Abstract: A combination electrospray/microwave induced plasma (MIP) ionization source is used as the ionization source for a mass spectrometer. The electrospray can be operated in positive mode, negative mode, or it can be switched off. The microwave-induced plasma can also be switched on or off. This allows the instrument to be operated in multiple modes. With the electrospray off and the MIP on, the instrument will normally have its maximum elemental sensitivity. Mixed mode operation potentially allows the determination of additional information about the chemical constituents present in the analyte. In pure electrospray mode, it is possible to obtain molecular information and to analyze organic compounds.

Abstract: A dual electrospray ionization source for use in connection with a mass spectrometer having an inlet port. The source includes a polymer nozzle holder having a drive axis and a pair of continuously spraying nozzles mounted to the nozzle holder at spaced-apart positions. An adjustment mechanism allows positional adjustment of one nozzle with respect to the other nozzle on the nozzle holder. A programmable motor is connected to the nozzle holder at the drive axis. The motor rotationally and reciprocally drives the nozzle holder to sequentially position each of the nozzles in alignment with an inlet port of mass spectrometer.

Abstract: The present invention provides a mass spectrometer including an ion source for atomizing a liquid sample into ionized droplets and spraying ions in a predetermined direction. According to the present invention, the ion source includes a gas transport pipe and a liquid supply pipe; the gas transport pipe has an ejection port at its front end and a gas supply passage for sending an assist gas to the ejection port; the inner surface of the gas supply passage has a tapered section located in proximity to the ejection port, where the diameter of the tapered section decreases toward the ejection port; the liquid supply pipe is inserted into the gas supply passage so that the front end of the liquid supply pipe is located in proximity to the ejection port; three or more spheres having the same size are inserted between the inner surface of the gas supply passage and the outer surface of the liquid supply pipe; and a pressing mechanism is used to press the spheres onto the tapered section.

Abstract: A method and system of identifying individual aerosol particles in real time. Sample aerosol particles are compared against and identified with substantially matching known particle types by producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer. Each test spectrum is compared to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types and a set of substantially matching spectra is obtained. Finally the identity of the individual aerosol particle is determined from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated with the best matching known particle type.

Abstract: A mass spectrometer has an ion source (10) with a plurality of atmospheric pressure sample ioniser (20) mounted in a front face (15) thereof. Each sample ioniser (20) extends into a corresponding sample region (30) and the tip of each sample ioniser is mounted at right-angles to a corresponding one of a plurality of entrance cones (50) each having an entrance orifice (40) therein. Each entrance cone (50) in turn opens into an inlet channel having first and second parts (60, 70). The two parts of the inlet channel are separated by an electrical gate (65). The inlet channels corresponding to each entrance cone (50) all merge into a common exit channel (90) to a mass spectrometer. By appropriate operation of the gates (65) dividing the inlet channels, rapid switching between the samples that are analysed in the mass analyser can be achieved.

Abstract: A method and apparatus for Flow Injection Analysis (FIA) into Atmospheric Pressure Ion sources (API) including Electrospray (ES) and Atmospheric Pressure Chemical Ionization (APCI) sources whereby the sampling and spray needles are one and the same. The sampling and spray needle configured with an autoinjector apparatus or used in manual injection is introduced directly into a mating ES or APCI probe configured in an API source. Such a sampling and spray needle eliminates the need for injector valves, transfer lines or additional fluid delivery systems in FIA into API sources interfaced to mass spectrometers or other chemical analyzers. The use of a sampling and spray needle configuration reduces component costs, liquid dead volume, sample dilution effects, and minimizes cross contamination effects, solvent consumption and waste while increasing sample throughput.

Abstract: An apparatus with means for controlling ion generation is discussed. The apparatus comprises a plurality of ion sources, at least one counter electrode mounted downstream for the ion sources and at least one ion controlling element mounted relative to at least one of the ion sources. Each ion controlling element is alternated between a first condition where the operation of at least one of the ion sources is enabled and a second condition where the operation of at least one of the ion sources is disabled. This concept may also be extended to an ion source apparatus having a single ion source with an ion lens mounted relative thereto. The present invention also provides a method for controlling the operation of the aforementioned apparatus. The invention further provides an apparatus and a method for the generation of ion pulses.

Abstract: A micromechanical field asymmetric ion mobility filter for a detection system includes a pair of spaced substrates defining between them a flow path between a sample inlet and an outlet; an ion filter disposed in the path and including a pair of spaced filter electrodes, one electrode associated with each substrate; and an electrical controller for applying a bias voltage and an asymmetric periodic voltage across the ion filter electrodes for controlling the paths of ions through the filter.

Abstract: A microfluidic chip formed with multiple fluid channels terminating at a common electrospray ionization tip for mass spectrometric analysis. The fluid channels may be formed within a substrate plate that are in fluid communication with corresponding reservoirs. The electrospray tip can be formed along a defined portion of the substrate plate, wherein the electrospray tip includes an open-tip region at which the fluid channels converge. A top laminate plate may substantially enclose most portions of the fluid channels formed in the bottom polymer plate except for the open-tip region. Another aspect of the invention provides methods for conducting mass spectrometric analysis of multiple samples flowing through individual fluid channels in a single microfluidic chip that is formed with a convergent electrospray tip. The convergent electrospray tip includes an open or exposed distal pointed tip region.

Abstract: A method for introducing ions generated in a region of relatively high pressure into a region of relatively low pressure by providing at least two electrospray ion sources, providing at least two capillary inlets configured to direct ions generated by the electrospray sources into and through each of the capillary inlets, providing at least two sets of primary elements having apertures, each set of elements having a receiving end and an emitting end, the primary sets of elements configured to receive a ions from the capillary inlets at the receiving ends, and providing a secondary set of elements having apertures having a receiving end and an emitting end, the secondary set of elements configured to receive said ions from the emitting end of the primary sets of elements and emit said ions from said emitting end of the secondary set of elements.

Abstract: The present invention provides an apparatus and method for automated and rapid loading of a large number of samples for mass spectrometric analysis using various ionization methods (e.g. matrix assisted desorption by laser bombardment (MALDI) and atmosperic pressure ionization (API) methods such as electrospray). The aparatus utilizes microtiter plates to hold the sample, optical elements (e.g. fiber optic) to facilitate automated transport of the ions, and a multiple part capillary comprising at least two capillary sections joined with airtight seal by a union for use in mass spectrometry (particularly with ionization sources) to transport ions between pressure regions of a mass spectrometer for analysis is described herein. Preferably, the capillary is useful to transport ions from an elevated pressure ionization source to a first vacuum region of a mass analysis system.

Abstract: The present invention is directed toward an apparatus and methods for detection and identification of target radionuclides and threatening radionuclides that may be present in a sample volume. One aspect of the invention discloses a digital computational apparatus that determines similarity or identity to a target radionuclide or a threatening radionuclide. In another aspect, the invention discloses a high throughput apparatus for detection of a target radionuclide in a sample volume, or for identifying a target radionuclide present in a sample volume, or both, that includes a detecting means, an analyzing means, and an identifying means. In a further aspect the invention discloses a high throughput apparatus for communicating the presence of a target radionuclide in a sample volume, the identity of a target radionuclide in a sample volume, or both to appropriate personnel.

Abstract: An improved mass analyzer capable of parallel processing one or more analytes is set fourth. The mass analyzer comprises a mass filter unit having a plurality of ion selection chambers disposed in parallel with one another. Each of the plurality of ion selection chambers respectively includes an ion inlet lying in an inlet plane and an ion outlet lying in an outlet plane. The mass analyzer further includes a plurality of electrodes disposed in the ion selection chambers and at least one RF signal generator connected to the plurality of electrodes to produce a non-rotating, oscillating electric field in each ion selection chambers. A plurality of ion injectors are each coupled to inject an ion beam into the ion inlet of a respective ion selection chambers. The ions meeting predetermined m/Q requirements pass through the ion selection chambers to contact corresponding detection surfaces of an ion detector array.

Abstract: The present invention provides an apparatus and method for automated and rapid loading of a large number of samples for mass spectrometric analysis using various ionization methods (e.g. matrix assisted desorption by laser bombardment (MALDI) and atmosperic pressure ionization (API) methods such as electrospray). The aparatus utilizes microtiter plates to hold the sample, optical elements (e.g. fiber optic) to facilitate automated transport of the ions, and a multiple part capillary comprising at least two capillary sections joined with airtight seal by a union for use in mass spectrometry (particularly with ionization sources) to transport ions between pressure regions of a mass spectrometer for analysis is described herein. Preferably, the capillary is useful to transport ions from an elevated pressure ionization source to a first vacuum region of a mass analysis system.

Abstract: An interface apparatus, for coupling a plurality of ion source to a mass spectrometer has a plurality of ion sources for generating a plurality of ion beams. An inlet device for passing ion beams into the mass spectrometer is provided as is a device or mechanism for selecting one of the ion beams for passage through into the mass spectrometer and for blocking the other ion beams. An outlet provides a connection to a mass spectrometer. A corresponding method is provided.

Abstract: An improved mass analyzer capable of parallel processing one or more analytes is set forth. The mass analyzer comprises a mass filter unit having a plurality of ion selection chambers disposed in parallel with one another. Each of the plurality of ion selection chambers respectively includes an ion inlet lying in an inlet plane and an ion outlet lying in an outlet plane. The mass analyzer further includes a plurality of electrodes disposed in the ion selection chambers and at least one RF signal generator connected to the plurality of electrodes to produce a non-rotating, oscillating electric field in each ion selection chambers. A plurality of ion injectors are each coupled to inject an ion beam into the ion inlet of a respective ion selection chambers. The ions meeting predetermined m/Q requirements pass through the ion selection chambers to contact corresponding detection surfaces of an ion detector array.

Abstract: There is provided an analyzer system capable of easily improving the efficiency of a charge reduction due to ion/ion reactions. A mass spectrometer system includes: a first ion source for ionizing a sample to be measured; a second ion source for producing ions of a polarity reversed from that of the ions produced in said first ion source; an ion deflector for introducing and deflecting the ions of said first and second ion sources; an ion-trap mass spectrometer including a ring electrode and a pair of endcap electrodes; and a detector for detecting the ions ejected from the mass spectrometer, wherein the ions from said first and second ion sources are introduced together through the ion deflector into the ion-trap mass spectrometer; the ions from the two ion sources are mixed in the ion-trap mass spectrometer; and in that the ions are then detected in the detector.

Abstract: A mass analysis apparatus comprising a first ion source which ionizes a sample and produces sample ions, a second ion source which produces reactant ions having a polarity opposite to the polarity of the sample ions, and a mass spectrometer, wherein said second ion source is provided between said first ion source and said mass spectrometer apart from the axis of a flow of the sample ions discharged from said first ion source and emits reactant ions to the flow of sample ions discharged from said first ion source.

Abstract: There is provided an analyzer system capable of easily improving the efficiency of a charge reduction due to ion/ion reactions. A mass spectrometer system includes: a first ion source for ionizing a sample to be measured; a second ion source for producing ions of a polarity reversed from that of the ions produced in said first ion source; an ion deflector for introducing and deflecting the ions of said first and second ion sources; an ion-trap mass spectrometer including a ring electrode and a pair of endcap electrodes; and a detector for detecting the ions ejected from the mass spectrometer, wherein the ions from said first and second ion sources are introduced together through the ion deflector into the ion-trap mass spectrometer; the ions from the two ion sources are mixed in the ion-trap mass spectrometer; and in that the ions are then detected in the detector.

Abstract: An electrospray device, a liquid chromatography device and an electrospray-liquid chromatography system are disclosed. The electrospray device comprises a substrate defining a channel between an entrance orifice on an injection surface and an exit orifice on an ejection surface, a nozzle defined by a portion recessed from the ejection surface surrounding the exit orifice, and an electrode for application of an electric potential to the substrate optimize and generate an electrospray; and, optionally, additional electrode(s) to further modify the electrospray.

Abstract: A source of ions for an analyzer includes a reservoir for containing a liquid, a manifold having a plurality of nozzles, a conduit connecting the reservoir to the manifold and a counter electrode having a potential difference between the counter electrode and the nozzles to enable liquid to be ejected from the nozzles in droplets and to enable ions to be ejected from the droplets.

Abstract: A mass spectrometer has an ion source (10) with a plurality of atmospheric pressure sample ioniser (20) mounted in a front face (15) thereof. Each sample ioniser (20) extends into a corresponding sample region (30) and the tip of each sample ioniser is mounted at right-angles to a corresponding one of a plurality of entrance cones (50) each having entrance orifice (40) therein. Each entrance cone (50) in turn opens into an inlet channel having first and second parts (60, 70). The two parts of the inlet channel are separated by an electrical gate (65). The inlet channels corresponding to each entrance cone (50) all merge into a common exit channel (90) to a mass spectrometer. By appropriate operation of the gates (65) dividing the inlet channels, rapid switching between the samples that are analysed in the mass analyser can be achieved.

Abstract: An electrospray apparatus employing multiple electrospray needles mounted on a rotatable plate sequentially delivers multiple sample streams to a mass spectrometer for analysis. The electrospray device includes an electrospray chamber, a rotatable needle supporting plate, a plurality of electrospray needles mounted on the plate, and a charger for applying a charge to droplets delivered to the electrospray chamber by the needles. The rotatable electrospray apparatus provides fast repetitive screening of simultaneously operating chromatography columns with a single mass spectrometer.

Abstract: There is provided an analyzer system capable of easily improving the efficiency of a charge reduction due to ion/ion reactions. A mass spectrometer system includes: a first ion source for ionizing a sample to be measured; a second ion source for producing ions of a polarity reversed from that of the ions produced in said first ion source; an ion deflector for introducing and deflecting the ions of said first and second ion sources; an ion-trap mass spectrometer including a ring electrode and a pair of endcap electrodes; and a detector for detecting the ions ejected from the mass spectrometer, wherein the ions from said first and second ion sources are introduced together through the ion deflector into the ion-trap mass spectrometer; the ions from the two ion sources are mixed in the ion-trap mass spectrometer; and in that the ions are then detected in the detector.

Abstract: A mass analysis apparatus is capable of performing a plurality of measurements in parallel by mounting a plurality of ion sources onto one mass spectrometer and speedily switching the ion sources. The mass analysis apparatus comprises a plurality of ion sources; and a deflecting means for deflecting ions from at least one ion source among the plurality of ion sources so that the ions travel toward the mass spectrometer by producing an electric field.

Abstract: A high-frequency power supply apparatus for a plasma generation apparatus having a modulator for generating an intermittent high-frequency output on the basis of a modulation reference signal and a peak value setting signal, the high-frequency power supply apparatus having: a first control loop for comparing the peak value of the intermittent high-frequency output detected by a peak value detector with a preset peak value of the high-frequency output so that the output controller controls the peak value of the high-frequency output to be the preset peak value; and a second control loop for calculating an average value of the intermittent high-frequency output based on the preset peak setting value and a preset duty ratio setting value and generating a modulation reference signal for controlling the modulator on the basis of the average value of the high-frequency output detected by a monitor and the average value of the high-frequency output.

Abstract: A mass analysis apparatus is capable of performing a plurality of measurements in parallel by mounting a plurality of ion sources onto one mass spectrometer and speedily switching the ion sources. In a mass analysis apparatus for performing mass analysis by introducing ions produced in an ion source into a mass spectrometer, the mass analysis apparatus comprises a plurality of ion sources; and a deflecting means for deflecting ions from at least one ion source among the plurality of ion sources so that the ions travel toward the mass spectrometer by producing an electric field.

Abstract: A combinatorial chemistry system allows for the dual processing of different molecules coated on a library of beads. The system includes beads coated with different molecules on each bead, a bead holder, screening equipment and characterization equipment. Molecules on the beads are both screened and characterized simultaneously.

Abstract: The invention relates to a device and a method for the alternating operation of ion sources at mass spectrometers equipped with RF multipole ion guides. Designing at least one of the RF multiple ion guides movable perpendicular to the axis, makes it possible to perform a vacuum-internal source exchange, without having to vent the vacuum system.

Abstract: A mass analysis apparatus is capable of performing a plurality of measurements in parallel by mounting a plurality of ion sources onto one mass spectrometer and speedily switching the ion sources. The mass analysis apparatus comprises a plurality of ion sources; and a deflecting means for deflecting ions from at least one ion source among the plurality of ion sources so that the ions travel toward the mass spectrometer by producing an electric field.

Abstract: A mass spectrometer utilizing an inlet nozzle having multiple atmospheric pressure inlets to provide multiple streams of different fluid samples such that their chemical contents can be analyzed simultaneously within a single mass spectrometer with limited or no interaction between the individual streams of sample. This capability is made possible by positioning the nozzle within a nozzle housing wherein the nozzle defines a plurality of orifices extending therethrough from the atmospheric pressure environment of the orifice inlets to the reduced air pressure environment of the nozzle outlets without allowing any mixing between the samples as they pass through the nozzle. Samples are provided to the nozzle by an electrospray ionization needle which simultaneously ionizes the fluid and supplies it to one individual nozzle orifice.

Abstract: A method and apparatus for Flow Injection Analysis (FIA) into Atmospheric Pressure Ion sources (API) including Electrospray (ES) and Atmospheric Pressure Chemical Ionization (APCI) sources whereby the sampling and spray needles are one and the same. The sampling and spray needle configured with an autoinjector apparatus or used in manual injection is introduced directly into a mating ES or APCI probe configured in an API source. Such a sampling and spray needle eliminates the need for injector valves, transfer lines or additional fluid delivery systems in FIA into API sources interfaced to mass spectrometers or other chemical analyzers. The use of a sampling and spray needle configuration reduces component costs, liquid dead volume, sample dilution effects, and minimizes cross contamination effects, solvent consumption and waste while increasing sample throughput.

Abstract: A mass analysis apparatus is provided. The mass analysis apparatus is capable of performing a plurality of measurements in parallel by mounting a plurality of ion sources onto one mass spectrometer and speedily switching the ion sources.

Abstract: A mass analysis apparatus is provided. The mass analysis apparatus is capable of performing a plurality of measurements in parallel by mounting a plurality of ion sources onto one mass spectrometer and speedily switching the ion sources.

Abstract: The ionization chamber consists of a plurality of ports to accept multiple identical devices or varying devices. Ports may be arranged at various positions on the ionization chamber and at various angles with respect to the sampling orifice leading into the vacuum chamber of the mass spectrometer. A plurality of sprayers may operate in a time modulated manner and thereby the simultaneous multiplexed analysis of a multitude of samples is facilitated.

Abstract: An electrospray apparatus employing multiple electrospray needles mounted in a circular arrangement sequentially delivers multiple sample streams to a mass spectrometer for analysis. One electrospray device includes an electrospray chamber, a rotatable needle supporting plate, a plurality of electrospray needles mounted on the plate, and a charger for applying a charge to droplets delivered to the electrospray chamber by the needles. Another electrospray device includes an electrospray chamber, a plurality of electrospray needles arranged in a circular arrangement, a charger, and a rotatable member for delivering gas phase ions from one needle at a time to the mass spectrometer. The rotatable electrospray apparatus provides fast repetitive analysis of simultaneously operating chromatography columns or other sample streams with a single mass spectrometer.

Abstract: The present invention relates to a method of detecting single nucleotide polymorphisms by providing a target nucleic acid molecule, an oligonucleotide primer complementary to a portion of the target nucleic acid molecule, a nucleic acid polymerizing enzyme, and a plurality of types of nucleotide analogs. The target nucleic molecule, the oligonucleotide primer, the nucleic acid polymerizing enzyme, and the nucleotide analogs, each type being present in a first amount, are blended to form an extension solution where the oligonucleotide primer is hybridized to the target nucleic acid molecule to form a primed target nucleic acid molecule and the nucleic acid polymerizing enzyme is positioned to add nucleotide analogs to the primed target nucleic acid molecule at an active site. The oligonucleotide primer in the extension solution is extended by using the nucleic acid polymerizing enzyme to add a nucleotide analog to the oligonucleotide primer at the active site.

Abstract: An electrospray apparatus employing multiple electrospray needles mounted on a rotatable plate sequentially delivers multiple sample streams to a mass spectrometer for analysis. The electrospray device includes an electrospray chamber, a rotatable needle supporting plate, a plurality of electrospray needles mounted on the plate, and a charger for applying a charge to droplets delivered to the electrospray chamber by the needles. The rotatable electrospray apparatus provides fast repetitive screening of simultaneously operating chromatography columns with a single mass spectrometer.

Abstract: A method of analyzing each of a plurality of fluid samples (11-16), comprising, simultaneously spraying a plurality fluid samples (11-16) from electrospray needle array (20) towards mass spectrometer (50); positioning blocking device (40) to block all but one (32-34) of fluid samples (31-34) from reaching mass spectrometer (50); moving electrospray needle array (20) and blocking device (40) relative to one another to permit at least two of the plurality of fluid samples (31, 32) to reach mass spectrometer (50) one at a time; and analyzing the mass spectrum of fluid samples (31, 32, 33, 34) sequentially reaching mass spectrometer (50).

Abstract: An LC-MS is provided with a plurality of ion sources which can be quickly and selectively disposed at a fixed working position, and capable of analyzing a large variety of substances. An APCI unit (1) and an ESI unit (2) are fixedly mounted on a rotating table (11) or a sliding carriage (19). The rotating table (11) is held for rotation on a base (13) with a holding ring (12), and the sliding carriage (19) is held for linear sliding movement on a bearing (22) on a base (21) with a holding member (20) and is moved by a feed screw (23). Either the APCI unit (1) or the ESI unit (2) is selectively disposed at a fixed working position opposite to a first aperture (16), a second aperture (17) and a mass spectrometric unit (18) to ionize a substance for mass spectrometry.

Abstract: The apparatus and method of the present invention multiplexes or gates particle beams to provide continuous data collection useful in time-of-flight mass spectrometry. The multiple particle beams are gated or combined to achieve an overall 100% duty cycle. This allows continuous data collection, thereby realizing the full advantages of abundance sensitivity and mass resolution in time-of-flight mass spectrometry.

Abstract: A composite apparatus is disclosed which includes in combination a secondary ion mass spectrometry instrument and a scanning electron microscope. A liquid metal ion source and an ion source other than the liquid metal ion source are installed in the same apparatus so that an ion beam emitted from the liquid metal ion source and an ion beam emitted from the ion source other than the liquid metal ion source are aligned with each other on a primary beam axis which is an optical axis of an irradiating system. The liquid metal ion source is disposed in rear of a primary ion separating device which mass-separates the ion beam emitted from the ion source other than the liquid metal ion source. Further, an electron gun is installed in the same apparatus so that an electron beam emitted from the electron gun is aligned with the ion beam on the primary beam axis.

Abstract: A mass spectrometer of the type wherein a solenoidal magnet produces a magnetic field that includes a region along its geometric central axis. That region is a region of high field intensity and high homogeneity with magnetic flux lines in the region being generally parallel to the magnet central axis. A high vacuum is established in the region and a sample cell is positioned at or within the region in which sample ions are formed, trapped, excited and detected. An ionizing device is positioned outside of the region and off the central axis while an additional ionizing device may be positioned on the central axis. In a preferred embodiment, the off axis ionizing device may be supported for movement relative to the central axis. A preferred ionizing device for the off axis device is an electron gun.

Abstract: A device and method is disclosed for detecting elemental ions by colliding a beam of the elemental ions with a beam of collision partners having an opposite charge to generate element specific radiation. The radiation whose wavelength is specific to the element is filtered and detected as a measure of the elemental ion. In one case using energy matched collision exchange partners, metal ions of an opposite charge are used as collision partners.

Abstract: The invention provides a process and device for the ionic analysis of an insulating sample brought to a given negative potential, of the type in which a target on the surface of the sample to be analyzed is bombarded by means of a primary electron beam and negative ions emitted by the bombarded target are used for producing an ion image of the sample. An electron beam whose normal speed component cancels out just at level of the surface of the target is directed perpendicularly to the target.The device comprises for this purpose a filament, brought substantially to the same negative potential as the sample, which emits the electron beam. The electron beam, after emission, is deflected by a magnetic prism so as to be brought into coincidence with the optical axis of the negative ion beam emitted by the target.

Abstract: A method and an apparatus are disclosed for adapting a conventional quadrupole mass spectrometer to substantially simultaneously produce and record both positive and negative ions. The apparatus includes a control circuit for rapidly switching the repeller, source and lens electrodes of a quadrupole mass spectrometer between positive and negative potentials. This switching of the potentials, along with the selection of appropriately favorable ionization conditions, permits the generation of suitable streams of positive and negative ions. A dual electron multiplier detector is used for separately sensing the positive and negative ions transmitted through the quadrupole mass spectrometer. The disclosed method and apparatus are particularly suitable for obtaining accurate mass measurements using a quadrupole mass spectrometer.

Abstract: A method and an apparatus are disclosed for adapting a conventional quadrupole mass spectrometer to substantially simultaneously produce and record both positive and negative ions. The apparatus includes a control circuit for rapidly switching the repeller, source and lens electrodes of a quadrupole mass spectrometer between positive and negative potentials. This switching of the potentials, along with the selection of appropriately favorable ionization conditions, permits the generation of suitable streams of positive and negative ions. A dual electron multiplier detector is used for separately sensing the positive and negative ions transmitted through the quadrupole mass spectrometer. The disclosed method and apparatus are particularly suitable for obtaining accurate mass measurements using a quadrupole mass spectrometer.