Abstract: A method and apparatus for manipulating ions using a two-dimensional substantially quadrupole field, and a method of manufacturing and operating an apparatus for manipulating ions using a two-dimensional substantially quadrupole field are described. The field has a quadrupole harmonic with amplitude A2 and a hexapole harmonic with amplitude A3. The amplitude A3 of the hexapole component of the field is selected to improve the performance of the field with respect to ion selection and ion fragmentation.

Abstract: A mass spectrometer system and a method of operating a mass spectrometer having an elongated rod set, the rod set having an entrance end, an exit end, a plurality of rods and a longitudinal axis, involving (a) admitting ions into the entrance end of the rod set; (b) producing an RF field between the plurality of rods to radially confine the ions in the rod set; (c) providing a static axial electric field within the rod set; and (d) separating the ions into a first group of ions and a second group of ions by providing an oscillating axial electric field within the rod set to counteract the static axial electric field, wherein the oscillating axial electric field varies along the longitudinal axis of the rod se.

Abstract: In the field of mass spectrometry, a method and apparatus for fragmenting ions with a relatively high degree of resolution and efficiency. The technique includes trapping the ions in a linear ion trap, in which the background or neutral gas pressure is preferably on the order of 10?5 Torr. The trapped ions are resonantly excited for a relatively extended period of time, e.g., exceeding 50 ms, at relatively low excitation levels, e.g., less than 1 Volt(0-pk). The technique allows selective dissociation of ions with a high discrimination. High fragmentation efficiency may be achieved by superimposing a higher order multipole field onto the quadrupolar RF field used to trap the ions. The multipole field, preferably an octopole field, dampens the radial oscillatory motion of resonantly excited ions at the periphery of the trap. This reduces the probability that ions will eject radially from the trap thus increasing the probability of collision induced dissociation.

Abstract: A system and method are described for producing a modifiable fringing field in a multipole instrument, such as a mass spectrometer or an ion guide. The system includes a conductor arrangement having a first pole pair, a second pole pair and an end device for allowing ions to enter or exit the conductor arrangement. A first power supply provides a first voltage to the first pole pair, such that the application of the first voltage results in a fringing field near the end device. An end device power supply provides an end device voltage to the end device for modifying the fringing field to facilitate the entrance or exit of the ions.

Abstract: A mass spectrometer and a method of operating same is provided. The mass spectrometer has an elongated rod set. The rod set has an entrance end and an exit end. An RF drive voltage is applied to the rod set to radially confine a first group of ions and a second group of ions of opposite polarity in the rod set. An entrance auxiliary RF voltage is applied to the entrance end and an exit auxiliary RF voltage to the exit end relative to the RF drive voltage, to trap both the first group of ions and the second group of ions in the rod set.

Abstract: A mass spectrometer system and a method of operating a mass spectrometer having an elongated rod set, the rod set having an entrance end, an exit end, a plurality of rods and a longitudinal axis, involving (a) admitting ions into the entrance end of the rod set; (b) producing an RF field between the plurality of rods to radially confine the ions in the rod set; (c) providing a static axial electric field within the rod set; and (d) separating the ions into a first group of ions and a second group of ions by providing an oscillating axial electric field within the rod set to counteract the static axial electric field, wherein the oscillating axial electric field varies along the longitudinal axis of the rod se.

Abstract: In the field of mass spectrometry, a method and apparatus for fragmenting ions with a relatively high degree of resolution and efficiency. The technique includes trapping the ions in a linear ion trap, in which the background or neutral gas pressure is preferably on the order of 10-5 Torr. The trapped ions are resonantly excited for a relatively extended period of time, e.g., exceeding 50 ms, at relatively low excitation levels, e.g., less than 1 Volt (0-pk). The technique allows selective dissociation of ions with a high discrimination. High fragmentation efficiency may be achieved by superimposing a higher order multipole field onto the quadrupolar RF field used to trap the ions. The multipole field, preferably an octopole field, dampens the radial oscillatory motion of resonantly excited ions at the periphery of the trap. This reduces the probability that ions will eject radially from the trap thus increasing the probability of collision induced dissociation.

Abstract: A method and apparatus for manipulating ions using a two-dimensional substantially quadrupole field, and a method of manufacturing and operating an apparatus for manipulating ions using a two-dimensional substantially quadrupole field are described. The field has a quadrupole harmonic with amplitude A2 and a hexapole harmonic with amplitude A3. The amplitude A3 of the hexapole component of the field is selected to improve the performance of the field with respect to ion selection and ion fragmentation.

Abstract: A system and method are described for producing a modifiable fringing field in a multipole instrument, such as a mass spectrometer or an ion guide. The system includes a conductor arrangement having a first pole pair, a second pole pair and an end device for allowing ions to enter or exit the conductor arrangement. A first power supply provides a first voltage to the first pole pair, such that the application of the first voltage results in a fringing field near the end device. An end device power supply provides an end device voltage to the end device for modifying the fringing field to facilitate the entrance or exit of the ions.

Abstract: A method and apparatus for the analysis of a narrow range of fragment ions by application of a notched broadband waveform during ion accumulation within a quadrupole collision cell operated as a linear ion trap. The fragment ions are formed via the axial acceleration and collision activated dissociation of mass resolved precursor ions. A narrow band of frequencies is purposefully omitted from the spectrum, so that the secular frequency of a particular fragment ion will fall within this notch of absent frequencies and as a result will not experience resonant excitation and are retained in the linear ion trap. Simultaneously, all other ions are lost either through neutralization when they strike electrodes or through (additional) collision activated dissociation. Accordingly, a particular mass or range of masses, whose secular frequencies fall within the notch of absent frequencies in the notched broadband waveform, may be selectively accumulated during the collision activated dissociation event.

Abstract: An improved method of operating a mass spectrometer having a linear ion trap wherein ions are axially ejected from the trap to a detector or subsequent mass analysis stage. The DC barrier field produced at the exit lens of the trap is scanned in conjunction with the scanning of other fields used to energize ions of select mass-to-charge ratios past the barrier field/exit lens. The technique can maximize the resolution obtainable from axial ejection over a wide mass range.

Abstract: An improved method of operating a mass spectrometer having a linear ion trap wherein ions are axially ejected from the trap to a detector or subsequent mass analysis stage. The DC barrier field produced at the exit lens of the trap is scanned in conjunction with the scanning of other fields used to energize ions of select mass-to-charge ratios past the barrier field/exit lens. The technique can maximize the resolution obtainable from axial ejection over a wide mass range.

Abstract: In the field of mass spectrometry, a method and apparatus for fragmenting ions with a relatively high degree of resolution. The technique includes trapping the ions in an ion trap, preferably a linear ion trap, in which the background or neutral gas pressure is preferably on the order of 10−5 Torr. The trapped ions are resonantly excited for a relatively extended period of time, e.g., exceeding 50 ms, at relatively low excitation levels, e.g., less than 1V(0−pk). The technique allows selective dissociation of ions with a discrimination of at least about 1 m/z at a practical fragmentation efficiencies. Apparatus and related methods are also disclosed for obtaining MS, MS2, MS3 and MSn spectrums at relatively high resolutions using the low pressure fragmentation technique.

Abstract: In the field of mass spectrometry, a method and apparatus for fragmenting ions with a relatively high degree of resolution and efficiency. The technique includes trapping the ions in a linear ion trap, in which the background or neutral gas pressure is preferably on the order of 10−5 Torr. The trapped ions are resonantly excited for a relatively extended period of time, e.g., exceeding 50 ms, at relatively low excitation levels, e.g., less than 1 Volt(0-pk). The technique allows selective dissociation of ions with a high discrimination. High fragmentation efficiency may be achieved by superimposing a higher order multipole field onto the quadrupolar RF field used to trap the ions. The multipole field, preferably an octopole field, dampens the radial oscillatory motion of resonantly excited ions at the periphery of the trap. This reduces the probability that ions will eject radially from the trap thus increasing the probability of collision induced dissociation.

Abstract: A method and apparatus for the analysis of a narrow range of fragment ions by application of a notched broadband waveform during ion accumulation within a quadrupole collision cell operated as a linear ion trap. The fragment ions are formed via the axial acceleration and collision activated dissociation of mass resolved precursor ions. A narrow band of frequencies is purposefully omitted from the spectrum, so that the secular frequency of a particular fragment ion will fall within this notch of absent frequencies and as a result will not experience resonant excitation and are retained in the linear ion trap. Simultaneously, all other ions are lost either through neutralization when they strike electrodes or through (additional) collision activated dissociation. Accordingly, a particular mass or range of masses, whose secular frequencies fall within the notch of absent frequencies in the notched broadband waveform, may be selectively accumulated during the collision activated dissociation event.

Abstract: A method of using a quadrupole ion trap mass spectrometer for high resolution mass spectroscopy is disclosed. High resolution of a mass spectrum of a desired species is achieved by first using a slow scanning rate and by first ridding the trap of unwanted ions. Accurate mass calibration is achieved by using a reference compound of known mass and using a second supplemental AC dipole voltage to eject the reference ions at nearly the same time as the sample ions of interest are ejected from the trap. This eliminates the need to scan the trap between the masses of the sample and reference ions. Space charge in the trap is held constant, thereby eliminating a major source of mass axis instability, by using the results of one scan to control the ionization time during the next scan. Preferably, during ionization a broadband supplemental dipole voltage is applied to the ion trap to rid it of unwanted ions.

Abstract: A variable cooling time is imposed on ions in a quadrupole ion trap prior to excitation through border effect operation. Continuous variation of the cooling time brings about continuous variation of the selected ion internal energy when subjected to the boundary effect such that the boundary effect competes more favorably with ion loss in the trap, and fragmentation reaction channels having successively greater energies of activation can be accessed preferentially.