Abstract:
A mass spectrometer includes a radio frequency ion trap; and a controller. The controller is configured to cause an ion population to be injected into the radio frequency ion trap; supply a first isolation waveform to the radio frequency ion trap for a first duration, and supply a second isolation waveform to the radio frequency ion trap for a second duration. The first isolation waveform has at least a first wide notch at a first mass-to-charge ratio, and the second isolation waveform has at least a first narrow notch at the first mass-to-charge ratio. The first and second isolation waveforms are effective to isolate one or more precursor ions from the ion population.
Abstract:
A mass spectrometer includes a radio frequency ion trap; and a controller. The controller is configured to cause an ion population to be injected into the radio frequency ion trap; supply a first isolation waveform to the radio frequency ion trap for a first duration, and supply a second isolation waveform to the radio frequency ion trap for a second duration. The first isolation waveform has at least a first wide notch at a first mass-to-charge ratio, and the second isolation waveform has at least a first narrow notch at the first mass-to-charge ratio. The first and second isolation waveforms are effective to isolate one or more precursor ions from the ion population.
Abstract:
A mass spectrometry method for analyzing isobarically-labeled analyte compounds comprising (a) ionizing compounds including the isobarically-labeled analyte compounds to generate a plurality of precursor ion species comprising different respective m/z ratios, (b) isolating a precursor ion species, (c) fragmenting the precursor ion species to generate a plurality of first-generation fragment ion species comprising different respective m/z ratios, and (d) selecting and co-isolating two or more of the first-generation product-ion species, the method characterized by: (e) fragmenting all of the selected and isolated first-generation product ion species so as to generate a plurality of second-generation fragment ion species including released label ions; (f) generating a mass spectrum of the second-generation fragment ion species; and (g) generating quantitative information relating to at least one analyte compound based on peaks of the mass spectrum attributable to the released label ions.
Abstract:
A mass spectrometer capable of analysis at high speed and high accuracy comprising a device for applying a high frequency signal not containing resonance frequencies for plural precursor ions but containing resonance frequencies of other ions, and having different amplitudes on every frequencies to an electrode constituting the mass spectrometer thereby controlling the selection for the plural precursor ions, and a device for applying a high frequency signal having amplitudes set individually on every resonance frequencies of the plural precursor ions and superimposed with the resonance frequencies for the plural precursor ions to the electrode constituting the mass spectrometer thereby controlling the dissociation of the plural precursor ions, and judging the presence or absence of the aimed chemical substance based on the mass spectra of the obtained by dissociating the plural fragment 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:
A method of isolating selected ion species in a quadrupole ion trap mass spectrometer is disclosed. One or more ranges of masses to be eliminated from the ion trap are ejected by applying a supplemental dipole excitation waveform, sparsely populated with frequency components, while the trapping field is modulated. The spacing of the frequency components in the supplemental excitation waveform varies across the range of frequencies in the waveform. Preferably, the frequency range is divided into a plurality of subranges, and the spacing of the frequency components in each of the subranges is constant. A method of creating a master set of frequencies used for generating a supplemental excitation waveform is also shown. Likewise, a method of calculating edge frequencies defining a gap in the mass spectrum that is excited by the supplemental waveform is also shown. Modulation of the trapping field may be varied while the supplemental excitation waveform is applied to change the width of the gap in the mass spectrum.
Abstract:
A method and apparatus is described which determines a plurality of spaced discrete frequencies covering the range of frequencies of the characteristic motion of unwanted ions and processes said discrete frequencies to generate a plurality of time dependent voltage amplitude values which vary throughout the time domain such that the frequency content of said plurality of time dependent voltage amplitude values is relatively uniform over the entire time domain, and such that the magnitude associated with the discrete frequencies is relatively uniform over the frequency domain.
Abstract:
A mass spectrometry method in which notch-filtered noise is applied to an ion trap to resonate all ions except selected reagent ions out of the region of the trapping field. Preferably, the trapping field is a quadrupole trapping field defined by a ring electrode and a pair of end electrodes positioned symmetrically along a z-axis, and the filtered noise is applied to the ring electrode to eject unwanted ions in radial directions rather than toward a detector mounted along the z-axis. Also preferably, the trapping field has a DC component selected so that the trapping field has both a high frequency and low frequency cutoff, and is incapable of trapping ions with resonant frequency below the low frequency cutoff or above the high frequency cutoff. Application of the filtered noise signal to such a trapping field is functionally equivalent to filtration of the trapped ions through a notched bandpass filter having such high and low frequency cutoffs. Application of filtered noise in accordance with the invention avoids accumulation of contaminating ions during the process of storing desired reagent ions, and permits ejection of unwanted ions in directions away from an ion detector to enhance the detector's operating life and rapid ejection of unwanted ions having mass-to-charge ratio below a minimum value, above a maximum value, and outside a window (between the minimum and maximum values) determined by the filtered noise signal.
Abstract:
A method for performing mass analysis with dynamic mass resolution, in which a time-varying notch filtered broadband voltage signal (sometimes denoted as a time-varying "filtered noise" signal) is applied to a quadrupole mass filter. The time-varying filtered noise signal can consist of a rapid sequence of static (time-invariant) filtered noise signals, each defining a notch having a selected width and center location. The invention facilitates performance of mass analysis over a wide range of ion mass-to-charge ratios ("mass ranges") with adequate mass resolution. By appropriately choosing the width of each notch in the applied time-varying filtered noise, mass analysis can be performed with substantially constant mass separation over a wide mass range. In order to maintain substantially constant mass separation while analyzing a selected consecutive or non-consecutive sequence of ions (by passing such sequence of ions through the mass filter), the applied filtered noise should have narrower notches at times when ions with higher mass-to-charge ratio are to be selected, and wider notches at times when ions with lower mass-to-charge ratio are to be selected.
Abstract:
A mass spectrometry method in which notch-filtered noise is applied to an ion trap to resonate all ions except selected ions out of the region of the trapping field. Preferably, the trapping field is a quadrupole trapping field defined by a ring electrode and a pair of end electrodes positioned symmetrically along a z-axis, and the filtered noise is applied to the ring electrode to eject unwanted ions in radial directions rather than toward a detector mounted along the z-axis. Also preferably, the trapping field has a DC component selected so that the trapping field has both a high frequency and low frequency cutoff, and is incapable of trapping ions with resonant frequency below the low frequency cutoff or above the high frequency cutoff. Application of the filtered noise signal to such a trapping field is functionally equivalent to filtration of the trapped ions through a notched bandpass filter having such high and low frequency cutoffs. Application of filtered noise in accordance with the invention avoids accumulation of contaminating ions during the process of storing desired parent ions, and permits ejection of unwanted ions in directions away from an ion detector to enhance the detector's operating life and rapid ejection of unwanted ions having mass-to-charge ratio below a minimum value, above a maximum value, and outside a window determined by the filtered noise signal.