Ion source and analyzer using the same

Abstract

Provided is a new ion source that produces microdroplets from a liquid sample continuously supplied from a liquid chromatograph or the like, electrically charges the microdroplets, executes a series of treatments for vaporizing a solvent at a low gas flow rate, and introduces ions of a solute component contained in the liquid sample into an analysis block. This ion source is for supplying, to an analysis block for analyzing a liquid sample containing a solute component, ions of the solute component, the ion source comprising: a droplet production unit that produces droplets of the liquid sample; a heated and pressure-adjusted gas supply block that heats a carrier gas that flows therein from the droplet production unit together with the droplets; and an electrically charging unit that electrically charges the solute component and ionizes the same. The heated and pressure-adjusted gas supply block includes: a sample transport tube path that is arranged between the analysis block and the droplet production unit; a heated and pressure-adjusted gas reservoir unit that is configured to be in contact with the sample transport tube path so that heat can be transferred therebetween; a gas-heating unit that heats a prescribed gas to a prescribed temperature; and a pressure-adjusting unit that maintains the pressure of the prescribed gas in a prescribed range. The droplets and the carrier gas are heated by the heated prescribed gas. The droplets and the carrier gas are supplied from the droplet production unit to the sample transport tube path. The heated prescribed gas is introduced from the heated and pressure-adjusted gas reservoir unit into the sample transport tube path.

Description

Technical Field

[0001] The present disclosure relates to an ion source and an analyzer using the same.

Background Art

[0002] In an apparatus for analyzing components in a liquid sample having various solute components, etc., a method is used in which the liquid sample is sprayed to form fine droplets, the solvent component is vaporized and removed to atomize the solute component of the sample, and the sample is introduced into an analysis unit or the like. As a typical example of an apparatus for performing analysis by such a method, there is a liquid chromatography mass spectrometer.

[0003] In a liquid chromatography mass spectrometer, a liquid sample having various components separated by a liquid chromatograph is made into fine droplets, and ions of the solute component are generated by charging and heating and vaporizing in an ion source. Then, the ionized solute component is introduced into a mass spectrometer and separated by mass-to-charge ratio to identify the components.

[0004] As methods used in an ion source, there are an electrospray method (ESI: Electrospray ionization), an atmospheric pressure chemical ionization method (APCI: Atmospheric Pressure Chemical Ionization), an atmospheric pressure photoionization method (APPI: Atmospheric pressure photoionization), and the like.

[0005] For atomizing a liquid sample in a liquid chromatography mass spectrometer or the like, a gas spray method is usually used. Here, the gas spray method refers to a method in which a liquid is torn apart by applying a high-speed gas jet to the liquid to form fine droplets and spray them.

[0006] In the ion source, since it is necessary to make the liquid sample into very small droplets having a diameter of about several μm, a gas spray using an ultra-high-speed gas flow with an ejection speed reaching several hundred m / s is used.

[0007] In addition, a device for generating microdroplets to be introduced into an ion source using an ultrasonic vibrator is also being developed.

[0008] As prior art applying an atomization device using an ultrasonic vibrator to an ion source, there are the following.

[0009] Patent Document 1 discloses a configuration in which an eluent of liquid chromatography is sprayed and adhered onto the surface of an ultrasonic vibrator using a high-pressure gas nebulizer, and extremely fine mist is generated by the action of the ultrasonic vibrator. The solvent is removed from the mist, and the desolvated sample is led to the next atmospheric pressure ion source and subjected to mass spectrometry.

[0010] Patent Document 2 discloses an ion generation device having a configuration in which, in a mass spectrometry system, a liquid containing a sample having an ionic group and a protic polar solvent is atomized using an ultrasonic vibrator, and the liquid is heated to remove the protic polar solvent.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0012] In a liquid chromatography mass spectrometer, a plurality of types of liquid samples to be analyzed are continuously supplied from a liquid chromatograph through a thin tube with a diameter of several hundred μm or less. The amount of each supplied liquid sample is extremely small, several hundred μL or less. In a droplet generation device used in a mass spectrometer, it is required to continuously form these liquid samples into microdroplets without mixing with each other, charge the generated microdroplets, remove the solvent by heating, generate ions of the solute component, and continuously supply them to the analysis unit.

[0013] Since the droplets formed by the ultra-high-speed gas flow of the gas spray used in the ion source are sprayed at an ultra-high speed, the energy required for processes such as charging and heating vaporization is large, and the time for performing these processes is shortened. Therefore, there are also problems in terms of stabilizing these processes.

[0014] In addition, since the liquid sample is atomized into fine droplets in a high-speed and large-volume gas flow, the sample droplets that can be introduced into the mass spectrometer are only a very small part of the supplied liquid sample, and most of the sample will be discharged without being used.

[0015] The devices described in Patent Documents 1 and 2 do not provide a solution to the loss of fine droplets in the path of sending the generated mist-like fine droplets to the analyzer.

[0016] An object of the present disclosure is to provide a new ion source that generates fine droplets from a liquid sample continuously supplied from a liquid chromatograph or the like, imparts a charge to the fine droplets, performs a series of processes of vaporizing the solvent with a small gas flow rate, and introduces ions of solute components contained in the liquid sample into the analysis block.

Means for Solving the Problems

[0017] The ion source of the present disclosure supplies ions of a solute component to an analysis block that analyzes a liquid sample containing the solute component, and includes a droplet generation unit that generates droplets of the liquid sample, a heating and pressure-regulating gas supply block that heats the carrier gas flowing in with the droplets from the droplet generation unit, and a charge application unit that imparts a charge to the solute component to ionize it. The heating and pressure-regulating gas supply block includes a sample transfer pipeline disposed between the analysis block and the droplet generation unit, a heating and pressure-regulating gas retention unit having a configuration that is heat-transferably in contact with the sample transfer pipeline, a gas heating unit that heats a predetermined gas to a predetermined temperature, and a pressure adjustment unit that maintains the pressure of the predetermined gas within a predetermined range. The droplets and the carrier gas are heated by the heated predetermined gas. The sample transfer pipeline is configured such that droplets and the carrier gas are supplied from the droplet generation unit, and the heated predetermined gas is introduced from the heating and pressure-regulating gas retention unit.

Advantages of the Invention

[0018] According to the present disclosure, it is possible to provide a new ion source that generates micro-droplets from a liquid sample continuously supplied from a liquid chromatograph or the like, imparts a charge to the micro-droplets, and performs a series of processes of vaporizing the solvent with a small gas flow rate, and introduces ions of the solute component contained in the liquid sample into the analysis block.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Mode for Carrying Out the Invention

[0020] The present disclosure relates to an ion source for ionizing components contained in a liquid sample to be analyzed in an analyzer such as a liquid chromatography mass spectrometer and introducing them into an analysis block, and an analyzer equipped with such an ion source.

[0021] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings.

Example

[0022] FIG. 1 is a cross-sectional view of the main part showing the analyzer of the embodiment.

[0023] The analyzer shown in this figure has a liquid sample atomization block 1 (droplet generation part), a heated pressure-regulated gas supply block 11, a charge application block 21, and an analysis block 25. These are connected in series. Among these, the liquid sample atomization block 1, the heated pressure-regulated gas supply block 11, and the charge application block 21 constitute an ion source. The ion source is connected to the analysis block 25 via a connection block 22 having a capillary connection part 23. The inside of the analysis block 25 is kept in a substantially vacuum state (reduced pressure state).

[0024] The liquid sample atomization block 1 has a thin plate-shaped liquid flow path plate 2 and an ultrasonic vibration applying unit 3. The holder 9 is composed of a liquid sample supply side member 9a and a connecting member 9b, and the holder 10 is composed of a holder main body 10a and a flange-shaped member 10b. The holder main body 10a has a substantially cylindrical shape. The liquid flow path plate 2 is sandwiched between the liquid sample supply side member 9a and the connecting member 9b. The ultrasonic vibration applying unit 3 is a bolted Langevin type vibrator (BLT) composed of a tip vibration part 3a, a piezoelectric element part 3b, and a screw housing 3c (piezoelectric element fixing main body). Inside the holder main body 10a, the ultrasonic vibration applying unit 3 and the rectifying plate 4 are inserted and fixed. The holder main body 10a is inserted into the through hole of the liquid sample supply side member 9a.

[0025] The ultrasonic vibration applying unit 3 is arranged to contact the liquid flow path plate 2, and by pressing the flange-shaped member 10b attached to the holder main body 10a with a spring 7 (pressing member), the tip vibration part 3a of the ultrasonic vibration applying unit 3 is configured to be in close contact with the liquid flow path plate 2.

[0026] A supply pipe 5 and a discharge pipe 8 are connected to the liquid sample supply side member 9a. The sample liquid 26a continuously supplied from the supply pipe 5 is supplied to the liquid flow path plate 2 and atomized. Then, the remaining liquid that is not atomized is discharged as the remaining sample liquid 26c from the discharge pipe 8.

[0027] A carrier gas supply pipe 6 is connected to the flange-shaped member 10b, and the carrier gas 27a is supplied into the holder main body 10a. The carrier gas 27a has a substantially uniform flow velocity distribution by the rectifying plate 4, passes around the ultrasonic vibration applying unit 3, and is supplied to the heating and pressure regulating gas supply block 11 together with the droplets generated on the liquid flow path plate 2. By the carrier gas 27a passing through the side surface of the ultrasonic vibration applying unit 3, the ultrasonic vibration applying unit 3 can also be cooled.

[0028] The heating and pressure-regulating gas supply block 11 includes an outer pipe 12a, an inner pipe 12b, a sample transfer pipe 13 (sample transfer pipeline), a heat insulation and insulation member 14, a mesh plate 15, an air heater 16 (gas heating part), and a pressure-regulating means 17 (pressure regulating part). The outer pipe 12a and the inner pipe 12b form the heating and pressure-regulating gas supply unit main body 12, which has a double-pipe structure. The annular part formed by the outer pipe 12a and the inner pipe 12b is the outer shell chamber 18 (heating and pressure-regulating gas retention part).

[0029] A heat insulation and insulation member 14 is sandwiched between the outer pipe 12a and the sample transfer pipe 13. Since the heat insulation and insulation member 14 is difficult to conduct heat, the liquid sample atomization block 1 is not heated by the heat of the high-temperature heating and pressure-regulating gas supply block 11. Also, since the heat insulation and insulation member 14 has electrical insulation properties, it also has the function of blocking the current from the charge application block 21.

[0030] In the sample transfer pipe 13, minute droplets 26b flow together with the transfer gas 27b. The minute droplets 26b and the transfer gas 27b are supplied into the inner pipe 12b.

[0031] The air heater 16 heats a gas at a predetermined flow rate to a predetermined temperature and supplies it as heated gas 27c to the outer shell chamber 18. In this embodiment, nitrogen gas is used as the gas supplied to the outer shell chamber 18. As the gas used in this case, in addition to nitrogen, inert gases such as argon and helium are desirable.

[0032] The pressure in the outer shell chamber 18 is adjusted by the pressure-regulating means 17, and when the pressure becomes equal to or higher than a predetermined value, an exhaust gas flow 27g is generated.

[0033] The heated gas 27c passes through the inside of the outer shell chamber 18 and the mesh plate 15, becomes a swirling air flow 27d, is supplied into the inner pipe 12b, and merges with the solute fine particles 26d. The solute fine particles 26d are fine particles formed by heating the minute droplets 26b and vaporizing the solvent. The solute fine particles 26d are supplied to the charge application block 21 together with the transfer gas 27e.

[0034] In the charge imparting block 21, a discharge wire 20 stretched by a spring 19 is installed. The solute fine particles 26d supplied together with the carrier gas 27e are ionized by the discharge generated by the high voltage applied to the discharge wire 20.

[0035] The analysis block 25 includes an analysis unit (not shown) built in the housing 24. A connection block 22 having a capillary connection part 23 is sandwiched between the charge imparting block 21 and the housing 24. The ionized solute fine particles 26d pass through the capillary connection part 23 together with the carrier gas 27e and are supplied into the housing 24.

[0036] Note that the internal region including the heating and pressure regulating gas supply block 11 from the liquid flow path plate 2 to the connection block 22 has an airtight structure including the support part of the discharge wire 20 and the power supply terminal in order to prevent the carrier gas flow from leaking out of the central pipe line.

[0037] The solute fine particles 26d sent to the analysis block 25 are used for analysis processing such as components in the analysis block 25 as the ionized solute component 27f.

[0038] FIG. 2A is a front view showing the liquid flow path plate 2 of FIG. 1.

[0039] The liquid flow path plate 2 has a liquid flow path 2g inside thereof. At the ends of the liquid flow path 2g, a supply port 2f and a discharge port 2h for the liquid sample are provided. In the central part of the liquid flow path 2g, a micropore forming part 2d having a plurality of micropores is provided. Four through holes 2e for the carrier gas are provided around the micropore forming part 2d.

[0040] FIG. 2B is a cross-sectional view showing a state where the liquid flow path plate 2 of FIG. 2A is installed in the ion source. Note that since the liquid flow path plate 2 is a very thin plate compared to the dimensions of other components, in FIG. 2B, the thickness direction is enlarged and shown.

[0041] The liquid flow path plate 2 has a structure in which three thin plates 2a, 2b, and 2c are laminated and joined. On the thin plate 2c on the side where the sample liquid 26a is supplied, a supply port 2f and a discharge port 2h for the sample liquid 26a are formed. Both the supply port 2f and the discharge port 2h are through holes. In the central thin plate 2b, an elongated hole is formed. This hole constitutes the liquid flow path 2g in a state where the three thin plates 2a, 2b, and 2c are laminated. In the central portion of the thin plate 2a, a micropore forming portion 2d having a plurality of micropores (through holes) is provided. These micropores communicate the liquid flow path 2g with the outer surface of the thin plate 2a.

[0042] In this embodiment, the three thin plates 2a, 2b, and 2c are made of stainless steel with a thickness of 50 μm. By laminating and diffusion-joining these three thin plates 2a, 2b, and 2c, they are integrated into the liquid flow path plate 2 with a thickness of 150 μm. Since diffusion joining is a joining method that does not use an adhesive or the like, it is also possible to flow a liquid sample containing a solvent or the like through the liquid flow path plate 2.

[0043] The liquid flow path plate 2 is sandwiched between a liquid sample supply side member 9a and a connection member 9b. The liquid sample supply side member 9a and the connection member 9b each have a recess in the central portion and are configured not to directly contact the central portion of the liquid flow path plate 2. In other words, the liquid sample supply side member 9a and the connection member 9b sandwich the peripheral edge portion of the liquid flow path plate 2 and support the liquid flow path plate 2.

[0044] The tip vibration portion 3a of the ultrasonic vibration applying unit 3 is pressed against the central portion of the liquid flow path plate 2 (thin plate 2c).

[0045] The liquid sample supply side member 9a is provided with a through hole for supplying the sample liquid 26a and a through hole for discharging the remaining sample liquid 26c. The through hole for supplying the sample liquid 26a is connected to the supply port 2f of the thin plate 2c. The through hole for discharging the remaining sample liquid 26c is connected to the discharge port 2h of the thin plate 2c. The sample liquid 26a passes through the supply port 2f and is sent to the liquid flow path 2g in the liquid flow path plate 2. Then, a part of the sample liquid 26a is discharged from the fine holes of the fine hole forming portion 2d provided in the middle of the liquid flow path 2g by the ultrasonic vibration in the thickness direction of the liquid flow path plate 2 applied from the tip vibration portion 3a of the ultrasonic vibration applying unit 3, and becomes fine droplets 26b, and is sent to the left in the figure together with the conveying gas 27b that has passed through the through hole 2e for the conveying gas of the liquid flow path plate 2. The conveying gas 27b flows so as to surround the flow of the fine droplets 26b. In other words, the fine droplets 26b flow through the central part of the flow path, and the conveying gas 27b flows through the outer peripheral part of the flow path.

[0046] The rest of the sample liquid 26a passes through the discharge port 2h and is discharged as the remaining sample liquid 26c.

[0047] With such a structure, even when the type of the continuously supplied sample liquid 26a is changed, the sample liquid 26a flowing through the liquid flow path 2g does not mix, and continuous generation of fine droplets is realized according to the switching of the type of the sample liquid 26a.

[0048] Since the fine droplets 26b flow while being surrounded by the conveying gas 27b, they are stably conveyed toward the heating and pressure regulating gas supply block 11 as shown in FIG. 1.

[0049] FIG. 3A is a partially enlarged view showing the fine hole forming portion 2d of FIG. 2A.

[0050] In FIG. 3A, a number of fine holes provided in the fine hole forming portion 2d are shown as dots. Also, the liquid flow path 2g inside the liquid flow path plate 2 and the tip vibration portion 3a in contact with the back surface of the liquid flow path plate 2 are shown by dotted lines.

[0051] FIG. 3B is a longitudinal sectional view of the portion shown in FIG. 3A.

[0052] In FIG. 3B, a configuration in which three thin plates 2a, 2b, and 2c are laminated, a tip vibration part 3a in contact with the thin plate 2c, and a large number of micropores of a micropore forming part 2d formed in the thin plate 2a are shown. In other words, the tip vibration part 3a of the ultrasonic vibration applying unit 3 is in contact with the surface on the opposite side of the liquid flow path plate 2 provided with the micropore forming part 2d.

[0053] The diameter of the microdroplets 26b shown in FIG. 2B is affected by the ultrasonic vibration frequency and the diameter of the micropores. In this embodiment, in order to form microdroplets 26b of about several μm, the frequency of the ultrasonic vibration was set to about 150 kHz, and the diameter of the narrowest part of the micropores was set to 4 μm. As a result, droplets with a diameter of 4 to 6 μm could be formed. There were almost no droplets with a diameter of 10 μm or more, and no droplets with a diameter of 20 μm or more were observed.

[0054] From this experimental result, it was found that in order to form microdroplets of about several μm, it is necessary to apply vibration at a frequency of about several hundred kHz and form micropores with a narrowest part diameter of several μm or less.

[0055] Also, for the formation of such micropores, methods such as laser processing and electroforming can be used. In this embodiment, YAG laser processing was used in consideration of the large number of micropores, the selection of stainless steel as the material, and the cost.

[0056] In many processing methods, in such microfabrication, a difference occurs in the diameter of the hole in the thickness direction. In the microfabrication of micropores by the YAG laser in this embodiment, the hole diameter on the irradiation side when forming micropores with a diameter of 4 μm was about several tens of μm. In the thin plate 2a of this embodiment, the diameter of the micropores on the surface side is set to about 4 μm. This is because, as a result of consideration, when the diameter on the flow path side is large and the diameter on the surface side is small, the liquid is more likely to be discharged in a mist form, and it is less likely for liquid droplets to be generated on the surface of the flow path plate. When liquid droplets are generated on the surface side of the flow path plate, the discharge of the liquid becomes unstable.

[0057] In addition, since the micro-droplet 26b shown in FIG. 2B has a slow initial velocity and a small droplet diameter, stable conveyance of the micro-droplet 26b can be achieved even when the flow rate of the conveyance gas 27b is low.

[0058] In this embodiment, nitrogen gas at 1 L / min is used as the conveyance gas 27b, and stable conveyance of the micro-droplet 26b is achieved at a conveyance speed of about 1 m / s inside the sample conveyance pipe 13 shown in FIG. 1.

[0059] In addition, in this embodiment, the droplet generation unit has a configuration including the liquid flow path plate 2 which is a plate-like member. However, the droplet generation unit according to the present disclosure is not limited thereto, and a configuration in which a liquid flow path is formed inside a pipe may be used.

[0060] In addition, in this embodiment, the droplet generation unit has a configuration in which droplets are generated by the ultrasonic vibration applying unit 3. However, the droplet generation unit according to the present disclosure is not limited thereto, and a configuration in which droplets are generated by a gas spray method or the like may be used.

[0061] FIG. 4 is a cross-sectional view showing the heating and pressure-regulating gas supply block 11 of FIG. 1.

[0062] In FIG. 4, a cross-section passing through the central axes of the air heater 16 and the pressure-regulating means 17 is shown, and the direction in which the micro-droplet 26b shown in FIG. 1 is conveyed is perpendicular to the drawing.

[0063] As shown in FIG. 4, the heated gas 27c supplied from the air heater 16 flows through the outer shell chamber 18 inside the outer pipe 12a and becomes an air flow 27h swirling around the inner pipe 12b.

[0064] The volume of a gas changes significantly upon heating. When a change in the volume of the heated gas 27c supplied from the air heater 16 occurs, the pressure inside the outer shell chamber 18 changes. In this embodiment, by disposing the pressure regulating means 17 in the outer shell chamber 18, the configuration is such that the pressure inside the outer shell chamber 18 does not change even when a change occurs in the volume of the heated gas supplied from the air heater 16. The pressure regulating means 17 of this embodiment utilizes a component in which a valve opens when the internal pressure reaches a predetermined pressure. By providing the pressure regulating means 17, when the pressure of the air flow 27h supplied from the air heater 16 into the outer tube 12a rises to a predetermined value, a part of the gas inside the outer shell chamber 18 is discharged from the pressure regulating means 17. Thereby, it is possible to keep the pressure of the heated gas inside the outer shell chamber 18 constant.

[0065] The heated and pressure-regulated air flow 27h inside the outer shell chamber 18 passes through the mesh plate 15 and is supplied to the inner tube 12b. The swirling air flow 27d is introduced from the outer peripheral portion inside the inner tube 12b and flows into the inner tube 12b so as to wrap around the minute droplets 26b and the carrier gas 27b conveyed from the sample conveyance tube 13 shown in FIG. 1 while swirling.

[0066] In this embodiment, the inner diameter of the inner tube 12b is made larger than the inner diameter of the sample conveyance tube 13.

[0067] This is due to the following reason.

[0068] This is to prevent the gas flow velocity inside the inner tube 12b from increasing when the carrier gas 27b containing the swirling air flow 27d and the minute droplets 26b merge. When the gas flow velocity increases, it is necessary to increase the flow path length in consideration of ensuring the distance required for the swirling air flow 27d and the carrier gas 27b containing the minute droplets 26b to mix and the time for the solvent of the minute droplets 26b to vaporize.

[0069] When the flow path is lengthened, not only does the size of the device increase, but the possibility also increases that the minute droplets 26b and their solute components contained in the carrier gas 27b come into contact with the inner wall surface of the inner tube 12b. The solute components contained in the minute droplets 26b to be analyzed will burn out when they come into contact with the inner wall surface of the high-temperature inner tube 12b.

[0070] Although the burnout of solute components and the like is effective in preventing contamination with components contained in another liquid sample sent later, there arises a problem that the amount of solute components that can be introduced into the analysis block decreases.

[0071] Therefore, the inner diameter of the inner tube 12b is made larger than the inner diameter of the sample conveyance tube 13.

[0072] In this embodiment, while making the inner diameter of the inner tube 12b larger than the inner diameter of the sample conveyance tube 13, by keeping the pressure of the heated gas within a predetermined range by the pressure regulating means 17, the change in the air flow accompanying the confluence of the swirling air flow 27d and the carrier gas 27b is suppressed.

[0073] Also, by making the swirling air flow 27d supplied to the inner tube 12b a gentle flow and wrapping it around from the periphery of the carrier gas 27b while swirling, more solute components can be introduced into the analysis block.

[0074] In this way, by supplying the heated gas to the inner tube 12b after regulating the pressure, the pressure of the inner tube 12b is also kept within a predetermined range, and in this state, the solvent contained in the minute droplets 26b can be heated and vaporized.

[0075] Next, the charge imparting section of this embodiment will be described.

[0076] FIG. 5A is a cross-sectional view showing the charge imparting block 21 of FIG. 1.

[0077] Since the configuration shown in FIG. 5A is shown in FIG. 1, the description thereof will be omitted here.

[0078] FIG. 5B is a partial cross-sectional view of the charge application block 21 as seen from the side of the analysis block 25 in FIG. 1.

[0079] Both FIGS. 5A and 5B show cross-sections including the position where the discharge wire 20 is stretched.

[0080] In FIG. 5B, the part of the connection block 22 is a view seen from the front. The capillary connection part 23 (micropores) connected to the analysis block is provided at the center of the connection block 22. The inner diameter (diameter) of the capillary connection part 23 is desirably 1 / 5 or less of the inner diameter of the downstream end of the sample conveyance pipe, and more desirably 1 / 10 or less. As the actual dimension, the inner diameter of the capillary connection part 23 is desirably 1 mm or less, and more desirably 100 μm or less.

[0081] The discharge wire 20 is stretched across the pipe hole provided in the center of the charge application block 21. The charge application block 21 is made of an insulating material. The discharge wire 20 has a spring 19 for stretching it and a power supply terminal arranged.

[0082] A high-voltage power supply 28 is connected to the discharge wire 20. By applying a high voltage to the discharge wire 20 by the high-voltage power supply 28, a potential difference is given between the discharge wire 20 and the connection block 22 to generate a corona discharge. Positive ions and electrons generated by the corona discharge can charge the solute components in the carrier gas. The current and polarity of the high-voltage power supply 28 are controlled according to the solute components.

[0083] The carrier gas 27e containing the solute components to which charges are applied passes through the capillary connection part 23 provided in the connection block 22 and is supplied as the solute component 27f into the housing 24. The inside of the housing 24 is kept almost in a vacuum state, and the amount of the carrier gas 27e passing through the capillary connection part 23 is affected by the pressure of the carrier gas 27e in the conveyance pipe.

[0084] In this embodiment, by adopting a structure in which the pressure and flow rate of the carrier gas 27e in the carrier pipeline are stably maintained at predetermined conditions, almost all of the carrier gas 27e containing the solute component (ions) in the carrier pipeline can be supplied to the inside of the housing 24. To achieve this, a pressure regulating means 17 is provided in the heating and pressure regulating gas supply block 11.

[0085] Next, an example of the setting conditions in this embodiment will be described.

[0086] Under the condition that the external atmospheric pressure is approximately atmospheric pressure, the amount of the carrier gas 27e passing through the capillary connection part 23 of the connection block 22 is about 7 L / min. Therefore, the flow rate of the carrier gas supplied from the liquid sample atomization block 1 is set to about 1 L / min, and the flow rate of the swirling air flow 27d supplied from the heating and pressure regulating gas supply block 11 is set to about 6 L / min. As an example of the actual setting, a heating gas slightly more than about 6 L / min is supplied from the air heater 16 to the outer shell chamber 18 of the heating and pressure regulating gas supply block 11, and the leakage pressure of the pressure regulating means 17 is set to 1 atm (atmospheric pressure).

[0087] By setting in this way, the pressure of the carrier gas 27e flowing through the pipeline becomes approximately atmospheric pressure, and only the amount that balances with the amount of the carrier gas 27e passing through the capillary connection part 23 of the connection block 22 is supplied as the swirling air flow 27d from the outer shell chamber 18 of the heating and pressure regulating gas supply block 11 to the inner pipeline.

[0088] In the structure of this embodiment, as described above, it is possible to stably introduce all of the gas flow containing the sample liquid atomized by the liquid sample atomization block 1 and the gas flow for heating and vaporizing the same into the analysis block. As a result, since the solute components contained in many liquid samples can be introduced into the analysis block, a significant improvement in the sensitivity of the analyzer can be achieved.

[0089] Next, another charge imparting part in this embodiment will be described.

[0090] As described above, the charge imparting unit shown in FIGS. 5A and 5B evaporates and vaporizes the solvent component of the droplet sample in the heating and pressure regulating gas supply block 11, and then irradiates the solute component with corona ions in the charge imparting block 21 to ionize it.

[0091] In the ion source of the current mass spectrometer, in addition to imparting a charge to the solute component in which the solvent component is completely vaporized as in the charge imparting block 21 shown in FIGS. 5A and 5B, a method of imparting a charge to the droplet immediately after the formation of the micro-droplet is also used. These methods are called the atmospheric pressure chemical ionization method (APCI) and the electrospray method (ESI), respectively. These two methods are selectively used depending on the type of solute component because there are differences in analysis sensitivity and the like due to characteristics such as the molecular weight of the solute component to be analyzed.

[0092] Also in this embodiment, it is desirable to provide a charge imparting unit that imparts a charge to the droplet immediately after the formation of the micro-droplet, together with the charge imparting unit shown in FIGS. 5A and 5B that imparts a charge to the solute component after the solvent is vaporized.

[0093] FIG. 6A is a cross-sectional view showing another charge imparting unit in this embodiment.

[0094] In this figure, a charge imparting unit is arranged in the sample transfer pipe 13 which is the inlet of the heating and pressure regulating gas supply block 11 shown in FIG. 1. The liquid sample supply side member 9a which is the holding body 9 of the liquid flow path plate 2 of the liquid sample atomization block 1 is made of a conductive material, and the connecting member 9b is made of an insulating material. Further, the sample transfer pipe 13 is made of a conductive material and is connected to the heating and pressure regulating gas supply block 11 side via a heat insulating and insulating member 14.

[0095] And a variable power supply 29 capable of applying positive and negative electrodes for applying a voltage is arranged between the sample transfer pipe 13 and the liquid sample supply side member 9a. The liquid sample supply side member 9a is in electrical contact with the liquid flow path plate 2. Thereby, an electric field can be generated between the surface of the liquid flow path plate 2 that discharges the sample droplets and the sample transfer pipe 13.

[0096] Since an electric field is also generated in the sample droplets released from the liquid flow path plate 2 where an electric field is present, the formed droplets are given an electric charge. This action of imparting an electric charge to the droplets is the same as the current electrospray method. That is, even in the droplet atomization configuration in which the thin plate-like liquid flow path plate 2 of the present disclosure is ultrasonically vibrated, it is possible to realize an electric charge imparting to the droplets equivalent to the electrospray method.

[0097] FIG. 6B is a cross-sectional view of the sample transfer tube 13 in FIG. 6A as viewed from the heating and pressure-regulating gas supply block 11 side.

[0098] In FIG. 6B, as an electrode for generating an electric field on the surface of the liquid flow path plate 2, an electric wire 61 is disposed not on the wall surface of the sample transfer tube 13 but inside the flow path of the sample transfer tube 13. Three electric wires 61 are provided in a Y shape (radially) at 120-degree intervals.

[0099] As a result, the direction of the electric field generated on the surface of the liquid flow path plate 2 is more consistent with the direction of the transfer gas 27b flowing in the sample transfer tube 13. Thereby, the traveling direction of the charged micro-droplets 26b is stabilized, preventing the micro-droplets 26b from colliding with the wall surface of the sample transfer tube 13 or the like, and reducing the disappearance amount of the micro-droplets 26b. As a result, more micro-droplets 26b are supplied to the heating and pressure-regulating gas supply block 11 side.

[0100] When an electric charge is imparted to the micro-droplets 26b containing a solvent in a state released from the liquid flow path plate 2 by the configuration shown in FIGS. 6A and 6B, the electric charge imparting by the corona ions shown in FIGS. 5A and 5B is not necessary.

[0101] By performing control to switch between the electric charge imparting by the corona ions shown in FIGS. 5A and 5B and the electric charge imparting at the time of droplet formation shown in FIGS. 6A and 6B, two types of electric charge imparting means can be selected and appropriately implemented in one ion source.

[0102] As described above, the ion source of the present disclosure can suppress and appropriately control the amount of the gas flow for transporting the micro droplets and the heating gas flow for vaporizing the solvent. Therefore, the analyzer including the ion source of the present disclosure can introduce most of the solute components contained in the sample liquid into the analysis block, and can significantly improve the sensitivity of the analyzer.

[0103] According to the present disclosure, it is possible to provide a new ion source capable of introducing most of the generated solute component ions into a mass spectrometer, and to provide a mass spectrometer with high analysis sensitivity using the ion source.

[0104] Hereinafter, desirable embodiments according to the present disclosure will be collectively described.

[0105] In the ion source, the droplet generation unit has an ultrasonic vibration applying unit, and has a configuration in which droplets are generated by the ultrasonic vibration applying unit.

[0106] The droplet generation unit has a liquid flow path formed inside a pipe or a plate-like member. The pipe or the plate-like member has fine holes communicating the outside thereof with the liquid flow path. The ultrasonic vibration applying unit is configured to apply ultrasonic vibration to the liquid sample flowing through the liquid flow path, and the droplets are discharged from the fine holes.

[0107] The droplet generation unit has a configuration in which the droplets flow into the central portion of the sample transport pipe, and the transport gas flows into the sample transport pipe so as to surround the flow of the droplets.

[0108] The predetermined gas introduced from the heated regulated gas retention portion into the sample transport pipe has a configuration of flowing in so as to surround the flow of the droplets and the transport gas.

[0109] On the downstream side of the position where the predetermined gas flows in, the sample transport pipe has a larger flow path cross-sectional area than that on the upstream side. When the flow path cross-section of the sample transport pipe is circular, on the downstream side of the position where the predetermined gas flows in, the inner diameter of the flow path cross-section is larger on the downstream side than on the upstream side.

[0110] The charge imparting unit is configured to be disposed between the analysis block and the heated pressure-regulated gas supply block.

[0111] The charge imparting unit is disposed between the heated pressure-regulated gas supply block and the droplet generation unit.

[0112] The analyzer includes an ion source and an analysis block.

[0113] The ion source and the analysis block are connected by a capillary connection part, and the ionized solute component is supplied to the analysis block through the capillary connection part.

Explanation of Signs

[0114] 1: Liquid sample atomization block, 2: Liquid flow path plate, 2a, 2b, 2c: Thin plates, 2d: Micro-pore forming part, 2e: Through-hole for carrier gas, 2f: Supply port, 2g: Liquid flow path, 2h: Discharge port, 3: Ultrasonic vibration imparting unit, 3a: Tip vibration part, 3b: Piezoelectric element part, 3c: Screw housing, 4: Rectifying plate, 5: Supply pipe, 6: Carrier gas supply pipe, 7: Spring, 8: Discharge pipe, 9 Holder, 9a: Liquid sample supply side member, 9b: Connection member, 10: Holder, 10a: Main body of the holder, 10b: Flange-shaped member, 11: Heated pressure-regulated gas supply block, 12: Main body of the heated pressure-regulated gas supply part, 12a: Outer pipe, 12b: Inner pipe, 13: Sample transfer pipe, 14: Heat insulation and insulation member, 15: Mesh plate, 16: Air heater, 17: Pressure regulating means, 18: Outer shell chamber, 19: Spring, 20: Discharge wire, 21: Charge imparting block, 22: Connection block, 23: Capillary connection part, 24: Housing, 25: Analysis block, 26a: Sample liquid, 26b: Tiny droplets, 26c: Remaining sample liquid, 26d: Solute fine particles, 27a, 27b: Carrier gas, 27c: Heated gas, 27d: Swirling air flow, 27e: Carrier gas, 27f: Solute component, 27g: Exhaust gas flow, 27h: Air flow, 28: High voltage power supply, 29: Variable power supply, 61: Electric wire.

Claims

1. An ion source for supplying ions of a solute component to an analysis block for analyzing a liquid sample containing the solute component, comprising: a droplet generation unit for generating droplets of the liquid sample; a heated regulated gas supply block for heating a carrier gas flowing in with the droplets from the droplet generation unit; a charge imparting unit for imparting a charge to the solute component to ionize it, wherein the heated regulated gas supply block includes a sample transfer pipe disposed between the analysis block and the droplet generation unit; a heated regulated gas retention part having a configuration in heat-transferable contact with the sample transfer pipe; a gas heating part for heating a predetermined gas to a predetermined temperature; a pressure adjustment part for maintaining the pressure of the predetermined gas within a predetermined range, wherein the droplets and the carrier gas are heated by the heated predetermined gas, the sample transfer pipe is supplied with the droplets and the carrier gas from the droplet generation unit, and the heated predetermined gas from the heated regulated gas retention part is introduced from the upstream part of the sample transfer pipe so as to surround the droplets and the carrier gas while swirling; the inner diameters of the flow paths of the droplets, the carrier gas, and the predetermined gas from the upstream part of the sample transfer pipe to the upstream part of the capillary connection part of the analysis block are substantially constant; the inner diameter of the upstream part of the sample transfer pipe is larger than the inner diameter of the part where the droplets and the carrier gas of the droplet generation unit are introduced. Ion source.

2. The droplet generation unit has an ultrasonic vibration application unit, The ion source according to claim 1, wherein the droplets are generated by the ultrasonic vibration application unit.

3. The droplet generation unit has a liquid flow path formed inside a pipe or a plate-like member, The pipe or the plate-like member has fine holes communicating the outside thereof with the liquid flow path, The ultrasonic vibration application unit is configured to apply ultrasonic vibration to the liquid sample flowing in the liquid flow path, The ion source according to claim 2, wherein the droplets are discharged from the fine holes.

4. The ion source according to claim 1, wherein the droplet generation unit is configured such that the droplets flow into the central part of the sample transfer pipe and the carrier gas flows into the sample transfer pipe so as to surround the flow of the droplets.

5. The ion source according to claim 1, wherein the predetermined gas introduced from the heated regulated gas retention part into the sample transfer pipe is configured to flow in so as to surround the flow of the droplets and the carrier gas.

6. The ion source according to claim 5, wherein the sample transfer pipe has a larger flow path cross-sectional area on the downstream side than on the upstream side from the position where the predetermined gas flows in.

7. The ion source according to claim 1, wherein the charge imparting unit is configured to be disposed between the analysis block and the heated regulated gas supply block.

8. The ion source according to claim 1, wherein the charge imparting unit is disposed between the heated regulated gas supply block and the droplet generation unit.

9. An ion source according to any one of claims 1 to 8, and the analysis block. An analyzer comprising

10. The ion source and the analysis block are connected by the capillary connection part, and the ionized solute component is supplied to the analysis block through the capillary connection part. The analyzer according to claim 9.

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