JP2007194097A - Charged particle transport mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle transport mechanism which can prevent two sets of flexible cables for electrically connecting between opposed two lens electrodes from touching each other, as well as can reduce the number of the producing steps of the device therewith and simplify the fabrication method of those portions, thereby improving its reliability and maintainability. <P>SOLUTION: An assembling method of this charged particle transport mechanism comprises the steps of inserting a fastening screw 23 into a hole formed at a predetermined position for a lens electrode 4 which makes a set with four ones; engaging a nut 24 onto the fastening screw 23 and screwing it to an intermediate position; inserting a connection half ring 21 which is formed from parts of a connection part 21A, a stepped part 21B, and a contact 21C, from the side direction of the fastening screw 23 into a gap between the nut and a lens electrode, and fastening the fastening screw 23 tight; fixing a connection half ring 21 at opposed two lens electrodes 4, respectively; and inserting the other connection half ring 22 which has the reversed structure of the connection half ring 21 from the side direction on the rear side of the shown drawing, and fixing it to the other opposed two lens electrodes 4, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mass spectrometer (hereinafter referred to as MS), particularly a liquid, which selects charged particles by utilizing a phenomenon in which motility varies depending on the mass of the charged particles and the number of charges, and obtains a mass spectrum of a test substance. The present invention relates to a liquid chromatograph mass spectrometer (hereinafter referred to as LC / MS) that performs mass spectrometry in combination with a chromatograph (hereinafter referred to as LC). In LC / MS, separation according to the moving speed of the sample and quantitative analysis of the separated substance are performed in the preceding LC. Also, ionization (ionization) of the separated substance is performed in the subsequent MS, the ionized charged particles are transported to the charged particle sorting unit, and the charged particle sorting unit sorts the charged particles based on the mass and the number of charges. A qualitative analysis is performed. In order to conduct detailed qualitative analysis with a small amount of separation, a transport mechanism with little loss of charged particles is important.

  Hereinafter, LC / MS will be described as an example. In LC / MS, a sample solution as a test substance is first separated for each solute in the previous LC, and then sprayed from the spray to the atmosphere. A high voltage is applied to the spray tip, and mist-like charged particles (generally positive ions, hereinafter referred to as ions) ionized at this high voltage are attracted from the MS inlet to the MS entrance. Sample ion flow. The sample ion stream is transported by a Q-array and octopole at the rear stage of the incident part. A Q array generally comprises an even number of lens electrodes as a set. For example, Patent Document 1 describes ion transport by the even number of lens electrodes.

  The sample ion flow that has passed through the Q array and the octopole is sorted (filtered) by the mass-to-charge ratio of the ions with a quadrapole mass filter (QMS) and depends on the voltage applied to the QMS electrode (superposed voltage of high frequency and direct current). Only ions having a specific mass-to-charge ratio are extracted as current. A mass spectrum is obtained by scanning the voltage applied to the QMS electrode.

  Hereinafter, the basic structure of a conventional MS will be described with reference to FIG. In FIG. 5A, a sprayed sample ion stream (hereinafter referred to as a sample ion stream) ionized and radiated at the tip of the spray 1 to which a high voltage is applied is incident on an incident portion composed of a cover 2 and a sampling cone 3. , It passes through a Q-array part composed of several sets of lens electrodes 4. At this time, most of the solvent that is not necessary for mass spectrometry is removed by the nitrogen gas flow introduced from the suction hole S and ejected to the outside through the gap between the sampling cone 3 and the cover 2.

  One set of lens electrodes 4 is composed of four lens electrodes 4 as shown in FIG. 5B, and equal transport voltages are applied to the opposing lens electrodes 4, for example, the upper and lower lens electrodes 4. Is done. In general, the transport voltage is a high-frequency voltage. A high frequency voltage having a phase opposite to that of the high frequency voltage is applied to the other two left and right lens electrodes 4. Hereinafter, both are simply referred to as RF voltage. The sample ion flow passes through the skimmer 5 while being focused by the RF electric field generated by the RF voltage, and is guided to the octopole section at the rear stage and further to the MS filter section. In the Q array section, a plurality of sets of lens electrodes 4 are used as required in the design. Although the shape of the lens electrode 4 may be different for each stage, FIG. 5 illustrates three sets of lens electrodes 4 having the same shape.

  The octopole part is composed of an octopole 6 composed of eight rods, and the sample ion stream is further transported by the voltage applied to the octopole 6 and passes through the aperture 7 and enters the MS filter part. The sample ion flow depends on the mass-to-charge ratio (M / e), and on the analysis voltage (superposed voltage of high frequency and direct current) applied to the four rods or the quadrupole composed of four electrodes whose cross sections are hyperbolic. After being subjected to mass selection, only ions having a specific mass-to-charge ratio are extracted from the collector 9 as current. The collector 9 is often a secondary electron multiplier. A mass spectrum of the sample ion stream can be obtained by scanning the analysis voltage.

  Neutral particles mainly composed of solvent / carrier gas attracted to the incident part along with the sample ion flow, and neutralized by colliding with each electrode after meandering the diverging orbit by mass selection when passing through the MS filter part The converted particles and the like are always exhausted and removed from the exhaust port A, exhaust port B, and exhaust port C provided in each part by a vacuum pump (not shown) connected to each exhaust port.

  FIGS. 6A and 6B show an assembly example of the lens electrode 4 portion and a conductive connection example of the opposing lens electrode 4 in the case of three sets of lens electrodes 4. A set of four lens electrodes 4 are insulated from each other via an insulating holding ring 10 and an insulating insulating spacer 13 and fastened by a fastening screw 12 and a nut 14. The opposing lens electrodes 4 are electrically connected by lead wires 11a and 11b, respectively. Since the lead wires 11a and 11b are arranged so as not to contact each other, the portion where the lead wires 11a and 11b overlap is shown symbolically in FIG.

JP 2000-149865 A

  The structure of the conventional mass spectrometer is as described above. However, in this structure, there is a problem in the structure for electrical connection of the facing lens electrodes 4 in the Q array section. That is, the flexible lead wires 11a and 11b, which are basically indeterminate, have a problem in covering with an organic insulating tube having a large amount of released gas because they are placed in a vacuum environment, and they are covered with glass. Even so, problems such as bending limitations and breakage during use occur, and therefore, it is usually used with bare wires. However, in this method, the higher the material hardness of the bare wire, the worse the workability, and the lower the hardness, the multiple lead wires arranged in a limited space or a conductor envelope, etc. There is always a danger of contact, hindering the reliability of the equipment.

  Further, in order to securely fasten the lead wires 11a and 11b to the lens electrode 4 when the lens electrode 4 is assembled, an auxiliary component such as a lug fitting is previously brazed to the end portions of the lead wires 11a and 11b. Although it is desirable to keep it fixed, this method increases the amount of released gas even when used at room temperature, and especially during the baking process (bakeout) to improve the vacuum, and the baking temperature. However, there was a problem with the performance of the equipment used in vacuum.

  Furthermore, in conventional structures, assembly is performed with the shape of the irregularly shaped flexible part appropriately maintained, and the parts and the device are protected so that unexpected contact with the lead wires or the envelope of the mass spectrometer does not occur. There is a problem in work efficiency, reliability, and maintainability because it is necessary to store, transport, and manage the equipment. An object of the present invention is to provide means for solving such problems, and is an invention for reducing the number of manufacturing steps of the device, and improving reliability and maintainability.

  In order to solve the above-described problems, the present invention provides a charged particle transport mechanism in which a contact plate that is in contact with and electrically contacts each lens electrode facing each other, and is disposed outside a passage region of the charged particle flow. A connection plate for electrically connecting each contact plate is provided.

  According to the present invention, the lens electrodes facing each other can be easily and reliably electrically connected to each other using a part having a small amount of released gas with a fixed shape, and no change in shape after assembly occurs. Thus, the number of manufacturing steps of the device can be reduced, and reliability and maintainability can be improved.

  A feature of the mass spectrometer provided by the present invention is that a contact plate that contacts each of the opposing lens electrode surfaces is connected to the contact plate by a connection plate.

  This will be described with reference to the illustrated example. In FIGS. 1 and 2, the structure and operation of components having the same reference numerals as those in FIGS. 5 and 6 are the same as those in FIGS. 1A is a front view showing the configuration of the lens electrode 4 portion of the present invention, FIG. 1B is a perspective view of the same portion, and FIG. 2 is a detailed view of a portion where the lens electrode 4 and the contact plate 21C are in contact with each other. . The connection half ring 21 functioning as the connection means of the present invention is composed of a connection plate 21A, a step portion 21B, and a contact plate 21C, and is integrated. Examples of the material of the connection half ring 21 include materials having good conductivity such as a copper plate, an aluminum plate, and a stainless plate. The contact plate 21 </ b> C has a U-shaped recess U at its end, and the connection half ring 21 is fastened to the lens electrode 4 by the U-shaped recess U, the fastening screw 23 and the nut 24.

  At this time, first, the fastening screw 23 is inserted into the prescribed hole of the lens electrode 4 and the nut 24 is screwed to the intermediate position. Then, the connection half ring 21 is formed using the U-shaped recess U as shown in FIG. It can be inserted from the side and final tightening can be completed. The step portion 21B integrates the connecting plate 21A and the contact plate 21C while securing a step of, for example, several mm in the axial direction. The integration method is simply cutting out a single flat plate and bending it so as to match the dimensions of the connecting plate 21A, stepped portion 21B and contact plate 21C, and fixing by a conductive method such as welding. May be.

  The connection half ring 21 and the connection half ring 22 are connected to the lens electrode 4 from opposite directions. In addition, although the connection half ring 22 which functions as a connection means of the present invention together with the connection half ring 21 is given a different symbol from the connection half ring 21 for the sake of explanation, both are parts having the same structure arranged on the front and back, A detailed description of the connection half ring 22 is omitted. Since the U-shaped recess U is provided as described above, the contact plate 21C can be inserted from the lateral position with the nut 24 screwed into the intermediate screw 23 in advance as shown in FIG. Is efficient and the assembly process is accelerated. In FIG. 1A, the connection half ring 21 and the connection half ring 22 overlap each other within a range of about 90 °. However, because of the effect of the stepped portion 21B, both are arranged in front and rear in the axial direction. There is no interference. In FIG. 1, the fastening screw 23 is shown on the paper surface side on the connection half ring 21 side, and the nut 24 is shown on the paper surface side on the connection half ring 22 side. Even if all the nuts 24 are arranged on the back side, no special trouble occurs.

  The present invention is not limited to the above-described embodiments, and various modifications can be given. For example, in FIG. 1, the pair of lens electrodes 4 is two to four, but two or more pairs are sufficient. Therefore, the connecting plate 21A does not necessarily need to be orthogonal to the axial direction. Further, the connecting plate 21A does not have to be semicircular, and may have an elliptical shape, a partial shape of a polygon, or a straight portion. The direction of the stepped portion 21B is not necessarily limited to the direction parallel to the axis. A plurality of step portions 21B may be provided. The step portion 21B is useful as a means for avoiding contact between the connection plates 21A, but without using the step portion 21B, the connection plate 21A and the contact plate 21C are directly connected, and the connection plate 21A itself is an axis. It may be curved three-dimensionally in the direction to avoid contact between the connecting plates. Furthermore, the contact between the lens electrode 4 and the contact plate 21C does not have to be a surface contact. For example, a protrusion may be formed on a part of the contact plate 21C to make a point contact.

  As shown in the connection plate 25A in FIG. 3, the connection plate 21A may have a thickness direction in a direction different from that in FIG. 1B, and the step portion 25B and the contact plate 25C may be integrated there. Further, the shape of the U-shaped recess U is not limited to the U-shape, and for example, a bulge having a cross section of a flask may be provided at the bottom of the U-shape to further improve the positioning and retaining effect during assembly. The effect of the present invention is not impaired even if the concave portion has a hooked shape (such as a bowl shape) or a circular hole instead of the concave portion. Also, as shown in the contact plate 26C in FIG. 4, the end of the U-shaped recess U is not flat but slightly lifted so that the contact plate 26C and the fastening screw 23 in FIG. It can be improved. The present invention includes all of these. Although the fastening screw 23 has been described as an example of the fastening member, a fastening member that does not use a screw can be used and is not limited to the fastening screw.

The present invention relates to a mass spectrometer that obtains a mass spectrum of a test substance by using a phenomenon in which motility is different depending on the mass of ions and the number of charges, and in particular a liquid for mass analysis in combination with a liquid chromatograph It can be applied to a chromatograph mass spectrometer.

FIG. 1A is a diagram illustrating a configuration of the present invention, FIG. 1A is a cross-sectional view, and FIG. 2B is a perspective view illustrating a relationship between a lens electrode and a connection plate. It is a figure which shows the fixing method of the connection half ring and lens electrode of this invention. It is a figure which shows the modification Example of this invention. It is a figure which shows the other modified Example of this invention. It is a figure which shows the structural example of the conventional mass spectrometer. It is a figure which shows the longitudinal cross-section of the lens electrode part of the conventional mass spectrometer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spray 2 Cover 3 Sampling cone 4 Lens electrode 5 Skimmer 6 Octapole 7 Aperture 8 Quadrapole 9 Collector 10 Holding ring 11a Lead wire 11b Lead wire 12 Fastening screw 13 Insulating spacer 14 Nut 21 Connection half ring 21A Connection plate 21B Step part 21C Contact Plate 22 Connection half ring 23 Fastening screw 24 Nut 25A Connection plate 25B Stepped portion 25C Contact plate 26C Contact plate A Exhaust port B Exhaust port C Exhaust port S Suction hole U U-shaped recess

Claims (3)

  An incident part for allowing the charged particle flow of the sample to enter along the axial center and at least two pairs of lens electrodes facing each other with the axial center in the subsequent stage of the incident part, and applying a transport voltage to each of the lens electrodes In the charged particle transport mechanism for transporting the sample charged particles to the next stage by the electric field generated around the axis, the contact plates that are in contact with and electrically connected to the opposing lens electrodes, and the charge A charged particle transport mechanism characterized in that a connection plate is provided outside the particle flow passage region to electrically connect the contact plates.   The charged particle transport mechanism according to claim 1, wherein the contact plate is formed with a recess into which a fastening member for fixing contact with the lens electrode can be inserted.   The charged particle transport mechanism according to claim 1, wherein the charged particle is an ion.

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