US3725700A - Multipole mass filter with artifact-reducing electrode structure - Google Patents

Multipole mass filter with artifact-reducing electrode structure Download PDF

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Publication number
US3725700A
US3725700A US00113312A US3725700DA US3725700A US 3725700 A US3725700 A US 3725700A US 00113312 A US00113312 A US 00113312A US 3725700D A US3725700D A US 3725700DA US 3725700 A US3725700 A US 3725700A
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Prior art keywords
electrodes
mass filter
multipole
primary electrodes
auxiliary
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Expired - Lifetime
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US00113312A
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English (en)
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W Turner
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HP Inc
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Hewlett Packard Co
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    • 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
    • H01J49/421—Mass filters, i.e. deviating unwanted ions without trapping
    • H01J49/4215—Quadrupole mass filters
    • 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
    • H01J49/4255—Device types with particular constructional features

Definitions

  • An ion source is positioned adjacent to the entrance end of the multipole mass filter for v transmitting ions generally along the central axis to an ion detector positioned adjacent to the exit end of the multipole mass filter.
  • Auxiliary electrodes are disposed between adjacent pairs of the primary electrodes along the length thereof outside the central region defined by a cylinder inscribed between the primary electrodes. These auxiliary electrodes are driven by a plurality of independently adjustable D.C. control voltages to reduce artifacts in the mass spectra obtained from the multipole mass filter.
  • VOLTAGE -1 VOLTAGE VOLTAGE VOLTAGE SOURCE SOURCE SOURCE OUADRUPOLE DRIVE GlRCUiT U +VCOS ml PATEHTFUAPRQ? I973 ADJUST. D.C. VOLTAGE SOURCE sum 1 OF 4 ADJUST. DC.
  • This invention relates generally to multipole mass spectrometers and more particularly to an improved multipole mass filter structure that may be employed therein.
  • the mass spectrum obtained from a multipole mass filter should comprise a series of sharply defined ion peaks.
  • ion peaks in the mass spectrum typically exhibit tailing, cursors, or other artifacts that may either obscure other ion peaks present in the mass spectrum or be mistaken for ion peaks not present in the mass spectrum. This seriously impairs the resolution of the multipole mass filter.
  • Another problem commonly associated with a multipole mass filter is that both the ion peak shape and the sensitivity change with time due at least in part to ion build-up on the electrodes of the multipole mass filter.
  • auxiliary electrodes that may be operated at different potentials and that are disposed between adjacent pairs of the primary electrodes along the length thereof and outside the central region defined by a cylinder inscribed between the primary electrodes.
  • auxiliary electrodes may comprise, for example, electrically conductive tubes, rods, bars, combs, or bifilar helices. They are driven by FIG. 4 is a logarithmic plot of the intensities of the same ion peaks that was obtained by employing the multipole mass filter of FIGS. 1 and 2 with the auxiliary electrodes.
  • FIGS. 5 and 6 are simplified cross-sectional views of multipole mass filters according to others of the preferred embodiments of this invention.
  • a plurality of independently adjustable D.C. voltage sources may be operated at the same potential or at different potentials as required for optimum performance of the multipole mass filter.
  • the potentials at which the auxiliary electrodes are operated may be readjusted from time to time as may be required for optimum performance over different mass ranges and as required to compensate for changes in ion peak shape and sensitivity with time.
  • FIG. 1 is an end view of a multipole mass filter according to one of the preferred embodiments of the invention.
  • FIG. 2 is a sectional side view of the multipole mass filter of FIG. 1 taken along line 2--2.
  • FIG. 3 is a logarithmic plot of the intensities of ion peaks 69 and 70 from a perfluorotributylamine mass spectrum that was obtained by employing a multipole mass filter like that of FIGS. 1 and 2 without the auxiliary electrodes.
  • FIGS. 7A through 9B are side and cross-sectional views of various auxiliary electrodes that may be employed in the multipole mass filters of FIGS. 1 and 2, 5, and 6 in lieu of the auxiliary electrodes illustrated therein.
  • FIGS. 1 and 2 there is shown a quadrupole mass filter including a cylindrical and electrically-conductive housing 10 made, for example, of stainless steel. Housing 10 is operated at a reference potential, such as ground potential, and is positioned within an evacuated enclosure when the quadrupole mass filter is to be employed in the laboratory. This evacuated enclosure is unnecessary when the quadrupole mass filter is to be employed for upper atmospheric research in the vacuum of outer space.
  • a reference potential such as ground potential
  • housing 10 Four parallel, coextensive, electrically-conductive, cylindrical primary electrodes 12, 14, 16, and 18 electrically insulated from one another are fixedly mounted within housing 10 by, for example, a pair of electrically-insulating annular ceramic supports 19 fixedly secured to housing 10, provided with aligned, symmetrically-spaced, generally-semicircular indentations in their inner peripheries for receiving the primary electrodes, and metallized and brazed along these generally semicircular indentations to the primary electrodes.
  • the primary electrodes are symmetrically disposed about the central axis Z of the quadrupole mass filter with the central axes of primary electrodes 12 and 14 being diametrically opposed and lying in the YZ plane and with the central axes of primary electrodes 16 and 18'being diametrically opposed and lying in the orthogonal XZ plane.
  • diametrically-opposed primary electrodes 12 and 14 are electrically connected in common to one terminal of a quadrupole drive circuit 20 such as that shown and described in copending U.S. Patent application Ser. No. 738,142 entitled QUADRUPOLE MASS FILTER WITI-I ELECTRODE STRUCTURE FOR FRINGING-FIELD COMPENSA- TION, filed on June 19, l968, by Edward F. Barnett, Donald L. Hammond, and William S. W. Tandler and issued on Nov. 2, 1971, as U.S. Pat. No. 3,617,736.
  • Diametrically-opposed primary electrodes 16 and 18 are similarly connected in common to another terminal of quadrupole drive circuit 20.
  • An excitation voltage comprising both a balanced D.C. component :U and a balanced A.C. component iVcos an is applied between diametrically-opposed primary electrodes 12 and 14 and diametrically-opposed primary electrodes 16 and 18 to provide a quadrupolar electric field having both A.C. and D.C. components between the diametricallyopposed primary electrodes.
  • the positive D.C. component +U of the excitation voltage is applied to diametrically-opposed primary electrodes 16 and 18, and the negative D.C. component U is applied to diametrically-opposed primary electrodes 12 and 14. All voltages are referred to quadrupole ground, which is maintained at the reference potential of housing 10.
  • a separate pair of parallel, coextensive, electricallyconductive, flattened, tubular, kovar auxiliary electrodes 22 electrically insulated from one another is fixedly mounted within housing between and substantially parallel to each adjacent pair of primary electrodes 12 and 18, 18 and 14, 14 and 16, and 16 and 12.
  • the auxiliary electrodes are substantially symmetrically disposed about the central axis Z and between the primary electrodes outside the central region defined by a cylinder inscribed between the primary electrodes.
  • Each pair of auxiliary electrodes 22 is bonded together at spaced intervals by electrically-insulating glass beads 24 and is mounted in place, for example, by spot welding the auxiliary electrodes at each end to electricallyconductive kovar studs 26 that are in turn spot welded to electrically-conductive stainless steel supports 28.
  • These stainless steel supports are fixedly mounted adjacent to the ends of the primary electrodes by electrically insulating ceramic spacers 30 secured to the ends of the primary electrodes and provided with circular projections 32 for engaging mating holes in the stainless steel supports.
  • the two auxiliary electrodes 22 supported by each stainless steel support 28 are electrically insulated from the other auxiliary electrodes by the glass beads 24 and are electrically connected in common by the stainless steel support and associated kovar studs 26 and by a separate resistor 34 of about 5 megohms to an associated different one of four independently adjustable sources 36 of D.C.
  • control voltages E, through E This provides four independently controllable parameters B, through E, that may be adjusted for altering the quadrupolar electric field between primary electrodes 12 through 18 to reduce artifacts in the mass spectra obtained from the quadrupole mass filter and thereby improve the resolution of the quadrupole mass filter, to compensate for changes with time in ion peak shape and sensitivity due to ion build-up on the primary electrodes or other factors, and to otherwise control ion peak shape and optimize the performance of the quadrupole mass filter over different mass ranges.
  • control voltages E 1 through B may range in value from 40 to +40 volts. Moreover, in some applications involving scanning over large mass ranges it may be desirable to vary one or more of the parameters E, through E, with the D.C. component U of the excitation voltage.
  • FIG. 3 there are shown ion peaks 69 and 70 from a perfiuorotributylamine mass spectrum that was obtained by employing a mass spectrometer including an ion source 38 such as that shown and described in a copending U. S. patent application entitled IONIZA- TION CHAMBER and filed on or about Feb. 1, I97 I by William P. Kruger and Wilson R. Turner, a quadrupole mass filter like that of FIGS. 1 and 2 without auxiliary electrodes 22, a fringing field penetrating structure like that shown and described in US. Pat. No.
  • FIG. 4 For comparison, the same ion peaks obtained by employing the same mass spectrometer with auxiliary electrodes 22 is shown in FIG. 4. It may be seen that artifact 42 has been reduced by more than a factor of 10 to about 0.04 percent of the magnitude of the most significant ion peak 69 and to substantially less than 10 percent of the magnitude of the next most significant ion peak 70. This represents a significant improvement in resolution.
  • a D.C. excitation voltage component U of approximately $35 volts and an A.C. excitation voltage component V of approximately :210 volts were employed, and in obtaining the ion peaks of FIG. 4 D.C. control voltages E E and E of 0 volts and a D.C. control voltage E of 2 volts were employed.
  • the auxiliary electrodes may be arranged in configurations other than that shown in FIGS. 1 and 2.
  • a single auxiliary electrode 44 may be fixedly mounted between each adjacent pair of primary electrodes 12 and 18, 18 and 14, 14 and 16, and 16 and 12 as shown in FIG. 5.
  • a pair of auxiliary electrodes 44 positioned one outside the other and electrically insulated from each other may be fixedly mounted between each of these pairs of primary electrodes as shown in FIG. 6.
  • the auxiliary electrodes may comprise electrically-conductive flattened tubes 22 as shown in FIGS. 1 and 2, circular rods 44 as shown in FIGS. 5 and 6, rectangular bars 46 as shown in FIGS. 7A and 7B, pairs of spaced combs 48 as shown in FIGS.
  • auxiliary electrodes of whatever configuration or type may be operated at the same or different potentials as required for optimum performance of the quadrupole mass filter.
  • a multipole mass filter comprising:
  • a plurality of substantially parallel primary electrodes for separating charged particles on the bases of their mass to charge ratio, said primary electrodes being spaced symmetrically about a central axis for receiving an excitation voltage including A.C. and D.C. components balanced with respect to a reference potential to produce alternating and static multipole electric field components in the central region between the primary electrodes;
  • auxiliary electrodes for altering the multipole electric field components in the central region between the primary electrodes to reduce artifacts in a mass spectrum obtained from the mass filter, at least two of said auxiliary electrodes being independently operable at different potentials and at least one of said auxiliary electrodes being positioned between each adjacent pair of the primary electrodes along the length thereof outside the central region between the primary electrodes.
  • auxiliary electrodes comprise a single auxiliary electrode positioned between each of the adjacent pairs of the primary electrodes.
  • each of said auxiliary electrodes comprises an electrically conductive rod or tube.
  • auxiliary electrodes comprise a pair of auxiliary electrodes positioned between each of the adjacent pairs of the primary electrodes.
  • each of said pairs of auxiliary electrodes comprises a pair of electrically conductive rods or tubes that may be operated at different potentials.
  • each of said pairs of auxiliary electrodes comprises a pair of electrically conductive combs that may be operated at different potentials.
  • each of said pairs of auxiliary electrodes comprises a pair of electrically conductive bifilar helices that may be operated at different potentials.
  • said primary electrodes comprise four substantially parallel, coextensive, electrically-conductive cylindrical rods
  • auxiliary electrodes comprise electrically conductive members supported from the ends of the primary electrodes
  • an ion source is positioned adjacent to one end of the central region between the primary electrodes for focusing ions along the central axis;
  • an ion detector is positioned adjacent to the other end of the central region between the primary electrodes for detecting ions passing therethrough.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Electron Tubes For Measurement (AREA)
US00113312A 1971-02-08 1971-02-08 Multipole mass filter with artifact-reducing electrode structure Expired - Lifetime US3725700A (en)

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US (1) US3725700A (enExample)
JP (1) JPS5322874B1 (enExample)
DE (1) DE2202589A1 (enExample)
FR (1) FR2124551B1 (enExample)
GB (1) GB1361761A (enExample)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4885470A (en) * 1987-10-05 1989-12-05 The United States Of America As Represented By The United States Department Of Energy Integrally formed radio frequency quadrupole
US4985626A (en) * 1990-01-09 1991-01-15 The Perkin-Elmer Corporation Quadrupole mass filter for charged particles
US5051593A (en) * 1989-11-22 1991-09-24 Jeol Ltd. Electrostatic multipole lens for charged-particle beam
WO1997043036A1 (en) * 1996-05-14 1997-11-20 Analytica Of Branford, Inc. Ion transfer from multipole ion guides into multipole ion guides and ion traps
US6452167B1 (en) * 1998-05-20 2002-09-17 Sandia National Laboratories Miniature quadrupole mass spectrometer having a cold cathode ionization source
GB2390222A (en) * 2003-07-31 2003-12-31 Reliance Gear Company Ltd Quadrupole Mass Filter
US20040084617A1 (en) * 2002-01-03 2004-05-06 Burns Donald Matthew Quadrupole mass filter
US20050224711A1 (en) * 2000-03-13 2005-10-13 Loucks Harvey D Jr Manufacturing precision multipole guides and filters
US7166836B1 (en) * 2005-09-07 2007-01-23 Agilent Technologies, Inc. Ion beam focusing device
CN102820190A (zh) * 2012-08-28 2012-12-12 复旦大学 一种四极杆质量分析器的装配方法
US20210327700A1 (en) * 2018-08-24 2021-10-21 Dh Technologies Development Pte. Ltd. RF/DC Cutoff to Reduce Contamination and Enhance Robustness of Mass Spectrometry Systems

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3147445A (en) * 1959-11-05 1964-09-01 Thompson Ramo Wooldridge Inc Quadrupole focusing means for charged particle containment
US3321623A (en) * 1963-05-13 1967-05-23 Bell & Howell Co Multipole mass filter having means for applying a voltage gradient between diametrically opposite electrodes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3147445A (en) * 1959-11-05 1964-09-01 Thompson Ramo Wooldridge Inc Quadrupole focusing means for charged particle containment
US3321623A (en) * 1963-05-13 1967-05-23 Bell & Howell Co Multipole mass filter having means for applying a voltage gradient between diametrically opposite electrodes

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4885470A (en) * 1987-10-05 1989-12-05 The United States Of America As Represented By The United States Department Of Energy Integrally formed radio frequency quadrupole
US5051593A (en) * 1989-11-22 1991-09-24 Jeol Ltd. Electrostatic multipole lens for charged-particle beam
US4985626A (en) * 1990-01-09 1991-01-15 The Perkin-Elmer Corporation Quadrupole mass filter for charged particles
WO1997043036A1 (en) * 1996-05-14 1997-11-20 Analytica Of Branford, Inc. Ion transfer from multipole ion guides into multipole ion guides and ion traps
US6452167B1 (en) * 1998-05-20 2002-09-17 Sandia National Laboratories Miniature quadrupole mass spectrometer having a cold cathode ionization source
US20050224711A1 (en) * 2000-03-13 2005-10-13 Loucks Harvey D Jr Manufacturing precision multipole guides and filters
US20040084617A1 (en) * 2002-01-03 2004-05-06 Burns Donald Matthew Quadrupole mass filter
US6940068B2 (en) 2002-01-03 2005-09-06 Reliance Gear Company Limited Quadrupole mass filter
GB2390222B (en) * 2003-07-31 2004-05-19 Reliance Gear Company Ltd Quadrupole mass filter
GB2390222A (en) * 2003-07-31 2003-12-31 Reliance Gear Company Ltd Quadrupole Mass Filter
US7166836B1 (en) * 2005-09-07 2007-01-23 Agilent Technologies, Inc. Ion beam focusing device
CN102820190A (zh) * 2012-08-28 2012-12-12 复旦大学 一种四极杆质量分析器的装配方法
CN102820190B (zh) * 2012-08-28 2015-04-22 复旦大学 一种四极杆质量分析器的装配方法
US20210327700A1 (en) * 2018-08-24 2021-10-21 Dh Technologies Development Pte. Ltd. RF/DC Cutoff to Reduce Contamination and Enhance Robustness of Mass Spectrometry Systems

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Publication number Publication date
DE2202589A1 (de) 1972-09-07
FR2124551B1 (enExample) 1976-07-23
JPS5322874B1 (enExample) 1978-07-11
FR2124551A1 (enExample) 1972-09-22
GB1361761A (en) 1974-07-30

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