US3555272A - Process for chemical ionization for intended use in mass spectrometry and the like - Google Patents

Process for chemical ionization for intended use in mass spectrometry and the like Download PDF

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Publication number
US3555272A
US3555272A US716274A US3555272DA US3555272A US 3555272 A US3555272 A US 3555272A US 716274 A US716274 A US 716274A US 3555272D A US3555272D A US 3555272DA US 3555272 A US3555272 A US 3555272A
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Prior art keywords
gasiform
accordance
ions
gasiform material
conditions
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US716274A
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English (en)
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Milam S B Munson
Frank H Field
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ExxonMobil Technology and Engineering Co
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Exxon Research and Engineering Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
    • H01J5/02—Vessels; Containers; Shields associated therewith; Vacuum locks
    • 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

Definitions

  • lonizable substances are reacted by continu ously ionizing a mixture ofa first gasiform material and second gasiform material to form stable ions from the first gasiform material which undergo ion-molecule reactions with the second gasiform material to produce ions characteristic of the second material.
  • the reaction may be conducted in a mass spectrometer which provides a volume of high pressure relative to the pressure in the mass spectrometer envelope.
  • ION BEAM 7 MAGNET ION INDICATOR ELECTRICAL- OUTLET IONIZATION HEAD l2 4 TO DIFFUSION/ PUMPS 9 l8 A PRESSURE I? INDICATOR C I80 PRESSURIZED E SAMPLE GAS PRESSURIZED INVENIORS.
  • the present invention is directed to mass spectrometry. More particularly. the invention is concerned with method and apparatus in which chemical ionization is obtained. In its more specific aspects, the invention is concerned with chemical ionization of a second gasiform material by a first gasiform material in a mass spectrometer.
  • the present invention may be briefly summarized as involving reaction ionizable substances in which a mixture of a first gasiform material and a second gasiform material at a pressure within the range from about 0.2 to about 5 torr (torr mm. Hg) is ionized under continuous ionizing conditions to form stable ions from the first gasiform material.
  • the stable ions and the second gasiform material undergo ion-molecule reactions under said pressure and ionizing conditions to produce ions characteristic of the second gasiform material.
  • the present invention also involves improved apparatus in a mass spectrometer having a tube provided with means for introducing a gasiform sample thereto and means for generating and collecting ions from an ion beam formed in the mass spectrometer tube. said tube providing an envelope of reduced pressure.
  • a feature of the present invention is a housing in the mass spectrometer tube forming a substantially gastight ionization chamber to provide a volume of high pressure relative to the pressure of the envelope with means in the housing separating the ionization chamber from at least a second chamber.
  • the housing is provided with an electron entrance orifice having a width within the range from about 0.025 to about 0.05 mm. and a length within the range from about I to about 3 mm., the separation means being provided with an ion exit orifice having a width from about 0.025 to about 0.05 mm. and a length within the range from about 4 to about 5 mm.
  • a barrier means in the mass spectrometer tube is provided with an orifice having a width within the range from about 0.005 to about 0.25 mm. and a length from about 5 to about 10 mm., the barrier means separating a first region in the envelope surrounding the housing from a second region in the envelope wherein the ion beam is deflected and collected to minimize gas flow between the housing and the collection means. It is within the purview of this invention to provide a plurality of regions in the envelope and which may be three, four or more regions as desired.
  • a first pump means is connected to the first region and a second pump means is connected to the second region.
  • the first and second pump means may suitably be diffusion pumps of high capacity which are capable of maintaining a differential pressure from the first region to the second region. As stated, a plurality of three or more pressure regions may be provided.
  • the second gasiform material is employed in an amount sufficient to provide a concentration less than about 1 percent by volume of the mixture.
  • a suitable concentration range may be from about 0.001 to about 1 percent by volume of the mixture.
  • the first gasiform material may be any compound or substance which is capable of transferring protons or more massive positively or negatively charged molecular or atomic entities or may be any substance or compound which has the capability of abstracting hydride ions from more massive molecular entities.
  • the compound or substance may be one which ionizes by energy transfer from excited states such as by the Penning process.
  • the second gasiform material may be any substance which will undergo ion-molecule reactions under the pressure and ionizing conditions to which the mixture is subjected.
  • examples of the first gasiform material are hydrogen, methane, propane, isobutane, water, hydrogen sulfide, methanol, ammonia, and the like.
  • the second gasiform material may be exemplified by way of illustration, and not by way of limitation, by paraffinic, olefinic, naphthenic and aromatic hydrocarbons having from 1 to 50 carbon atoms in the molecule and boiling in the range from about to about +600 C. Specific examples of such compounds are: hexadecane, eicosane, 2, 2, 4 trimethyl pentane, toluene, butyl cyclohexane, l-dodecene, and the like. Other organic and inorganic compounds may also be employed, the only limitation being that the compound must be placed in a gasiform condition.
  • FIG. 1 is a general view of the mass spectrometer of the present invention
  • FIG. 2 is a cross-sectional view of the ionization head of FIG. 1;
  • FIG. 3 is a view taken along the line 3-3 of FIG. 2;
  • FIG. 4 is a view taken along the line 4-4 of FIG. 3;
  • FIG. 5 is a view in greater detail of the ionization head of FIG. 1.
  • numeral 11 generally designates a mass spectrometer tube provided with an ionization end 12 having an ionization head 12a arranged therein, a magnet 13, an ion collector 14 and a recorder 15.
  • a sample introduction means 16 Leading into the ionization end i2 is a sample introduction means 16 provided with branches l7 and 18 controlled, respectively, by valves 17a and 18a and connecting to pressurized sample gas A and pressurized reactant gas B.
  • a wire probe 6 is inserted into the tube 11 so as to project into the path of the ion beam.
  • the probe 6 is electrically connected to an ion indicator 7.
  • a pressure responsive means 8 is inserted through the introduction means i6 and projects into the ionization chamber 20 of head 12a (see F I05. 2 and 3). The pressure in chamber 20 is thus indicated on indicator 9.
  • the ionization head 12a is provided with an ionization chamber 20 which in turn is provided with an electron entry slit or orifice 21 and a repeller 22.
  • the ionization head 12a is suitably comprised of a plurality of plate members, one of which is plate member 23 which defines the exit orifice from chamber 20 for the ion beam.
  • Other plate members provide a kinetic energy analyzer 24 and focusing electrodes 25 and 26, each of the several members 23, 24 25 and 26 being spaced apart by beads 27, 28 and 29, the plate 26 being spaced from the upper end of a housing base 30 by beads 31.
  • a ground electrode member 32 rests on the base 30 of head 12a above a plate member 33 in which is formed the analyzer entrance slit 34.
  • Members 23, 24 and 25 are each provided respectively with orifices 35, 36 and 37 and the ground electrode 32 is likewise provided with an orifice 38.
  • the orifice in plate 23 is the ion exit orifice, the dimensions of which are selected in accordance with the present-invention.
  • the ionization chamber 20 is enclosed within a member 40 which rests on the member 23.
  • a member 40 Arranged on the member 40 is an inlet member 41 which connects to the inlet 16 as will be described further.
  • This member 41 is bolted to the member 40 by threaded bolts 42.
  • Arranged on the member 4l0 is another member 43 through which threaded bolts 44 extend.
  • the head of bolts 44 rests on spring members 45 which in turn rest on member 43.
  • the threaded bolts 44 extend through the several plate members and the base member 30 and are secured by hex-nuts 46 which bear against spring member 47 which in turn bears against the base flange 48 of the base 30.
  • the plate 43 is spaced from the member 40 by glass beads 49.
  • An electrical lead 50 connects to the member 24 and is insulated by bead 51 through which it extends and in turn connects to electrical lead 52.
  • Dowel pins 53 and 54 maintain the relative positions of the ground electrode 32 relative to member 33 and member 33 relative to the base 30. Likewise, dowel pin 55 maintains the member 40 in its relationship to the member 23.
  • the ionization chamber 20 is provided with gun electrodes and with slits 61 adjacent to filament 62 which on energizing electrodes 60 causes a continuous beam of electrons to be directed into the ionization chamber 20 through the electron entry slit 21.
  • the electrons are produced from a heated wire filament 62.
  • the gun electrodes 60 are connected by electrical leads 63 to a source of electrical energy outside the mass spectrometer tube 11 which will be described further.
  • Electrical lead 64 is provided with glass insulator beads 65 and lead 64 connects to an electron collector 66 receiving electrons through orifice 67 from the ionization chamber 20.
  • a clamp 70 supports the filament assembly 71 to which the filament 62 is connected.
  • the filament 62 and the filament assembly 71 are arranged within a semicylindrical member 72 which serves to protect same.
  • a heater for the ionization chamber block is provided and is identified by the numeral 73.
  • the repeller 22 is spaced from the member 23 and this distance is carefully selected and should range from about 1 to about 25 mm. Provision is made for selecting this distance by spacing the repeller by spacing means 74 and insulation means, such as bead 75, which rests against the inlet member4'l i' Leads 76'pass-t-hro'ugh beads 77 and 75, support 74 and corinect to repeller 22 .691
  • the ionization end 12 is closed by suitable flange members 80 wliich are" 'bolted together by threaded bolts 81.
  • the ionization end l2' is bfo'lt ed' t othe mass spectrometer tube assembly 11"by'flarig'ineinbersSZ connected by threaded bolts 83. his tbFbc-notedj that there is a gold seal 84 between the flange membersfiggo forma gastight connection.
  • the ionization end 12 is. tied T anelectrical lead outlet 85 through which the, H dsate collected and taken to the outside to a suitage cal energy. Likewise, the ionization end 12 is prov w outlet 86 to which a diffusion pump (not shown) isiconnected.
  • the mass spectrometer tube assembly is connectedby flange member 82 to the ionization end 12 and is provided-with a flanged outlet member 88 which also connects to adiffusion pump (not shown).
  • adiffusion pump not shown
  • the base 30 ofippization head 12:: and flange 48 rest on a plate 90 which in turn rests on the lower portion of flange members 82.
  • the base 30 is connected as has been described by threaded bolts 44 and the flange 48 connects to the plate 90 by threaded bolts 91 while the plate 90 connects to the lower portion .otI-; the flange member 82 by threaded bolts 92.
  • a first gasiform material which may be called a reactant gas
  • a second gasiform material which may be called a sample gas
  • A'suitable pressure ismaintained on the sources of the reactant and sample gases to pr'ovide; in the ionization chamber a pressure of about'0.25 vtorr while the high capacity diffusion pump 87 maintainsa pressure-in the envelope surrounding the ionization chamber inthe range from about lO to about 10- torr. Likewise, the diffusion pumps maintain a pressure in the deflecting and'collection section of the mass spectrometer in the range from about 10- to about 10- torr.
  • the present invention is based on the occurrence of ionic reactions in the gaseous phase and it is to these reactions that the term chemical ionization" refers.
  • a mass spectrometer is operated at pressures in the ionization chamber as high as about 5 torr. Under these pressures, certain gases, which are referred to as reactant gases, are continuously ionized to produce ions which are stable in the gas; that is, they react with the gas at a negligibly slow rate.
  • the wire probe 6 projecting into the ion beam serves as a monitor on the total ionization.
  • the current collected by this wire probe 6 may, if desired, be used to actuate' a'control circuit which maintains the total ionizationconstant
  • Such a device makes the method described herein applicable to quantitative analysis.
  • I a j i The pressure responsive means 8 measures and indicated on indicator 9 the pressure within the ionization and reaction chamber 20. This device may also be used to actuate a control circuit to maintain the chamber pressure constant and may be quite advantageous in accurate quantitative work.
  • the reactant gas may be any one of several gases and it is intended that the present invention is not to be limited by the specific examples. These gases may be chosen to produce desired characteristics of the distribution of ions formed from the added compound, that is, the chemical ionization mass spectrum.
  • the second compound is added in low concentration to minimize ionization of the compound and reactions of the ions formed by direct ionization of the compound itself.
  • the present invention achieves a situation where a very large majority of the ions formed from the added compound are produced by chemical ionization reactions with the stable ions from the reactant gas.
  • the ions of the reactant gas may be produced by any suitable method or combination of methods such as ionization by electron impact, photo-ionization, ionization with products of radioactive decay, thermal ionization, and the like. If the reactant ions are produced by reactions of primary ions which are produced, for example, by electron impact ionization with the reactant gas, conditions must be selected such that a large fraction of the primary ions have reacted yielding a distribution of stable ions which does not depend strongly on pressure or lifetime of the ions in the ionization chamber. It has been found in the present invention that source pressures of about 0.2 to 5.0 torr with ion path lengths of 0.5 to mm will satisfy these conditions.
  • the present invention is broadly applicable to all types of compounds which may be subjected to chemical ionization in accordance with the present invention where stable ions from the reactant gas undergo ionmolecule reactions with the added material.
  • the present invention allows identification of parent compounds which heretofore were identified only with difficulty, if at all, and also allows the bringing about of selective ionization of compounds and mixtures of substances.
  • the present invention is quite important and useful and represents a substantial advance in the art.
  • the present invention has been described and illustrated by reference to ionizing a mixture of a first gasiform material with a second gasiform material, the present invention may be practiced by ionizing a first gasiform material under the conditions set forth herein and then admixing a second gasiform material with the stable ions to produce ions characteristic of the second gasiform material. This is possible because the ions of the reactant gas are stable and will exist for a period of time up to about I() seconds and thus advantage thereof will be taken.
  • a method for reacting ionizable organic substances which comprises: continuously ionizing a mixture of a first gasiform organic material and a second gasiform organic material to form stable ions from said first gasiform material, said stable ions and said second gasiform material undergoing ion-molecule reactions under said continuous ionizing conditions to produce ions characteristic of said second material.
  • Electron impact 2 A method in accordance with claim 1 in which the mixture is ionized at a pressure within the range from about 0.2 to about 5 torr.
  • the first gasiform material is a compound which ionizes by energy transfer from excited states.
  • a method in accordance with claim l in which the stable ions are formed by subjecting said first gasiform material to thermal ionization.
  • a method for reacting ionizable substances which comprises:
  • a method for reacting ionizable organic substances which comprises: contacting a second gasiform organic material with stable ions continuously'formed from a first gasiform organic material under conditions to produce-ions characteristic of said second gasiforrn material;
  • a method for reacting ionizable substances which'comprises: contacting a second gasiform organic material with stable ions continuously formed from a gasiform material selected from the group consisting of organic materials, hydrogen, water, hydrogen sulfide, and ammonia under conditions to produce ions characteristic of said second gasiform material.
  • a method for a reacting ionizable substances which comprises: contacting a second gasiform organic material with stable ions continuously formed from a gasiform material selected from the group consisting of hydrogen, methane, propane, isobutane, water, hydrogen sulfide, methanol, and ammonia under conditions to produce ions characteristic of said second gasiform material.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Tubes For Measurement (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US716274A 1968-03-14 1968-03-14 Process for chemical ionization for intended use in mass spectrometry and the like Expired - Lifetime US3555272A (en)

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Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886365A (en) * 1973-08-27 1975-05-27 Hewlett Packard Co Multiconfiguration ionization source
US3920987A (en) * 1972-09-14 1975-11-18 Stanford Research Inst Method and system for detecting explosives
US3992632A (en) * 1973-08-27 1976-11-16 Hewlett-Packard Company Multiconfiguration ionization source
US4005291A (en) * 1972-01-04 1977-01-25 Massachusetts Institute Of Technology Ionization method for mass spectrometry
US4037108A (en) * 1975-04-03 1977-07-19 Helmut Jordan Ion source with capability of changing between operation modes
US4066894A (en) * 1976-01-20 1978-01-03 University Of Virginia Positive and negative ion recording system for mass spectrometer
US4136280A (en) * 1976-01-20 1979-01-23 University Of Virginia Positive and negative ion recording system for mass spectrometer
USRE30171E (en) * 1973-08-27 1979-12-18 Hewlett-Packard Company Multiconfiguration ionization source
US4220545A (en) * 1977-08-23 1980-09-02 Dr. Franzen Analysentechnik Gmbh & Co. Kommanditgesellschaft Ionization chamber for chemical ionization
US4321467A (en) * 1980-06-04 1982-03-23 Sri International Flow discharge ion source
US4368388A (en) * 1975-12-15 1983-01-11 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Detection of polar vapors
US4551624A (en) * 1983-09-23 1985-11-05 Allied Corporation Ion mobility spectrometer system with improved specificity
US4975576A (en) * 1987-05-14 1990-12-04 V & F Analyse- Und Messtechnik Gmbh Method and apparatus for measuring concentrations of gas mixtures
US5192865A (en) * 1992-01-14 1993-03-09 Cetac Technologies Inc. Atmospheric pressure afterglow ionization system and method of use, for mass spectrometer sample analysis systems
US6147346A (en) * 1997-09-19 2000-11-14 Shimadzu Corporation Mass spectrometer
US6329653B1 (en) * 1999-02-09 2001-12-11 Syagen Technology Photoionization mass spectrometer
US20030155500A1 (en) * 1999-02-09 2003-08-21 Syage Jack A. Interfaces for a photoionization mass spectrometer
US6630664B1 (en) 1999-02-09 2003-10-07 Syagen Technology Atmospheric pressure photoionizer for mass spectrometry
US6737642B2 (en) 2002-03-18 2004-05-18 Syagen Technology High dynamic range analog-to-digital converter
US7109476B2 (en) 1999-02-09 2006-09-19 Syagen Technology Multiple ion sources involving atmospheric pressure photoionization
US20090039252A1 (en) * 2006-03-07 2009-02-12 Shimadzu Corporation Mass spectrometer
US20090039283A1 (en) * 2005-09-16 2009-02-12 Bruker Daltonik Gmbh Ionization of desorbed molecules
US20120273668A1 (en) * 2006-07-20 2012-11-01 Owlstone Nanotech Inc. Smart faims sensor
US8704171B2 (en) 2007-10-10 2014-04-22 Mks Instruments, Inc. Chemical ionization reaction or proton transfer reaction mass spectrometry
US11328919B2 (en) * 2018-05-11 2022-05-10 Leco Corporation Two-stage ion source comprising closed and open ion volumes

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5215078U (enExample) * 1975-07-21 1977-02-02

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3254209A (en) * 1962-11-29 1966-05-31 Gen Dynamics Corp Method and apparatus for increasing the ionization of impurity ions in a mass spectrometer

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
US3254209A (en) * 1962-11-29 1966-05-31 Gen Dynamics Corp Method and apparatus for increasing the ionization of impurity ions in a mass spectrometer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Mass Spectrometer For the Study of Ion-Molecule Collision Processes by G. F. Wells et al. from The Review of Scientific Instruments, Vol. 28, No. 12, Dec., 1957, Pages 1065 to 1069. *

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005291A (en) * 1972-01-04 1977-01-25 Massachusetts Institute Of Technology Ionization method for mass spectrometry
US3920987A (en) * 1972-09-14 1975-11-18 Stanford Research Inst Method and system for detecting explosives
USRE30171E (en) * 1973-08-27 1979-12-18 Hewlett-Packard Company Multiconfiguration ionization source
US3992632A (en) * 1973-08-27 1976-11-16 Hewlett-Packard Company Multiconfiguration ionization source
US3886365A (en) * 1973-08-27 1975-05-27 Hewlett Packard Co Multiconfiguration ionization source
US4037108A (en) * 1975-04-03 1977-07-19 Helmut Jordan Ion source with capability of changing between operation modes
US4368388A (en) * 1975-12-15 1983-01-11 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Detection of polar vapors
US4136280A (en) * 1976-01-20 1979-01-23 University Of Virginia Positive and negative ion recording system for mass spectrometer
US4066894A (en) * 1976-01-20 1978-01-03 University Of Virginia Positive and negative ion recording system for mass spectrometer
US4220545A (en) * 1977-08-23 1980-09-02 Dr. Franzen Analysentechnik Gmbh & Co. Kommanditgesellschaft Ionization chamber for chemical ionization
US4321467A (en) * 1980-06-04 1982-03-23 Sri International Flow discharge ion source
US4551624A (en) * 1983-09-23 1985-11-05 Allied Corporation Ion mobility spectrometer system with improved specificity
US4975576A (en) * 1987-05-14 1990-12-04 V & F Analyse- Und Messtechnik Gmbh Method and apparatus for measuring concentrations of gas mixtures
US5192865A (en) * 1992-01-14 1993-03-09 Cetac Technologies Inc. Atmospheric pressure afterglow ionization system and method of use, for mass spectrometer sample analysis systems
US6147346A (en) * 1997-09-19 2000-11-14 Shimadzu Corporation Mass spectrometer
CN1110836C (zh) * 1997-09-19 2003-06-04 株式会社岛津制作所 一种质谱仪及其使用方法
US7119342B2 (en) 1999-02-09 2006-10-10 Syagen Technology Interfaces for a photoionization mass spectrometer
US20030155500A1 (en) * 1999-02-09 2003-08-21 Syage Jack A. Interfaces for a photoionization mass spectrometer
US6630664B1 (en) 1999-02-09 2003-10-07 Syagen Technology Atmospheric pressure photoionizer for mass spectrometry
US7109476B2 (en) 1999-02-09 2006-09-19 Syagen Technology Multiple ion sources involving atmospheric pressure photoionization
US6329653B1 (en) * 1999-02-09 2001-12-11 Syagen Technology Photoionization mass spectrometer
US6737642B2 (en) 2002-03-18 2004-05-18 Syagen Technology High dynamic range analog-to-digital converter
US20090039283A1 (en) * 2005-09-16 2009-02-12 Bruker Daltonik Gmbh Ionization of desorbed molecules
US7504640B2 (en) * 2005-09-16 2009-03-17 Bruker Daltonik, Gmbh Ionization of desorbed molecules
US20090039252A1 (en) * 2006-03-07 2009-02-12 Shimadzu Corporation Mass spectrometer
US7858933B2 (en) * 2006-03-07 2010-12-28 Shimadzu Corporation Mass spectrometer
US20120273668A1 (en) * 2006-07-20 2012-11-01 Owlstone Nanotech Inc. Smart faims sensor
US8704171B2 (en) 2007-10-10 2014-04-22 Mks Instruments, Inc. Chemical ionization reaction or proton transfer reaction mass spectrometry
US11328919B2 (en) * 2018-05-11 2022-05-10 Leco Corporation Two-stage ion source comprising closed and open ion volumes

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DE1912533A1 (de) 1969-11-20
JPS5036190B1 (enExample) 1975-11-21

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