Abstract: A method of setting a fill time for a mass spectrometer including a linear ion is provided. The mass spectrometer is operated first in a transmission mode and ions are supplied to the mass spectrometer. Ions are detected as they pass through at least part of the mass spectrometer in a preset time period, to determine the ion current. From a desired maximum charge density for the ion trap and the ion current, a fill time for the ion trap is determined. The mass spectrometer is operated in a trapping mode to trap ions in the ion trap, and the ion trap is filled for the fill time, as just determined. This utilizes the ion trap to its maximum, while avoiding problems due to overfilling the trap, causing space charge effects.

Abstract: A mass spectrometer apparatus has one mass analyzer stage for selecting and rejecting ions having a particular mass-to-charge ratio and one fragmentation stage downstream from the first mass analysis stage for causing fragmentation of ions. Another mass analysis stage downstream from the fragmentation stage selects ions of a particular mass-to-charge ratio and rejects other ions. A synchronization unit is connected between the two mass analysis stages, for causing ions excited and removed in the one mass analysis stage to have the same mass-to-charge ratio as the ions selected by the other mass analysis stage, whereby ions detected by the detector are ions selected by the other mass analysis stage and generated by fragmentation in the fragmentation stage.

Abstract: There is provided a method of effecting mass analysis on an ion stream, the method comprising passing the ion stream through a first mass resolving spectrometer, to select parent ions having a first desired mass-to-charge ratio. The parent ions are then subject to collision-induced dissociation (CID) to generate product ions, and the product Ions and any remaining parent ions are trapped the CID and trapping can be carried out together in a linear ion trap. Periodically pulses of the trapped ions are released into a time of flight (TOF) instrument to determine the mass-to-charge ratio of the ions. The delay between the release of the pulses and the initiation of the push-pull pulses of the TOF instrument are adjusted to maximize the duty cycle efficiency and hence the sensitivity for a selected ion with a desired mass-to-charge ratio. This technique can be used to optimize the performance for a parent ion scan, and MRM scan or a neutral loss scan.

Abstract: A mass spectrometer method and apparatus has a mass analyzer and a collision cell. The collision cell is configured to trap ions. Precursor ions are selected in the first mass analyzer and then subject to collision-induced dissociation in the collision cell. The fragment ions are then scanned out axially by application of suitable excitation to the ions. The fragment ions can then be detected by a time of flight (TOF) mass spectrometer. For a TOF spectrometer, trapping fragment ions in the collision cell and scanning them out can give enhanced sensitivity.

Abstract: A mass spectroscopy apparatus having two quadrupole mass analyzer stages is disclosed. Both stages are configured to transmit ions of the same mass to charge ratio and they are operated in series to provide a tandem mass analyzer having greater resolution than either stage has separately. The poles of the two quadrupoles are positioned axially and close together to minimize ion loss between the two stages. The RF component of the potential across the two stages are kept in phase such that some poles of the first stage are always 180° out of phase with some poles of the other stage. Capacitors are provided to couple the out of phase poles of the two stages to one another, thereby compensating for a stray capacitance which arises between the in phase poles of the two stages.

Abstract: A mass spectrometer has an ion source for producing sample ions. The ions pass through an ion interface, to a reaction/collision cell section. An ion-neutral decoupling device is provided between the ion interface and the reaction/collision cell section, to provide substantial separation between ions and neutral particles, whereby only ions pass on to the reaction/collision cell section. The supersonic jet entering the spectrometer can have sufficient energy to cause the plasma gases, such as argon, to overcome the pressure differential between the reaction/collision cell and an upstream section of the spectrometer so as to penetrate into the reaction/collision cell; the decoupling device prevents this. The decoupling device can have offset apertures provided by plates or rods or other comparable arrangements, or can comprise a quadrupolar electrostatic deflector, an electrostatic sector deflector or a magnetic sector deflector.

Abstract: There is provided a method of effecting mass analysis on an ion stream, the method comprising passing the ion stream through a first mass resolving spectrometer, to select parent ions having a first desired mass-to-charge ratio. The parent ions are then subject to collision-induced dissociation (CID) to generate fragment ions, and the fragment ions and any remaining parent ions are trapped; the CID and trapping can be carried out together in a linear ion trap. Periodically pulses of the trapped ions are released into a time of flight (TOF) instrument to determine the mass-to-charge ratio of the ions. The delay between the release of the pulses and the initiation of the push-pull pulses of the TOF instrument are adjusted to maximize the duty cycle efficiency and hence the sensitivity for a selected ions with a desired mass-to-charge ratio. This technique can be used to optimize the performance for a parent ion scan, and MRM scan or a neutral loss scan.

Abstract: A method of and apparatus for mass analysis utilizes two quadrupole rod sets located in a vacuum chamber, this first rod set is intended to collimate the ions with an RF-only voltage. An RF-only voltage to the second quadrupole rod set and this is operated so that desired ions having a mass-to-charge ratio giving a q value of substantially 0.907 gain additional axial kinetic energy upon leaving the second quadrupole rod set. These desired ions are then detected by separating the ions with increased axial kinetic energy. It has been discovered that the pressure within the first quadrupole rod can be adjusted to enhance separation between ions gaining the additional axial kinetic energy and other ions, the pressure times the length in the first quadrupole rod set can be in the range 4×10−2 torr-cm. to 1.6×10−1 torr-cm.

Abstract: An ion source having a capillary for spraying analyte to form ions, which are charged and attracted to the edge of an insulating film on a spinning disk having a metal core. The disk carries the ions through a slot into a vacuum chamber where they are removed, resulting in continuous transfer of the ions into the vacuum chamber while greatly reducing the amount of gas which enters the vacuum chamber.

Abstract: A method of operating a mass spectrometer having an elongated multipole rod set, in which a two dimensional RF field radially contains trapped ions in a mass to charge range of interest, and in which the ions are contained axially by a barrier field on an end lens and to which a low voltage DC is applied. Trapped ions are axially mass selectively ejected by taking advantage of the mixing of the degrees of freedom induced by the fringing fields and other anti-harmonicities in the vicinity of the end lens. Thus, ions can be mass selectively ejected at the exit end at the same time as ions are being admitted into the entrance end of the rod set, thereby taking better advantage of the ion flux from a continuous ion source. The axial mass selective ejection is performed by applying an auxiliary AC voltage to the end lens, or to the rods themselves, or both, and by scanning either the auxiliary AC voltage or the RF voltage on the rod set.

Abstract: A method of improving the signal-to-noise using first and second mass spectrometers in tandem, with an ion detector and data system coupled to the second mass spectrometer, comprising selecting precursor ions with the first mass spectrometer, at least some of the parent ions being multiply charged, colliding or reacting the precursor ions in an intermediate chamber so that multiply charged parent ions produce product ions which have at least one fewer charge than the multiply charged precursor ions, and using the second mass spectrometer or the ion detector and data system to allow only those ions which have an m/z value higher than the multiply charged precursor ions to be recorded for analysis by the ion detector and data system, so that only a signal due to multiply charged precursor ions is obtained in said data system.

Abstract: A method of reducing isobaric interferences by transmitting ions from an ion source through an ion transmission device, typically a quadrupole collision cell, and then into an analyzing mass spectrometer, in which the collision cell is operated with a pass band which rejects intermediate ions which would otherwise tend to react to form isobaric interferences. Preferably ammonia is used as a reaction gas in the collision cell. Depending on the chemistry involved, the collision cell may be operated to set the low mass cutoff at an appropriate level, or more usually, the pass band will have both high and low mass cutoffs determined by applying both RF and DC to the collision cell. The collision cell may also be operated with a pass band to transmit ions into a time-of-flight (TOF) mass spectrometer, thus limiting the mass range of ions entering the TOF and thereby improving the duty cycle of the TOF.

Abstract: An RF-only quadrupole mass spectrometer in which an auxiliary RF field (dipole or quadrupole) excites selected ions at low q (typically between 0.20 and 0.89). The excited ions experience radial excursions, but many do not experience excursions sufficient to strike the rods, and are therefore transmitted and acquire increased kinetic energy in the fringing fields at the exit ends of the rods. The excited ions may therefore be selected from the non-excited ions either by their increased axial kinetic energy, or by their radial dispersion, or both, and are detected for analysis, producing sharp peaks of high sensitivity at low q, while retaining the high acceptance and other advantages of RF-only mass spectrometers. Operated in converse fashion, a high quality notch filter can be achieved. In the notch filter, an auxiliary RF field again excites ions and notches some of them out by causing them to strike the rods.

Abstract: A mass spectrometer system in which ions are mass selected in an RF-only quadrupole at relatively high pressure (1 to 7 torr) using FNF or SWIFT, and are then fragmented in a following collision cell which is in the same vacuum chamber, thus reducing pumping needs. The fragments can be mass analyzed in any desired way, including by another RF-only quadrupole in the same vacuum chamber and also using FNF or SWIFT. Triple MS can be performed in the same way.

Abstract: A method of operating a mass spectrometer having a rod set, comprising: directing ions into the rod set, applying an unbalanced RF voltage to the rod set, and applying a low level resolving DC voltage, e.g. 0.3 to 15.5 volts, to the rod set, thus increasing the sensitivity of the mass spectrometer and also improving the resolution. Alternatively, instead of unbalancing the RF voltage on the rod set, suitably phased RF can be applied to an end lens spaced from the exit end of the rod set.

Abstract: The method of operating a rod-type mass spectrometer in which precursor ions are introduced into the mass spectrometer together with a collision gas. Sufficient RF voltage, and a small but sufficient amount of resolving DC voltage, are applied to the rods to operate the mass spectrometer near the .beta.=0 boundary for the precursor ions, thus inducing boundary activated dissociation of at least some of the precursor ions to produce fragment ions. The fragment ions together with any residual precursor ions are directed into a subsequent mass spectrometer for detection and analysis. The method allows moderate mass resolution of the precursor ion which can be used to obtain MSMS information from a single quadrupole and MS.sup.3 information from a triple quadrupole. When the DC is scanned over only part of the spectrum, fragmentation information can be obtained within a pre-specified region of the spectrum, and the remainder of the spectrum will display spectral features of unfragmented precursor ions.

Abstract: A method is provided of operating a mass spectrometer having first and second rod sets, which can be a focusing set of rods and an analysis rod set, the second rod set being downstream from the first rod set at an outlet of a spectrometer. Ions are directed into the first rod set and an RF voltage applied to the two rod sets, the RF voltage can be the same or different for the two rod sets. A low level DC voltage is applied to the first rod set sufficient to reduce a continuum background ion signal, thereby to increase the signal-to-noise ratio of the spectrometer.

Abstract: A spray chamber for producing a sample for an analyzer which may contain a plasma torch. In the chamber, a heated sheath gas is fed into the periphery of the spray surrounding the spray, adjacent the origin of the spray, thus reducing the size of droplets which are recirculated, thereby reducing agglomeration of the droplets and promoting rapid drying of the spray. Preferably all of the spray solvent is evaporated in a very short chamber, thus further reducing the amount of spray recirculated, and all of the combined flow of dried particulates from the spray, nebulizing gas and sheath gas is directed into the torch. In one embodiment, the central core of the combined flow is directed to the torch and the peripheral portion of the combined flow is ducted to waste.

Abstract: In a mass spectrometer, typically a quadrupole, one of the rod sets is constructed to create an axial field, e.g. a DC axial field, thereon. The axial field can be created by tapering the rods, or arranging the rods at angles with respect to each other, or segmenting the rods, or by providing a segmented case around the rods, or by providing resistively coated or segmented auxiliary rods, or by providing a set of conductive metal bands spaced along each rod with a resistive coating between the bands, or by forming each rod as a tube with a resistive exterior coating and a conductive inner coating, or by other appropriate methods. When the axial field is applied to Q0 in a tandem quadrupole set, it speeds passages of ions through Q0 and reduces delay caused by the need to refill Q0 with ions when jumping from low to high mass in Q1. When used as collision cell Q2, the axial field reduces the delay needed for daughter ions to drain out of Q2.