Abstract: Apparatus and method for delivering collisional gas to a mass spectrometer at a desired flow rate which employs a capillary flow restrictor having internal diameter and length selected to provide the desired flow rate.

Abstract: A capacitor for connecting to components within a vacuum system in which the space between the capacitor plates is at the pressure of the vacuum system is provided. One of the be plates provides a feed-through which permits closer coupling of the capacit or to other circuits the system and also eliminates the need for additional components. The capacitor can be a mounted and thus thermally coupled to a vacuum manifold which provides temperature stabilization.

Abstract: An apparatus for delivering calibrant gas at selected flow rates to the ionization region of a mass spectrometer which employs capillary flow restrictors for metering the flow.

Abstract: An ion cyclotron resonance cell having a large ion trapping volume is described. The cell includes elongated spaced concentric electrodes having a common axis in which the trapping volume is the space between the electrodes. The cell may also include trapping electrodes disposed at the ends of the elongated concentric electrodes.

Abstract: An ion transmission system for transferring ions from an atmospheric pressure ionization source to an analyzer including a capillary having an input orifice which is indirectly coupled to the ion 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: A method for automatedly administering an audiometric test includes the steps of controlling an audiometer to selectively switch the audiometer output between test tones generated by the audiometer and sound signals generated from digital information; first switching the audiometer output to sound signals when the step of controlling indicates a beginning of a new test, a completion of a current test, or a test error; outputting sound representative of the sound signals after the step of first switching; second switching the audiometer output to test tones after the step of outputting; and outputting test tones until the next step of first switching.

Abstract: An external ion source assembly in which ion are formed in an ion volume by the interaction of energetic electrons and gas molecules. The effective energy of the electrons entering the ion volume is controlled by changing the voltage between the electron source (filament) and the ionization volume whereby ions having sufficient energy for ionizing atoms and molecules leave the electron source and enter the ionization volume only during an ionization period. The ion source assembly can be used both for electron impact ionization (EI) and for chemical ionization (CI).

Abstract: A method of reducing noise due to undesolved charged droplets or charged particles in an ion trap mass spectrometer coupled to an atmospheric pressure ionization source.

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 filament assembly is disclosed for providing an electron beam to an ion source volume to ionize molecules or particles in the ion source volume. The filament assembly includes an electron lens which accelerates electrons emitted by the filament and focuses the electrons into a beam.

Abstract: The present invention relates generally to an ion trap mass spectrometer for analyzing ions and more particularly to a substantially quadrupole ion trap mass spectrometer with an enlarged ion occupied volume. Described herein are electrode geometries that enlarge the ion occupied volume. Improved ion sensitivities, detection limits and dynamic range should be realized for the same charge density in these devices because the increased ion occupied volume allows for the storage of a greater number of ions. The essence of this invention is that these ion trap geometries may apply all modes of operation of substantially quadrupole ion traps such as the mass selective instability mode, resonance excitation/ejection, and MS.sup.n.

Abstract: An electrospray interlace apparatus is disclosed. The apparatus includes an inner needle for transferring a liquid sample to an ionizing region at one end of the needle. A first outer tube surrounds and is spaced apart from the needle to form a cylindrical space through which a flowing liquid may pass. The tube has one end extending beyond the end of the needle to define a mixing volume where the sample and liquid can mix. A second outer tube surrounds the first tube to define a second cylindrical space for flowing a gas past the end of the first tube and needle to focus the electrospray. A voltage is also provided between the tips of the needle and the tubes and an adjacent surface.

Abstract: The invention relates to an ion filter and a method for the production of the ion filter. The ion filter comprises a plurality of elongated solid, rod assemblies. Typically, four rod assemblies, corresponding to four rod electrodes, are utilized. Each rod assembly has a curved rod surface, and at least two abutment surfaces. In one embodiment, the rod is hyperbolic in curvature. These surfaces are formed with one profiled grinding tool simultaneously in such a manner and angle of contact from a processing direction such that no undercuts are formed from this processing direction. The abutment surfaces are shaped such that one abutment surface of one rod assembly can be aligned with another abutment surface of another rod assembly when the rod surfaces are directed toward a longitudinal axis located in the interior of the ion filter. The rod assemblies are electrically insulated from each other with an insulating piece adhesively bonded to each rod assembly.

Abstract: There is described a method of operating an ion trap mass spectrometer. The method is carried out by trapping ions of selected masses in a three-dimensional field and then generating at least two fields in said trap having different frequencies to excite multiple trapped ions.

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 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: The method and apparatus of the present invention detects and records a convolved series of impulses, and then mathematically extracts the intensity and position of each impulse using least squares with the constraint that the impulses are spaced with a constant interval and that the instrument's response to a single impulse is known. This constraint allows the expression of the problem in a form which is amenable to rapid solution in a mathematically robust manner that is tolerant to noise.

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.

Abstract: An electrospray ion source having a capillary tube for directing ions from an ionizing region to an analyzing region including a skimmer in which the capillary tube is oriented to cause undesolvated droplets to strike the skimmer.