RF field for different modes of operation such as ion ejection and ion dissociation. For dissociation and other procedures involving ion excitation, the voltages applied to the one or more compensation electrodes may be different from the voltages applied to the one or more main electrodes. Electrode structures may include main trapping electrodes, one or more compensation electrodes, one or more ion exit apertures, and a device or circuitry for applying the various desired voltages.

Adjusting field conditions in linear ion processing apparatus for different modes of operation

Methods for applying an RF field in a two-dimensional electrode structure include applying RF voltages to main electrodes and to compensation electrodes. The voltages on the compensation electrodes may be proportional to the voltages on the main electrodes so as to optimize the RF field for processes involving ion excitation, including collision-induced dissociation. Electrode structures may include main trapping electrodes, one or more compensation electrodes, one or more ion exit apertures, and a device or circuitry for applying the various desired voltages.

Field conditions for ion excitation in linear ion processing apparatus

In a method for increasing the kinetic energy of an ion in a linear electrode structure, axial motion of the ion is constrained substantially to a selected axial end the electrode structure. The ion is driven to move axially from the selected end toward the other end and to reflect back toward the selected end. Constraining may be effected by adjusting one or more DC voltages applied to the ends and a central region of the electrode structure to create an axial potential well in the selected end. Driving may be affected by adjusting the DC voltage applied to the selected end to a magnitude greater than the value applied during the constraining step. The constraining and driving steps may be repeated a number of times. The method may be performed in connection with collision-induced dissociation.

Increasing ion kinetic energy along axis of linear ion processing devices

Methods for applying an RF field in a two-dimensional electrode structure include applying RF voltages to main electrodes and to compensation electrodes. The voltages on the compensation electrodes may be adjusted to be proportional to the voltages on the main electrodes. The adjustment(s) may be done to optimize the RF field for different modes of operation such as ion ejection and ion dissociation. For dissociation, a supplemental RF dipole may be applied, or two mutually orthogonal dipoles may be applied in phase quadrature to form a circularly polarized field. Electrode structures may include main trapping electrodes, one or more compensation electrodes, one or more ion exit apertures, and means for applying the various desired voltages.

Rotating excitation field in linear ion processing apparatus

In some embodiments, a tandem (MS/MS) mass spectrometry method includes selecting a collision-induced dissociation (CID) voltage amplitude and a q-parameter value for a quadrupole ion trap to optimize a daughter ion fragmentation process for a given parent ion mass-to-charge (m/z) ratio. The q and CID voltage values may be selected according to a look-up table and/or using approximate analytical expressions. The correspondence between m/z values and (q, CID) value pairs may be established by pre-measurement calibration. A fragmentation-optimized q value may be computed according to m/z, and a CID voltage value may be determined according to the computed q value. A user may also force q to another value, for example in order to facilitate trapping of a desired daughter ion mass range, and the controller computes a CID voltage value according to the forced q value.

Ion fragmentation parameter selection systems and methods

A linear ion trap includes four electrodes and operates with an asymmetrical trapping field in which the center of the trapping field is displaced from a geometrical center of the trap structure. The asymmetrical trapping field can include a main AC potential providing a quadrupole component and an additional AC potential. The main AC potential is applied between opposing pairs of electrodes and the additional AC potential is applied across one pair of electrodes. The additional AC potential can add a dipole component for rendering the trapping field asymmetrical. The additional AC potential can also add a hexapole component used for nonlinear resonance. A supplementary AC potential can be applied across the same pair of electrodes as the additional AC potential to enhance resonant excitation. The operating point for ejection can be set such that a pure resonance condition can be used to increase the amplitude of ion oscillation preferentially in one direction. Ions trapped in the composite field can be mass-selectively ejected in a single direction to an aperture in one of the electrodes.

Linear ion trap apparatus and method utilizing an asymmetrical trapping field

An integrated ion focusing and gating lens for use in an ion trap mass spectrometer includes first and second members of combined generally cylindrical configuration with the members focusing an ion beam along an axis of the generally cylindrical configuration when biased with the same voltage on each member, and the members deflecting an ion beam when the members are biased with different voltages. In a preferred embodiment, the first and second members are identical in configuration.

Integrated ion focusing and gating optics for ion trap mass spectrometer

An ion source for use in mass spectrometry, and particularly an atmospheric pressure chemical ionization (APCI) source, comprises a chamber having a central axis, a sample conduit that includes a sample outlet communicating with the chamber, an ionizing device disposed downstream from the sample conduit, and a gas conduit that includes a gas outlet communicating with the chamber. The gas conduit defines a flow path directed into the chamber. The flow path includes a velocity component that is tangential with respect to the central axis of the chamber. The gas so directed into the chamber establishes a vortex gas flow therein, forcing the sample emitted from the sample outlet to flow toward the heated wall of the chamber. Vaporization of the sample prior to ionization is consequently improved.

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Fairfield, CA, United States of America

Gregory J Wells