Ion analysis device

Abstract

The present application relates to an ion analysis device, and aims to improve ionization efficiency and ion collection efficiency in an ESI ion source, improve analysis output, and improve analysis sensitivity. One aspect of the ion analysis device of the present application is an ion analysis device provided with an ion source using an ESI method, the ion source (2) being provided with: a plurality of capillaries (211 to 218) that spray a supplied liquid sample in the same direction; one or a plurality of auxiliary electrodes (23, 231 to 238) disposed so as to be surrounded by the plurality of capillaries; and a voltage application unit (24) that applies a direct-current high voltage to the plurality of capillaries with reference to the potential of the one or the plurality of auxiliary electrodes.

Description

TECHNICAL FIELD

[0001] The present application relates to an ion analysis device including a mass analysis device and an ion mobility analysis device, and more particularly to an ion analysis device provided with an ion source utilizing an ElectroSpray Ionization (ESI) method. BACKGROUND

[0002] In a liquid chromatograph mass spectrometer (hereinafter referred to as LC-MS) in which a mass analysis device is used as a detector of a liquid chromatograph (LC), an ion source based on an atmospheric pressure ionization method that ionizes compounds in a liquid sample at atmospheric pressure is used. In the atmospheric pressure ionization method, the most representative one is the ESI method. Hereinafter, the ion source using the ESI method will be referred to as an ESI ion source.

[0003] As disclosed in Patent Literature 1 and the like, the ESI ion source includes a capillary that is thin in diameter and has electrical conductivity, and a cylindrical gas tube that is arranged in a concentric manner so as to surround the periphery of the capillary. If a liquid sample is supplied to the capillary and a direct-current high voltage is applied to the capillary, an electric charge is imparted to the liquid sample by an electric field formed near the front end of the capillary. The liquid sample is blown out as a charged droplet from the front end of the capillary with the help of an atomizing gas blown out from the gap between the outer periphery of the capillary and the inner periphery of the gas tube. The charged droplet is fine by contacting with the surrounding gas molecules, and the solvent (flowing phase used in the liquid chromatograph) in the droplet is vaporized. In this process, the compound molecules contained in the charged droplet become ions and fly out from the droplet. In this way, in the ESI ion source, the compounds contained in the liquid sample can be ionized.

[0004] Further, in order to improve the ionization efficiency, an ESI ion source having the following configuration is also known: a heated inert gas is blown to the spray stream of the charged droplet independently of the atomizing gas, thereby promoting the fine of the charged droplet and the vaporization of the solvent.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2015-49077

[0008] Patent Literature 2: Japanese Patent Application Publication No. 2012-58122

[0009] Patent Literature 3: U.S. Patent Application Publication No. 2009 / 0230296

[0010] Patent Literature 4: U.S. Patent No. 8207496 SUMMARY

[0011] Technical problem to be solved by the invention

[0012] In recent years, in LC-MS, there is a tendency to increase the flow rate of the mobile phase supplied to the chromatographic column in the liquid chromatograph in order to improve the throughput of analysis. Along with this, the amount of the liquid sample supplied to the ion source of the mass spectrometer is also increased. However, the conventional general ESI ion source does not necessarily correspond to such an increase in the flow rate, and sometimes an increase in the flow rate causes problems such as a decrease in ionization efficiency.

[0013] As an ESI ion source capable of corresponding to an increase in the flow rate of the liquid sample, an ion source having a structure in which a plurality of capillaries are arranged in a bundle and the liquid sample supplied through a sample supply tube is distributed to the plurality of capillaries is known as disclosed in Patent Documents 2 to 4. In such an ion source, it is possible to reduce the amount of the liquid sample supplied to one capillary. However, in such a conventional ESI ion source, although it is possible to make the charged droplets fine in principle and thereby improve the ionization efficiency, there is still a problem in that it is difficult to improve the analysis sensitivity in practice.

[0014] The present invention has been achieved in order to solve such a technical problem, and the main object thereof is to provide an ion analysis device capable of ensuring a high ionization efficiency and improving the analysis sensitivity even in a case where the flow rate of the liquid sample is increased.

[0015] Solution to the problem

[0016] One aspect of the ion analysis device of the present invention is an ion analysis device provided with an ion source utilizing an electrospray ionization method, the ion source including:

[0017] a plurality of capillaries configured to spray the supplied liquid sample in the same direction;

[0018] one or a plurality of auxiliary electrodes configured to be surrounded by the plurality of capillaries;

[0019] a voltage application unit configured to apply a direct-current high voltage to the plurality of capillaries with reference to the potential of the one or the plurality of auxiliary electrodes.

[0020] Another aspect of the ion analysis device of the present invention is an ion analysis device provided with an ion source utilizing an electrospray ionization method, the ion source including:

[0021] a plurality of capillaries configured to spray the supplied liquid sample in the same direction;

[0022] one or a plurality of auxiliary electrodes configured to surround the plurality of capillaries;

[0023] A voltage application unit applies a direct-current high voltage with respect to the potential of the plurality of capillaries to the one or more auxiliary electrodes.

[0024] Inventive Effects

[0025] In the ion analysis device according to the above aspect of the present application, a liquid sample containing a component to be analyzed is distributed to a plurality of capillaries, and charged droplets are sprayed from each of the capillaries. Therefore, in the ion analysis device according to the above aspect of the present application, the amount of the liquid sample introduced into the ion source as a whole can be increased, and thus the throughput of analysis can be improved. Alternatively, the amount of the liquid sample flowing through one capillary can be reduced, and thus the sprayed droplets can be made finer and the generation of ions can be promoted.

[0026] Further, in the ion analysis device according to the above aspect of the present application, the electric field intensity around the front end of the capillary is enhanced, and thus the charge separation of the liquid sample reaching the front end of the capillary can be promoted, and the ionization efficiency is improved. Further, the charged droplets sprayed from the capillary or the ions generated from the droplets do not diffuse but travel in a converging manner by the action of the electric field formed by the auxiliary electrode. Therefore, the generated ions easily enter, for example, a transport tube for transporting the ions into a vacuum chamber, and the trapping efficiency of the ions is improved. Thus, the amount of the ions for analysis is increased, and a higher analysis sensitivity can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a whole configuration diagram of a mass spectrometer as an embodiment of the present application.

[0028] Figure 2 is a front plan view (A) and a A-AA line sectional view (B) of an ESI ion source in the mass spectrometer of the embodiment.

[0029] Figure 3 is a configuration diagram of a modification example of the ESI ion source shown in Figure 2

[0030] Figure 4 is a configuration diagram of another modification example of the ESI ion source shown in Figure 2

[0031] Figure 5 is a front plan view (A) and a A-AA line sectional view (B) of still another modification example of the ESI ion source shown in Figure 2

[0032] Figure 6 is a front plan view of still another modification example of the ESI ion source shown in Figure 2

[0033] ​​​​Figure 7 This is a top view (A) and a cross-sectional view (B) of the ESI ion source in a mass analysis apparatus according to another embodiment of the present invention. Detailed Implementation

[0034] The ion analysis apparatus of the present invention includes a mass analysis apparatus, an ion mobility analysis apparatus, and an ion mobility-mass analysis apparatus combining the two. The ion source in the ion analysis apparatus of the present invention is an ESI ion source, and all other components besides the ion source, such as the presence or absence of mass separation methods or ion dissociation operations in the mass analysis apparatus and the methods of dissociation, can be appropriately selected.

[0035] [First Implementation]

[0036] A mass analysis apparatus, which is one embodiment of the ion analysis apparatus of the present invention, will be described with reference to the accompanying drawings.

[0037] Figure 1 This is an overall configuration diagram of the quality analysis device in this embodiment. Figure 2 These are a top front view (A) and a cross-sectional view (B) along line A-AA, showing the configuration of the ESI ion source in the mass analysis device.

[0038] This mass analyzer is a single-type atmospheric pressure ionization quadrupole mass analyzer. Additionally, for ease of explanation, as... Figure 1 , Figure 2 As shown, three mutually orthogonal axes, X, Y, and Z, are defined in space.

[0039] like Figure 1 As shown, in the mass analysis apparatus of this embodiment, the interior of chamber 1 is divided into four regions: 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 maintains a near-atmospheric pressure atmosphere, while the analysis chamber 14 is maintained at a high vacuum atmosphere by vacuum exhaust from a high-performance vacuum pump (typically a combination of a turbomolecular pump and a rotary pump, not shown). The first intermediate vacuum chamber 12 and the second intermediate vacuum chamber 13 are also vacuum exhausted by vacuum pumps, thus forming a multi-stage differential exhaust system where the vacuum level increases sequentially from the ionization chamber 11 to the analysis chamber 14.

[0040] An ESI probe 2, serving as an ion source, is disposed within the ionization chamber 11. A liquid sample containing the sample components is sprayed from the ESI probe 2 in a roughly X-axis direction as fine charged droplets. These charged droplets, sprayed from the ESI probe 2, come into contact with the gas within the ionization chamber 11 and are thus miniaturized. Furthermore, the continuous evaporation of solvent from the droplets further reduces their size. During this process, the sample components within the droplets acquire an electric charge and are ejected as ions.

[0041] The ionization chamber 11 and the first intermediate vacuum chamber 12 are communicated through a desolvation tube 3 of a small diameter. The central axis of an ion intake port 3a, which is an opening of the ionization chamber 11 side of the desolvation tube 3, extends substantially in parallel with the Z-axis. That is, the direction of spraying from the ESI probe 2 is substantially orthogonal to the central axis of the ion intake port 3a (i.e., the direction of suction of ions). Due to a pressure difference between both open ends of the desolvation tube 3, a gas flow from the ionization chamber 11 to the first intermediate vacuum chamber 12 through the desolvation tube 3 is formed by the pressure difference. The ions generated in the ionization chamber 11, which are derived from the components of the sample, are mainly sucked into the desolvation tube 3 through the ion intake port 3a along with the gas flow, and are ejected to the first intermediate vacuum chamber 12 along with the gas flow.

[0042] A multipole type ion guide 4 is arranged inside the first intermediate vacuum chamber 12. A tapered orifice body 5 having a small hole at the top is provided at a partition wall that separates the first intermediate vacuum chamber 12 and the second intermediate vacuum chamber 13. Ions are converged near the small hole of the tapered orifice body 5 by the action of an electric field formed by the ion guide 4, and are transported to the second intermediate vacuum chamber 13 through the small hole.

[0043] A multipole type ion guide 6 is also arranged inside the second intermediate vacuum chamber 13, and ions are converged and transported to the analysis chamber 14 by the action of an electric field formed by the ion guide 6. A quadrupole mass filter 7 and an ion detector 8 are arranged inside the analysis chamber 14. Ions are introduced into a space in the direction of the long axis of the quadrupole mass filter 7 along an ion optical axis C, and only ions having a specific mass-to-charge ratio pass through the quadrupole mass filter 7 and reach the ion detector 8 due to the action of an electric field formed by a voltage applied to the quadrupole mass filter 7. The ion detector 8 generates a detection signal corresponding to the amount of ions that have reached, and transports the detection signal to a data processing section not shown. In this mass spectrometer, the analysis sensitivity can be improved by feeding more ions into the quadrupole mass filter 7, i.e., by providing more ions for analysis.

[0044] Next, the configuration of the ESI probe 2 will be described in detail with reference to Figure 2

[0045] Figure 2 (A) of FIG. 1 is a view of the ESI probe 2 as viewed from the front of the advancing direction of the spray stream of charged droplets. Figure 2 (B) of FIG. 1 is a view of the ESI probe 2 as viewed from the side of the advancing direction of the spray stream of charged droplets. Figure 2 (A) of FIG. 1 is a view of the ESI probe 2 as viewed from the front of the advancing direction of the spray stream of charged droplets.

[0046] As shown in (A) of FIG. 1, the ESI probe 2 includes a probe body 21, a capillary 22, and a needle 23. Figure 2 ​As shown in (A), the ESI probe 2 includes eight capillaries 211 to 218 having electrical conductivity, which are arranged at substantially the same angle (in this case, at an angle interval of 45°) on the same circumference U and extend in a direction parallel to the axis S of the circle. Further, the ESI probe 2 includes cylindrical nebulizing gas tubes 221 to 228, which are double-tube structures concentric with the eight capillaries 211 to 218, respectively. In addition, the ESI probe 2 includes a cylindrical auxiliary electrode 23 extending in a direction parallel to the axis S at a position of the center of the circle on which the eight capillaries 211 to 218 are arranged, i.e., at the position of the axis S. The front end of the auxiliary electrode 23 protrudes more toward the X-axis direction than the front ends of the capillaries 211 to 218.

[0047] That is, in the ESI probe 2, one auxiliary electrode 23 is arranged to be surrounded by the eight capillaries 211 to 218. The distance of the auxiliary electrode 23 from each of the eight capillaries 211 to 218 is substantially the same. The configuration of one capillary and the nebulizing tube in a double-tube structure with the capillary is the same as that of a capillary and a nebulizing tube in a general ESI probe of the related art.

[0048] The auxiliary electrode 23 is grounded so that the potential is fixed to zero. A direct-current high voltage of, for example, several kV or more is applied from a direct-current high voltage power supply 24 to each of the capillaries 211 to 218. The polarity of the voltage is the same as that of the ions to be measured, and in the case where the ions to be measured are positive ions, a direct-current high voltage Vh of positive polarity is applied to the capillaries 211 to 218 (wherein, in order to avoid complication of the drawing, the voltage application lines connected to the capillaries 211 to 218 are not depicted in (A) of FIG. 2). Figure 2

[0049] The ion generation operation in the ESI probe 2 will be described. Here, as an example, the ions to be measured are assumed to be positive ions.

[0050] Although not shown, for example, if a liquid sample containing a compound separated by a column of a liquid chromatograph is supplied to the ESI probe 2, the liquid sample is almost equally distributed to the eight capillaries 211 to 218 one by one, and reaches the front end portions of the capillaries 211 to 218. On the other hand, an appropriate inert gas is supplied to the nebulizing gas tubes 221 to 228 as a nebulizing gas.

[0051] If a high voltage of positive polarity is applied to the capillaries 211 to 218, a strong electric field is formed in the vicinity of the front end portions of the capillaries 211 to 218 due to the potential difference between the auxiliary electrode 23 having a potential of zero and each of the capillaries 211 to 218. In a general ESI ion source, the potential serving as a potential reference of the capillary (which is usually a ground potential) is Figure 1 ​the vicinity of the inlet end of the desolvation tube 3. In contrast, in the mass spectrometer of the present embodiment, the auxiliary electrodes 23 at the ground potential are arranged in the vicinity of the capillaries 211 to 218. Therefore, the strength of the electric field formed in the vicinity of the front end of each of the capillaries 211 to 218 is increased, and the Coulomb repulsion acting on the charged droplets formed at the front end of each of the capillaries 211 to 218 is increased. As a result, the charged droplets are easily micronized, and a large number of fine charged droplets are sprayed from each of the capillaries 211 to 218 with the aid of the nebulizing gas.

[0052] Although a large number of fine charged droplets are sprayed by arranging a plurality of capillaries and arranging auxiliary electrodes at a reference potential in the vicinity of the capillaries, the Coulomb repulsion acts between the charged droplets because the charged droplets are charged with the same polarity. Therefore, if there is no influence of an electric field from the outside, the spray flow of the charged droplets spreads in a direction orthogonal to the axis S as the charged droplets travel, and thus it is difficult to efficiently draw ions generated from the charged droplets into the desolvation tube.

[0053] In contrast, in the mass spectrometer of the present embodiment, the potential of the auxiliary electrodes 23 arranged on the axis S is lower than the potentials of the capillaries 211 to 218 around the auxiliary electrodes 23, and thus a potential gradient from the surroundings toward the axis S is formed in a plane (Y-Z plane) orthogonal to the axis S. That is, a converging electric field that converges positively charged particles (charged droplets, ions) in the vicinity of the axis S is formed in front of the front ends of the capillaries 211 to 218. Because of this converging electric field, the charged droplets sprayed from the capillaries 211 to 218 or the ions generated from the charged droplets are Figure 2 As indicated by the thick arrow in (B), the charged droplets or the ions are subjected to a force in the direction close to the axis S. Therefore, it is possible to suppress the spread of the spray flow containing the charged droplets or the ions due to the Coulomb repulsion, and to efficiently draw the ions generated thereinto the desolvation tube 3.

[0054] As described above, in the mass spectrometer of the present embodiment, the auxiliary electrodes 23 have the function of increasing the strength of the electric field in the vicinity of the front end of each of the capillaries 211 to 218 and the function of converging the spray flow containing the charged droplets or the ions in the vicinity of the axis S. Therefore, it is possible to improve the ionization efficiency by the ESI probe 2, to generate a larger amount of ions, and to improve the collection efficiency of the ions, and to more efficiently take the generated ions into the desolvation tube 3 and to transport the ions to the subsequent stage.

[0055] [First Modification of the First Embodiment]

[0056] Figure 3 and Figure 4are drawings showing a modification example of the ESI probe 2 in the mass spectrometer of the above-described embodiments. Also, only a part of the capillaries 211 to 218 and the nebulizing gas tubes 221 to 228 is described, but the configurations thereof are the same as those shown in FIG. 1. Figure 2

[0057] Figure 3 The ESI probe 2A shown in FIG. 2A is provided with a heating gas supply portion 25 of a circular ring shape that is arranged so as to surround the plurality of capillaries 211 to 218. The heating gas supply portion 25 has heating gas ejection ports 251 that are continuously provided around the entire circumference of the shaft S or are provided at regular angular intervals around the shaft S. The heating gas ejection ports 251 are obliquely provided inwardly so that the gas ejected therefrom is directed toward the shaft S. Thus, the heating gas ejected from the heating gas ejection ports 251 surrounds the spray stream of charged droplets and comes into contact with the outer periphery thereof.

[0058] In the ESI probe 2A, the distribution of droplets is shown in which, due to the effects of both the converging electric field formed by the auxiliary electrode 23 and the nebulizing gas streams ejected from the respective nebulizing gas tubes 221 to 228, the charged droplets that are smaller in mobility, i.e., larger in size, are located on the outer periphery side of the spray stream P. The charged droplets that are larger in size have difficulty in the internal Coulomb repulsion acting thereon, and thus have difficulty in advancing toward miniaturization, and also have difficulty in improving ionization efficiency.

[0059] In contrast, the heating gas ejected from the heating gas ejection ports 251 efficiently comes into contact with the charged droplets that are larger in size and are located on the outer periphery of the spray stream P. Thus, the vaporization of the solvent of such charged droplets can be promoted, and the miniaturization and ion generation of the droplets can be promoted. Thus, by the ESI probe 2A used in this modification example, ionization efficiency can be further improved.

[0060] On the other hand, Figure 4 The ESI probe 2B shown in FIG. 3B is provided with a heating gas supply portion 26 that ejects heating gas so as to cross the spray stream P of charged droplets from the plurality of capillaries 211 to 218. In this configuration, the heating gas also efficiently comes into contact with the charged droplets that are larger in size and are located on the outer periphery of the spray stream P, and the vaporization of the solvent from the charged droplets can be promoted.

[0061] [2nd Modification Example of 1st Embodiment]

[0062] ​In the ESI probe 2, 2A, 2B of the mass spectrometer of the above embodiment, the plurality of capillaries 211 to 218 are arranged at substantially the same angle and at intervals on a substantially same circumference U. Thereby, the charged droplets are sprayed in a substantially equal amount in the circumferential direction around the auxiliary electrode 23. However, the amount of ions generated from the charged droplets thus sprayed and sucked into the desolvation tube 3 becomes difficult to be equal in the circumferential direction around the auxiliary electrode 23. The first reason for this is that the desolvation tube 3 and the partition wall separating the ionization chamber 11 and the first intermediate vacuum chamber 12 are at a ground potential or a potential close to the ground potential (at least a potential significantly close to the ground potential compared to the potentials of the capillaries 211 to 218), and thus the generation efficiency of ions is relatively low in the spray flow from the capillary located at a position close to the desolvation tube 3 or the above partition wall. Further, the second reason is that the electric field generated by the auxiliary electrode 23 has a converging action, but since the charged droplets sprayed from the ESI probe 2 or the ions generated therefrom are not converged into a beam shape, the ions generated from the spray flow sprayed from the capillary located at a position close to the desolvation tube 3 (the capillary located at the positive direction of the Z axis in Figure 1 the above embodiment) are relatively difficult to be sucked into the desolvation tube 3.

[0063] Further, there is a problem that the charged droplets sprayed from the capillary located at a position close to the desolvation tube 3 or the ions generated therefrom easily adhere to the ion intake port 3a of the desolvation tube 3 or the outer surface of the tube and become a cause of contamination. Figure 5 A modification of the mass spectrometer of the above embodiment shown in the drawing can cope with such a problem. Figure 5 is a front view (A) and a cross-sectional view (B) taken along the line A-AA of the ESI probe 2C of this modification. In Figure 5 the desolvation tube 3 not described in Figure 2 the above embodiment is also partially described in Figure 2 the same drawing reference numerals are attached to the same constituent elements as those shown in

[0064] In this ESI probe 2C, eight capillaries 211 to 218 are arranged on the same circumference U, and in Figure 5In (A), within the clockwise direction from capillary 211 to capillary 218, the angular interval between two adjacent capillary tubes in the circumferential direction is the same. On the other hand, the angular interval between capillary 218 and its adjacent capillary 211 is larger than the others (intervals between capillary tubes). Specifically, the former is 40°, while the latter is twice that, 80°. The eight capillary tubes 211 to 218 of the ESI probe 2C can be viewed as a state in which one capillary tube is extracted from a state in which nine capillary tubes containing these eight capillary tubes are arranged at equal angular intervals on the same circumference U. The extracted capillary tube is the one located on the extension line of the central axis of the capillary tube where the desolvation tube 3 is located.

[0065] Therefore, as Figure 5 As shown in (A), if we observe the positional relationship between the desolvation tube 3 and the multiple capillaries 211-218 in the YZ plane, the desolvation tube 3 is located at a position where the multiple capillaries 211-218 do not exist, that is, at a position where the distance between two adjacent capillaries along the circumferential direction on the circumference U is relatively large. In addition, in order to hold the auxiliary electrode 23 in a position in the YZ plane that overlaps with the desolvation tube 3 and is away from the negative direction of the X-axis, and to provide a ground potential to the auxiliary electrode, a conductive electrode holding part 28 that is substantially integrated with the auxiliary electrode 23 is provided.

[0066] By applying a high DC voltage Vh to each capillary 211-218, a strong electric field is formed near the tip of each capillary 211-218. The liquid sample dispensed into each capillary 211-218 is charged by this electric field and is sprayed out as tiny charged droplets with the help of the atomizing gas. It is the same as the mass analysis apparatus of the above embodiment. In this modified mass analysis apparatus, each capillary 211-218 is relatively far from the desolvation tube 3, and the electric field formed near the tip of each capillary 211-218 is less affected by the potential of the desolvation tube 3 or the partition wall. Therefore, charged droplets can be well generated and ionization can be performed efficiently in each capillary 211-218. Furthermore, since there is no desolvation tube 3 in front of the spray stream emitted from any of the capillaries 211-218, the fine charged droplets in the spray stream or the ions generated from the spray stream will not adhere to the ion intake 3a or the tubing of the desolvation tube 3, and will be easily drawn into the desolvation tube 3. Therefore, the ion collection efficiency is also improved.

[0067] This allows for the delivery of a larger quantity of ions to subsequent stages, resulting in higher analytical sensitivity. Furthermore, it reduces contamination caused by charged droplets or ions adhering to the ion intake 3a or other tubing in the desolvation tube 3. Consequently, the device's performance can be maintained for a longer period, and maintenance workload is reduced. Moreover, by positioning the electrode holding portion 28 of the auxiliary electrode 23 within a space that ensures a large spacing between adjacent capillaries, electrical insulation between the electrode holding portion 28 and each capillary 211-218 and the nebulizing gas tubes 221-228 can be reliably ensured, while simultaneously maintaining the auxiliary electrode 23 stably.

[0068] Furthermore, it is obvious that it is also possible to add, for example, to this variant. Figure 3 , Figure 4 The configuration of the heating gas supply units 25 and 26 shown.

[0069] Furthermore, in areas outside of larger spaces, it is not necessary for adjacent capillaries to be spaced at equal angles as described above. Additionally, the central axis of the ion inlet 3a of the desolvation tube 3 may be oblique to the axis S of the ESI probe 2C, rather than orthogonal.

[0070] [Other variations]

[0071] Furthermore, the configuration of the ESI probes 2, 2A, 2B, and 2C in the above embodiments and variations can be modified in various ways. For example, the number of capillaries is not limited to those described above, and multiple capillaries can be appropriately determined. Moreover, it is not necessary to arrange the multiple capillaries 211-218 on the same circumference U, but they can be arranged appropriately. However, if the distance between each capillary and the auxiliary electrode 23 is different, the intensity of the electric field formed near the tip of the capillary will deviate, and the size deviation of the charged droplets sprayed from the capillary will also increase. Therefore, in order to improve ionization efficiency by making the size of the charged droplets as uniform as possible, it is best to make the distance between each of the multiple capillaries 211-218 and the auxiliary electrode 23 as equal or similar as possible.

[0072] Furthermore, the shape of the auxiliary electrode 23 is not limited to the cylindrical shape described above. In particular, by making the shape of the front end of the auxiliary electrode 23 not a planar shape parallel to the YZ plane, but a suitable shape such as a hemispherical shape, the potential gradient of the convergent electric field can be adjusted and the convergence of the spray flow can be improved.

[0073] Furthermore, the auxiliary electrode 23 is not limited to one; multiple auxiliary electrodes can also be provided. Figure 6 This is a diagram showing a modified example where one auxiliary electrode 231-238 is provided for each of the eight capillary tubes 211-218. This diagram is derived from... Figure 2the same view angle as (A) of the ESI probe 2. In a case where the configuration is set as such, it is also possible to form a strong direct-current electric field near the front end portions of the capillaries 211 to 218, and to form an electric field that converges the spray flow of the charged droplets ejected from the capillaries 211 to 218 near the axis S.

[0074] [2nd Embodiment]

[0075] Next, a mass spectrometer as another embodiment of the ion analysis apparatus of the present application will be described. The overall configuration of this mass spectrometer is the same as that of the apparatus of the 1st embodiment, and thus the description will be omitted. Figure 7 is a front view (A) and a line cross-sectional view (B) along the A-A line that show the configuration of the ESI ion source in the mass spectrometer of the present embodiment. In Figure 7 , the same reference numerals are assigned to the configuration elements that are substantially the same as the configuration elements of the ESI ion source in the mass spectrometer of the 1st embodiment, and the description will be omitted unless particularly needed.

[0076] In the ESI probe 2E of the ESI ion source, the configuration and arrangement of the capillaries 211 to 218 and the nebulizing gas tubes 221 to 228 are the same as those of the 1st embodiment, but the shape and arrangement of the auxiliary electrode and the voltage applied thereto are different from those of the 1st embodiment. That is, the auxiliary electrode 27 is a substantially cylindrical conductor arranged so as to surround the capillaries 211 to 218. The axis of the auxiliary electrode 27 coincides with the axis S of the circle in which the eight capillaries 211 to 218 are arranged. Therefore, in this embodiment, the distance between the auxiliary electrode 27 and each of the capillaries 211 to 218 is also substantially the same.

[0077] The eight capillaries 211 to 218 are each grounded (wherein, in order to avoid the drawing becoming complicated, only the ground line connected to one of the capillaries 215 is depicted in (A) of Figure 7 ). On the other hand, a direct-current high voltage of, for example, several kV or more is applied to the auxiliary electrode 27 from the direct-current high voltage power supply 24. The polarity of this voltage is the same as that of the ions to be measured, and in a case where the ions to be measured are positive ions, the voltage is a direct-current high voltage of positive polarity.

[0078] If the liquid sample is introduced into each of the capillaries 211 to 218, and a direct-current high voltage of positive polarity is applied to the auxiliary electrode 27, the capillaries 211 to 218 are close to the auxiliary electrode 27, and thus a strong electric field is formed near the front end portions of the capillaries 211 to 218. As a result, the charged droplets formed at the front ends of the capillaries 211 to 218 are easily micronized, and a large number of fine charged droplets are sprayed from the capillaries 211 to 218 with the assistance of the nebulizing gas.

[0079] The charged droplets have a positive charge, but due to the application of a high positive voltage to the auxiliary electrodes 27 surrounding the eight capillaries 211-218, an electric field is formed that acts as a force pushing the positively charged droplets (and the positive ions ejected from the droplets) towards the inner circumference, i.e., near the axis S. Thus, similar to the first embodiment, there is Coulomb repulsion between the charged droplets, but the spray of charged droplets is difficult to diffuse and converges near the axis S. As a result, ions efficiently generated from the charged droplets are efficiently drawn into the desolvation tube 3 and then transported to the subsequent stage.

[0080] In this second embodiment, various modifications similar to those in the first embodiment can also be made.

[0081] That is, it can be with Figure 3 as well as Figure 4 Similarly, in the configuration shown, a ring-shaped heating gas supply section 25 is added to the outer periphery of the auxiliary electrode 27, or a heating gas supply section 26 is added to spray heating gas in the manner of a spray flow P of charged droplets from multiple capillaries 211 to 218.

[0082] Furthermore, the number of capillaries or their configuration can be appropriately changed. The shape of the auxiliary electrode 27 is not limited to a cylindrical shape, and it can also be appropriately divided into multiple auxiliary electrodes 27.

[0083] Furthermore, the first and second embodiments described above, as well as their variations, are merely examples of the present invention. Appropriate changes, modifications, and additions may be made within the scope of the spirit of the present invention, and these are naturally included within the scope of the claims of this application.

[0084] For example, the above-described embodiment is a single-type quadrupole mass analyzer. However, as described above, the mass separation method, the presence or absence of ion dissociation operation, and the dissociation method can be appropriately selected. Therefore, the present invention can certainly be applied to various mass analyzers such as time-of-flight mass analyzers, ion trap mass analyzers, triple quadrupole mass analyzers, quadrupole-time-of-flight mass analyzers, and ion trap time-of-flight mass analyzers.

[0085] Furthermore, the present invention can be applied to all devices that ionize and analyze sample components using an ESI ion source, and is therefore not limited to mass analysis devices. It can also be an ion mobility analysis device, an ion mobility-mass analysis device that combines an ion mobility analysis device and a mass analysis device, etc.

[0086] [Various options]

[0087] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following solutions.

[0088] (1) An ion analysis apparatus according to the present application includes an ion source using an ESI method, the ion source including:

[0089] a plurality of capillaries that spray a liquid sample supplied in the same direction;

[0090] one or more auxiliary electrodes disposed so as to surround the plurality of capillaries;

[0091] a voltage application unit that applies a direct-current high voltage to the one or more auxiliary electrodes with reference to the potential of the plurality of capillaries.

[0092] (10) Another aspect of the ion analysis apparatus according to the present application includes an ion source using an ESI method, the ion source including:

[0093] a plurality of capillaries that spray a liquid sample supplied in the same direction;

[0094] one or more auxiliary electrodes disposed so as to surround the plurality of capillaries;

[0095] a voltage application unit that applies a direct-current high voltage to the one or more auxiliary electrodes with reference to the potential of the plurality of capillaries.

[0096] In the ion analysis apparatus according to (1) and (10), a liquid sample containing a component to be analyzed is distributed to the plurality of capillaries, and charged droplets are sprayed from each of the capillaries. Thus, the amount of the liquid sample introduced into the ion source as a whole can be increased, and the throughput of analysis can be improved. Alternatively, the amount of the liquid sample flowing through one capillary can be reduced, and thus the sprayed droplets can be made finer, thereby promoting the generation of ions.

[0097] Further, in the ion analysis apparatus according to (1) and (10), since the auxiliary electrodes are disposed in close proximity to the capillaries, the electric field intensity around the front ends of the capillaries is enhanced. Thus, the separation of charges of the liquid sample reaching the front ends of the capillaries is promoted, and the ionization efficiency is further improved. Further, at the same time, the charged droplets sprayed from the capillaries or the ions generated from the droplets do not diffuse due to the electric field formed by the auxiliary electrodes, but rather travel in a converging manner. Thus, the generated ions are more likely to enter, for example, a transport tube for transporting the ions into a vacuum chamber, and the collection efficiency of the ions is improved. Thus, the amount of the ions supplied to the analysis can be increased, and higher analysis sensitivity can be achieved.

[0098] (2nd item, 11th item) In the ion analysis device according to the 1st item or the 10th item, the ion source can be configured to further include an atomizing gas tube provided so as to face each of the plurality of capillaries and to emit atomizing gas in the same direction as the direction of spraying of the liquid sample from the capillary.

[0099] According to the ion analysis device according to the 2nd item and the 11th item, the charged droplets can be sprayed well from the tip end of the capillary.

[0100] (3rd item) In the ion analysis device according to the 1st item or the 2nd item, the ion source can be configured to include a plurality of capillaries, and the plurality of capillaries can be disposed on substantially the same circumference.

[0101] The plurality of capillaries can be disposed on substantially the same circumference.

[0102] The auxiliary electrode can be one, and can be disposed at substantially the center of the circle on which the plurality of capillaries are disposed.

[0103] (12th item) Similarly, in the ion analysis device according to the 10th item or the 11th item, the ion source can be configured to include a plurality of capillaries, and the plurality of capillaries can be disposed on substantially the same circumference.

[0104] The plurality of capillaries can be disposed on substantially the same circumference.

[0105] The auxiliary electrode can be one, and can be a cylindrical shape coaxial with the circle on which the plurality of capillaries are disposed.

[0106] In the ion analysis device according to the 3rd item and the 12th item, the electric field intensity around the tip end of each capillary is substantially the same, and thus the charged droplets can be sprayed from each capillary in a state of being micronized at the same level. Thus, ionization efficiency can be improved. In the ion analysis device according to the 3rd item and the 12th item, the potential gradient of the electric field in the region in which the spray flow of the charged droplets is formed is substantially rotationally symmetrical around the axis of the spray flow, according to the potential of each capillary and the potential of the auxiliary electrode. Thus, the spray flow of the charged droplets becomes easy to converge around the axis, and the utilization efficiency of ions generated from the charged droplets is improved. Thus, a larger amount of ions can be supplied to analysis, and the analysis sensitivity can be further improved.

[0107] (4th item) In the ion analysis device according to the 3rd item, the ion source can be configured to include an ion transport tube that collects ions generated from the spray flow from the plurality of capillaries and transports the ions to a later stage, the ion transport tube having an ion inlet in front of the spray flow and including a pipe extending in a direction intersecting the direction of spraying from the capillaries.

[0108] The plurality of capillaries can be disposed on substantially the same circumference, on the extension of the direction of spraying and at a position other than the position at which the ion transport tube is present.

[0109] (5) In the ion analysis device described in item 4, the ion transport tube can be configured such that the tube extends in a direction substantially orthogonal to the direction of the spray from the capillary.

[0110] Generally, the ion transport tube is set to a ground potential or a potential close to the ground potential, and thus the electric field formed at the front end of the capillary near the ion transport tube is easily weakened due to the influence thereof. In addition, the charged droplets sprayed from the capillary near the ion transport tube or the ions generated therefrom are difficult to be taken into the ion transport tube along with the gas flow into the ion transport tube. In contrast, according to the ion analysis device described in item 4 or item 5, since the plurality of capillaries are all disposed farther from the ion transport tube, a stronger electric field is formed near the front end of the capillary, and thus the charged droplets are favorably generated. In addition, the fine charged droplets included in the spray flow or the ions generated therefrom are efficiently taken into the ion transport tube. Thus, more ions can be transported to the subsequent stage, and the analysis sensitivity can be improved. In addition, the case where the charged droplets or the ions adhere to the ion transport tube or the ion intake port to cause contamination can be reduced.

[0111] (6) In the ion analysis device described in item 4 or item 5, the plurality of capillaries can be disposed such that the interval of the capillaries adjacent to each other in the circumferential direction is largest at a position where the ion transport tube exists in the extension of the direction of the spray,

[0112] In the space where the interval of the adjacent capillaries is largest, a holding portion that holds the auxiliary electrode and / or a wiring that applies a potential to the auxiliary electrode is disposed.

[0113] According to the ion analysis device described in item 6, the holding portion of the auxiliary electrode or the wiring can be disposed in a space sufficiently large between the adjacent capillaries, and the electrical insulation between the holding portion or the wiring and the capillaries can be sufficiently ensured.

[0114] (7, 13) The ion analysis device described in any one of items 1 to 6 or any one of items 10 to 12 can further include a heated gas supply portion that blows heated gas to the outside of the spray flow from the plurality of capillaries.

[0115] In the ion analysis device described in the item 7 and the item 13, the heated gas emitted from the heated gas supply portion mainly contacts with the portion of the spray stream of the charged droplets emitted from the plurality of capillaries on the outer periphery side. Although there are charged droplets of a relatively large size in this portion, since vaporization of the solvent in such charged droplets is promoted, it is effective for improving ionization efficiency. Further, since the heated gas stream is formed in a manner of surrounding the spray stream of the charged droplets, it is possible to further suppress diffusion of the spray stream, and ion utilization efficiency is further improved.

[0116] (Items 8, 14) In the ion analysis device described in any one of the items 1 to 6 or any one of the items 10 to 12, it can be provided to further include a heated gas supply portion that blows heated gas in a manner of intersecting with the spray stream from the plurality of capillaries.

[0117] In the ion analysis device described in the item 8 and the item 14, the heated gas emitted from the heated gas supply portion mainly contacts with the portion of the spray stream of the charged droplets emitted from the plurality of capillaries on the outer periphery side. Although there are charged droplets of a relatively large size in this portion, since vaporization of the solvent in such charged droplets is promoted, it is effective for improving ionization efficiency.

[0118] (Items 9, 15) In the ion analysis device described in any one of the items 1 to 8 or any one of the items 10 to 14, it can be provided to be a single quadrupole type mass spectrometer, a triple quadrupole type mass spectrometer, or a quadrupole-time of flight type mass spectrometer having the ion source.

[0119] In such a mass spectrometer, it is necessary to transport ions generated from the ion source located in an atmosphere pressure atmosphere to a vacuum chamber of a rear stage through a desolvation tube or a sampling cone, and in the mass spectrometer described in the item 9 and the item 15, it is possible to efficiently collect ions generated from the ion source and transport to the rear stage. Thus, according to the mass spectrometer described in the item 9 and the item 15, it is possible to achieve higher analysis sensitivity.

[0120] Explanation of Reference Numerals

[0121] 1 Chamber

[0122] 11 Ionization chamber

[0123] 12 First intermediate vacuum chamber

[0124] 13 Second intermediate vacuum chamber

[0125] 14 Analysis chamber

[0126] 2, 2A, 2B, 2C, 2D, 2E ESI probe

[0127] 211-218 capillary

[0128] 221-228 atomizing gas tube

[0129] 23, 231-238, 27 auxiliary electrode

[0130] 24 direct current high voltage power supply

[0131] 25, 26 heating gas supply section

[0132] 251 heating gas ejection port

[0133] 28 electrode holding section

[0134] 3 desolvation tube

[0135] 4, 6 ion guide

[0136] 5 skimmer

[0137] 7 quadrupole mass filter

[0138] 8 ion detector

Claims

1. An ion analysis apparatus comprising an ion source utilizing electrospray ionization, characterized in that, The ion source comprises: Multiple capillaries spray the supplied liquid sample in the same direction. One or more auxiliary electrodes are configured to be surrounded by the plurality of capillaries; The voltage application section applies a high DC voltage, based on the potential of one or more auxiliary electrodes, to the multiple capillaries.

2. The ion analysis apparatus as described in claim 1, characterized in that, The ion source further includes an atomizing gas tube, which is respectively arranged relative to the plurality of capillaries, and sprays atomizing gas in the same direction as the spray direction of the liquid sample from the capillaries.

3. The ion analysis apparatus as described in claim 1, characterized in that, The multiple capillaries are arranged on approximately the same circumference. The auxiliary electrode is a single electrode, positioned approximately at the center of the circle containing the plurality of capillaries.

4. The ion analysis apparatus as described in claim 3, characterized in that, It includes an ion delivery tube that collects ions generated from the spray stream from the multiple capillaries and delivers them to a subsequent stage. The ion delivery tube has an ion intake port upstream of the spray stream and includes a conduit extending in a direction intersecting the direction of the spray from the capillaries. The multiple capillaries are arranged on approximately the same circumference at positions other than the location of the ion delivery tube, along the extension of the spray direction.

5. The ion analysis apparatus as described in claim 4, characterized in that, The ion delivery tube extends in a direction approximately orthogonal to the direction of the spray from the capillary.

6. The ion analysis apparatus as described in claim 4, characterized in that, The multiple capillaries are configured such that the spacing between the circumferentially adjacent capillaries is maximized along the extension of the spray direction at the location where the ion delivery tube exists. Within the maximum available space between the adjacent capillaries, a holding portion for holding the auxiliary electrode and / or wiring for applying a potential to the auxiliary electrode are configured.

7. The ion analysis apparatus as described in claim 1, characterized in that, It further includes a heating gas supply unit that blows heating gas outwards in a manner that surrounds the spray flow from the multiple capillaries.

8. The ion analysis apparatus as described in claim 1, characterized in that, It further includes a heating gas supply unit that blows heating gas out of the spray stream from the multiple capillaries in a manner that intersects with the spray stream.

9. The ion analysis apparatus as described in claim 1, characterized in that, The ion analysis device is a single-type quadrupole mass analysis device, a triple quadrupole mass analysis device, or a quadrupole-time-of-flight mass analysis device with the ion source.

10. An ion analysis apparatus comprising an ion source utilizing electrospray ionization, characterized in that, The ion source comprises: Multiple capillaries spray the supplied liquid sample in the same direction. One or more auxiliary electrodes are configured to surround the plurality of capillaries; The voltage application section applies a high DC voltage, based on the potential of the multiple capillaries, to one or more auxiliary electrodes.

11. The ion analysis apparatus as described in claim 10, characterized in that, It further includes an atomizing gas tube, which is respectively arranged relative to the plurality of capillaries, and sprays atomizing gas in the same direction as the spray direction of the liquid sample from the capillaries.

12. The ion analysis apparatus as described in claim 10, characterized in that, The multiple capillaries are arranged on approximately the same circumference. The auxiliary electrode is a single cylindrical electrode that is coaxial with the circle containing the multiple capillaries.

13. The ion analysis apparatus as described in claim 10, characterized in that, It further includes a heating gas supply unit that blows heating gas outwards in a manner that surrounds the spray flow from the multiple capillaries.

14. The ion analysis apparatus as described in claim 10, characterized in that, It further includes a heating gas supply unit that blows heating gas out of the spray stream from the multiple capillaries in a manner that intersects with the spray stream.

15. The ion analysis apparatus as described in claim 10, characterized in that, The ion analysis device is a single-type quadrupole mass analysis device, a triple quadrupole mass analysis device, or a quadrupole-time-of-flight mass analysis device with the ion source.

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