Abstract: A method of ion detection comprises: (a) setting electrical potentials of a dynode and a scintillator electrode of a Daly detector and of a focusing lens disposed at an ion inlet of the Daly detector so as to detect negatively charged ions received from a mass analyzer or mass filter; (b) transferring the negatively charged ions from the mass analyzer or mass filter to the Daly detector through the lens and detecting said negatively charged ions by a photodetector of the Daly detector; (c) setting electrical potentials of the dynode, the scintillator electrode and the focusing lens of the Daly detector so as to detect positively charged ions received from the mass analyzer or mass filter; and (d) transferring the positively charged ions from the mass analyzer or mass filter to the Daly detector through the lens and detecting said positively charged ions by the photodetector.

Abstract: The present disclosure relates to an apparatus and method to achieve electrospray ionization at femtoliter/minute to nanoliter/minute flow rates including relatively rapid alternation between such flow rates within the same device. These flow rates provide enhanced and relatively more uniform ionization of sprayed compounds for subsequent analytical evaluations.

Abstract: An ion detector that can detect either positive or negative ions comprises: an ion inlet comprising an ion focusing lens; a dynode having a surface configured to intercept, within a zone of interception, a stream of ions passing through the ion focusing lens, wherein a plane that is tangent to the dynode surface at the zone of interception is disposed at an angle to a line that passes through the center of the dynode surface and the center of the focusing lens; a scintillator having a surface that is configured to receive secondary electrons emitted from the zone of interception; a scintillator electrode affixed to the scintillator surface; a photodetector configured to receive photons emitted by the scintillator and to generate an electric signal in response thereto; and one or more power supplies electrically coupled to the focusing lens, the dynode, the scintillator electrode and the photodetector.

Abstract: A dual polarity ion detector comprises: an entrance electrode disposed to receive ions and maintained at a reference voltage, V0; a first dynode maintained at a voltage, V1, that is negative relative to V0; a second dynode maintained at a voltage, V2, that is positive relative to V0; a shielding electrode disposed between the first and second dynodes and maintained at a voltage, V3; and an ion detector comprising an entrance aperture configured to receive first secondary particles from the first dynode and second secondary particles from the second dynode, the entrance aperture maintained at a voltage, Vaperture; that is intermediate between the voltage, V1, and the voltage, V2. In some instances, the voltage, V3, may be equal to or approximately equal to the voltage, V0.

Abstract: An ion detector that can detect either positive or negative ions comprises: an ion inlet comprising an ion focusing lens; a dynode having a surface configured to intercept, within a zone of interception, a stream of ions passing through the ion focusing lens, wherein a plane that is tangent to the dynode surface at the zone of interception is disposed at an angle to a line that passes through the center of the dynode surface and the center of the focusing lens; a scintillator having a surface that is configured to receive secondary electrons emitted from the zone of interception; a scintillator electrode affixed to the scintillator surface; a photodetector configured to receive photons emitted by the scintillator and to generate an electric signal in response thereto; and one or more power supplies electrically coupled to the focusing lens, the dynode, the scintillator electrode and the photodetector.

Abstract: The invention generally relates to sample analysis with a miniature mass spectrometer. In certain embodiments, the invention provides methods that involve generating ions of a first analyte and ions of a second analyte. Those ions are transferred through a discontinuous sample introduction interface into a first ion trap of a mass spectrometer in a manner in which the discontinuous sample introduction interface remains open during the transferring. The discontinuous sample introduction interface is closed and the ions are sequentially transferred to a second ion trap of the mass spectrometer where they are sequentially analyzed.

Abstract: The invention generally relates to sample analysis with a miniature mass spectrometer. In certain embodiments, the invention provides methods that involve generating ions of a first analyte and ions of a second analyte. Those ions are transferred through a discontinuous sample introduction interface into a first ion trap of a mass spectrometer in a manner in which the discontinuous sample introduction interface remains open during the transferring. The discontinuous sample introduction interface is closed and the ions are sequentially transferred to a second ion trap of the mass spectrometer where they are sequentially analyzed.

Abstract: A method of quantitative mass analysis of precursor ion species of different mass-to-charge (m/z) ratios from the same or common ion injection event is disclosed. A plurality of precursor ion species with different respective m/z ratios are introduced into an ion trap mass analyzer at the same time. The precursor ion species are isolated. A first subset of the isolated precursor ions, which are multiply charged and have a first m/z ratio range, is fragmented and scanned by dividing the scan into at least two separate scan windows. A first mass spectrum is generated for the fragment ions of the first subset of precursor ions. A second subset of the isolated precursor ions having a second m/z ratio is fragmented and scanned, and a second mass spectrum is generated for the fragment ions of the second subset of precursor ions.

Abstract: A mass spectrometry apparatus includes an ion source, an ion trap and a mass spectrometer controller. The ion source is configured to generating ions. The ion trap is configured to trap ions within a RF field; eject unwanted ion while retaining target ions; and fragment target ions. The mass spectrometer controller is configured to determine an injection time for the ion trap based on a precursor ion flux and a product ion flux; fill the ion trap with ions from the ion source for an amount of time equal to the injection time; isolate target precursor ions in the ion trap; fragment the target precursor ions to generate product ions; and mass analyzing the product ions.

Abstract: A method of quantitative mass analysis of precursor ion species of different mass-to-charge (m/z) ratios from the same or common ion injection event is disclosed. A plurality of precursor ion species with different respective m/z ratios are introduced into an ion trap mass analyzer at the same time. The precursor ion species are isolated. A first subset of the isolated precursor ions, which are multiply charged and have a first m/z ratio range, is fragmented and scanned by dividing the scan into at least two separate scan windows. A first mass spectrum is generated for the fragment ions of the first subset of precursor ions. A second subset of the isolated precursor ions having a second m/z ratio is fragmented and scanned, and a second mass spectrum is generated for the fragment ions of the second subset of precursor ions.

Abstract: The invention generally relates to systems for analyzing a sample and methods of use thereof. In certain aspects, the invention provides systems that include an ionization probe and a mass analyzer. The probe includes a hollow body that has a distal tip. The probe also includes a substrate that is at least partially disposed within the body and positioned prior to the distal tip so that sample extracted from the substrate flows into the body prior to exiting the distal tip. The probe also includes an electrode that operably interacts with sample extracted from the substrate.

Abstract: A method of quantitative mass analysis of precursor species of different mass-to-charge (m/z) ratios from a single or the same ion injection event is disclosed. A plurality of precursor ion species having different respective m/z ratios are introduced into a mass spectrometer at the same time. The precursor ion species are isolated. A first subset of the isolated precursor ions having a first m/z ratio is fragmented and analyzed. A second subset of the isolated precursor ions having a second m/z ratio is fragmented and analyzed. A first mass spectrum is generated for the fragment ions of the first subset of precursor ions, and a second mass spectrum is generated for the fragment ions of the second subset of precursor ions.

Abstract: A method of quantitative mass analysis of precursor species of different mass-to-charge (m/z) ratios from the same ion injection event is disclosed. A plurality of precursor ion species is introduced into a mass spectrometer at the same time, and isolated. A first subset of the isolated precursor ions having a first m/z ratio and a second subset of the isolated precursor ions having a second m/z ratio are fragmented. The fragmented ions are analyzed at the same time. A mass spectrum is generated for the fragment ions of the first and second subsets of precursor ions.

Abstract: The invention generally relates to sample analysis with a miniature mass spectrometer. In certain embodiments, the invention provides methods that involve generating ions of a first analyte and ions of a second analyte. Those ions are transferred through a discontinuous sample introduction interface into a first ion trap of a mass spectrometer in a manner in which the discontinuous sample introduction interface remains open during the transferring. The discontinuous sample introduction interface is closed and the ions are sequentially transferred to a second ion trap of the mass spectrometer where they are sequentially analyzed.

Abstract: The invention generally relates to systems for analyzing a sample and methods of use thereof. In certain aspects, the invention provides systems that include an ionization probe and a mass analyzer. The probe includes a hollow body that has a distal tip. The probe also includes a substrate that is at least partially disposed within the body and positioned prior to the distal tip so that sample extracted from the substrate flows into the body prior to exiting the distal tip. The probe also includes an electrode that operably interacts with sample extracted from the substrate.