Abstract: A mass spectrometer 10 comprises an ion source 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16. Ions within a window of m/z of interest are extracted via a quadrupole mass filter 24 and passed to a linear trap 30. Ions are trapped in a potential well in the linear trap 30 and are bunched at the bottom of the potential well adjacent an exit segment 50. Ions are gated out of the linear trap 30 into an electrostatic ion trap 130 and are detected by a secondary electron multiplier 10. By bunching the ions in the linear trap 30 prior to ejection, and by focussing the ions in time of flight (TOF) upon the entrance of the electrostatic trap 130, the ions arrive at the electrostatic trap 130 as a convolution of short, energetic packets of similar m/z. Such packets are particularly suited to an electrostatic trap because the FWHM of each packet's TOF distribution is less than the period of oscillation of those ions in the electrostatic trap.

Abstract: A detector assembly has a current measuring device with a saturation threshold level, and a gain variation means. A signal is generated in response to the particles detected, a first data point corresponding to a peak of interest is acquired from the signal. If the first data point is near, at or above the saturation threshold level of the current measuring device, the gain of the gain variation means is adjusted such that the peak of interest in the signal is reduced in intensity.

Abstract: An aperture design for a linear ion trap is provided in which the aperture is optimized to minimize possible axial field inhomogeneities whilst preserving the structural integrity of the quadrupole rods. In general, the invention provides a linear ion trap for trapping and subsequently ejecting ions. The linear ion trap comprises a plurality of rods which define an interior trapping volume which has an axis extending longitudinally. One or more of the rods includes an aperture which extends both radially through the rod and longitudinally along the rod. The aperture being configured such that the ions can pass from the interior trapping volume through the aperture to a region outside the interior trapping volume. At least one recess is disposed adjacent the aperture, extending longitudinally along the rod and facing the interior trapping volume, the recess not extending radially through the rod.

Abstract: Method and apparatus, including computer program products, implement techniques for operating a mass spectrometer that includes a source of ions, a mass analyzer, and a detector, in which a gain of the detector or the number of ions detected by the detector is calculated based on intensity measurements for ions having a plurality of different m/z values. In particular implementations, the detector gain or the number of ions detected by the detector can be calculated based on a ratio of or difference between intensity values for at least two of the ions having different m/z values.

Abstract: Rapid and efficient fragmentation of ions in an ion trap for MS/MS analysis is achieved by a pulsed fragmentation technique. Ions of interest are placed at an elevated value of Q and subjected to a relatively high amplitude, short-duration resonance excitation pulse to cause the ions to undergo collision-induced fragmentation. The Q value of the ions of interest is then rapidly reduced, thereby decreasing the low-mass cutoff and allowing retention and subsequent analysis of low-mass ion fragments.

Abstract: A three section linear or two-dimensional (2D) quadrupole ion trap as a high performance mass spectrometer is described. Mass analysis is performed by ejecting ions radically out slots formed in at least two of the rods using the mass selective instability mode of operation. The slot geometry is optimized to enable ions of different mass ranges to be scanned out of differently dimensioned slots. Multiple detectors arranged to receive ejected ions in multiple directions provide the ability to simultaneously or sequentially scan or perform mass analysis of ions of different natures.

Abstract: A mass spectrometer 10 comprises an ion source 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16. Ions within a window of m/z of interest are extracted via a quadrupole mass filter 24 and passed to a linear trap 30. Ions are trapped in a potential well in the linear trap 30 and are bunched at the bottom of the potential well adjacent an exit segment 50. Ions are gated out of the linear trap 30 into an electrostatic ion trap 130 and are detected by a secondary electron multiplier 10. By bunching the ions in the linear trap 30 prior to ejection, and by focussing the ions in time of flight (TOF) upon the entrance of the electrostatic trap 130, the ions arrive at the electrostatic trap 130 as a convolution of short, energetic packets of similar m/z. Such packets are particularly suited to an electrostatic trap because the FWHM of each packet's TOF distribution is less than the period of oscillation of those ions in the electrostatic trap.

Abstract: Rapid and efficient fragmentation of ions in an ion trap for MS/MS analysis is achieved by a pulsed fragmentation technique. Ions of interest are placed at an elevated value of Q and subjected to a relatively high amplitude, short-duration resonance excitation pulse to cause the ions to undergo collision-induced fragmentation. The Q value of the ions of interest is then reduced before significant numbers of ion fragments are expelled from the ion trap, thereby decreasing the low-mass cutoff and allowing retention and subsequent measurement of lower-mass ion fragments.

Abstract: There is provided a quadruple ion trap (22) of the type including a ring electrode (24) and first and second end cap electrodes (26, 28), which define a trapping volume. The end cap electrodes (26, 28) include central apertures (30) for the injection of ions or electrons into the trapping volume and for the ejection of stored ions during the analysis of a sample. Field faults in the RF trapping field are compensated by addition of a concentric recess or depression in the surface of at least one end cap (26, 28) around the aperture (30). There is also provided an ion trap mass spectrometer employing the ion trap.

Abstract: A mass spectrometer 10 comprises an ion source 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16. Ions within a window of m/z of interest are extracted via a quadrupole mass filter 24 and passed to a linear trap 30. Ions are trapped in a potential well in the linear trap 30 and are bunched at the bottom of the potential well adjacent an exit segment 50. Ions are gated out of the linear trap 30 into an electrostatic ion trap 130 and are detected by a secondary electron multiplier 10. By bunching the ions in the linear trap 30 prior to ejection, and by focussing the ions in time of flight (TOF) upon the entrance of the electrostatic trap 130, the ions arrive at the electrostatic trap 130 as a convolution of short, energetic packets of similar m/z. Such packets are particularly suited to an electrostatic trap because the FWHM of each packet's TOF distribution is less than the period of oscillation of those ions in the electrostatic trap.

Abstract: Method and apparatus, including computer program products, implement techniques for operating a mass spectrometer that includes a source of ions, a mass analyzer, and a detector, in which a gain of the detector or the number of ions detected by the detector is calculated based on intensity measurements for ions having a plurality of different m/z values. In particular implementations, the detector gain or the number of ions detected by the detector can be calculated based on a ratio of or difference between intensity values for at least two of the ions having different m/z values.

Abstract: There is provided a quadruple ion trap (22) of the type including a ring electrode (24) and first and second end cap electrodes (26, 28), which define a trapping volume. The end cap electrodes (26, 28) include central apertures (30) for the injection of ions or electrons into the trapping volume and for the ejection of stored ions during the analysis of a sample. Field faults in the RF trapping field are compensated by addition of a concentric recess or depression in the surface of at least one end cap (26, 28) around the aperture (30). There is also provided an ion trap mass spectrometer employing the ion trap.

Abstract: A three section linear or two-dimensional (2D) quadrupole ion trap as a high performance mass spectrometer is described. Mass analysis is performed by ejecting ions radically out a slot formed in one of the rods using the mass selective instability mode of operation. The slot geometry is optimized to yield high ejection efficiencies. Resolution can be controlled by using appropriate end section potentials to control the axial spread of the ion cloud. Multiple detectors can be used for enhancing sensitivity and for enabling enhanced ion analysis techniques in the ion trap.

Abstract: A mass spectrometer 10 comprises an ion source 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16. Ions within a window of m/z of interest are extracted via a quadrupole mass filter 24 and passed to a linear trap 30. Ions are trapped in a potential well in the linear trap 30 and are bunched at the bottom of the potential well adjacent an exit segment 50. Ions are gated out of the linear trap 30 into an electrostatic ion trap 130 and are detected by a secondary electron multiplier 10.

Abstract: A three section linear or two-dimensional (2D) quadrupole ion trap as a high performance mass spectrometer is described. Mass analysis is performed by ejecting ions radically out a slot formed in one of the rods using the mass selective instability mode of operation. The slot geometry is optimized to yield high ejection efficiencies. Resolution can be controlled by using appropriate end section potentials to control the axial spread of the ion cloud. Multiple detectors can be used for enhancing sensitivity and for enabling enhanced ion analysis techniques in the ion trap.

Abstract: An ion transfer assembly for transferring ions from an atmospheric pressure ion source into an ion trap mass spectrometer with reduced random noise during analysis of the transferred ions. A method of reducing noise due to charged particles, undesolvated charged droplets, or ions in an ion trap mass spectrometer connected to an atmospheric pressure ionization source.

Abstract: There is described a method of generating product ions in a quadrupole ion trap in which the amplitude of the applied excitation voltage for an ion of a given mass-to-charge ratio (m/z) is linearly related to its mass-to-charge ratio (m/z).

Abstract: This invention is directed to a method and apparatus of increasing the dynamic range and sensitivity of an ion trap mass spectrometer with the use of external ionization. An increased number of sample ions are introduced into the mass spectrometer for mass analysis with the aid of an automatic ion supply control, or feedback, feature. The feedback portion of the invention controls the gating time, and hence the number of sample ions gated into the mass spectrometer, based on previous measurements of the ion content in the mass spectrometer to gate an amount relative to where space charge and saturation begins. A mass filter may also be used between the ion source and the mass spectrometer to improve the signal-to-noise ratio and increase the net processing time. This mass analyzing system may be used with various methods of mass analysis including mass selective instability, resonance ejection, MS/MS, and MS/MS with a supplemental AC field.

Abstract: A method is disclosed for operating an ion trap mass spectrometer in such a way as to distinguish resonantly ejected ions from non-resonantly ejected ions. A supplementary AC field is superimposed on the three-dimensional quadrupole trapping field and the combined fields are scanned to resonantly eject ions of consecutive mass-to-charge ratio. The ejected ions are detected and the output signal of the resonantly ejected ions has a frequency component at the frequency of the supplementary AC field.

Abstract: A method of mass analyzing a sample including the steps of defining a trap volume with a three-dimensional quadrupole field for trapping ions within a predetermined range of mass-to-charge ratio, forming or injecting ions within the trap volume such that those within the predetermined mass-to-charge ratio range are trapped within the trap volume, applying a supplementary AC field superimposed on the three-dimensional quadrupole field to form combined fields, scanning the combined fields to eject ions of consecutive mass-to-charge ratio from the trap volume for detection characterized in that the supplementary field has an amplitude just sufficient to eject the ions and that the supplementary field has a beta value below 0.891 and that the combined fields are scanned at a rate so that a length of time corresponding to 200 cycles or more of the supplementary AC field passes per consecutive thomson.