EP0200645B1 - Verfahren und Probeneinlassvorichtung für ein Massenspektrometer - Google Patents

Verfahren und Probeneinlassvorichtung für ein Massenspektrometer Download PDF

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Publication number
EP0200645B1
EP0200645B1 EP19860400902 EP86400902A EP0200645B1 EP 0200645 B1 EP0200645 B1 EP 0200645B1 EP 19860400902 EP19860400902 EP 19860400902 EP 86400902 A EP86400902 A EP 86400902A EP 0200645 B1 EP0200645 B1 EP 0200645B1
Authority
EP
European Patent Office
Prior art keywords
tube
gaseous
source
heating
microsample
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19860400902
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English (en)
French (fr)
Other versions
EP0200645A1 (de
Inventor
Robert Boyer
Jean-Pierre Journoux
Claude Duval
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Orano Demantelement SAS
Original Assignee
Compagnie Generale des Matieres Nucleaires SA
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Publication of EP0200645A1 publication Critical patent/EP0200645A1/de
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
    • H01J49/0422—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components for gaseous samples
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
    • H01J49/0468—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components with means for heating or cooling the sample
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
    • H01J49/0495—Vacuum locks; Valves

Definitions

  • the invention relates to the field of analysis of samples by mass spectrometry and it relates more particularly to the methods and devices making it possible to introduce, into the spectrometer, a sample microdebit whose ions are subjected to analysis.
  • mass spectrometers use either a source of thermionic ions or a source of ions with electron bombardment of a gas flow.
  • the first solution has the advantage of making it possible to use samples of very low mass, frequently between 0.1 and 10 micrograms.
  • the sample is deposited, usually in liquid form, on a refractory metal tape. By evaporation of the liquid, a solid deposit is obtained.
  • the ribbon is placed in the ion source of the device, then brought to high temperature (2600 ° C for example) by Joule effect.
  • the sample then emits neutral molecules and ions. The latter, accelerated and focused in the form of a particle beam, are subjected to analysis.
  • a mass spectrometer using a thermionic source cannot be used to conduct chemical composition analyzes and can very easily be connected online to a separation or treatment line.
  • the usual method consists in introducing the sample from a sealed container through piping and micro-leakage valves allowing a well determined and very low gas flow to pass without altering the very low pressure which must prevail in the analyzer of the spectrometer.
  • the molecules of gas or vapor which pass at very low flow rate are subjected to the action of a beam of electrons of determined energy which ionizes the gas to give rise to ions subjected to analysis.
  • the intensity of ion currents obtained is usually of the order of 10 -9 A, that is to say, much higher than the thermal-spectrometer, which simplifies the measurement.
  • measurements made using a spectrometer using an ion source by electron bombardment are generally differential measurements, which guarantee high precision, typically 50 to 100 times higher than with a thermionization source.
  • document US-A-3 888 107 describes a thermal analysis cell using a reactive gas, the necessity of which stems from the requirements of the analysis method used.
  • the present invention aims to provide a supply method and device for a mass spectrometer, using the ionization technique of a very low flow rate, typically using an electron beam, but responding better than those previously known to the requirements of the practice, in particular in that they authorize the use of samples of very low mass.
  • the invention provides a method of introducing micro-samples in accordance with the characterizing part of claim 1 and a device making it possible to implement this method, in accordance with the characterizing part of claim 2.
  • this device keeps the device all the advantages of using an electron bombardment source it allows to work with relatively intense ion beams, which simplifies their measurement it avoids breaking the vacuum in the source to introduce the sample it is not necessary to have watertight containers to handle the samples and connect them to the device.
  • the proposed device has many advantages: the size of the samples to be analyzed is reduced to a few micrograms; It is not necessary to have sealed containers for handling the samples and introducing them into the device. The consumption of standards or reference products can be reduced to the order of magnitude of that of the samples, the preparation of which is simple and fast.
  • the device shown in Figures 1 and 2 can be viewed as comprising a reactor 10, the essential element of which is a micro-oven with adjustable temperature, a passage 12 sufficiently constricted for the flow to take place therein in the form of molecular flow, and a micro- sublimers 14.
  • the microsublimeter is connected, by means of a valve 16, to the ion source 18 of the spectrometer, which can be of any of the types making it possible to ionize a low flow of gas which penetrates him. Typically, this source will perform ionization by electron bombardment.
  • the reactor 10 the schematic diagram of which is shown in FIG. 1, comprises an enclosure, generally cylindrical, in the axis of which is placed the actual micro-oven 20 consisting of a metal tube capable of withstanding high temperatures, for example nickel , nichrome or "monel". Means are provided for heating the oven by the Joule effect.
  • these means are shown in the form of an electrical source 22 connected to one end of the tube of which the other is grounded.
  • Another solution consists in winding an electric heating resistor around the tube 20.
  • This tube can carry a temperature sensor 24 connected to a circuit 26 for regulating the temperature by modulating the electric power supplied by the source 22.
  • a sample holder 28 is provided to allow the introduction of a very small quantity of samples, in the form of a deposit on a needle or a thread.
  • the head of this sample holder will be provided to seal the microfour.
  • One end of the tube 20 forming a micro oven is connected, by a valve 30, to a vacuum source 32 (mechanical primary pump for example) and to a source 34 of reagent. of a nature such that it gives rise, with the sample, to a gaseous or volatile compound.
  • the sources 32 and 34 are each provided with a shut-off valve 36 and 38.
  • the valves 30 and 38 at least must be made of a material resistant to very corrosive gases, since it will frequently be necessary to use highly reactive chemical species, such as fluorine.
  • the valve 30 must also be strictly sealed.
  • the constricted passage 12 may have a fixed passage section.
  • a diaphragm or capillary conduit can also be adjustable and formed by a conventional type micro-leakage valve or a piezoelectric valve, the opening of which is caused by the deformation of a piezoelectric crystal under the action of an electric field.
  • the passage must prohibit any entry of ambient air and it must offer a passage section having a sufficiently small diameter (typically a few microns) so that the gas flow between the reactor 10 and the microsublimation tube maintained at low pressure or in molecular regime. We know that in this regime the free path of the gaseous molecules is greater than the transverse dimensions of the passage.
  • the microsublimator 14 will generally consist of a tube 40 of small diameter, one end of which is tightly connected to the passage 12 and the other end is connected, by means of the valve 16, to the ion source 18.
  • This tube is provided with cryogenic temperature cooling means.
  • cryogenic temperature cooling means These means are shown in Figure 1 in the form of an enclosure 42 provided with an inlet and an outlet for fluid at very low temperature.
  • adjustable heating means are associated with it. In the case of FIG. 1, these means consist of a heating resistor 44 wound around the tube 40 and supplied by an electric generator 46 of adjustable power.
  • a temperature probe can be placed on the tube 40 to regulate, via a circuit similar to circuit 26, the temperature of the tube to an adjustable value. This temperature can also be slaved to a reference value by the intensity of the ion beams received at the collectors of the mass spectrometer.
  • a signal is taken from the ion current amplifier. This is constantly compared with a reference representing the chosen temperature, this reference being able to be programmed itself using a computer. A voltage is therefore obtained which is converted into calibrated pulses giving quantities of energy supplying the heating systems of the tube 40.
  • a valve 46a in parallel with the valve 16, makes it possible to connect the outlet of the tube 40 to a vacuum pump.
  • An additional connector provided with a valve 47 may be provided to connect the ion source to a reference gas supply and / or to another device similar to that which has just been described.
  • the elements 10, 12 and 14 of FIG. 1 are grouped together to constitute a one-piece assembly in several assembled parts, for example by welding.
  • the reactor is delimited by two nozzles 48 and 50 and a cylindrical shell in the axis of which the tube 20 is placed, a few millimeters in internal diameter, forming the micro-oven.
  • the downstream end of this tube is grounded via the end piece 50.
  • the upstream end isolated from ground by a pin 52, is connected to the electrical heating source by means of a tab 54 which crosses the shell in a sealed manner.
  • the sample holder 28 comprises a head screwable into the end piece 48, the seal being ensured by a seal 58.
  • a locking screw 60 provided in the head makes it possible to retain a thread or a needle 62 for supporting the dry sample.
  • a channel 64 formed in the end piece 48 makes it possible to connect the tube 20 to a valve 30 for admitting the reagent (gaseous fluorinating agent in general) or to a vacuum pump.
  • a seat 66 intended to receive the micro-leakage valve (not shown) constituting the passage 12 towards the micro-sublimator 14.
  • the latter has a constitution very comparable to that of the reactor 10, if this n 'is that the ferrule is provided with inlet and outlet fittings 68 and 70 for cryogenic fluid.
  • the micro-sublimation tube 40 is connected, via an insulating pin 72, to the end piece 50 and its downstream end is welded to an end piece 74 provided with a seat intended for the valve 46a (not shown) .
  • this nozzle comprises a tubular extension 76 intended to be connected to the valve 16.
  • the device used is of the type shown in FIG. 2.
  • the sample must first be transferred to the sample holder 28.
  • the wire 62 which for example is 0.8 mm in diameter and 7 cm long, is deposited, using a micro-pipette , a few drops of uranyl nitrate containing a total of for example 10 micrograms of uranium to be analyzed.
  • Uranyl nitrate transforms into a deposit of U0 3 , then U 3 0 8 when the temperature exceeds 350 ° C.
  • the wire covered with the deposit is placed in the sample holder 28 and the latter fixed on the end piece 48.
  • the tube 20 is put under vacuum by pumping up to a pressure of the order of 0.133 Pa (10- 3 torr). Then we heat the tube 20, by current flow. up to a temperature of around 400 ° C to remove residual water vapor.
  • the temperature of the microsublimation tube 40 is then brought to that of the liquid nitrogen by circulation of this nitrogen around the tube 40, from the connector 68 to the connector 70 by the circulation of a heat transfer gas (helium for example) brought to the temperature. liquid nitrogen.
  • a heat transfer gas helium for example
  • valve 12 is closed.
  • the pumping valve 46a is open, and the tube 40 is very gradually heated by passing an electric current. The oxygen sublimes and it is evacuated by the vacuum pump, through the valve 46a.
  • the valve 46 is closed and the valve 16 is opened.
  • the heating is carried out with a temperature programming such that, as soon as the hexafluoride flow rate reaches a predetermined value (that is to say when the value is reached of the intensity of the ion beam in the spectrometer), the temperature is controlled, so that the flow rate, measured by means not shown, remains constant until the mass of trapped uranium hexafluoride is used up
  • a predetermined value that is to say when the value is reached of the intensity of the ion beam in the spectrometer
  • Another solution consists in using two devices of the kind shown in FIG. 2. One of them receives a wire carrying a deposit whose isotopic ratio is to be measured, the other a deposit of U 3 0 8 of known isotopic composition .
  • the invention is not however limited to these particular embodiments. It is applicable whenever a reaction giving a gaseous compound of the sample is available.
  • the method is applicable to the case of carbon, which can be fluorinated to give CF 4 , which is particularly interesting for the isotopic analysis C 12 / C l4 used in dating.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Claims (8)

1. Einlaßverfahren für gasförmige Mikroproben in die lonisationsquelle eines Massenspektrometers gemäß welchem Verfahren man die Probe aufheizt, um ihre Strömung in gasförmigem Zustand in Richtung auf die Quelle zu bewirken, dadurch gekennzeichnet, daß man die Mikroprobe auf einem Träger in Form einer Nadel oder eines Fadens (62) anordnet, man die auf ihrem Träger plazierte Mikroprobe in eine gasförmige Zusammensetzung transformiert durch Heizen in einer Atmosphäre eines Reagenzgases in einem Raum von wo an man eine Strömung im Bereich der molekularen Ausbeute der Zusammensetzung und des Reagenzgases in Richtung auf ein Sublimationsrohr organisiert, dessen Wand (40) man auf einer Temperatur hält, die ausreichend niedrig ist, um die gasförmige Zusammensetzung und das Reagenz aufzufangen, man selektiv die gasförmige Zusammensetzung durch progressives Heizen des Sublimationsrohres sublimiert und man eine Regelung der Ausgangsausbeute der gasförmigen Zusammensetzung durch Steuerung der Temperatur der besagten Wand bewirkt, indem man das Rohr in Verbindung mit der lonisationsquelle bringt.
2. Einlaßvorrichtung für Mikroproben in die lonisationsquelle (18) eines Massenspektrometers, das Heizmittel (20, 22, 26) der Mikroprobe und einen eingeengten und kalibrierten Durchgang (12) für die Strömung der gasförmigen Produkte der Beheizung aufweist, dadurch gekennzeichnet, daß sie einen Reaktor (10), der mit Aufnahmemitteln für einen Probenträger in Form einer Nadel (62) versehen ist, die bestimmt ist, einen Ansatz der Mikroprobe aufzunehmen, besagte Heizungsmittel der Mikroprobe, Verbindungsmittel mit einer Vakuumquelle (32) und Zuführmittel (38, 30) für eine regelbare Ausbeute des Transformationsreagenzes der Mikroprobe bei den besagten gasförmigen Zusammensetzungen, die vom Reaktor fließen, und ein Sublimationsrohr (40) aufweist, das einerseits mit dem Durchgang (12) und andererseits mit der ionenquelle (18) des Spektrometers unter Zwischenschaltung eines Ventils (16) und von Verbindungsmittel (46a) mit einer Vakuumquelle verbunden ist, wobei das besagte Rohr in einer Einfassung (42) eines Kreislaufs einer Tiefsttemperaturflüssigkeit angeordnet und mit Heizmitteln versehen ist, die es erlauben, die Ausgangsausbeute in Richtung auf die lonenquelle zu regeln.
3. Einrichtung nach Anspruch 2, dadurch gekennzeichnet, daß der Reaktor ein Rohr (20) aufweist, das dazu bestimmt ist, den Mikroprobenträger aufzunehmen, und das mit Heizmitteln, die durch den Jouie'schen Effekt programmiert sind, versehen ist.
4. Einrichtung nach Anspruch 2 oder 3, dadurch gekennzeichnet, daß der eingeengte und kalibrierte Durchgang (12) solche Abmessungen hat, daß die Strömung dort molekular ist.
5. Einrichtung nach Anspruch 4, dadurch gekennzeichnet, daß der Durchgang durch ein Diaphragma gebildet ist, das mit einer kalibrierten Düse, einer Kapillare oder einem Mikro-Leckage-Ventil durchstoßen ist.
6. Einrichtung nach Anspruch 2, dadurch gekennzeichnet, daß der Reaktor (10) und das Sublimationsrohr (40) mit Temperatursonden (24) versehen sind, die mit der Regelungsschaltung (26) der Heizmittel (22) verbunden sind.
7. Einrichtung nach Anspruch 3, dadurch gekennzeichnet, daß das Rohr (20) des Reaktors und das Sublimationsrohr (40) koaxial und in Ausrichtung zueinander angeordnet sind.
8. Einrichtung nach irgendeinem der Ansprüche 2 bis 7, dadurch gekennzeichnet, daß die Tiefsttemperaturflüssigkeit durch gasförmiges Helium gebildet ist, das bei der Temperatur von flüssigem Stickstoff gehalten ist.
EP19860400902 1985-04-24 1986-04-24 Verfahren und Probeneinlassvorichtung für ein Massenspektrometer Expired EP0200645B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8506257 1985-04-24
FR8506257A FR2581246B1 (fr) 1985-04-24 1985-04-24 Procede et dispositif d'introduction d'echantillons pour spectrometre de masse

Publications (2)

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EP0200645A1 EP0200645A1 (de) 1986-11-05
EP0200645B1 true EP0200645B1 (de) 1989-07-12

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EP19860400902 Expired EP0200645B1 (de) 1985-04-24 1986-04-24 Verfahren und Probeneinlassvorichtung für ein Massenspektrometer

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EP (1) EP0200645B1 (de)
CA (1) CA1263765A (de)
DE (1) DE3664401D1 (de)
FR (1) FR2581246B1 (de)
WO (1) WO1986006545A1 (de)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2629270B2 (fr) * 1988-03-25 1990-12-28 Cogema Dispositif d'introduction d'echantillons pour spectrometre de masse

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1132049A (fr) * 1954-05-26 1957-03-04 Thomson Houston Comp Francaise Dispositif d'introduction d'un échantillon dans un spectrographe de masse
US3888107A (en) * 1969-10-08 1975-06-10 Dow Chemical Co Differential thermal analysis cell assembly
DE3269499D1 (en) * 1981-11-30 1986-04-03 Vg Instr Group Automatic mass spectrometer inlet system

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DE3664401D1 (en) 1989-08-17
FR2581246A1 (fr) 1986-10-31
FR2581246B1 (fr) 1987-07-10
WO1986006545A1 (fr) 1986-11-06
EP0200645A1 (de) 1986-11-05
CA1263765A (fr) 1989-12-05

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