Vortex-flow-generating device and mass spectrometer

Abstract

The present invention has a plate-shaped part (110) and a first thin tube (112) in order to generate a vortex flow with a simple configuration, said plate-shaped part (110) being a plate-shaped member of prescribed thickness having an opening part (111) that is a through-hole, and said first thin tube (112) guiding out an airflow inside the opening part (111) in the direction tangent to the outer contour of the opening part (111) and in the axial direction of the opening part (111), the opening part (111) having a circular cross section in the direction perpendicular to the axial direction of the opening part (111). The thin tube (112) is provided at an angle greater than 0° and less than 90° with respect to the central axis of the opening (111). Further, the predetermined angle is an angle at which the airflow can rotate at least once inside the opening (111).

Description

Vortex generator and mass spectrometer

[0001] The present invention relates to vortex generator and mass spectrometer technology.

[0002] Electrospray is a known method for ionizing biomolecules contained in a solution in a mass spectrometer. In an ion source using this electrospray method (electrospray ion source), a vortex flow is generated from the first aperture toward the metal probe. This is known to improve the performance of the mass spectrometer.

[0003] Patent Document 1 discloses a vortex gas flow interface for electrospray mass spectrometry, comprising: "an electrospray interface device comprising a transfer means for transporting a spray emitted from an electrospray needle to a low-pressure region, the transfer means having an inlet for receiving the spray; a source of heated gas; a means for applying centrifugal force to the spray, the means having a structure for forming a vortex gas flow from the heated gas, the vortex gas flow having a velocity component substantially transverse to the inlet of a mass spectrometer and a velocity component in the opposite direction to the direction of transport of the spray by the transfer means; and an outlet for supplying the formed product of the interface device to the inlet of the mass spectrometer" (see claim 1).

[0004] Patent Document 2 and Non-Patent Document 1 describe a configuration in which an inert gas is introduced into a spiral groove to generate a vortex flow from the mass spectrometer side toward the metal probe side (see Figures 1 and 2 of Patent Document 2).

[0005] Patent Document 3 describes generating a vortex by introducing an airflow from a direction inscribed in a conical structure. The vortex is generated from the ion source toward the mass analyzer while gradually reducing the diameter of the cone (see FIGS. 1 and 2). This structure allows charged droplets introduced into the vortex to have a relatively large angular velocity and a relatively small axial velocity of the cone. Therefore, the charged droplets remain in the conical structure for a long time, allowing them to be sufficiently dried (see column 5, lines 60 to 66). Furthermore, because the diameter of the conical structure decreases toward the mass analyzer, ions resulting from the dried charged droplets can be focused toward the outlet (see column 6, lines 34 to 37).

[0006] Patent No. 4657451 Chinese Patent No. 110112051 U.S. Patent No. 7595487

[0007] Yuze Li, Lingwei Meng, Guanghui Wang, Xiaoyu Zhou, Zheng Ouyang, and Zongxiu Nie, “A Gas-phase Reaction Accelerator using vortex flow” Analytical Chemistry (US), 2020, Vol.92, p.12049

[0008] As mentioned above, it is known that the performance of a mass spectrometer can be improved by causing a spiral swirling flow (vortex flow) to flow from the first orifice side toward the metal probe side. However, in the techniques described in Patent Documents 1 to 3 and Non-Patent Document 1, the structure of the vortex flow generating component is complicated, for example, a spiral groove is provided in a component placed upstream of the first orifice to generate the vortex flow. This causes an increase in costs.

[0009] The present invention has been made in view of the above background, and an object of the present invention is to generate a vortex flow with a simple configuration.

[0010] In order to solve the above-mentioned problems, the present invention provides a plate-like portion that is a plate-like member having a predetermined thickness and that has an opening that is a through hole, the opening having a circular cross section perpendicular to the axial direction of the opening, and an outlet portion inside the opening that outlets an airflow in a tangential direction to the outer shape of the opening and in the axial direction of the opening. Other means for solving the problems will be described as appropriate in the embodiments.

[0011] According to the present invention, a vortex flow can be generated with a simple configuration.

[0012] 1 is a front view of a vortex generator according to a first embodiment; FIG. 2 is a top view of the vortex generator according to the first embodiment; FIG. 3 is a circumferentially expanded view of an opening; FIG. 4 is a view showing the results of a fluid calculation indicating the flow of air at the opening; FIG. 5 is a view showing the installation location of a vortex generator in a mass spectrometer; FIG. 6 is a view showing the relationship between the air supply flow rate and the signal strength detected by the mass spectrometer; FIG. 7 is a view showing the relationship between the exhaust flow rate and the signal strength when exhaust is performed through a second capillary; FIG. 8 is a front view of a vortex generator according to a second embodiment; FIG. 9 is a top view of a vortex generator according to the second embodiment; FIG. 10 is a top view of a vortex generator according to a third embodiment; FIG. 11 is a top view of a vortex generator according to the third embodiment; FIG. 12 is a top view of a vortex generator according to the third embodiment; FIG. 13 is a view showing an example of a mass spectrometer using a commonly used ion source.

[0013] Next, a mode for carrying out the present invention (referred to as an "embodiment") will be described in detail with reference to the drawings as appropriate. In this embodiment, dimensions of components are described for reference, but the dimensions are not limited to those described in this embodiment. Furthermore, the z-axis direction in FIG. 1 will be referred to as the up-down direction, and the x-axis direction as the left-right direction. Furthermore, the y-axis direction in FIG. 2 will be referred to as the depth direction. Furthermore, the positive side of the z-axis in FIG. 1 will be referred to as the top side, and the negative side as the bottom side. Furthermore, the positive side of the x-axis in FIGS. 1 and 2 will be referred to as the right side, and the negative side as the left side. Furthermore, the positive side of the y-axis in FIG. 2 will be referred to as the back side, and the negative side as the front side. The back side is the side of the first micropore 301 (see FIG. 5), and the front side is the side of the metal probe 201 (see FIG. 5).

[0014] [First embodiment] Fig. 1 is a view of the vortex generator 100 according to the first embodiment as seen from the front (i.e., from the metal probe 201 side toward the first fine hole 301 side). Fig. 2 is a view of the vortex generator 100 according to the first embodiment as seen from above. In Fig. 1, the front side is the metal probe 201 side. In Fig. 2, the lower side of the paper is the metal probe 201 side, and the upper side of the paper is the first fine hole 301 side. Note that the insulating part 122 and the heater 121 are omitted from Fig. 2.

[0015] The vortex generator 100 includes a plate-like portion 110, a first capillary tube 112, a second capillary tube 113, a heater 121, and an insulating portion 122. The plate-like portion 110 is a plate-like member having a predetermined thickness and an opening 111, which is a through-hole. In the example shown in FIGS. 1 and 2, the plate-like portion 110 is, for example, a plate-like member measuring 20 mm in length and width and made of a conductive material. The opening 111 is located at the center of the plate-like portion 110 and has a circular cross section perpendicular to the axial direction of the opening 111. Note that the opening 111 need only be located in a position that allows ions N (see FIG. 5) to be introduced into the first aperture 301 (see FIG. 5), and does not necessarily have to be located at the center of the plate-like portion 110. In the example shown in FIGS. 1 and 2, the diameter of the opening 111 is 5 mm. In the example shown in FIGS. 1 and 2, the length of the cylindrical opening 111 of the vortex generator 100, i.e., the thickness of the plate-like portion 110, is 5 mm.

[0016] Although the plate-like portion 110 shown in the first embodiment is made of metal, specifically stainless steel, it may be made of any conductive material.

[0017] Furthermore, the vortex generator 100 is provided with a first capillary tube 112, which serves as an outlet. The first capillary tube 112 enters the interior of the plate-shaped portion 110 at position a1 from the outside of the plate-shaped portion 110 and terminates at position a2 of the opening 111. Inside the opening 111, the first capillary tube 112 outputs an airflow F1 in a tangential direction to the outer shape of the opening 111 and in the axial direction of the opening 111. Specifically, inside the opening 111, the first capillary tube 112 outputs the airflow F1 from the side of the first capillary tube 301 (FIG. 5), which is a small hole, toward the side of the metal probe 201 (see FIG. 5). In FIGS. 1 and 2, an outline arrow A11 indicates the gas being introduced into the first capillary tube 112.

[0018] In this manner, the airflow F1 is ejected (guided) from the first capillary tube 112 into the opening 111. The ejected airflow F1 may be compressed air, dry air, nitrogen, a rare gas, or the like. Because the first capillary tube 112 is open at position a2 under the above-described conditions, the ejected airflow F1 swirls along the inner wall surface of the opening 111 from the back side to the front side. This generates a vortex flow F flowing from the back side to the front side inside the opening 111. Note that gas is sent to the first capillary tube 112 by a pump (not shown). The diameter of the first capillary tube 112 is, for example, an inner diameter of 0.5 mm and an outer diameter of 0.8 mm.

[0019] The opening 111 of the vortex generator 100 is also connected to the end of a second capillary tube 113, which serves as a suction section. The second capillary tube 113 sucks in the discharged (ejected) airflow F1. This allows excess gas in the vortex flow F to be exhausted. The exhaust of excess gas by the second capillary tube 113 stabilizes the airflow near the outlet side (the metal probe 201 side) of the vortex flow F outside the opening 111. Without the exhaust of excess gas by the second capillary tube 113, the vortex flow F discharged from the opening 111 would collide with the airflow sent from the metal probe 201, causing turbulence. The exhaust of excess gas by the second capillary tube 113 will be described later. The second capillary tube 113 can be omitted. The exhaust of excess gas by the second capillary tube 113 is performed by an exhaust pump (not shown). 1 and 2, the outline arrow A12 indicates the gas being discharged from the second capillary tube 113.

[0020] As shown in FIG. 2 , the terminal end (position a2) of the first capillary tube 112 opens on the first orifice 301 side (rear side) of the opening 111. The terminal end of the second capillary tube 113 opens on the metal probe 201 side (front side) of the opening 111. As shown in the example of FIG. 2 , the first capillary tube 112 is provided in the opening 111 from the first orifice 301 side (rear side) toward the metal probe 201 side (front side). Furthermore, the first capillary tube 112 (its terminal end) is provided at an angle of 5° with respect to the surface of the plate-like portion 110 on the side of the first orifice 301. In other words, the terminal end of the first capillary tube 112 (the direction in which the airflow F is ejected by the first capillary tube 112) opens at a predetermined angle (85° in the example of FIG. 1 ) with respect to the central axis 151 of the opening 111. By opening the first capillary tube 112 under these conditions, the vortex flow F advances from the first orifice 301 side (rear side) toward the metal probe 201 side (front side). The angle of 5° between the opening 111 of the first capillary tube 112 and the surface of the plate-like portion 110 facing the first orifice 301 is an example. The angle between the opening 111 of the first capillary tube 112 and the surface of the plate-like portion 110 facing the first orifice 301 is determined by the thickness of the plate-like portion 110, the diameter of the opening 111, and the like. The first capillary tube 112 (outlet portion) at position a2 (the direction in which the airflow F1 is ejected by the first capillary tube 112) may be arranged at an angle greater than 0° and less than 90° (a predetermined angle) with respect to the central axis 151 of the opening 111. The line extending from the first aperture 301 toward the metal probe 201 with respect to the central axis 151 is defined as 0°.

[0021] A heater 121, which is a heating unit, is attached around the periphery of the plate-shaped portion 110 via an insulating portion 122. The heater 121 heats the plate-shaped portion 110 to a predetermined temperature (for example, 200°C). When the heater 121 heats the plate-shaped portion 110, the airflow F1 (vortex F) formed in the opening 111 is heated. The effect of heating by the heater 121 will be described later. Also, as will be described in detail later, a voltage is applied to the plate-shaped portion 110 during analysis by the mass spectrometer 1. By providing the insulating portion 122 between the plate-shaped portion 110 and the heater 121, the heater 121 can be protected from the effects of the voltage applied to the plate-shaped portion 110.

[0022] In the example shown in FIG. 1 , the insulating portion 122 and the heater 121 are provided on the upper and lower sides of the plate-shaped portion 110. However, as long as the insulating portion 122 and the heater 121 can heat the plate-shaped portion 110 and do not interfere with the configuration of the vortex generator 100, the locations where the insulating portion 122 and the heater 121 are provided are not limited to the upper and lower sides of the plate-shaped portion 110. For example, the insulating portion 122 and the heater 121 may be provided on the left and right sides of the plate-shaped portion 110, or on the rear and front sides of the plate-shaped portion 110. In this manner, the heater 121 is provided on the plate-shaped portion 110 via the insulating portion. Note that when the insulating portion 122 and the heater 121 are provided on the rear and front sides of the plate-shaped portion 110, the insulating portion 122 and the heater 121 are provided with openings 111 whose diameters are equal to or larger than the diameters of the openings 111 provided in the plate-shaped portion 110.

[0023] Furthermore, the heater 121 and the insulating part 122 may be provided only on the upper side or the lower side of the plate-shaped part 110, but providing the heater 121 on both the upper and lower sides of the plate-shaped part 110 allows for more uniform heating of the vortex generator 100. The same applies when the heater 121 is provided on the left and right sides or on the rear and front sides of the plate-shaped part 110.

[0024] The first capillary tube 112 itself is also heated by the heater 141, which is a heating unit, so that the airflow F1 (vortex flow F) flowing inside the first capillary tube 112 is heated.

[0025] (Flow of Airflow F1 at Opening 111) Figure 3 is a circumferentially expanded view of the opening 111, starting from positions b1 and b2. Reference is made to Figures 1 and 2 as appropriate. As shown in Figures 1 and 2, the airflow F1 ejected through the first capillary tube 112 generates a vortex F at the opening 111 of the vortex generator 100. The vortex F flows from the first orifice 301 side toward the metal probe 201 side. Hereinafter, to clarify the positional relationship, a line is defined as passing through position a2 where the first capillary tube 112 terminates, running along the wall surface of the opening 111, and parallel to the axial direction of the opening 111. As shown in Figure 2, the end position of this line on the first orifice 301 side is defined as position b1, and the end position on the metal probe 201 side is defined as position b2. Figure 3 shows an expanded view of the opening 111 cut along the line connecting positions b1 and b2. In Figure 3, line L11 and line L12 indicate the same location. A line L21 indicates the circumference of the opening 111. In the example shown in Fig. 3, the circumference of the opening 111 is approximately 15.7 mm.

[0026] In FIG. 3 , the solid arrow A1 indicates the direction of the airflow F1 along the wall surface of the opening 111. As described above, the first capillary tube 112 opens at position a2 of the cylindrical opening 111 at a 5° angle relative to the surface of the plate-like portion 110 facing the first orifice 301 at position a1 of the vortex generator 100. The airflow F1 ejected from the first capillary tube 112 forms a vortex F by flowing along the wall surface of the opening 111. Incidentally, one end and the other end of the dashed line DL in FIG. 3 indicate the same location on the wall surface of the opening 111. In the example shown in FIG. 3 , it can be seen that the airflow F1 ejected from position a2 rotates approximately three times inside the cylindrical opening 111. However, the three rotations of the airflow F1 inside the opening 111 are merely an example. The number of times the airflow F1 rotates inside the opening 111 depends on the dimensions of the opening 111, such as the diameter and length of the opening 111, and the angle at which the first capillary tube 112 is attached. However, the airflow F1 rotates at least one time. In other words, the predetermined angle at which the first capillary tube 112 is installed at position a1 is an angle at which the airflow F1 can rotate at least one time inside the opening 111. Incidentally, as the predetermined angle increases (as the angle becomes deeper), the number of times the airflow F1 can rotate decreases.

[0027] If the rotation of the airflow F1 inside the opening 111 is less than one rotation, unevenness (density and sparseness) of the airflow F1 occurs inside the opening 111. In other words, a strong airflow F1 occurs on one part of the wall surface of the opening 111, but the airflow F1 on the other wall surface becomes weak. This results in a decrease in the number of ions N reaching the first aperture 301. By rotating the airflow F1 one or more rotations inside the opening 111, it is possible to prevent such unevenness (density and sparseness) of the airflow F1, and the ions N can reach the first aperture 301.

[0028] (Fluid Calculation Results) FIG. 4 is a diagram showing the results of a fluid calculation showing the flow of the airflow F1 (vortex F) at the opening 111. Note that FIG. 4 omits the exhaust by the second capillary tube 113. In FIG. 4 , the airflow F1 enters from position a1 by the first capillary tube 112 and is ejected into the opening 111 at position a2. Since the airflow F1 spreads radially upon ejection, as shown in FIG. 4 , the airflow F1 is not as simple as shown in FIG. 3 , but it can be seen that the airflow F1 forms a vortex F and rotates multiple times until it reaches position b2, which is the outlet side of the opening 111. Positions b1 and b2 correspond to positions b1 and b2 shown in FIG. 2 .

[0029] [Layout of the vortex generator 100] Figure 5 is a diagram showing the location of the vortex generator 100 in the mass spectrometer 1. Refer to Figure 1 as appropriate. Figure 5 shows the periphery of the ion source 2 in the mass spectrometer 1. Around the ion source 2, the ion source 2, the vortex generator 100, a counter electrode 300, and an electrode 400 with a second orifice 401 are provided. In this embodiment, the ion source 2 refers to an electrospray ion source. The counter electrode 300 has a first orifice 301. The first orifice 301 is a orifice for introducing ions N generated from charged droplets Q into a vacuum. The second orifice 401 is provided in the pressure reduction unit 4. A mass analysis unit 510 (see Figure 13) for mass analysis of the ions N introduced through the first orifice 301 (and the second orifice 401) is provided downstream of the pressure reduction unit 4, but is not shown in Figure 5.

[0030] The ion source 2 is equipped with a metal probe 201 that sprays the sample solution LQ. In addition, depending on the flow rate and composition of the sample solution LQ, the ion source 2 may be configured as a double pipe by providing an assist flow piping 202 on the outside of the metal probe 201. In such a configuration, an assist flow airflow F11, which is an airflow for assisting spraying, may be used between the metal probe 201 and the assist flow piping 202. In the example shown in FIG. 5 , the assist flow airflow F11 is used. A vortex generator 100 is provided between the metal probe 201 and the first aperture 301.

[0031] Furthermore, the metal probe 201 is positioned at an angle relative to the opening 111 of the vortex generator 100 and the central axis of the first fine hole 301. By positioning the metal probe 201 at an angle relative to the opening 111 and the first fine hole 301 in this manner, large droplets present in large numbers at the center of the spray are prevented from reaching the first fine hole 301. This reduces contamination near the first fine hole 301. Furthermore, in the example shown in Figure 5, the vortex generator 100 and the first fine hole 301 are positioned at a distance of about 1 mm, but they do not have to be positioned at this distance.

[0032] The droplets sprayed from the metal probe 201 have the property that large droplets exist in the center and small droplets exist on the periphery. By positioning the metal probe 201 at an angle with respect to the opening 111 of the vortex generator 100, the large droplets located in the central part of the spray reach a location away from the opening 111. In contrast, the small droplets located in the peripheral part of the spray reach the opening 111.

[0033] A high voltage is also applied between the metal probe 201 and the vortex generator 100. This enables electrostatic spraying of the sample solution LQ. The charged droplets Q that are generated as a result of the sample solution LQ being sprayed by the metal probe 201 are introduced into the opening 111. In this way, the sample solution LQ is introduced into the metal probe 201, and a high voltage is applied, causing the sample solution LQ to be sprayed as charged droplets Q. The charged droplets Q are then exposed to the airflow F1 that forms the vortex F inside the opening 111, thereby drying. As a result of the drying, ions N are generated from the charged droplets Q, and the generated ions N move in the following order: opening 111 → first aperture 301 → second aperture 401.

[0034] Furthermore, during mass analysis, a voltage (DC voltage) is also applied between the vortex generator 100 and the counter electrode 300 through which the first aperture 301 opens. This causes ions N to drift toward the first aperture 301 inside the opening 111, making it easier for the ions N to pass through the first aperture 301. For example, when measuring positive ions, 4 kV is applied to the metal probe 201, 1 kV to the plate-like portion 110 of the vortex generator 100, 24 V to the counter electrode 300, and 5 V to the electrode 400 through which the second aperture 401 opens. Voltages are applied to the metal probe 201, the vortex generator 100 (plate-like portion 110), the counter electrode 300, and the electrode 400 through which the second aperture 401 opens, respectively, by power supplies 601 to 604. In this manner, voltages are applied to the metallic probe 201, the plate-like portion 110 of the vortex generator 100, and the counter electrode 300, which is the electrode in which the first aperture 301 is provided. This voltage is applied so that ions N generated from charged droplets Q sprayed from the metallic probe 201 move toward the first aperture 301. The application of voltages by the power supplies 501 to 504 is controlled by a control device (not shown). When negative ions are measured, the polarities of the voltages applied to the metallic probe 201, the vortex generator 100, the counter electrode 300, and the electrode 400 through which the second aperture 401 is opened are reversed compared to when positive ions are measured. In this manner, ions N can be moved from the aperture 111 to the mass analysis unit 510 (see FIG. 13 ).

[0035] As shown in FIG. 1 , the vortex generator 100 and the first capillary tube 112 are heated by the heaters 121 and 141, thereby heating the airflow F1 (vortex F) generated inside the opening 111 of the vortex generator 100. Note that the heaters 121 and 141 and the insulating portion 122 are not shown in FIG. 5 . In this manner, the charged droplets Q introduced into the opening 111 are exposed to the heated airflow F1 (vortex F). As a result, the drying of the charged droplets Q is promoted, as described above. If a gap exists between the counter electrode 300 and the vortex generator 100, outside air will flow in through the gap, lowering the temperature of the airflow F1.

[0036] To prevent such a decrease in the temperature of the airflow F1, the mass spectrometer 1 shown in Figure 5 is provided with an intervening portion 131 between the vortex generator 100 and the counter electrode 300. The intervening portion 131 seals the space between the first aperture 301 and the vortex generator 100. In the example shown in Figure 5, the intervening portion 131 has a size similar to that of the vortex generator 100 and a hollow rectangular parallelepiped shape. The intervening portion 131 seals the space between the ion outlet side of the vortex generator 100 and the ion inlet side of the first aperture 301.

[0037] However, the interposed portion 131 may be configured to prevent outside air from flowing in through the gap between the vortex generator 100 and the counter electrode 300. For example, the interposed portion 131 may be solid except for the portion corresponding to the counter electrode 300, the opening 111, and the hole communicating with the first orifice 301. When the temperature of the first capillary 112 is about 200°C, the provision of the interposed portion 131 makes it possible to maintain the temperature of the airflow F1 at about 100°C.

[0038] As described above, different voltages are applied to the vortex generator 100 (plate-like portion 110) and the counter electrode 300 during mass spectrometry, and therefore the interposed portion 131 is made of an insulating material.

[0039] In FIG. 5, the diameter of the first pore 301 and the diameter of the opening 111 are approximately the same, but in reality, the diameter of the first pore 301 is approximately 0.2 mm, while the diameter of the opening 111 is approximately 5 mm, as described above.

[0040] (Relationship between Airflow Rate and Signal Intensity) Figure 6 shows the relationship between the airflow rate and the signal intensity detected by the mass spectrometer 1 when the vortex generator 100 according to the first embodiment is used. Reference is made to Figures 1 and 5 as appropriate. Figures 6 and 7 show results when amino acids are used as samples. The signal intensity refers to the intensity of the detection signal detected by the mass spectrometer 1. In Figure 6, the horizontal axis indicates the flow rate (airflow rate) of the airflow F1 ejected from the first capillary 112, and the vertical axis indicates the signal intensity. In Figure 6, the white circles indicate the average value of the signal intensity, and the error bars indicate the standard deviation of the fluctuations in the signal intensity. The sizes of the components (component sizes) of the vortex generator 100 used in the experiment in Figure 6 are the same as those shown in Figures 1 to 3.

[0041] When the airflow F1 is ejected from the first capillary tube 112, a vortex F is generated at the opening 111 of the vortex generator 100, and the charged droplets Q are exposed to the vortex F, accelerating their drying. This improves the efficiency of generating gas-phase ions N, and the ions N are converged by the effect of the vortex F, thereby increasing the signal strength of the mass spectrometer 1. Gas-phase ions N refer to ions N floating in the air. As shown in FIG. 6, with the vortex generator 100 having the component sizes shown in FIGS. 1 to 3, the strongest signal strength was obtained when the airflow rate was approximately 1 L / min. In other words, sensitivity was improved.

[0042] (Relationship Between Exhaust Flow Rate and Signal Intensity) FIG. 7 is a diagram showing the relationship between the exhaust flow rate and signal intensity when exhaust is performed through the second capillary tube 113. FIGS. 1 and 5 are referenced as appropriate. In FIG. 7, the flow rate (airflow rate) of the airflow F1 ejected from the first capillary tube 112 to the opening 111 is set to 1 L / min. The diagram shows the relationship between the exhaust flow rate and the signal intensity detected by the mass spectrometer 1 when a portion of the airflow F1 is exhausted through the second capillary tube 113. As shown in FIG. 7, even if the exhaust flow rate increases, the signal intensity detected by the mass spectrometer 1 changes little. However, FIG. 7 shows that fluctuations in signal intensity are suppressed when the exhaust flow rate is an appropriate flow rate (0.6 L / min or less in the example shown in FIG. 7). At an exhaust flow rate other than an appropriate value (0.6 L / min or less in the example shown in FIG. 7 ), the vortex F generated within the opening 111 of the vortex generator 100 becomes turbulent when it is ejected to the outside of the opening 111 (toward the metal probe 201). At an air flow rate other than an appropriate value (0.6 L / min or less in the example shown in FIG. 7 ), the generated turbulence disrupts the airflow between the vortex generator 100 and the ion source 2, which is thought to result in large fluctuations in signal intensity.

[0043] 1 and 2, excess airflow F1 is exhausted from the second capillary tube 113 that opens on the metallic probe 201 side of the opening 111. This reduces turbulence near the outlet side (the metallic probe 201 side) of the opening 111. As a result, the airflow between the vortex generator 100 and the metallic probe 201 is stabilized, and fluctuations in the signal intensity of ions detected by the mass spectrometer 1 are suppressed.

[0044] In the vortex generating device 100 shown in the first embodiment, an opening 111, which is a circular through-hole, is provided in a plate-shaped member 110, and a vortex F is generated by ejecting an airflow F1 at an angle from the opening 111.

[0045] According to the first embodiment, it is possible to generate a vortex F with a simple structure from the first aperture 301 side of the mass spectrometer 1 toward the metal probe 201 side, without processing a complicated structure such as a spiral groove. It has been confirmed that the effect of the vortex F improves the sensitivity of the mass spectrometer 1. This makes it possible to provide a highly sensitive ion source 2 and mass spectrometer 1 at low cost.

[0046] Furthermore, by generating the vortex flow F, it is possible to remove large charged droplets Q by centrifugal force and extract only small charged droplets Q. This improves the analytical accuracy of the mass spectrometer 1.

[0047] [Second Embodiment] In the first embodiment, a detailed description of the vortex generator 100 was given, but the present invention is not limited to the first embodiment and various modifications are possible. Referring to Figures 8 to 10, vortex generators 100a and 100b according to a second embodiment of the present invention are shown. In the vortex generators 100a and 100b shown in Figures 8 to 10, a third capillary tube 112a is provided in the opening 111 to supply air from multiple locations to generate vortex flows F. In the second embodiment, an example is shown in which multiple first capillary tubes 112 (two in Figures 8 to 10) are provided as outlets.

[0048] 8 and 9 are diagrams showing the configuration of a vortex generator 100a used in the second embodiment. FIG. 8 is a front view of the vortex generator 100a according to the second embodiment. In FIG. 8, the front side is the side of the metal probe 201. FIG. 9 is a top view of the vortex generator 100a according to the second embodiment. In FIG. 9, the lower side of the page indicates the side of the metal probe 201, and the upper side indicates the side of the first pore 301. In addition, the heater 121 and the insulating portion 122 shown in FIG. 1 are omitted in FIGS. 8 to 10. In FIGS. 8 to 10, components similar to those shown in FIGS. 1 and 2 are designated by the same reference numerals, and their description will be omitted.

[0049] As in FIG. 1 , the terminal end of the first capillary tube 112 opens at a position inscribed in the opening 111. Also, as shown in FIG. 8 , the terminal end of the third capillary tube 112a, which serves as the outlet, also opens at a position inscribed in the cylinder of the opening 111. However, as shown in FIGS. 8 and 9 , the terminal end of the first capillary tube 112 and the terminal end of the third capillary tube 112a open at different positions. In the example shown in FIGS. 8 and 9 , the opening of the third capillary tube 112a is opposite the opening of the first capillary tube 112. Also, as shown in FIG. 9 , both the first capillary tube 112 and the third capillary tube 112a are located on the side of the first orifice 301 (the positive side of the y-axis). Furthermore, as shown in FIG. 9 , the opening of the third capillary tube 112a is angled from the side of the first orifice 301 toward the side of the metal probe 201. Inside the opening 111 of the vortex generator 100a, the airflows F1a and F1b ejected through the first capillary tube 112 and the third capillary tube 112a each generate a vortex F. The airflows F1a and F1b flow as a whole from the first capillary tube 301 side toward the metal probe 201 side. In Figures 8 to 10, the outline arrow A13 indicates the gas introduced into the third capillary tube 112a.

[0050] In the example shown in Figures 8 and 9, the airflow F1a ejected from the first capillary tube 112 and the airflow F1b ejected from the third capillary tube 112a form a double-spiral vortex flow F. The double-spiral vortex flow F formed by the airflow F1a and the airflow F1b flows inside the opening 111 from the first orifice 301 side to the metal probe 201 side. By forming the vortex flow F in this way, it is possible to reduce the unevenness of the airflow F1 (see Figure 1) near the wall surface of the opening 111. In other words, if there is only one vortex flow F, the density of the airflow F1 will be uneven. However, by forming the vortex flow F in a double-spiral shape, the sparse areas of the airflow F1 due to one airflow F1a are compensated for by the other airflow F1b. This reduces the unevenness of the airflow F1 near the wall surface of the opening 111. As a result, the vortex generator 100 shown in the first embodiment can converge the charged droplets Q at the center of the opening 111 .

[0051] In this way, in the vortex generator 100a, the airflows F1a and F1b are emitted (spouted) from the first capillary tube 112 and the third capillary tube 112a, respectively. The first capillary tube 112 and the third capillary tube 112a are arranged so that the airflows F1a and F1b flow through the opening 111 while forming a spiral with respect to each other.

[0052] FIG. 10 illustrates a vortex generator 100b, another example of the second embodiment. In the example illustrated in FIG. 10 , the third capillary tube 112a, which serves as another outlet, has an open end such that the airflow F1c ejected from the third capillary tube 112a runs parallel to the airflow F1 ejected from the first capillary tube 112, which serves as a predetermined outlet. With this configuration, the airflow F1 ejected from the first capillary tube 112 is energized by the airflow F1c ejected from the third capillary tube 112a. In other words, the first capillary tube 112 and the third capillary tube 112a are configured so that the airflow F1 ejected from the predetermined outlet (the first capillary tube 112 in the example of FIG. 10 ) is energized by the airflow F1c ejected from the other outlet (the third capillary tube 112a in the example of FIG. 10 ). This strengthens the centrifugal force of the vortex F, making it possible to remove large charged droplets Q by the centrifugal force. This makes it possible to obtain stable mass analysis results.

[0053] In the example shown in FIGS. 8 to 10, two thin tubes are provided to eject the airflow F1 (see FIG. 10), but three or more may be provided.

[0054] In the second embodiment, air is delivered from multiple locations inside the opening 111 of the vortex generator 100. The vortex generator 100a shown in FIGS. 8 and 9 can generate vortex flows F in a well-balanced manner, making the vortex flows F more uniform than the vortex generator 100 shown in the first embodiment. This reduces the bias of the air flows F1a and F1b inside the opening 111, suppressing fluctuations in the signal intensity of the ions N detected by the mass spectrometer 1. Furthermore, the vortex generator 100c shown in FIG. 10 can energize the vortex flows F inside the opening 111. As a result, as described above, the centrifugal force of the vortex flows F can remove large charged droplets Q, thereby obtaining stable mass analysis results.

[0055] 8 to 10, a second capillary tube 113 is provided on the metal probe 201 side of the opening 111, and the second capillary tube 113 exhausts excess airflow of the vortex flow F. The second capillary tube 113 can be omitted.

[0056] [Third Embodiment] Next, a third embodiment of the present invention will be described with reference to Figures 11 and 12. The opening 111 of the vortex generator 100 is not limited to a cylindrical shape (5 mm diameter, 5 mm length in the example shown in Figure 1) as shown in the first and second embodiments. In other words, the shape of the opening 111 can be modified depending on the composition and flow rate of the sample solution LQ (see Figure 5) introduced into the ion source 2. For example, even if the opening 111 is cylindrical, the diameter can be changed. In the example shown in Figures 10 and 11, the openings 111c and 111d have a truncated cone shape. Note that in Figures 11 and 12, components similar to those in Figure 2 are designated by the same reference numerals and will not be described again.

[0057] Figure 11 is a top view of a vortex generator 100c according to the third embodiment. The diameter of the opening 111c of the vortex generator 100c shown in Figure 11 is larger on the side of the metal probe 201 than on the side of the first micropore 301. In other words, the opening 11c is narrower on the side of the first micropore 301 and wider on the side of the metal probe 201. The opening 111c shown in Figure 11 can have a larger diameter on the side where the charged droplets Q (see Figure 5) are introduced, making it easier to introduce the charged droplets Q (see Figure 5) into the opening 111c.

[0058] Figure 12 is a top view of a vortex generator 100d according to the third embodiment. The diameter of the opening 111d of the vortex generator 100d shown in Figure 12 is smaller on the side of the metal probe 201 than on the side of the first fine hole 301. The opening 111d is wider on the side of the first fine hole 301 and narrower on the side of the metal probe 201. This configuration results in a stronger centrifugal force caused by the vortex F on the side of the opening 111d facing the metal probe 201 than in the vortex generator 100 shown in the first embodiment. As a result, large charged droplets Q are excluded by the centrifugal force, allowing only small charged droplets Q to be introduced into the opening 111d.

[0059] In both the vortex generator 100c shown in Fig. 11 and the vortex generator 100d shown in Fig. 12, an airflow F1 is sent from the first capillary 112, as in the first embodiment. As a result, a vortex F is generated within the opening 111 of the vortex generator 100. This increases the signal intensity detected by the mass spectrometer 1, as in the first embodiment.

[0060] 13 is a diagram showing an example of a mass spectrometer 1z using a commonly used ion source 2. The mass spectrometer 1z has an ion source (electrospray ion source) 2, a pressure reduction section 4, and a vacuum section 5. A counter electrode 300 having a first aperture 301 is provided between the ion source 2 and the pressure reduction section 4, and an electrode 400 having a second aperture 401 is provided between the pressure reduction section 4 and the vacuum section 5. Furthermore, the vacuum section 5 is provided with a mass analysis section 510 and an ion detector 520.

[0061] The ion source 2 is composed of a metal probe 201 and a high-voltage power supply 21. After a high voltage of several kV is applied between the metal probe 201 and the opposing electrode 300, a sample solution LQ is introduced into one end of the metal probe 201. The sample solution LQ is then sprayed from the nozzle of the metal probe 201 toward the opposing electrode 300. This spray contains a large number of charged droplets Q. If the particle size of the charged droplets Q is sufficiently small, they dry (desolvate) while traveling in the atmosphere, and ions N are extracted from the charged droplets Q into the gas phase. The ions N generated in this manner are introduced into the mass analysis unit 510 located in the vacuum unit 5 via the first aperture 301, the pressure reduction unit 4, and the second aperture 401.

[0062] A voltage of several tens of volts (drift voltage) is applied between the first aperture 301 and the second aperture 401 to drift the ions N toward the second aperture 401. The pressure reduction section 4 and the vacuum section 5 are each evacuated by a vacuum pump (not shown) having an appropriate pumping speed. The mass analysis section 510 employs various techniques, such as a quadrupole type, an ion trap type, or a time-of-flight type. The ions N are separated by the mass analysis section 510 based on the difference in m / z and detected by the ion detector 520. It is known that the performance of the mass spectrometer 1z is improved by generating a vortex flow (vortex flow F) from the first aperture 301 toward the ion source 2. A component for generating the vortex flow F is installed upstream of the first aperture 301, but is not shown in FIG. 13 .

[0063] In the mass spectrometer 1z shown in Figure 13, the structure of the component that generates the vortex F is complex, such as providing a spiral groove in the component placed in front of the first aperture 301 to generate the vortex F, which is a factor in increasing costs.

[0064] The vortex generators 100, 100a to 100d according to the first to third embodiments can generate a vortex F with a simple structure from the first aperture side toward the ion source 2 side. This makes it possible to provide a highly sensitive ion source 2 and mass spectrometer 1 at low cost.

[0065] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0066] The size and shape of the plate-like portion 110 may be any size as long as the opening 111 can be provided therein. Regarding the circular cross-sectional shape of the opening 111, a perfect circle or a nearly perfect circle is preferable, but any circular shape may be used as long as it achieves the objectives and effects of the present invention. Furthermore, the cross section may be an ellipse, an elongated hole, or a polygon, as long as it does not impair the objectives and effects.

[0067] In addition, in each embodiment, the control lines and information lines shown are those that are considered necessary for explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are interconnected.

[0068] 1, 1z Mass spectrometer 2 Ion source (electrospray ion source) 100, 100a to 100d Vortex generator 110 Plate-shaped portion 111, 111c, 111d Opening 112 First capillary tube (outlet portion) 112a Third capillary tube (outlet portion) 113 Second capillary tube (suction portion) 121 Heater (heating portion) 122 Insulating portion 131 Interposed portion 141 Heater (heating portion) 151 Central axis 201 Metal probe 300 Counter electrode 301 First capillary tube (aperture) 400 Electrode 401 Second capillary tube 510 Mass analysis portion 520 Ion detector 601 to 604 Power supply a1, a2, b1, b2 Position A1 Solid arrow A11 to A13 Open arrow F: Vortex flow F1, F1a to F1c: Air flow LQ: Sample solution L11: Line L12: Line L21: Line N: Ion Q: Charged droplet

Claims

1. A vortex generating device comprising: a plate-like portion which is a plate-like member having a predetermined thickness and an opening which is a through hole; the opening having a circular cross section perpendicular to the axial direction of the opening; and an outlet portion within the opening which outlets an airflow in a tangent direction to the outer shape of the opening and in the axial direction of the opening.

2. The vortex generating device according to claim 1, characterized in that the outlet portion is provided at a predetermined angle greater than 0° and less than 90° with respect to the central axis of the opening portion.

3. The vortex generating device according to claim 2, characterized in that the predetermined angle is an angle at which the airflow can rotate at least once inside the opening.

4. The vortex generating device according to claim 1, further comprising a heating section for heating the airflow.

5. The vortex generating device according to claim 4, characterized in that the heating portion is provided on the plate-shaped portion via an insulating portion.

6. The vortex generating device according to claim 1, further comprising a suction section for sucking in the guided airflow.

7. The vortex generating device according to claim 1, characterized in that a plurality of said outlet portions are provided.

8. The vortex generating device according to claim 7, characterized in that the plurality of outlet sections are arranged so that the air currents discharged from each of the plurality of outlet sections form a spiral with respect to each other and flow through the opening.

9. The vortex generating device according to claim 7, characterized in that the plurality of outlet sections are arranged so that the airflow outlet from a given outlet section is energized by the airflow outlet from the other outlet sections.

10. A mass spectrometer having an electrospray ion source having a metal probe into which a sample solution is introduced and which sprays the sample solution as charged droplets when a high voltage is applied, an orifice for introducing ions generated from the charged droplets into a vacuum, and a mass analysis section for mass analyzing the ions introduced through the orifice, with a vortex generator provided between the metal probe and the orifice, wherein the vortex generator has a plate-like section which is a plate-like member having a predetermined thickness and which has an opening which is a through hole, the opening having a circular cross section perpendicular to the axial direction of the opening, and an outlet section which outlets an airflow inside the opening in a tangent direction to the outer shape of the opening and from the orifice side towards the metal probe side.

11. The mass spectrometer according to claim 10, further comprising an intervening part for sealing the space between the fine hole and the vortex generator.

12. The mass spectrometer described in claim 10, characterized in that the plate-like portion is made of a conductive material, and a voltage is applied to each of the metal probe, the plate-like portion of the vortex generator, and the electrode in which the fine hole is provided, and the voltage is applied so that ions based on the charged droplets sprayed from the metal probe move in the direction of the fine hole.

13. The mass spectrometer according to claim 10, wherein the opening has a truncated cone shape, and the opening is narrow on the side of the aperture and wide on the side of the metal probe.

14. The mass spectrometer according to claim 10, wherein the opening has a truncated cone shape, and the opening is wider on the side of the aperture and narrower on the side of the metal probe.

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