EP0575777B1 - Verfahren zur Verwendung eines Massenspektrometers - Google Patents

Verfahren zur Verwendung eines Massenspektrometers Download PDF

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Publication number
EP0575777B1
EP0575777B1 EP19930108670 EP93108670A EP0575777B1 EP 0575777 B1 EP0575777 B1 EP 0575777B1 EP 19930108670 EP19930108670 EP 19930108670 EP 93108670 A EP93108670 A EP 93108670A EP 0575777 B1 EP0575777 B1 EP 0575777B1
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EP
European Patent Office
Prior art keywords
ions
sample
trap
ion trap
field
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EP19930108670
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English (en)
French (fr)
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EP0575777A3 (de
EP0575777A2 (de
Inventor
Gregory J. Wells
Mingda Wang
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Varian Medical Systems Inc
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Varian Associates Inc
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Priority to EP97104015A priority Critical patent/EP0786796B1/de
Priority to EP98103434A priority patent/EP0852390B1/de
Publication of EP0575777A2 publication Critical patent/EP0575777A2/de
Publication of EP0575777A3 publication Critical patent/EP0575777A3/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/10—Ion sources; Ion guns
    • H01J49/14—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers
    • H01J49/145—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers using chemical ionisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/004—Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn
    • H01J49/0045—Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn characterised by the fragmentation or other specific reaction
    • H01J49/005—Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn characterised by the fragmentation or other specific reaction by collision with gas, e.g. by introducing gas or by accelerating ions with an electric field
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers
    • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
    • H01J49/4205—Device types
    • H01J49/424—Three-dimensional ion traps, i.e. comprising end-cap and ring electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers
    • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
    • H01J49/426—Methods for controlling ions
    • H01J49/427—Ejection and selection methods

Definitions

  • the present invention relates to methods of using ion trap mass spectrometers ("ion traps”) by applying supplemental voltages to the trap, and is particularly related to methods of operating ion traps in the chemical ionization mode, and for conducting multiple mass spectroscopy experiments ("MS n ").
  • ion traps mass spectrometers
  • the quadrupole ion trap is a well-known device for performing mass spectroscopy.
  • a ion trap comprises a ring electrode and two coaxial end cap electrodes defining an inner trapping volume.
  • Each of the electrodes preferably has a hyperbolic surface, so that when appropriate AC and DC voltages (conventionally designated “V” and “U”, respectively) are placed on the electrodes, a quadrupole trapping field is created. This may be simply done by applying a fixed frequency (conventionally designated "f") AC voltage between the ring electrode and the end caps. The use of an additional DC voltage is optional.
  • an ion trap is operated by introducing sample molecules into the ion trap where they are ionized.
  • ions may be stably contained within the trap for relatively long periods of time. Under certain trapping conditions, a large range of masses may be simultaneously held within the trap.
  • Various means are known for detecting ions that have been so trapped.
  • One known method is to scan one or more of the trapping parameters so that ions become sequentially unstable and leave the trap where they may be detected using an electron multiplier or equivalent detector.
  • Another method is to use a resonance ejection technique whereby ions of consecutive masses can be sequentially scanned out of the trap and detected.
  • ⁇ is equal to 2 ⁇ f.
  • the equations set forth actually relate to stability in the direction of the z axis, i.e. , the direction of the axis of the electrodes. Ions will become unstable in this direction before becoming unstable in the r direction, i.e. , a direction radial to the axis. Thus, it is normal to limit consideration of stability to z direction stability.
  • the differential in stability results in the fact that unstable ions will leave the trap in the z direction, i.e. , axially.
  • the DC voltage, U is set at 0.
  • U the DC voltage
  • a z 0 for all mass values.
  • the value of q z will be inversely proportional to the mass of the particle, i.e., the larger the value of the mass the lower the value of q z .
  • V the higher the value of q z .
  • EI electron impact ionization
  • Chemical ionization involves the use of a reagent gas which is ionized, usually by EI within the trap, and allowed to react with sample molecules to form sample ions.
  • Commonly used reagent gases include methane, isobutane, and ammonia. Chemical ionization is considered to be a "softer" ionization technique. With many samples CI produces fewer ion fragments than the EI technique, thereby simplifying mass analysis.
  • Chemical ionization is a well known technique that is routinely used not only with quadrupole ion traps, but also with most other conventional types of mass spectrometers such as quadrupole mass filters, etc.
  • photoionization is a well known technique that, similar to electron impact ionization, will affect all molecules contained in the trap.
  • ion trap mass spectrometer systems in use today include a gas chromatograph ("GC") as a sample separation and introduction device.
  • GC gas chromatograph
  • sample which elutes from the GC continuously flows into the mass spectrometer, which is set up to perform periodic mass analyses.
  • Such analyses may, typically, be performed at a frequency of about one scan per second. This frequency is acceptable since peaks typically elute from a modern high resolution GC over a period of several seconds to many tens of seconds.
  • a continuous flow of reagent gas is maintained. As a practical matter it is undesirable to interrupt the flow of sample gas from the GC to the ion trap.
  • the trap when operating using the RF only method, which is preferred in the '367 patent and which is the method used in all known commercial embodiments of the ion trap, the trap inherently traps all masses above a cut-off mass which is set by the value of the RF trapping voltage.
  • V When V is set low enough the trap inherently has a poor efficiency in trapping high mass ions due to space charge effects.
  • a theoretical way of looking at this is that the volume of the interior of the ion trap which stores ions of a particular mass is proportional to the value of V and is inversely proportionally to the mass.
  • V a smaller volume of the ion trap is available to store high mass ions than low mass ones.
  • the volume is quite small the number of ions than can be stored is reduced due to space charge effects.
  • Some reagent molecules form a variety of ions having different masses. Ionization at RF voltages substantially below that necessary to trap the lowest mass reagent ion, which is necessary to remove most of the high mass sample ions, will reduce the number of reagent ions that are trapped, as well as the high mass sample ions. This effect is related to mass so that the higher mass reagent ions will be disproportionately lost from the trap.
  • the method of the lowering the trapping voltage is not applicable, however, to solving this problem since it would not eliminate low mass reagent ions from the trap.
  • One solution used to solve this problem is to raise the RF trapping voltage so as not to store the low mass reagent ions.
  • this has the undesired effect of changing the trapping conditions from those which are normally used. For example, when the trapping voltage is set to store ions of mass 20 and above, the average ionizing energy of electron entering the trap is 70 eV. Raising the trapping voltage to store only ions of mass 45 and above, so as to eliminate methane reagent ions at mass 43, would double the average electron energy. Such an increase would change the mass spectrum of many compounds and would reduce the trapping efficiency for the sample ions.
  • product ions In a CI process it is desirable to optimize the number of product ions that undergo mass analysis. If there are too few product ions, the mass analysis will be noisy, and if there are too many product ions resolution and linearity will be lost.
  • the formation of product ions is a function of the number of reagent ions present in the trap, the number of sample molecules in the trap, the reaction rate between the reagent ions and the sample ions, and the reaction time during which reagent ions are allowed to react with sample molecules.
  • This prescan is a complete CI scan cycle in which the ionization and reaction times are fixed at values smaller than those that would be used in a normal analytical scan, and in which the product ions are scanned out of the trap faster than in a normal analytical scan.
  • the resulting product ions that are ejected from the trap during the prescan are not mass resolved and the ion signal is only integrated to give a total product ion signal.
  • the prescan the total number of product ions in the trap are measured and the parameters, i.e. , the ionization time and/or the reaction time for the subsequent mass analysis scan are adjusted.
  • the patent covers a two-step process consisting of first conducting a "prescan" of the contents of the ion trap to obtain a gross determination of the number of product ions in the trap, followed by a mass analysis scan of the type taught in the '367 patent, with the parameters of mass analysis scan being adjusted based on the data collected during the prescan.
  • the disadvantage of the prior art method of extending the dynamic range by using a prescan to estimate the sample amounts in the trap is that it requires additional time to perform the prescan, and thus fewer analytical scans can be performed in the same time period. Not only does each of the prescans consume time, but each produces data which has no independent value apart from its use in adjusting the parameters for the mass analysis scan.
  • MS n experiments There is a demand to employ the ion trap mass spectrometer in conducting so-called MS n experiments.
  • MS n experiments a single ion species is isolated in the trap and is dissociated into fragments.
  • the fragments created directly from the sample species are known in the art as daughter ions, and the sample is referred to as the parent ion.
  • the daughter ions may also be fragmented to create granddaughter ions, etc.
  • the value of n refers to the number of ion generations that are formed; thus, is an MS 2 or MS/MS experiment, only daughter ions are formed and analyzed.
  • the ions oscillate within the trap they collide with molecules of the damping gas in the trap and undergo collision induced dissociation thereby forming daughter ions.
  • the ions can similarly be fragmented.
  • the difficulty with the method of the '101 patent is that the precise resonant frequency of the ions of interest cannot be determined a priori but must be determined a posteriori .
  • the resonant frequency of an ion also referred to as its secular frequency, varies with the ion mass-to-charge ratio, the number of ions in the trap, hardware variances and other parameters which cannot be precisely determined in a simple way.
  • the precise resonant frequency must of an ion species be determined empirically. While empirical determination can be performed without great difficulty when a static sample is introduced into the trap, it is quite difficult to accomplish when a dynamic sample, such as the output of a GC, is used.
  • One prior art approach to overcoming the foregoing problem in determining the precise resonant frequency of a sample ion of interest is to use a broadband excitation centered around the calculated frequency.
  • a broadband excitation may have a bandwidth of about 10 KHz.
  • Another method is to conduct a frequency prescan, i.e. , sweep the supplemental field across a frequency range in the area of interest and observe the resonant frequency empirically.
  • a frequency prescan i.e.
  • EP-0 362 432 a method is disclosed for analyzing a sample by eliminating specific ions by means of a supplemental RF-field. Sample ions remaining in the storage field are then mass-analyzed.
  • the invention comprises adjusting the trapping field parameters of an ion trap mass spectrometer so that ions having mass-to-charge ratios within a desired range will be stably trapped, introducing sample and reagent gas into the trap, ionizing the contents of the trap, and eliminating sample ions from the trap by applying a supplemental AC voltage to the trap which cause the sample ions, but not the reagent ions, to be ejected from the trap.
  • the supplemental AC voltage may be a broadband voltage having frequency components corresponding to the resonant frequencies of the higher mass sample ions.
  • FIG. 1 is a plot of the stability diagram associated with an ion trap.
  • FIG. 2 is a partially schematic view of apparatus used to practice the method of the present inventions.
  • FIG. 3 is a graph showing the control of the supplemental broadband AC field in relation to the gating of the electron beam used for electron impact ionization in accordance with the present invention.
  • FIGS. 4A - 4G are mass spectra of various samples comparing the present invention with the method of the prior art.
  • FIG. 5 shows an alternate arrangement of the apparatus of FIG. 2 for use in practicing the present invention.
  • Ion trap 10 shown schematically in cross-section, comprises a ring electrode 20 coaxially aligned with upper and lower end cap electrodes 30 and 35, respectively.
  • the trap electrodes have hyperbolic inner surfaces, although other shapes, for example, electrodes having a cross-sections forming an arc of a circle, may also be used to create trapping fields.
  • the design and construction of ion trap mass spectrometers is well-known to those skilled in the art and need not be described in detail.
  • a commercial model ion trap of the type described herein is sold by the assignee hereof under the model designation Saturn.
  • Sample gas for example from a gas chromatograph 40, is introduced into the ion trap 10. Since GC's typically operate at atmospheric pressure while ion traps operate at greatly reduced pressures, pressure reducing means (not shown) are required. Such pressure reducing means are conventional and well known to those skilled in the art. While the present invention is described using a GC as a sample source, the source of the sample is not considered a part of the invention and there is no intent to limit the invention to use with gas chromatographs. Other sample sources, such as, for example, liquid chromatographs with specialized interfaces, may also be used.
  • Sample and reagent gas that is introduced into the interior of ion trap 10 may be ionized by electron bombardment as follows.
  • a beam of electrons such as from a thermionic filament 60 powered by filament power supply 65, is controlled by a gate electrode 70.
  • the center of upper end cap electrode 30 is perforated (not shown) to allow the electron beam generated by filament 60 and gate electrode 70 to enter the interior of the trap.
  • the electron beam collides with sample and reagent molecules within the trap thereby ionizing them.
  • Electron impact ionization of sample and reagent gases is also a well-known process that need not be described in greater detail.
  • a trapping field is created by the application of an AC voltage having a desired frequency and amplitude to stably trap ions within a desired range of mass-to-charge ratios.
  • RF generator 80 is used to create this field, and is applied to the ring electrode. While it is well known that one may also apply a DC voltage to modify the trapping field and to work at a different portion of the stability diagram of FIG. 1, as a practical matter, commercially available ion traps all operate using an AC trapping field only.
  • a variety of methods are known for determining the mass-to-charge ratios of the ions which are trapped in the ion trap to thereby obtain a mass spectrum of the sample.
  • One known method is to scan the trap so that ions of sequential mass-to-charge ratio are ejected in order.
  • a first known method of scanning the trap is to scan one of the trapping parameters, such as the magnitude of the AC voltage, so that ions sequentially become unstable and leave the trap where they are detected using, for example, electron multiplier means 90.
  • a supplemental AC dipole voltage applied across end caps 30 and 35 of ion trap 10.
  • a voltage may be created by a supplemental waveform generator 100, coupled to the end caps electrodes by transformer 110.
  • the supplemental AC field is used to resonantly eject ions in the trap.
  • Each ion in the trap has a resonant frequency which is a function of its mass-to-charge ratio and of the trapping field parameters.
  • Ions ejected in this manner can also be detected by electron multiplier 90 or an equivalent detector.
  • the contents of the trap can be scanned in sequential order by either scanning the frequency of the supplemental RF field or by scanning one of the trapping parameters such as the magnitude of V, the AC trapping voltage. As a practical matter, scanning the magnitude of the AC voltage is preferred.
  • supplemental RF generator 100 which may also be used for scanning the trap as described above, is capable of generating a broadband RF field which is used to resonantly eject sample ions created by EI during the time that the reagent gas is being ionized.
  • FIG. 3(a) shows the gating of the electron beam used to ionize the reagent gas. Beginning at t1 and ending at t2, electron gate 70 is turned on to allow the electron beam to enter the trap to form reagent ions from the neutral reagent gas. As shown in FIG.
  • supplemental waveform generator 100 applies a broadband signal to the end caps of the trap, 30, 35, for a period of time that begins at t1 and ends at t3. As shown, the broadband excitation exceeds the gate time. Alternately, the supplemental broadband signal could be applied starting at a time later than t1, or even later than t2, i.e. , after the electron ionization is complete. Likewise, the supplemental signal could also start at a time prior to t1. The important aspect being that the supplemental field for elimination of unwanted sample ions be kept "on" for a period of time extending after the end of the period during which ions are created.
  • the broadband AC voltage applied to the end caps can either be out of phase (dipole excitation) or in phase (quadrupole excitation).
  • An alternative method of obtaining quadrupole excitation is the application of the supplemental waveform to the ring electrode as shown in FIG. 5, rather than to the end caps.
  • the supplemental waveform contains a range of frequencies of sufficient amplitude to eject unwanted sample ions of mass greater than the highest mass reagent ion, by means of resonant power absorption by the trapped ions.
  • Each of the sample ions is in resonance with a frequency component of the supplementary waveform. Accordingly, they absorb power from the supplementary field and leave the trapping field. After the supplemental field has ejected the unwanted ions it is turned off and the CI reagent ions react with the sample molecules to produce CI sample ions. These ions are then scanned from the trap for detection in a conventional manner as described above.
  • the supplemental waveform described above is broadband and has a first frequency component corresponding to the lowest mass to be ejected and a last frequency corresponding to the highest mass to be ejected. Between the first and last frequencies are a series of discrete frequency components which may be spaced evenly or unevenly, and which may have phases that are either random or with a fixed functional relationship.
  • the amplitudes of the frequency components can either be uniform or they can be tailored to a functional form so as to compensate for frequency dependencies of the hardware or to compensate for the distribution of q values due to the distribution of the masses that are stored in the trap.
  • the broadband waveform has a sufficient number of frequency components so that any ion with a resonant frequency between the first and last components of the waveform will be resonantly ejected by this supplemental field.
  • all sample ions formed during EI will be eliminated from the trap before the mass analysis scan and there will be no gaps in the mass range that is affected.
  • the reagent gases that are used in CI experiments are all low in molecular weight such that the reagent ions formed during EI of the contents of the trap will, in almost all cases, be lower in mass-to-charge ratio than the sample ions.
  • a specific frequency may be added to the broadband excitation to cause that specific mass to be ejected along with others.
  • the advantage of the invention over prior art is the ability to remove unwanted sample ions formed by EI during the ionization of the CI reagent gas.
  • the ability to reject these ions will allow longer ionization times and greater emission currents to be used, thus increasing the sensitivity of CI.
  • FIG. 4A shows the residual EI spectrum of a sample of tetrachloroethane using the scan conditions that are used in the prior art method.
  • FIG. 4B shows the elimination of the sample ions formed during the ionization step using the broadband waveform.
  • FIG. 4C shows the residual EI spectrum of a sample of trichloroethane and PFTBA with methane reagent gas present in the trap using the prior art method.
  • FIG. 4D shows the elimination of the sample ions formed during the ionization step using the broadband waveform of the present invention. It can be seen that the reagent ions at mass 43 are still present even though the sample ions that are just above them in mass are removed.
  • FIG. 4E shows the spectrum under the same conditions as in FIG.
  • FIG. 4F shows a spectrum of hexachlorobenzene using the prior art method. A mixture of EI ion fragments are observed at mass 282, 284, 286, 288 and 290. In addition, ions due to the protonated sample (from CI) are observed at mass 283, 285, 287, 289 and 291.
  • FIG. 4G shows the spectrum using the method described herein. It can be seen that the unwanted ions from the EI process are almost completely removed.
  • data obtain from one scan are used, if necessary, to adjust the parameters of the subsequent scan to ensure that the trap is operated within its dynamic range.
  • the amplitude of the most intense ion of a scan (the base peak) is used to adjust the ionization and/or reaction time for the next scan.
  • the magnitude of the base peak is used to adjust the ionization and reaction times for the subsequent scan so as to maintain a substantially constant number of ions of the base peak. Since most of the charge ejected from the trap during the scan is due to the base peak, it is a good representation of the total amount of charge from the sample in the trap. By keeping the total sample charge nearly constant in the trap the dynamic range of the sample can be increased.
  • the mass spectral information from one scan it is possible to adjust the parameters of the subsequent mass analysis scan to focus, for example, on only particular sample ions of interest, i.e. , to optimize for a particular species.
  • both the reaction time and the ionization time are changed in a set ratio. This makes it easier to normalize the results from one scan to the next.
  • An advantage of this inventive method is the reduction in the scan time for large dynamic range samples. This is accomplished by using the intensity of the base peak from the previous scan as a measure of the amount of sample in the trap; thus eliminating the need for a time-consuming prescan as is used in the prior art.

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Claims (23)

  1. Verfahren zur Verwendung eines Ionenfallen-Massenspektrometers im chemischen Ionisationsmodus, das folgende Schritte umfaßt:
    Einstellen der Einfangfeldparameter eines Ionenfallen-Massenspektrometers derart, daß Ionen mit Verhältnissen von Masse zu Ladung innerhalb eines gewünschten Bereichs in der Ionenfalle (10) stabil eingefangen werden;
    Einleiten eines Probengases in das Ionenfallen-Massenspektrometer;
    Einleiten eines Reagenzgases (50) in das Ionenfallen-Massenspektrometer;
    Ionisieren des Proben- und des Reagenzgases (50) in der Ionenfalle (10), so daß Proben- und Reagenzionen mit Verhältnissen von Masse zu Ladung innerhalb des gewünschten Bereichs in der Ionenfalle (10) gebildet werden; und
    gekennzeichnet ist durch den Schritt des Anlegens eines zusätzlichen Wechselstromfeldes an die Ionenfalle (10), um zu bewirken, daß Probenionen, die während des Ionisationsschritts gebildet werden, aus der Ionenfalle (10) ausgestoßen werden,
    wobei das zusätzliche Wechselstromfeld an die Ionenfalle so angelegt wird, daß es nicht später als der Zeitpunkt (t1), zu dem der Ionisationsschritt anfängt, beginnt und für einen Zeitraum (t3) andauert, nachdem der Ionisationsschritt vollendet wurde (t2), und
    wobei das zusätzliche Wechselstromfeld eine Breitbandanregung darstellt, um zu bewirken, daß die Probenionen frequenzabhängig aus der Ionenfalle (10) ausgestoßen werden, und wobei die in dem zusätzlichen Breitband-Wechselstromfeld enthaltene höchste Frequenzkomponente geringer ist als die Frequenz, die erforderlich ist, um zu bewirken, daß die Reagenzionen die Ionenfalle (10) verlassen, so daß das zusätzliche Breitband-Wechselstromfeld bewirkt, daß nur Probenionen frequenzabhängig aus der Ionenfalle (10) ausgestoßen werden.
  2. Verfahren nach Anspruch 1, wobei der
    Ionisationsschritt das Aussetzen des Inhalts der Ionenfalle (10) einem Elektronenstrahl umfaßt, so daß die Proben- und Reagenzionen durch Elektronenstoß-Ionisation gebildet werden.
  3. Verfahren nach Anspruch 1, wobei der Ionisationsschritt das Aussetzen des Inhalts der Ionenfalle (10) einem Licht umfaßt, so daß die Proben- und Reagenzionen durch Photoionisation gebildet werden.
  4. Verfahren nach einem der Ansprüche 1 bis 3, wobei das zusätzliche Wechselstromfeld ein Quadrupolfeld ist.
  5. Verfahren nach einem der Ansprüche 1 bis 3, wobei das zusätzliche Wechselstromfeld annähernd ein Dipolfeld ist.
  6. Verfahren nach einem der Ansprüche 1 bis 3, wobei das zusätzliche Wechselstromfeld ein Monopolfeld ist.
  7. Verfahren nach einem der Ansprüche 1 bis 6, wobei das zusätzliche Wechselstromfeld an die Abschlußkappenelektroden (30, 35) der Ionenfalle (10) angelegt wird.
  8. Verfahren nach einem der Ansprüche 1 bis 6, wobei das zusätzliche Wechselstromfeld an die Ringelektrode (20) der Ionenfalle (10) angelegt wird.
  9. Verfahren nach einem der Ansprüche 1 bis 8, wobei das zusätzliche Wechselstromfeld eine höchste Frequenz aufweist, die dem aus der Falle (10) auszustoßenden Probenion mit dem geringsten Verhältnis von Masse zu Ladung entspricht, und eine niedrigste Frequenz aufweist, die dem aus der Falle (10) auszustoßenden Probenion mit dem höchsten Verhältnis von Masse zu Ladung entspricht.
  10. Verfahren nach einem der Ansprüche 1 bis 8, wobei das zusätzliche Wechselstromfeld eine Reihe von diskreten Frequenzkomponenten zwischen der höchsten und der niedrigsten Frequenz umfaßt, so daß im wesentlichen alle Probenionen in der Falle (10) durch das zusätzliche Wechselstromfeld ausgestoßen werden.
  11. Verfahren nach Anspruch 10, wobei die diskreten Frequenzkomponenten in gleichen Abständen angeordnet sind.
  12. Verfahren nach Anspruch 10, wobei die diskreten Frequenzkomponenten in ungleichen Abständen angeordnet sind.
  13. Verfahren nach Anspruch 10, wobei die diskreten Frequenzkomponenten willkürliche Phasen besitzen.
  14. Verfahren nach Anspruch 10, wobei die diskreten Frequenzkomponenten Phasen mit einer festen funktionellen Beziehung besitzen.
  15. Verfahren nach Anspruch 10, wobei die diskreten Frequenzkomponenten gleiche Amplituden aufweisen.
  16. Verfahren nach Anspruch 10, wobei die diskreten Frequenzkomponenten Amplituden aufweisen, die auf eine ausgewählte Funktionsform zugeschnitten sind.
  17. Verfahren nach einem der Ansprüche 1 bis 16, das außerdem den Schritt umfaßt, daß die Probenionen mit den Reagenzionen für einen ausgewählten Reaktionszeitraum reagieren können, nachdem die während des Ionisationsschritts gebildeten Probenionen aus der Falle (10) entfernt wurden, wobei die Probenionen durch chemische Ionisation gebildet werden.
  18. Verfahren nach Anspruch 17, wobei das Einfangfeld während des Ionisations- und des Reaktionsschritts konstant gehalten wird.
  19. Verfahren nach Anspruch 17, das außerdem den Schritt des Abtastens der Ionenfalle (10), nachdem die Probenionen durch chemische Ionisation gebildet wurden, umfaßt, so daß Probenionen mit fortlaufenden Verhältnissen von Masse zu Ladung aus der Falle ausgestoßen und der Reihe nach erfaßt werden.
  20. Verfahren nach Anspruch 19, das außerdem das Wiederholen der Schritte von Anspruch 17 nach dem Einstellen des Reaktionszeitraums auf der Basis der Größe des während des Abtastschritts erfaßten größten Maximums umfaßt.
  21. Verfahren nach Anspruch 19, das außerdem das Wiederholen der Schritte von Anspruch 17 nach dem Einstellen der Ionisationszeit auf der Basis der Größe des während des Abtastschritts erfaßten größten Maximums umfaßt.
  22. Verfahren nach Anspruch 19, das außerdem das Wiederholen der Schritte von Anspruch 17 nach dem Einstellen sowohl des Zeitraums für den Ionisationsschritt als auch des Reaktionszeitraums auf der Basis der Größe des während des Abtastschritts erfaßten größten Maximums umfaßt.
  23. Verfahren nach Anspruch 19, wobei der Reaktionszeitraum so eingestellt wird, daß die Gesamtmenge an Ladung in der Ionenfalle (10) von einer Abtastung zur nächsten im wesentlichen konstant bleibt.
EP19930108670 1992-05-29 1993-05-28 Verfahren zur Verwendung eines Massenspektrometers Expired - Lifetime EP0575777B1 (de)

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EP98103434A EP0852390B1 (de) 1992-05-29 1993-05-28 Verfahren zum Betreiben eines Ionenfallen-Massenspektrometers

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US5448061A (en) * 1992-05-29 1995-09-05 Varian Associates, Inc. Method of space charge control for improved ion isolation in an ion trap mass spectrometer by dynamically adaptive sampling
US5291017A (en) * 1993-01-27 1994-03-01 Varian Associates, Inc. Ion trap mass spectrometer method and apparatus for improved sensitivity
US5396064A (en) * 1994-01-11 1995-03-07 Varian Associates, Inc. Quadrupole trap ion isolation method
DE4425384C1 (de) * 1994-07-19 1995-11-02 Bruker Franzen Analytik Gmbh Verfahren zur stoßinduzierten Fragmentierung von Ionen in Ionenfallen
US5714755A (en) * 1996-03-01 1998-02-03 Varian Associates, Inc. Mass scanning method using an ion trap mass spectrometer
DE19932839B4 (de) * 1999-07-14 2007-10-11 Bruker Daltonik Gmbh Fragmentierung in Quadrupol-Ionenfallenmassenspektrometern
JP4384542B2 (ja) 2004-05-24 2009-12-16 株式会社日立ハイテクノロジーズ 質量分析装置
DE102005061425B4 (de) * 2005-12-22 2009-06-10 Bruker Daltonik Gmbh Rückgesteuerte Fragmentierung in Ionenfallen-Massenspektrometern
JP4996962B2 (ja) 2007-04-04 2012-08-08 株式会社日立ハイテクノロジーズ 質量分析装置
DE102013213501A1 (de) * 2013-07-10 2015-01-15 Carl Zeiss Microscopy Gmbh Massenspektrometer, dessen Verwendung, sowie Verfahren zur massenspektrometrischen Untersuchung eines Gasgemisches

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EP0409362B1 (de) * 1985-05-24 1995-04-19 Finnigan Corporation Betriebsverfahren für eine Ionenfalle
US4686367A (en) * 1985-09-06 1987-08-11 Finnigan Corporation Method of operating quadrupole ion trap chemical ionization mass spectrometry
EP0336990B1 (de) * 1988-04-13 1994-01-05 Bruker Franzen Analytik GmbH Methode zur Massenanalyse einer Probe mittels eines Quistors und zur Durchführung dieses Verfahrens entwickelter Quistor
EP0362432A1 (de) * 1988-10-07 1990-04-11 Bruker Franzen Analytik GmbH Methode zur Massenanalyse einer Probe
US5200613A (en) * 1991-02-28 1993-04-06 Teledyne Mec Mass spectrometry method using supplemental AC voltage signals

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CA2097211A1 (en) 1993-11-30
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DE69328979D1 (de) 2000-08-10
EP0575777A3 (de) 1994-03-16
JP2004004082A (ja) 2004-01-08
DE69328979T2 (de) 2001-02-15
JPH0696727A (ja) 1994-04-08
DE69321165T2 (de) 1999-06-02
DE69321165D1 (de) 1998-10-29
EP0575777A2 (de) 1993-12-29
DE69333589D1 (de) 2004-09-16

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