Method for manufacturing a quadrupole rod mass filter and quadrupole mass spectrometer

Abstract

To improve the yield at the time of manufacturing while maintaining the performance such as mass resolution. One aspect of the manufacturing method of the quadrupole rod mass filter according to the present invention is a method of manufacturing a quadrupole rod mass filter including four rod-shaped electrodes, characterized by including: a first step (S1, S2) of forming hyperboloids by cutting at least a part of a side surface or a peripheral surface of each of four rod-shaped members having a length in a range of 80 mm or more and 120 mm or less in a length direction thereof; and a second step (S3) of positioning and fixing the four rod-shaped members each of which is formed with the hyperboloids as the rod-shaped electrodes using a holding member so that the four rod-shaped electrodes surround a central axis and the hyperboloids of the respective rod-shaped electrodes face the central axis.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a quadrupole mass filter for a mass spectrometer, and a quadrupole mass spectrometer using the quadrupole mass filter. Background Technology

[0002] In a typical single quadrupole mass spectrometer, the various components (compounds) contained in the sample are ionized in the ion source. The resulting ions are separated by a quadrupole mass filter according to their mass-to-charge ratio (m / z), and the separated ions are detected by an ion detector.

[0003] A quadrupole mass filter typically has the following structure: four roughly cylindrical rod-shaped electrodes are arranged parallel to each other, tangent to an inscribed circle of a predetermined radius centered on a linear axis, and spaced at equal angular intervals (90°) in the circumferential direction. A DC voltage +U, i.e., voltage +(U+Vcosωt), superimposed with a high-frequency (RF) voltage +Vcosωt, is applied to two opposing rod-shaped electrodes sandwiching the central axis serving as the ion optical axis. A DC voltage -U, i.e., voltage -(U+Vcosωt), superimposed with a high-frequency (RF) voltage -Vcosωt that is phase-reversed (180° out of phase) from the aforementioned RF voltage +Vcosωt, and having a different polarity from the aforementioned DC voltage +U, is applied to the other two rod-shaped electrodes. When the voltage value U of this DC voltage and the amplitude value V of the RF voltage are set to predetermined values ​​corresponding to m / z, only ions with that m / z can selectively pass through the quadrupole electric field within the quadrupole mass filter.

[0004] It is well known that in quadrupole mass filters, making the rod electrodes longer in the axial direction is advantageous for improving mass resolution (mass selectivity). This is because, if the frequency ω of the high-frequency (RF) voltage is the same, the longer the rod electrode is in the axial direction, the more oscillations ions experience as they pass through the space enclosed by the rod electrode, thus stabilizing the oscillations of ions that should pass through (conversely, making the oscillations of ions that should not pass through more unstable). Furthermore, it is well known that in quadrupole mass filters, if the surface shape of each rod electrode facing the central axis is set to a hyperboloid (a surface with a hyperbolic profile on a plane orthogonal to the central axis), an ideal quadrupole electric field can be formed in the space enclosed by the rod electrodes (see Patent Document 1, etc.), thereby improving mass resolution and resulting in better peak shapes in the mass spectrum.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2018 / 138838 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] As mentioned above, to achieve high quality resolution and good peak shape, a rod-shaped electrode with a hyperboloidal surface facing the central axis and as long as possible in the axial direction is preferred for a quadrupole quality filter. However, machining the circumferential surface of the rod-shaped electrode requires micron-level precision, and forming a hyperboloid with high precision is much more difficult than forming a simple arc-shaped surface. Therefore, when attempting to manufacture a rod-shaped electrode with a hyperboloidal surface facing the central axis and a long axial direction, the manufacturing process is time-consuming and yields low results, leading to high costs. On the other hand, to reduce manufacturing costs, rod-shaped electrodes with a simple cylindrical shape are sometimes used, but in this case, good quality resolution and peak shape are inevitably sacrificed.

[0010] This invention was made to solve these problems, and its main objective is to provide a method for manufacturing a quadrupole mass filter that can reduce manufacturing costs while fully ensuring the performance of the quadrupole mass filter, such as high quality resolution and good peak shape, and to provide a quadrupole mass spectrometer using a quadrupole mass filter manufactured by this method.

[0011] Furthermore, in this specification, "quadrupole mass spectrometer" includes not only a general single quadrupole mass spectrometer, but also all mass spectrometers equipped with quadrupole mass filters, such as triple quadrupole mass spectrometers with quadrupole mass filters before and after the collision chamber, and quadrupole-time-of-flight (Q-TOF) mass spectrometers with a quadrupole mass filter in the front section of the collision chamber and a time-of-flight mass separator in the rear section.

[0012] Solution to the above technical problems

[0013] One aspect of the method for manufacturing a quadrupole mass filter according to the present invention is a method for manufacturing a quadrupole mass filter used in a mass spectrometer, characterized by comprising:

[0014] The first step involves forming hyperboloids by cutting at least a portion of the side or circumferential surface of each of four rod-shaped components, each with a length between 80mm and 120mm, along their entire length; and

[0015] The second step involves using four rod-shaped components, each with a hyperboloid, as rod-shaped electrodes. A retaining component is used to position and fix the four rod-shaped electrodes so that they surround the central axis and the hyperboloid of each rod-shaped electrode faces the central axis.

[0016] Furthermore, one aspect of the quadrupole mass spectrometer according to the present invention is characterized by comprising a quadrupole mass filter for separating analyte ions based on m / z, the quadrupole mass filter comprising:

[0017] Four rod-shaped electrodes, the length of which along the central axis is between 80 mm and 120 mm, and at least the surface facing the central axis is a hyperboloid; and

[0018] A retaining component is provided to fix the four rod-shaped electrodes in a position surrounding the central axis, with the hyperboloid of each rod-shaped electrode facing the central axis.

[0019] Invention Effects

[0020] The inventors conducted research from various angles on the manufacture of rod-shaped electrodes with a hyperboloidal inner surface. The results showed that when forming a hyperboloid by cutting the side or circumference of a long rod-shaped component, the bending of the rod-shaped component during processing leads to a decrease in the dimensional accuracy of the hyperboloid, which is the main reason for the reduced yield in manufacturing. In other words, by shortening the rod-shaped electrode, the bending of the rod-shaped component during processing can be reduced, thereby enabling more precise formation of the hyperboloid. On the other hand, as mentioned above, shortening the rod-shaped electrode reduces the number of oscillations of ions as they pass through the space surrounded by the rod-shaped electrode, which is detrimental in terms of mass resolution. Therefore, the inventors, while comprehensively considering other parameters such as ion velocity that affect the number of oscillations, conducted experimental and simulation studies to determine a rod length range that can improve the yield in manufacturing while maintaining the same or higher performance as before, thus completing this invention.

[0021] According to the manufacturing method of the quadrupole mass filter and the quadrupole mass spectrometer of the present invention, high-precision hyperboloids can be obtained with a cost-acceptable yield, and the required rod length can be ensured for target ion separation or selection. Therefore, in the manufacturing method of the quadrupole mass filter and the quadrupole mass spectrometer of the present invention, detection sensitivity can be improved while maintaining the same or higher mass resolution and good peak shape as before, and the cost can be significantly reduced. Attached Figure Description

[0022] Figure 1 This is a schematic structural diagram of the main parts of a single quadrupole mass spectrometer as one embodiment of the present invention.

[0023] Figure 2 This is a schematic plan view of the quadrupole mass filter in the single quadrupole mass spectrometer of this embodiment when viewed along the Z-axis.

[0024] Figure 3 This is a flowchart illustrating an example of the manufacturing steps of the quadrupole mass filter used in the single quadrupole mass spectrometer of this embodiment.

[0025] Figure 4 This is a schematic diagram showing an example of rod-shaped electrode fabrication.

[0026] Figure 5 This is a schematic diagram showing other examples of rod-shaped electrode processing.

[0027] Figure 6 This is a measured example of a mass spectrum obtained by analyzing PEG with an m / z of 1004.6 using a rod electrode with a rod length of 200 mm (existing product).

[0028] Figure 7 This is a measured example of a mass spectrum obtained by analyzing PEG with an m / z of 1004.6 using a rod electrode with a rod length of 120 mm.

[0029] Figure 8 This is a measured example of a mass spectrum obtained by analyzing PEG with an m / z of 1004.6 using a rod electrode with a rod length of 80 mm.

[0030] Figure 9 This is a measured example of a mass spectrum obtained by analyzing PEG with an m / z of 1893.4 using a rod electrode with a rod length of 200 mm (existing product).

[0031] Figure 10 This is a measured example of a mass spectrum obtained by analyzing PEG with an m / z of 1893.4 using a rod electrode with a rod length of 120 mm.

[0032] Figure 11 This is a measured example of a mass spectrum obtained by analyzing PEG with an m / z of 1893.4 using a rod electrode with a rod length of 80 mm. Detailed Implementation

[0033] [Supplementary explanations regarding the above aspects]

[0034] The quadrupole mass spectrometers described above can accept samples that are gaseous, liquid, or solid. The ionization method will naturally differ depending on the sample's morphology. In other words, the quadrupole mass spectrometers described above do not have particular limitations on the method for generating the analyte ions.

[0035] Furthermore, the quadrupole mass spectrometers mentioned above only require at least one quadrupole mass filter in their mass separators. Therefore, in addition to the very common single quadrupole mass spectrometer, these quadrupole mass spectrometers also include triple quadrupole mass spectrometers and quadrupole-time-of-flight mass spectrometers.

[0036] Alternatively, one or both of a pre-rod electrode and a post-rod electrode can be provided before or after the main rod electrode that plays a role in ion mass separation.

[0037] Furthermore, in the manufacturing method of the quadrupole mass filter mentioned above, there are no particular restrictions on the cross-sectional shape of the "rod-shaped component," but rods with round or square cross-sections are generally readily available.

[0038] Furthermore, in the manufacturing method of the quadrupole mass filter described above, there are no particular limitations on the machining method for cutting the side or circumferential surface of the rod-shaped component along its length to form a hyperboloid. However, it is naturally preferable to use a method that can obtain high dimensional accuracy. Specifically, one or more combinations of machining methods, including cutting, grinding, and polishing, electrical discharge machining, and etching can be employed.

[0039] [Structure and general operation of a quadrupole mass spectrometer according to one embodiment]

[0040] Hereinafter, a single quadrupole mass spectrometer and the quadrupole mass filter used therein, as one embodiment of the present invention, will be described with reference to the accompanying drawings.

[0041] Figure 1 This is a schematic structural diagram of the main components of the single quadrupole mass spectrometer of this embodiment. For ease of explanation, as shown... Figure 1 As shown, three mutually orthogonal axes, X, Y, and Z, are set in space.

[0042] like Figure 1 As shown, the quadrupole mass spectrometer has a chamber 1, which is roughly divided into four chambers: an ionization chamber 11, a first intermediate vacuum chamber 12, a second intermediate vacuum chamber 13, and an analysis chamber 14. The ionization chamber 11 is at approximately atmospheric pressure. The chambers after the first intermediate vacuum chamber 12 are evacuated under vacuum by a rotary pump (not shown) or a combination of a rotary pump and a turbomolecular pump.

[0043] An electrospray ionization (ESI) probe 2 is installed in the ionization chamber 11. The ionization chamber 11 is connected to the first intermediate vacuum chamber 12 via a desolvation tube 3 heated to a high temperature. A first ion guide 4 is installed in the first intermediate vacuum chamber 12. The first intermediate vacuum chamber 12 is connected to the second intermediate vacuum chamber 13 via a micropore located at the top of the conical orifice 5. A multi-polar second ion guide 6 composed of multiple rod-shaped electrodes is installed in the second intermediate vacuum chamber 13. A quadrupole mass filter 7, including four rod-shaped electrodes 70, and an ion detector 8 are arranged along the ion optical axis C in the analysis chamber 14.

[0044] During analysis, a predetermined voltage is applied to the ESI probe 2 (not shown), desolventizing tube 3, ion guides 4 and 6, conical orifice 5, quadrupole mass filter 7, and ion detector 8 by a power supply circuit (not shown). When a sample solution containing the analyte is introduced into the ESI probe 2, charged sample droplets are sprayed from the front end of the ESI probe 2 into the ionization chamber 11. As the charged droplets collide with the surrounding gas and become miniaturized, and the solvent in the droplets vaporizes, the molecules of the analyte in the sample droplets are ionized. The resulting ions are drawn into the desolventizing tube 3 and then sent to the first intermediate vacuum chamber 12.

[0045] Ions introduced into the first intermediate vacuum chamber 12 are focused near the micro-aperture of the cone-shaped aperture 5 under the influence of the electric field formed by the first ion guide 4, and enter the second intermediate vacuum chamber 13 through the micro-aperture. The ions are then focused and transported under the influence of the electric field formed by the second ion guide 6, entering the analysis chamber 14. In the analysis chamber 14, ions originating from the sample components are injected into the space surrounded by the four rod-shaped electrodes 70 of the quadrupole mass filter 7. Only ions with an m / z value corresponding to the voltage applied to these rod-shaped electrodes 70 can pass through this space and enter the ion detector 8. Other ions diverge along the way. That is, ions with a specific m / z are selected in the quadrupole mass filter 7. The ion detector 8 outputs an ion intensity signal corresponding to the amount of incident ions to a data processing unit (not shown).

[0046] [Structure of a quadrupole mass filter]

[0047] Figure 2 yes Figure 1 A schematic plan view of the quadrupole mass filter 7 as viewed from the left along the Z-axis.

[0048] like Figure 2 As shown, four rod-shaped electrodes 70 (70a, 70b, 70c, 70d; hereinafter, the symbols "70a, 70b, 70c, 70d" are used when describing individual rod-shaped electrodes, and "70" is used when describing a common rod-shaped electrode) made of a conductive material such as stainless steel are arranged parallel to each other and externally tangent to a virtual circle 75 with radius r0 centered on the central axis of the ion optical axis C, and are arranged at 90° angles in the circumferential direction. The cross-sectional shape of each rod-shaped electrode 70 is approximately cylindrical, but the portion of its circumferential surface facing the ion optical axis C, as described later, is formed into a hyperboloid by cutting away a portion of the circle. A hyperboloid, as referred to here, means a surface in the XY plane whose outline is hyperbolic, and which is continuously connected between the two ends of the rod-shaped electrode 70 along the Z-axis. The maximum distance in the cross-section of each rod-shaped electrode 70 is D, in this case, the radius of the circle before it was cut into a hyperboloid.

[0049] Four rod-shaped electrodes 70 are held by a slightly annular rod-shaped electrode holder (holding member) 71 made of an insulator such as ceramic. The position of the four rod-shaped electrodes 70 around the ion optical axis C is determined by mounting each rod-shaped electrode 70 at a predetermined position on the rod-shaped electrode holder 71 and fixing it, for example, with screws. Figure 1 As shown, the rod-shaped electrode holders 71 are positioned at two locations along the Z-axis, and these two rod-shaped electrode holders 71 are fixed to the base 72.

[0050] Furthermore, the structure for fixing the rod-shaped electrode 70 in the predetermined position is not limited to the structure described in this example, and various structures can be used. For example, instead of using the rod-shaped electrode holder 71 to hold a portion of the circumferential surface of each rod-shaped electrode 70 as in this example, a structure that holds both ends or one end of each rod-shaped electrode 70 can be used. Furthermore, instead of using a structure that places the rod-shaped electrode 70 or the rod-shaped electrode holder 71 on the base 72, it is also possible to consider suspending it from above, or fixing the rod-shaped electrode 70 to a wall surface located in front of and / or behind the rod-shaped electrode 70 (such as...). Figure 1 In the example, it is the structure on the wall separating the second intermediate vacuum chamber 13 from the analysis chamber 14.

[0051] In the quadrupole mass filter 7 of this embodiment, the lengths of the four rod-shaped electrodes 70 of the above-described shape are in a suitable range of 80 mm to 120 mm. This rod length is shorter than that of the rod electrodes constituting the quadrupole mass filter in a typical quadrupole mass spectrometer. While longer rod electrodes are generally advantageous for achieving high mass resolution, as will be described later, the inventors have confirmed that even with such relatively short rod-shaped electrodes 70, necessary and sufficient performance in terms of mass resolution can be ensured. Furthermore, the radius r0 of the virtual circle 75 circumscribed by the rod-shaped electrodes 70 is set in the range of approximately 2 to 6 mm, and the maximum distance D on the cross-section of the rod-shaped electrodes 70 is set in the range of approximately 7 to 12 mm.

[0052] The voltage applied to each rod electrode 70 of this quadrupole mass filter 7 is the same as before. That is, to the pair of opposing rod electrodes 70a and 70c sandwiching the ion optical axis C, a DC voltage +U is applied with an RF voltage +Vcosωt superimposed on it, and the DC bias voltage Vbias is added to the result: +(U+Vcosωt)+Vbias. To the other pair of rod electrodes 70b and 70d, a DC voltage -U with a polarity different from the DC voltage +U is applied with an RF voltage -Vcosωt superimposed on it, which is in phase opposite to the RF voltage +Vcosωt, and the common DC bias voltage Vbias is added to the result: -(U+Vcosωt)+Vbias. U and V are used to determine the m / z of the passing ions. On the other hand, Vbias affects the velocity of the ions injected into the quadrupole mass filter 7, and, as described later, affects the number of oscillations of the ions attempting to pass through the quadrupole mass filter 7. Typically, the RF voltage frequency is set in the range of approximately 0.8 to 1.6 MHz, and the DC bias voltage Vbias is set in the range of approximately -1 to -7 V (but this polarity is for positive ions; the polarity is different for negative ions).

[0053] [Manufacturing method of quadrupole mass filter]

[0054] The following reference Figures 3 to 5 The manufacturing steps of the above-mentioned quadrupole mass filter 7 are explained. Figure 3 Here is a flowchart of one of its manufacturing steps. Figure 4 and Figure 5 This is a schematic diagram showing an example of rod-shaped electrode fabrication.

[0055] The manufacturer first prepares four rod-shaped components of a specified length to serve as conductors (step S1). This specified length is a fixed length of 80 mm to 120 mm. Furthermore, the cross-sectional shape of the rod-shaped components is arbitrary, but the most commonly available material is a round bar (stainless steel) with a circular cross-section. Figure 4 The left side shows a cross-section of the rod-shaped component.

[0056] Next, the manufacturer processes a portion of the circumferential or lateral surface of each rod-shaped component along its entire length using a predetermined method to form a hyperboloid (step S2). This rod-shaped component with the hyperboloid is the rod-shaped electrode 70. The processing method is not particularly limited as long as it can form a hyperboloid with high precision, but any or a combination of machining methods including cutting, grinding, polishing, electrical discharge machining, and etching can be used. Figure 4 The right side shows the cross-section after the circumference of a rod-shaped component with a circular cross-section is cut into a hyperboloid.

[0057] In existing general-purpose quadrupole mass filters, the rod electrode length is 130 mm or more, typically around 200 mm. In contrast, the rod electrode used here is relatively short, ranging from 80 mm to 120 mm in length, about 1 / 3 to 3 / 5 of the standard rod length. According to the inventors' research, when attempting to process a portion of the circumferential or lateral surface of a rod-shaped component with a length of approximately 200 mm or more along its entire length as... Figure 4 When machining a hyperboloid shape as shown, the rod-shaped component is prone to bending during processing. This bending leads to a decrease in the accuracy of the hyperboloid shape, thus significantly reducing the yield rate during manufacturing. In contrast, if the length of the rod-shaped electrode is less than 120 mm, the bending of the rod-shaped component during machining can be suppressed to a practically negligible level. As a result, sufficiently high dimensional accuracy of the hyperboloid shape can be ensured.

[0058] Subsequently, the manufacturer fixes four rod-shaped electrodes 70 using rod-shaped electrode holders 71, such that the hyperboloids of each of the four rod-shaped electrodes 70 face the central axis, the vertices of their hyperboloids are externally tangent to the virtual circle 75, the angular interval between adjacent rod-shaped electrodes 70 in the circumferential direction is 90°, and each rod-shaped electrode 70 is parallel to the central axis (ion optical axis C) (step S3). Here, since the rod-shaped electrode holders 71 have arc-shaped rod-shaped electrode mounting portions for mounting the four rod-shaped electrodes 70, the position and circumferential orientation of each rod-shaped electrode 70 can be appropriately determined by mounting each rod-shaped electrode 70 to its respective rod-shaped electrode mounting portion and fixing it with screws or the like.

[0059] The manufacturer places the assembled rod-shaped electrode 70 onto the base 72 and secures it with screws or fasteners (step S4), thereby completing the process as described above. Figure 1 , Figure 2 The quadrupole mass filter 7 is shown.

[0060] As described above, by using shorter rod-shaped components (80-120 mm) to form the rod electrodes 70, a quadrupole mass filter 7 with a high-precision hyperboloid surface facing the central axis can be obtained. This allows for the formation of an ideal quadrupole electric field within the space enclosed by the rod electrodes 70 during analysis. Furthermore, despite the shorter rod electrodes 70, the number of oscillations of ions attempting to pass through the quadrupole mass filter 7 can be adequately ensured by appropriately setting parameters such as the DC bias voltage Vbias. This allows for improved detection sensitivity while maintaining the same or higher levels of mass resolution and good peak shape as before. Moreover, the increased yield during rod electrode manufacturing and the reduced cost of the rod components themselves due to the shorter rod length reduce the cost of the mass spectrometer. Furthermore, the shorter quadrupole mass filter 7 also offers the advantages of reducing the length (depth) of the mass spectrometer along the Z-axis, resulting in a smaller and lighter device.

[0061] [For the experiment to study the length of the rod]

[0062] To investigate how the length of the rod electrode affects the mass spectrometry performance when manufacturing a quadrupole mass filter according to the above steps, the inventors fabricated several quadrupole mass filters with only different rod lengths and conducted comparative experiments under the same conditions. The main conditions are as follows:

[0063] • Rod electrode length (L): 80mm, 120mm, 200mm (previously standard length)

[0064] • Maximum diameter of rod-shaped electrode cross-section: 10mm

[0065] • The radius r0 of the virtual circle circumscribed by the rod electrode is 4 mm.

[0066] • Frequency (f) of the RF voltage applied to the rod electrode: 1.2MHz

[0067] On the other hand, as mentioned above, the length of the rod-shaped electrode affects the number of oscillations of ions passing through the space surrounded by the rod-shaped electrode, and this number of oscillations affects the mass resolution. Therefore, even when the lengths of the rod-shaped electrodes are different, the number of oscillations is made approximately the same by adjusting the value of the DC bias voltage Vbias applied to all four rod-shaped electrodes. Changing the DC bias voltage Vbias changes the number of oscillations because changing the DC bias voltage Vbias changes the potential difference between it and the DC bias voltage applied to the front second ion guide 6, i.e., the energy of the ions changes, thereby causing a change in the velocity of the ions injected into the quadrupole mass filter 7. This change in ion velocity changes the residence time of the ions in the space surrounded by the rod-shaped electrodes 70, resulting in a change in the number of oscillations. Here, the relative value of the DC bias voltage Vbias when using a rod electrode with a rod length of 200 mm is set to 1, the relative value of the DC bias voltage Vbias when using a rod electrode with a rod length of 120 mm is set to 0.71, and the relative value of the DC bias voltage Vbias when using a rod electrode with a rod length of 80 mm is set to 0.5.

[0068] Figures 6 to 8 The measured waveforms of the peak of PEG with m / z 1004.6 are for rod lengths of 200mm, 120mm, and 80mm, respectively. Figures 9 to 11 The figures show the measured peak waveforms of PEG at m / z 1893.4 for rod lengths of 200mm, 120mm, and 80mm, respectively. The three peaks observed in each figure are monoisotope peaks and isotope peaks.

[0069] from Figures 6 to 11It can be seen that, in both m / z 1004.6 and m / z 1893.4 cases, the signal strength is increased for rod lengths of 120mm and 80mm compared to a rod length of 200mm. Furthermore, it can be confirmed that, in both rod lengths of 120mm and 80mm, the full width at half maximum (FWHM) of the peak can be adjusted to approximately the same 0.7u, and isotopes can be effectively separated.

[0070] Now, assuming the charge is e, the ion mass is m, the ion velocity through the rod electrode is v, and the DC bias voltage (accelerating voltage) is E, the following relationship theoretically holds.

[0071] (1 / 2)mv 2 =eE

[0072] v = √(2eE / m)

[0073] The number of oscillations N of the ions during their passage through the space enclosed by the rod-shaped electrode is given by...

[0074] N=ft=fL√(m / 2eE)…(1)

[0075] Established.

[0076] According to equation (1), in order to make the ion oscillation number N the same, when the DC bias voltage Vbias (relative value) corresponding to a rod length of 200 mm is set to 1, the DC bias voltage Vbias (relative value) corresponding to a rod length of 120 mm should be 0.36, and the DC bias voltage Vbias (relative value) corresponding to a rod length of 80 mm should be 0.16. That is, this shows that in practice, even if the DC bias voltage Vbias is set to be larger than the theoretical value (i.e., it does not need to be reduced that much), it is still possible to maintain high quality resolution and good peak shape. It can be inferred that this is because the length is shortened without changing the maximum distance D (the cross-sectional diameter of the rod-shaped component) of the rod electrode cross-section, thereby improving the machining accuracy of the hyperboloid of the rod electrode.

[0077] Furthermore, although experimental verification was not conducted for rod lengths beyond 200mm, 120mm, and 80mm, the above results suggest that when the rod length exceeds 120mm, the machining accuracy of the hyperboloid becomes problematic due to the bending of the rod-shaped component during formation. On the other hand, if the rod length is shorter than 80mm, there are concerns that the number of oscillations affecting quality resolution cannot be adequately guaranteed. Therefore, considering these factors comprehensively, it can be concluded that a reasonable range for rod length is between 80mm and 120mm.

[0078] In the above embodiment, the rod-shaped electrode 70 is formed of a round bar, but it can also be formed as follows: Figure 5As shown, a hyperboloid is formed by cutting a portion of the side surface of a rod-shaped component with a cross-sectional shape of a square or rectangle (or any other arbitrary quadrilateral). The cross-sectional shape of the rod-shaped component is not limited to this and can be any shape.

[0079] Furthermore, the above embodiments are merely one example of the present invention and are not limited to the various modifications described. Appropriate modifications, additions, and corrections made without departing from the spirit of the present invention should also be included within the scope of the claims of this application, which is obvious.

[0080] [Various aspects]

[0081] Those skilled in the art will understand that the above exemplary embodiments are specific examples of the following aspects.

[0082] (First item) One aspect of the method for manufacturing a quadrupole mass filter according to the present invention is a method for manufacturing a quadrupole mass filter used in a mass spectrometer, characterized in that it includes:

[0083] The first step involves forming hyperboloids by cutting at least a portion of the side or circumferential surface of each of four rod-shaped components, each with a length between 80mm and 120mm, along their entire length; and

[0084] The second step involves using four rod-shaped components, each with a hyperboloid, as rod-shaped electrodes. A retaining component is used to position and fix the four rod-shaped electrodes so that they surround the central axis and the hyperboloid of each rod-shaped electrode faces the central axis.

[0085] (Seventh) Furthermore, one aspect of the quadrupole mass spectrometer according to the present invention is characterized by comprising a quadrupole mass filter for separating analyte ions according to m / z, the quadrupole mass filter comprising:

[0086] Four rod-shaped electrodes, the length of which along the central axis is between 80 mm and 120 mm, and at least the surface facing the central axis is a hyperboloid; and

[0087] A retaining component is provided to fix the four rod-shaped electrodes in a position surrounding the central axis, with the hyperboloid of each rod-shaped electrode facing the central axis.

[0088] According to the manufacturing method of the quadrupole mass filter described in the first item and the quadrupole mass spectrometer described in the seventh item, by shortening the length of the rod electrode to less than 120 mm, a high-precision hyperboloid can be obtained with a cost-acceptable yield compared to existing general-purpose quadrupole mass filters. Furthermore, by setting the length of the rod electrode to 80 mm or more, the required rod length for target ion separation or selection can be ensured. Therefore, in the manufacturing method of the quadrupole mass filter described in the first item and the quadrupole mass spectrometer described in the seventh item, detection sensitivity can be improved while maintaining the same or higher mass resolution and good peak shape as before, and the cost can be significantly reduced.

[0089] (Second item) In the manufacturing method of the quadrupole mass filter described in the first item, in the second step, the four rod-shaped electrodes can be fixed as virtual circles tangent to the central axis with a radius of 2 to 6 mm.

[0090] (Third item) In the manufacturing method of the quadrupole mass filter described in the second item, the four rod-shaped electrodes produced in the first step may have a maximum distance of 7 to 12 mm in the cross section of each rod-shaped electrode in a direction parallel to the tangent of the rod-shaped electrode and the virtual circle.

[0091] (Item 8) In the quadrupole mass spectrometer described in Item 7, the four rod-shaped electrodes can be externally tangent to a virtual circle with a radius of 2 to 6 mm centered on the central axis.

[0092] (Item 9) In the quadrupole mass spectrometer described in Item 8, the four rod electrodes may have a maximum distance of 7 to 12 mm in the cross section of each rod electrode in a direction parallel to the tangent of the rod electrode and the virtual circle.

[0093] According to the manufacturing methods of the quadrupole mass filter described in items 2 and 3, and the quadrupole mass spectrometer described in items 8 and 9, except for the length of the rod electrode, the other dimensions can be the same as those of existing mass spectrometers, so the basic structure and configuration of the device can be used.

[0094] (Fourth item) In the manufacturing method of the quadrupole mass filter described in any one of items one through three, the hyperboloid can be formed by machining in the first step. The machining mentioned here includes grinding and cutting.

[0095] (Fifth item) Furthermore, in any of the manufacturing methods of the quadrupole mass filter described in the first to third items, the hyperboloid can be formed by electrical discharge machining in the first step.

[0096] (Sixth item) Furthermore, in the manufacturing method of the quadrupole mass filter described in any one of the first to third items, the hyperboloid can be formed by etching in the first step.

[0097] According to the manufacturing method of the quadrupole mass filter described in any one of items four to six, a good hyperboloid can be formed with high precision.

[0098] (Item 10) The quadrupole mass spectrometer described in any one of items 7 to 9 may further include a voltage application unit that applies a voltage to each rod electrode of the quadrupole mass filter, the voltage application unit being capable of applying an RF voltage in the frequency range of 0.8 to 1.6 MHz.

[0099] (Item 11) The quadrupole mass spectrometer described in any one of items 7 to 10 may further include a voltage application unit that applies a voltage to each rod electrode of the quadrupole mass filter, the voltage application unit being capable of applying a DC bias voltage with a voltage value of -1 to -7V.

[0100] According to the quadrupole mass spectrometer described in items 10 and 11, the voltage applied to the rod electrode can be the same as that of existing mass spectrometers, so existing circuits such as the voltage application section can be used.

[0101] (Item 12) In addition, in any of the quadrupole mass spectrometers described in Items 7 to 11, the maximum value of the m / z range can be in the range of 1000 to 2000.

[0102] (Item 13) In any of the quadrupole mass spectrometers described in Items 7 to 12, the half-peak width of the peaks in the mass spectrum can be in the range of 0.2 to 1.2 μ.

[0103] Explanation of reference numerals in the attached figures

[0104] 1…chamber

[0105] 11…Ionization Chamber

[0106] 12, 13... intermediate vacuum chambers

[0107] 14…Analysis Room

[0108] 2…ES I probe

[0109] 3…solvent removal tube

[0110] 4, 6... Ion Guides

[0111] 5… Tapered hole

[0112] 7… Quadrupole mass filter

[0113] 70… Rod-shaped electrode

[0114] 71… Rod-shaped electrode holder

[0115] 72…base

[0116] 75… Virtual Circle

[0117] 8…ion detector

[0118] C… ion optical axis (central axis).

Claims

1. A method for manufacturing a quadrupole mass filter, which is a method for manufacturing a quadrupole mass filter used in a mass spectrometer, characterized in that, include: The first step is to form a hyperboloid by cutting at least a portion of the side or circumference of each rod-shaped component along its entire length. as well as The second step involves using four rod-shaped components, each with a hyperboloid, as rod-shaped electrodes. A retaining component is used to position and fix the four rod-shaped electrodes so that they surround the central axis and the hyperboloid of each rod-shaped electrode faces the central axis.

2. The method for manufacturing a quadrupole mass filter as described in claim 1, characterized in that, In the second step, the four rod-shaped electrodes are fixed as virtual circles tangent to the central axis with a radius of 2 to 6 mm.

3. The method for manufacturing a quadrupole mass filter as described in claim 2, characterized in that, The longest distance between the four rod-shaped electrodes fabricated in the first step and the tangent of the virtual circle in the cross-section of each rod-shaped electrode is 7 to 12 mm.

4. The method for manufacturing a quadrupole mass filter as described in claim 1, characterized in that, In the first step, a hyperboloid is formed by machining.

5. The method for manufacturing a quadrupole mass filter as described in claim 1, characterized in that, In the first step, a hyperboloid is formed by electrical discharge machining.

6. The method for manufacturing a quadrupole mass filter as described in claim 1, characterized in that, In the first step, a hyperboloid is formed by etching.

7. A quadrupole mass spectrometer, characterized in that, This includes a quadrupole mass filter that separates analyte ions based on their mass-to-charge ratio. The quadrupole mass filter comprises: Four rod-shaped electrodes, the length of which along the central axis is between 80 mm and 120 mm, and at least the surface facing the central axis is a hyperboloid; and A retaining component is provided to fix the four rod-shaped electrodes in a position surrounding the central axis, with the hyperboloid of each rod-shaped electrode facing the central axis.

8. The quadrupole mass spectrometer as described in claim 7, characterized in that, The four rod-shaped electrodes are tangent to a virtual circle with a radius of 2 to 6 mm centered on the central axis.

9. The quadrupole mass spectrometer as described in claim 8, characterized in that, The longest distance between the four rod-shaped electrodes in the cross-section of each rod-shaped electrode in the direction parallel to the tangent of the rod-shaped electrode and the virtual circle is 7 to 12 mm.

10. The quadrupole mass spectrometer as described in claim 7, characterized in that, It also includes a voltage application section that applies a voltage to each rod electrode of the quadrupole mass filter, the voltage application section applying an RF voltage in the frequency range of 0.8 to 1.6 MHz.

11. The quadrupole mass spectrometer as described in claim 7, characterized in that, It also includes a voltage application section that applies a voltage to each rod electrode of the quadrupole mass filter, the voltage application section applying a DC bias voltage with a voltage value of -1 to -7V.

12. The quadrupole mass spectrometer as described in claim 7, characterized in that, The maximum range of the mass-to-charge ratio is 1000 to 2000.

13. The quadrupole mass spectrometer as described in claim 7, characterized in that, The peak width at half maximum (FWHM) in the mass spectrum is 0.2–1.2 μm.

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