Abstract: Apparatus and methods are provided that enable the interaction of low-energy electrons and positrons with sample ions to facilitate electron capture dissociation (ECD) and positron capture dissociation (PCD), respectively, within multipole ion guide structures. It has recently been discovered that fragmentation of protonated ions of many biomolecules via ECD often proceeds along fragmentation pathways not accessed by other dissociation methods, leading to molecular structure information not otherwise easily obtainable. However, such analyses have been limited to expensive Fourier transform ion cyclotron resonance (FTICR) mass spectrometers; the implementation of ECD within commonly-used multipole ion guide structures is problematic due to the disturbing effects of RF fields within such devices.

Abstract: A high pressure collision cell for use in a mass spectrometer. The high pressure collision cell has a cell length L selected to be in a range such that upon application of voltages to a pair of opposed elongate electrically conducting electrodes there is produced an electric field of sufficient strength across the collision cell length L in to aid in directing ions entering the collision cell to along a transverse flow axis. The pressure in the collision cell is maintained in a range from about 50 mTorr to 1000 mTorr and wherein the collision cell length L and the pressure are selected such that a target thickness, defined as a product of the collision cell length L and the pressure, is maintained in a range from about 0.2 to about 2 mm-Torr.

Abstract: An ion source and method for providing ionized particles to a molecular/atomic analyser, such as a mass spectrometer, are disclosed. The ion source includes a vessel defining a channel; a gas inlet extending from the gas source into the channel, for introducing a gas flow into the channel; a sample inlet extending into the channel for introducing sample within the channel; and an ionizer to ionize the sample in the channel. The vessel is sufficiently sealed to allow the channel to be pressurized, at a pressure in excess of 100 Torr. At least one gas source maintains the pressure of the channel at a pressure in excess of 100 Torr and the pressure exterior to the channel at a pressure in excess of 0.1 Torr and provides a gas flow that sweeps across the ionizer to guide and entrain ions from the ionizer to the outlet.

Abstract: An interface for mass spectrometers. The interface uses non coaxial sampling pathways of the analyte ion beam prior to entering the entrance of a mass spectrometer for decreasing chemical background, and can be done in such a way as to permit multiple sprayers, increasing sample throughput and sensitivity for LC/MS (liquid chromatography/MS). The interface includes an ion source having an exit from which a beam of analyte ions are emitted, a curtain plate and an aperture in the curtain plate member, an orifice plate having an orifice therein. The orifice plate is being spaced from the curtain plate member defining a flow passageway therebetween, and the aperture in the orifice plate is aligned with a sample entrance to a first vacuum stage of a mass spectrometer maintained substantially lower than atmospheric pressure.

Abstract: An ion guide includes a plurality of rods, arranged about an axis that extends lengthwise from one end to the other of the guide. The rods guide ions in a guide region along and about the axis. A conductive casing surrounds the rods. The casing and the rods are geometrically arranged to produce an axial electric field along the axis. Specifically, the geometry is such that a first constant applied DC voltage (UDC), applied to the rods, and a second constant applied DC voltage (UCASE) applied to the casing, produce a voltage gradient between said casing and said axis that has a different magnitude at different positions along said axis.

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: An ion guide includes a plurality of rods, arranged about an axis that extends lengthwise from one end to the other of the guide. The rods guide ions in a guide region along and about the axis. A conductive casing surrounds the rods. The casing and the rods are geometrically arranged to produce an axial electric field along the axis. Specifically, the geometry is such that a first constant applied DC voltage (UDC), applied to the rods, and a second constant applied DC voltage (UCASE) applied to the casing, produce a voltage gradient between said casing and said axis that has a different magnitude at different positions along said axis.

Abstract: A mass spectrometer includes an ion source and at least one vacuum stage, a means for delivering ions from the ion source to the vacuum stage, a collision cell, a detector, at least two multipole ion guide segments, and independent RF frequency and DC voltage sources applied to the multipole ion guide segments, the RF frequency and DC voltage sources being controlled independently of each other.

Abstract: An ion detector includes collision surfaces for converting both positively and negatively charged ions into emitted secondary electrons. Secondary electrons may be detected using an electron detector, than may, for example include an electron multiplier. Conveniently, secondary electrons (or electrons emitted by the multiplier) may be detected using an electron pulse counter.

Abstract: An ion source and method for providing ionized particles to a molecular/atomic analyser, such as a mass spectrometer, are disclosed. The ion source includes a vessel defining a channel; a gas inlet extending from the gas source into the channel, for introducing a gas flow into the channel; a sample inlet extending into the channel for introducing sample within the channel; and an ionizer to ionize the sample in the channel. The vessel is sufficiently sealed to allow the channel to be pressurized, at a pressure in excess of 100 Torr. At least one gas source maintains the pressure of the channel at a pressure in excess of 100 Torr and the pressure exterior to the channel at a pressure in excess of 0.1 Torr and provides a gas flow that sweeps across the ionizer to guide and entrain ions from the ionizer to the outlet.

Abstract: An interface for mass spectrometers. The interface uses non coaxial sampling pathways of the analyte ion beam prior to entering the entrance of a mass spectrometer for decreasing chemical background, and can be done in such a way as to permit multiple sprayers, increasing sample throughput and sensitivity for LC/MS (liquid chromatography/MS). The interface includes an ion source having an exit from which a beam of analyte ions are emitted, a curtain plate and an aperture in the curtain plate member, an orifice plate having an orifice therein. The orifice plate is being spaced from the curtain plate member defining a flow passageway therebetween, and the aperture in the orifice plate is aligned with a sample entrance to a first vacuum stage of a mass spectrometer maintained substantially lower than atmospheric pressure.

Abstract: An ion detector includes collision surfaces for converting both positively and negatively charged ions into emitted secondary electrons. Secondary electrons may be detected using an electron detector, than may, for example include an electron multiplier. Conveniently, secondary electrons (or electrons emitted by the multiplier) may be detected using an electron pulse counter.

Abstract: An interface for mass spectrometers. The interface uses non coaxial sampling pathways of the analyte ion beam prior to entering the entrance of a mass spectrometer for decreasing chemical background, and can be done in such a way as to permit multiple sprayers, increasing sample throughput and sensitivity for LC/MS (liquid chromatography/MS). The interface includes an ion source having an exit from which a beam of analyte ions are emitted, a curtain plate and an aperture in the curtain plate member, an orifice plate having an orifice therein. The orifice plate is being spaced from the curtain plate member defining a flow passageway therebetween, and the aperture in the orifice plate is aligned with a sample entrance to a first vacuum stage of a mass spectrometer maintained substantially lower than atmospheric pressure.

Abstract: An ion source and method for providing ionized particles to a molecular/atomic analyser, such as a mass spectrometer, are disclosed. The ion source includes a vessel defining a channel; a gas inlet extending from the gas source into the channel, for introducing a gas flow into the channel; a sample inlet extending into the channel for introducing sample within the channel; and an ionizer to ionize the sample in the channel. The vessel is sufficiently sealed to allow the channel to be pressurized, at a pressure in excess of 100 Torr. At least one gas source maintains the pressure of the channel at a pressure in excess of 100 Torr and the pressure exterior to the channel at a pressure in excess of 0.1 Torr and provides a gas flow that sweeps across the ionizer to guide and entrain ions from the ionizer to the outlet.

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: An ion source and method for providing ionized particles to a molecular/atomic analyser, such as a mass spectrometer, are disclosed. The ion source includes a vessel defining a channel; a gas inlet extending from the gas source into the channel, for introducing a gas flow into the channel; a sample inlet extending into the channel for introducing sample within the channel; and an ionizer to ionize the sample in the channel. The vessel is sufficiently sealed to allow the channel to be pressurized, at a pressure in excess of 100 Torr. At least one gas source maintains the pressure of the channel at a pressure in excess of 100 Torr and the pressure exterior to the channel at a pressure in excess of 0.1 Torr and provides a gas flow that sweeps across the ionizer to guide and entrain ions from the ionizer to the outlet.

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: A high pressure collision cell for use in a mass spectrometer. The high pressure collision cell has a cell length L selected to be in a range such that upon application of voltages to a pair of opposed elongate electrically conducting electrodes there is produced an electric field of sufficient strength across the collision cell length L in to aid in directing ions entering the collision cell to along a transverse flow axis. The pressure in the collision cell is maintained in a range from about 50 mTorr to 1000 mTorr and wherein the collision cell length L and the pressure are selected such that a target thickness, defined as a product of the collision cell length L and the pressure, is maintained in a range from about 0.2 to about 2 mm-Torr.

Abstract: An ion guide includes a plurality of rods, arranged about an axis that extends lengthwise from one end to the other of the guide. The rods guide ions in a guide region along and about the axis. A conductive casing surrounds the rods. The casing and the rods are geometrically arranged to produce an axial electric field along the axis. Specifically, the geometry is such that a first constant applied DC voltage (UDC), applied to the rods, and a second constant applied DC voltage (UCASE) applied to the casing, produce a voltage gradient between said casing and said axis that has a different magnitude at different positions along said axis.

Abstract: A mass spectrometer interface, having improved sensitivity and reduced chemical background, is disclosed. The mass spectrometer interface provides improved desolvation, chemical selectivity and ion transport. A flow of partially solvated ions is transported along a tortuous path into a region of disturbance of flow, where ions and neutral molecules collide and mix. Thermal energy is applied to the region of disturbance to promote liberation of at least some of the ionized particles from any attached impurities, thereby increasing the concentration of the ionized particles having the characteristic m/z ratios in the flow. Molecular reactions and low pressure ionization methods can also be performed for selective removal or enhancement of particular ions.