JP7692121B2 - Ion source and analytical device using same - Google Patents

Description

The present disclosure relates to an ion source and an analytical device using the same.

In devices that analyze components in liquid samples containing various solute components, the liquid sample is sprayed into fine droplets, the solvent components are vaporized and removed, and the solute components of the sample are atomized and introduced into the analysis section, etc. A typical example of a device that uses this method of analysis is a liquid chromatograph mass spectrometer.

In a liquid chromatograph mass spectrometer, a liquid sample containing various components separated by a liquid chromatograph is turned into tiny droplets, which are then charged and heated and vaporized in an ion source to generate ions of the solute components. The ionized solute components are then introduced into a mass spectrometer, where they are separated by their mass-to-charge ratio and the components are identified.

Methods used in ion sources include electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI).

The gas spray method is usually used to turn liquid samples into microdroplets in liquid chromatography mass spectrometry devices, etc. Here, the gas spray method refers to a method in which a high-speed gas jet is applied to the liquid, breaking it into microdroplets and spraying them.

In ion sources, the liquid sample must be converted into extremely small droplets with a diameter of only a few microns, so a gas spray is used using an ultra-high speed gas flow with a jet speed of several hundred meters per second.

Development is also underway on a device that uses an ultrasonic transducer to generate the tiny droplets to be introduced into the ion source.

Conventional technologies that apply an atomizing device using an ultrasonic vibrator to an ion source include the following:

Patent Document 1 discloses a configuration in which the eluent for liquid chromatography is sprayed and adhered to the surface of an ultrasonic transducer using a high-pressure gas nebulizer, creating an extremely fine mist through the action of the ultrasonic transducer, and the solvent is removed from the mist, and the desolvated sample is then introduced to an atmospheric pressure ion source for mass analysis.

Patent Document 2 discloses an ion generating device in a mass spectrometry system that uses an ultrasonic vibrator to atomize a liquid containing a sample having ionic groups and a protic polar solvent, and then heats the liquid to remove the protic polar solvent.

Japanese Patent Application Publication No. 11-051902 JP 2015-031650 A

In a liquid chromatograph mass spectrometer, multiple types of liquid samples to be analyzed are continuously supplied from a liquid chromatograph through thin tubes with diameters of several hundred micrometers or less. The amount of each liquid sample supplied is extremely small, less than several hundred microliters. The droplet generator used in the mass spectrometer is required to continuously convert these liquid samples into microdroplets without mixing with each other, impart an electric charge to the generated microdroplets, remove the solvent by heating, generate ions of the solute components, and continuously supply them to the analysis section.

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, so the energy required for processes such as charging and heating and vaporization is large, and the time required for these processes is short. For this reason, there are also challenges in terms of stabilizing these processes.

In addition, because the liquid sample breaks down into tiny droplets in the high-speed, large-volume gas flow, only a small portion of the sample droplets can be introduced into the mass spectrometer, with the majority of the sample being discharged unused.

The devices described in Patent Documents 1 and 2 do not provide a solution to the problem of loss of microdroplets in the path that sends the generated mist of microdroplets to an analytical device.

The objective of this disclosure is to provide a new ion source that generates microdroplets from a liquid sample continuously supplied from a liquid chromatograph or the like, imparts an electric charge to the microdroplets, and performs a series of processes of vaporizing the solvent at a low gas flow rate, thereby introducing ions of solute components contained in the liquid sample into the analysis block.

The ion source disclosed herein supplies ions of a solute component to an analysis block that analyzes a liquid sample containing a solute component, and includes a droplet generation unit that generates droplets of the liquid sample, a heated and pressure-adjusted gas supply block that heats the transport gas that flows in from the droplet generation unit along with the droplets, and a charge imparting unit that imparts an electric charge to the solute component to ionize it. The heated and pressure-adjusted gas supply block includes a sample transport pipeline disposed between the analysis block and the droplet generation unit, a heated and pressure-adjusted gas retention unit that is in heat-transferable contact with the sample transport pipeline, a gas heating unit that heats a specified gas to a specified temperature, and a pressure adjustment unit that maintains the pressure of the specified gas within a specified range. The droplets and transport gas are heated by the heated specified gas, and the sample transport pipeline is configured such that the droplets and transport gas are supplied from the droplet generation unit and the heated specified gas is introduced from the heated and pressure-adjusted gas retention unit.

According to the present disclosure, it is possible to provide a new ion source that generates microdroplets from a liquid sample continuously supplied from a liquid chromatograph or the like, imparts an electric charge to the microdroplets, and performs a series of processes of vaporizing the solvent with a low gas flow rate, thereby introducing ions of solute components contained in the liquid sample into an analysis block.

FIG. 2 is a cross-sectional view showing a main part of the analysis device of the embodiment. FIG. 2 is a front view showing the liquid flow path plate 2 of FIG. 1 . 2B is a cross-sectional view showing a state in which the liquid flow path plate 2 in FIG. 2A is installed in an ion source. FIG. 2B is a partially enlarged view showing the micropore forming portion 2d of FIG. 2A. FIG. 3B is a longitudinal cross-sectional view of the portion shown in FIG. 3A. 2 is a cross-sectional view showing a heating and pressure adjusting gas supply block 11 of FIG. 1. 2 is a cross-sectional view showing a charge-imparting block 21 of FIG. 1. 2 is a partial cross-sectional view of the charge-imparting block 21 as viewed from the analysis block 25 side of FIG. 1. FIG. 11 is a cross-sectional view showing another charge applying portion in the embodiment. 6B is a cross-sectional view of the sample transport tube 13 in FIG. 6A as viewed from the heating and pressure adjustment gas supply block 11 side.

The present disclosure relates to an ion source for ionizing components contained in a liquid sample to be analyzed in an analytical device such as a liquid chromatograph mass spectrometer and introducing the components into an analysis block, and an analytical device equipped with such an ion source.

Below, examples of the present disclosure are explained using drawings.

Figure 1 is a cross-sectional view of a key part of the analytical device of the embodiment.

The analytical device shown in this diagram has a liquid sample atomization block 1 (droplet generation section), a heated and pressure-adjusted gas supply block 11, an electric charge imparting block 21, and an analysis block 25. These are connected in series. Of these, the liquid sample atomization block 1, the heated and pressure-adjusted gas supply block 11, and the electric charge imparting block 21 constitute the ion source. The ion source is connected to the analysis block 25 via a connection block 22 having a capillary connection section 23. The inside of the analysis block 25 is kept in a nearly vacuum state (reduced pressure state).

The liquid sample atomization block 1 has a thin liquid flow path plate 2 and an ultrasonic vibration imparting unit 3. The holder 9 is composed of a liquid sample supply side member 9a and a connection member 9b, and the holder 10 is composed of a holder main part 10a and a flange-shaped member 10b. The holder main part 10a is approximately cylindrical. The liquid flow path plate 2 is sandwiched between the liquid sample supply side member 9a and the connection member 9b. The ultrasonic vibration imparting unit 3 is a bolt-tightened Langevin type transducer (BLT) composed of a tip vibration part 3a, a piezoelectric element part 3b, and a screw housing 3c (piezoelectric element fixing body). The ultrasonic vibration imparting unit 3 and a straightening plate 4 are inserted and fixed inside the holder main part 10a. The holder main part 10a is inserted into the through hole of the liquid sample supply side member 9a.

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

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. The remaining liquid that is not atomized is discharged from the discharge pipe 8 as the remaining sample liquid 26c.

A conveying gas supply pipe 6 is connected to the flange-shaped member 10b, and conveying gas 27a is supplied to the inside of the main holder part 10a. The conveying gas 27a is made to have a substantially uniform flow velocity distribution by the straightening plate 4, passes around the ultrasonic vibration imparting unit 3, and is supplied to the heating and pressure regulating gas supply block 11 together with the droplets generated in the liquid flow path plate 2. By passing the side of the ultrasonic vibration imparting unit 3, the ultrasonic vibration imparting unit 3 can also be cooled.

The heated and pressurized gas supply block 11 has an outer tube 12a, an inner tube 12b, a sample transport tube 13 (sample transport pipeline), a heat insulating member 14, a mesh plate 15, an air heater 16 (gas heating section), and a pressure adjusting means 17 (pressure adjusting section). The outer tube 12a and the inner tube 12b constitute the heated and pressurized gas supply section main body 12 and have a double tube structure. The annular section formed by the outer tube 12a and the inner tube 12b is the outer shell chamber 18 (heated and pressurized gas retention section).

A heat insulating member 14 is sandwiched between the outer tube 12a and the sample transport tube 13. The heat insulating member 14 does not easily transmit heat, so the liquid sample atomization block 1 is not heated by the heat of the high-temperature heating and pressure adjustment gas supply block 11. In addition, the heat insulating member 14 has electrical insulation properties, so it also has the function of blocking the current from the charge imparting block 21.

Microdroplets 26b flow together with carrier gas 27b in the sample transport tube 13. Microdroplets 26b and carrier gas 27b are supplied into the inner tube 12b.

The air heater 16 heats a predetermined flow rate of gas to a predetermined temperature and supplies it to the outer shell chamber 18 as heated gas 27c. In this embodiment, nitrogen gas is used as the gas supplied to the outer shell chamber 18. In this case, the gas to be used is preferably an inert gas such as nitrogen, argon, or helium.

The pressure in the outer shell chamber 18 is adjusted by a pressure regulating means 17, and when the pressure exceeds a predetermined value, an exhaust gas flow 27g is generated.

The heated gas 27c passes through the outer shell chamber 18 and the mesh plate 15, and is supplied to the inner tube 12b as a swirling air current 27d, where it merges with the solute particles 26d. The solute particles 26d are particles formed when the microdroplets 26b are heated and the solvent evaporates. The solute particles 26d are supplied to the charge imparting block 21 together with the carrier gas 27e.

A discharge wire 20 suspended by a spring 19 is installed in the charge imparting block 21. Solute particles 26d supplied together with the carrier gas 27e are ionized by a discharge generated by a high voltage applied to the discharge wire 20.

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

In addition, the internal area including the heated and pressure-adjusted gas supply block 11 from the liquid flow path plate 2 to the connection block 22 has an airtight structure, including the support part and power supply terminal of the discharge wire 20, to prevent the conveying gas flow from leaking from the central pipeline.

The solute particles 26d sent to the analysis block 25 are subjected to analysis processing of components, etc. in the analysis block 25 as ionized solute components 27f.

Figure 2A is a front view showing the liquid flow path plate 2 of Figure 1.

The liquid flow path plate 2 has a liquid flow path 2g therein. A supply port 2f and a discharge port 2h for the liquid sample are provided at the ends of the liquid flow path 2g. A micropore forming section 2d having a plurality of micropores is provided in the center of the liquid flow path 2g. Four through holes 2e for the carrier gas are provided around the micropore forming section 2d.

Figure 2B is a cross-sectional view showing the state in which the liquid flow path plate 2 of Figure 2A is installed in an ion source. Note that the liquid flow path plate 2 is a very thin plate compared to the dimensions of the other components, so in Figure 2B, it is shown enlarged in the thickness direction.

The liquid flow path plate 2 has a structure in which three thin plates 2a, 2b, and 2c are stacked and joined together. A supply port 2f and a discharge port 2h for the sample liquid 26a are formed in the thin plate 2c on the side to which the sample liquid 26a is supplied. The supply port 2f and the discharge port 2h are both through holes. A long and thin hole is formed in the central thin plate 2b. This hole constitutes the liquid flow path 2g when the three thin plates 2a, 2b, and 2c are stacked. A micropore forming section 2d in which multiple micropores (through holes) are formed is provided in the center of the thin plate 2a. This micropore connects the liquid flow path 2g to the outer surface of the thin plate 2a.

In this embodiment, the three thin plates 2a, 2b, and 2c are made of stainless steel with a thickness of 50 μm. These three thin plates 2a, 2b, and 2c are stacked and diffusion bonded to form a liquid flow path plate 2 with a thickness of 150 μm. Since diffusion bonding is a bonding method that does not use adhesives, it is also possible to flow liquid samples containing solvents into the liquid flow path plate 2.

The liquid flow path plate 2 is sandwiched between the liquid sample supply side member 9a and the connection member 9b. The liquid sample supply side member 9a and the connection member 9b each have a recess in their center so as not to come into direct contact with the center of the liquid flow path plate 2. In other words, the liquid sample supply side member 9a and the connection member 9b hold the peripheral portion of the liquid flow path plate 2 and support the liquid flow path plate 2.

The tip vibration portion 3a of the ultrasonic vibration imparting unit 3 is pressed against the center of the liquid flow path plate 2 (thin plate 2c).

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 released from the micropores of the micropore forming section 2d provided in the middle of the liquid flow path 2g by ultrasonic vibration in the thickness direction of the liquid flow path plate 2 given from the tip vibration section 3a of the ultrasonic vibration imparting unit 3, becomes microdroplets 26b, and is sent to the left in the figure together with the carrier gas 27b that has passed through the carrier gas through hole 2e of the liquid flow path plate 2. The carrier gas 27b flows so as to surround the flow of the microdroplets 26b. In other words, the microdroplets 26b flow through the center of the flow channel, and the carrier gas 27b flows around the outer periphery of the flow channel.

The remainder of the sample liquid 26a passes through the outlet 2h and is discharged as remaining sample liquid 26c.

With this structure, even if the type of sample liquid 26a being continuously supplied is changed, the sample liquid 26a flowing through the liquid flow path 2g does not mix, and continuous microdropletization is achieved in response to the change in the type of sample liquid 26a.

The microdroplets 26b flow as if surrounded by the transport gas 27b, and are stably transported toward the heating and pressure adjusting gas supply block 11 as shown in Figure 1.

Figure 3A is a partially enlarged view showing the micropore forming portion 2d of Figure 2A.

In Figure 3A, the numerous micropores provided in the micropore forming portion 2d are shown as dots. In addition, 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.

Figure 3B is a longitudinal cross-sectional view of the portion shown in Figure 3A.

3B shows a stacked configuration of three thin plates 2a, 2b, and 2c, a tip vibration part 3a in contact with thin plate 2c, and a number of micropores in micropore forming part 2d formed in thin plate 2a. In other words, the tip vibration part 3a of the ultrasonic vibration imparting unit 3 is in contact with the surface opposite to the liquid flow path plate 2 on which the micropore forming part 2d is provided.

The diameter of the microdroplets 26b shown in Figure 2B is affected by the ultrasonic vibration frequency and the diameter of the micropore. In this example, to form microdroplets 26b of about a few micrometers, the frequency of the ultrasonic vibration was set to about 150 kHz and the diameter of the narrowest part of the micropore was set to 4 μm. As a result, droplets with a diameter of 4 to 6 μm were formed. Almost no droplets with a diameter of 10 μm or more were observed, and no droplets with a diameter of 20 μm or more were observed at all.

The results of this experiment showed that in order to form tiny droplets of about a few micrometers, it is necessary to vibrate at a frequency of about several hundred kHz and to form micropores whose narrowest diameter is a few micrometers or less.

Although methods such as laser processing and electroforming can be used to form such micro-holes, in this embodiment, taking into consideration the large number of micro-holes, the selection of stainless steel as the material, and cost, YAG laser processing was used.

In many processing methods, this type of micromachining results in differences in hole diameter in the thickness direction. In the processing of microholes using a YAG laser in this embodiment, the hole diameter on the irradiated side when microholes with a diameter of 4 μm were formed was about several tens of μm. In thin plate 2a in this embodiment, the diameter of the microholes on the surface side is set to about 4 μm. This is because, as a result of investigation, it was found that when the diameter on the flow path side is larger and the diameter on the surface side is smaller, the liquid is more likely to be released in a mist and liquid droplets are less likely to form on the surface of the flow path plate. If liquid droplets form on the surface side of the flow path plate, the release of liquid becomes unstable.

In addition, since the microdroplets 26b shown in Figure 2B have a slow initial velocity and a small droplet diameter, stable transportation of the microdroplets 26b can be achieved even when the flow rate of the transport gas 27b is low.

In this embodiment, nitrogen gas of 1 L/min is used as the transport gas 27b, and stable transport of microdroplets 26b is achieved at a transport speed of approximately 1 m/s within the sample transport tube 13 shown in Figure 1.

In this embodiment, the droplet generating unit is configured to have a liquid flow path plate 2, which is a plate-shaped member, but the droplet generating unit according to the present disclosure is not limited to this and may also be configured to have a liquid flow path formed inside a pipe.

In addition, in this embodiment, the droplet generating unit is configured to generate droplets using an ultrasonic vibration imparting unit 3, but the droplet generating unit according to the present disclosure is not limited to this and may be configured to generate droplets using a gas spray method, etc.

Figure 4 is a cross-sectional view showing the heated and pressure-adjusting gas supply block 11 of Figure 1.

Figure 4 shows a cross section passing through the central axis of the air heater 16 and the pressure regulating means 17, and the direction in which the microdroplets 26b shown in Figure 1 are transported is perpendicular to the drawing.

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

The volume of gas changes significantly when heated. When the volume of the heated gas 27c supplied from the air heater 16 changes, the pressure in the outer shell chamber 18 changes. In this embodiment, a pressure regulating means 17 is placed in the outer shell chamber 18, so that the pressure in the outer shell chamber 18 does not change even if the volume of the heated gas supplied from the air heater 16 changes. The pressure regulating means 17 in this embodiment uses a part that opens a valve 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 to the outer tube 12a rises to a predetermined value, a portion of the gas in the outer shell chamber 18 is discharged from the pressure regulating means 17. This makes it possible to maintain the pressure of the heated gas in the outer shell chamber 18 constant.

The heated and pressurized airflow 27h in the outer shell chamber 18 passes through the mesh plate 15 and is supplied to the inner tube 12b. The swirling airflow 27d is introduced from the outer periphery of the inside of the inner tube 12b and flows into the inner tube 12b, swirling and enveloping the microdroplets 26b and the carrier gas 27b transported from the sample transport tube 13 shown in FIG.

In this embodiment, the inner diameter of the inner tube 12b is larger than the inner diameter of the sample transport tube 13.

This is for the following reasons:

This is to prevent the gas flow rate inside the inner tube 12b from increasing due to the merging of the swirling airflow 27d and the carrier gas 27b containing the microdroplets 26b. When the gas flow rate increases, it is necessary to lengthen the flow path length in consideration of the distance required for the swirling airflow 27d and the carrier gas 27b containing the microdroplets 26b to mix and the time required for the solvent of the microdroplets 26b to evaporate.

Increasing the length of the flow path not only increases the size of the device, but also increases the possibility that the microdroplets 26b and their solute components contained in the carrier gas 27b will come into contact with the inner wall surface of the inner tube 12b. The solute components contained in the microdroplets 26b to be analyzed will be burned up if they come into contact with the inner wall surface of the inner tube 12b, which is at a high temperature.

Although burning off solute components is effective in preventing contamination with components contained in other liquid samples sent later, it creates the problem of reducing the amount of solute components that can be introduced into the analysis block.

Therefore, the inner diameter of the inner tube 12b is made larger than the inner diameter of the sample transport tube 13.

In this embodiment, the inner diameter of the inner tube 12b is made larger than the inner diameter of the sample transport tube 13, and the pressure of the heated gas is maintained within a predetermined range by the pressure adjustment means 17, thereby suppressing changes in the air flow caused by the confluence of the swirling air flow 27d and the transport gas 27b.

In addition, the swirling airflow 27d supplied to the inner tube 12b is made to be a gentle flow that swirls around and wraps around the carrier gas 27b, allowing more solute components to be introduced into the analysis block.

In this way, by adjusting the pressure of the heated gas before supplying it to the inner tube 12b, the pressure in the inner tube 12b is also maintained within a predetermined range, and in this state the solvent contained in the microdroplets 26b can be heated and vaporized.

Next, we will explain the charge imparting section of this embodiment.

Figure 5A is a cross-sectional view showing the charge imparting block 21 of Figure 1.

The configuration shown in Figure 5A is shown in Figure 1, so its explanation is omitted here.

Figure 5B is a partial cross-sectional view of the charge imparting block 21 as viewed from the analysis block 25 side of Figure 1.

Figures 5A and 5B both show a cross section including the position where the discharge wire 20 is stretched.

In Figure 5B, the connection block 22 is shown as viewed from the front. The capillary connection part 23 (micropore) connecting to the analysis block is provided in the center of the connection block 22. The inner diameter (diameter) of the capillary connection part 23 is preferably one-fifth or less of the inner diameter of the downstream end of the sample transport pipeline, and more preferably one-tenth or less. In terms of actual dimensions, the inner diameter of the capillary connection part 23 is preferably 1 mm or less, and more preferably 100 μm or less.

The discharge wire 20 is stretched across a duct hole provided in the center of the charge imparting block 21. The charge imparting block 21 is made of an insulating material. The discharge wire 20 is provided with a spring 19 for stretching it and a power supply terminal.

A high-voltage power supply 28 is connected to the discharge wire 20. By applying a high voltage to the discharge wire 20 from the high-voltage power supply 28, a potential difference is created between the discharge wire 20 and the connection block 22, generating a corona discharge. The positive ions and electrons generated by the corona discharge can impart an electric charge to the solute components in the transport gas. The current and polarity of the high-voltage power supply 28 are controlled according to the solute components.

The carrier gas 27e containing the charged solute component is supplied as the solute component 27f to the inside of the housing 24 through the capillary connection 23 provided in the connection block 22. The inside of the housing 24 is kept in a substantially vacuum state, and the amount of the carrier gas 27e passing through the capillary connection 23 is affected by the pressure of the carrier gas 27e in the carrier pipeline.

In this embodiment, the pressure and flow rate of the carrier gas 27e in the carrier pipeline are stably maintained at predetermined conditions, so that the carrier gas 27e containing the solute components (ions) in the carrier pipeline can be supplied almost entirely to the inside of the housing 24. To achieve this, the heated pressure adjustment gas supply block 11 is provided with a pressure adjustment means 17.

Next, we will explain an example of setting conditions in this embodiment.

Under conditions where the external pressure is approximately atmospheric pressure, the amount of carrier gas 27e passing through the capillary connection part 23 of the connection block 22 is approximately 7 L/min. Therefore, the flow rate of the carrier gas supplied from the liquid sample atomization block 1 is set to approximately 1 L/min, and the flow rate of the swirling airflow 27d supplied from the heated pressure adjustment gas supply block 11 is set to approximately 6 L/min. As an example of an actual setting, heated gas is supplied from the air heater 16 to the outer shell chamber 18 of the heated pressure adjustment gas supply block 11 at a rate slightly more than approximately 6 L/min, and the leak pressure of the pressure adjustment means 17 is set to 1 atmosphere (atmospheric pressure).

By setting it in this manner, the pressure of the carrier gas 27e flowing through the pipeline becomes approximately atmospheric pressure, and only an amount that is balanced with the amount of carrier gas 27e passing through the capillary connection portion 23 of the connection block 22 is supplied as a swirling airflow 27d from the outer shell chamber 18 of the heated pressure regulating gas supply block 11 to the inner pipeline.

As described above, the structure of this embodiment makes it possible to stably introduce the gas flow containing the sample liquid atomized in the liquid sample atomization block 1 and the gas flow that heats and vaporizes it into the analysis block. This allows solute components contained in many liquid samples to be introduced into the analysis block, making it possible to significantly improve the sensitivity of the analysis device.

Next, we will explain other charge imparting sections in this embodiment.

As described above, the charge imparting section shown in Figures 5A and 5B evaporates the solvent components of the droplet sample in the heated and pressure-adjusted gas supply block 11, and then ionizes the solute components by irradiating them with corona ions in the charge imparting block 21.

In the ion sources of current mass spectrometers, in addition to the charge imparting block 21 shown in Figures 5A and 5B, which imparts a charge to the solute components after the solvent components have been completely vaporized, a method is also used in which a charge is imparted to the droplets immediately after they are formed. These methods are called atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), respectively. These two methods differ in analytical sensitivity depending on the molecular weight and other characteristics of the solute components being analyzed, so they are used differently depending on the type of solute components.

In this embodiment, it is also desirable to provide a charge imparting section that imparts a charge to the droplets immediately after the microdroplets are formed, in addition to the charge imparting section shown in Figures 5A and 5B that imparts a charge to the solute component after the solvent is evaporated.

Figure 6A is a cross-sectional view showing another charge imparting portion in this embodiment.

In this figure, a charge applying unit is placed in the sample transport tube 13, which is the inlet of the heated and pressure-adjusted gas supply block 11 shown in Figure 1. The liquid sample supply side member 9a, which is the holder 9 of the liquid flow path plate 2 of the liquid sample atomization block 1, is made of a conductive material, and the connection member 9b is made of an insulating material. The sample transport tube 13 is also made of a conductive material, and is connected to the heated and pressure-adjusted gas supply block 11 side via a heat-insulating and insulating member 14.

A variable power source 29 capable of applying both positive and negative voltages is disposed between the sample transport tube 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. This allows an electric field to be generated between the sample transport tube 13 and the surface of the liquid flow path plate 2 that releases sample droplets.

Since an electric field is also generated in the sample droplets released from the liquid flow path plate 2 in which an electric field is generated, the droplets that are formed are imparted with an electric charge. This effect of imparting a charge to the droplets is the same as in the current electrospray method. In other words, even in the configuration of droplet atomization in which the thin liquid flow path plate 2 of the present disclosure is subjected to ultrasonic vibration, it is possible to impart a charge to the droplets in a manner equivalent to that of the electrospray method.

Figure 6B is a cross-sectional view of the sample transport tube 13 in Figure 6A viewed from the heating and pressure-regulating gas supply block 11 side.

In Figure 6B, electric wires 61 are arranged inside the flow path of the sample transport tube 13, rather than on the wall of the sample transport tube 13, as electrodes for generating an electric field on the surface of the liquid flow path plate 2. Three electric wires 61 are arranged in a Y shape (radial) at 120 degree intervals.

This makes the direction of the electric field generated on the surface of the liquid flow path plate 2 more consistent with the direction of the transport gas 27b flowing inside the sample transport tube 13. This stabilizes the direction of travel of the charged microdroplets 26b, prevents the microdroplets 26b from colliding with the wall surface of the sample transport tube 13, and reduces the amount of microdroplets 26b lost. As a result, more microdroplets 26b are supplied to the heating and pressure adjustment gas supply block 11.

When the microdroplets 26b ejected from the liquid flow path plate 2 are charged while still containing a solvent using the configuration shown in Figures 6A and 6B, charging using corona ions as shown in Figures 5A and 5B is not necessary.

By controlling the switching between charging by corona ions as shown in Figures 5A and 5B and charging during droplet formation as shown in Figures 6A and 6B, two types of charging means can be selected and appropriately implemented in a single ion source.

As described above, the ion source of the present disclosure can reduce and appropriately control the amount of gas flow that transports the microdroplets and the heated gas flow that vaporizes the solvent. Therefore, an analytical device equipped with the ion source of the present disclosure can introduce many of the solute components contained in the sample liquid into the analysis block, enabling a significant improvement in the sensitivity of the analytical device.

The present disclosure provides a new ion source capable of introducing many of the generated solute component ions into a mass spectrometer, and also provides a mass spectrometer using the ion source with high analytical sensitivity.

Preferred embodiments of the present disclosure are summarized below.

In the ion source, the droplet generating section has an ultrasonic vibration imparting unit, and is configured so that droplets are generated by the ultrasonic vibration imparting unit.

The droplet generating section has a liquid flow path formed inside a pipe or a plate-like member, the pipe or the plate-like member has micropores connecting its outside with the liquid flow path, the ultrasonic vibration imparting unit is configured to impart ultrasonic vibrations to the liquid sample flowing in the liquid flow path, and the droplets are released from the micropores.

The droplet generation section is configured so that droplets flow into the center of the sample transport pipeline, and the transport gas flows into the sample transport pipeline so as to surround the flow of droplets.

A specific gas introduced from the heated and pressurized gas retention section into the sample transport pipeline is configured to flow in such a way as to surround the flow of droplets and transport gas.

The sample transport conduit has a larger cross-sectional area downstream of the position where the specified gas flows in than the upstream side. If the cross-section of the sample transport conduit is circular, the inner diameter of the cross-section of the sample transport conduit is larger downstream of the position where the specified gas flows in than the upstream side.

The charge imparting section is configured to be positioned between the analysis block and the heated and pressure-adjusted gas supply block.

The charge imparting section is positioned between the heating and pressure adjusting gas supply block and the droplet generating section.

The analysis apparatus comprises an ion source and an analysis block.

The ion source and the analysis block are connected by a capillary connection, and the ionized solute components are supplied to the analysis block through the capillary connection.

1: Liquid sample atomization block, 2: Liquid flow path plate, 2a, 2b, 2c: Thin plate, 2d: Micropore forming section, 2e: Carrier gas through hole, 2f: Supply port, 2g: Liquid flow path, 2h: Discharge port, 3: Ultrasonic vibration imparting unit, 3a: Tip vibration section, 3b: Piezoelectric element section, 3c: Screw housing, 4: Straightening 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 part of holder, 10b: Flange-shaped member, 11: Heating and pressure-regulating gas supply block, 12: Heating and pressure-regulating gas supply section main body, 12a: Outer tube, 12 b: inner tube, 13: sample transport tube, 14: heat insulation/insulation member, 15: mesh plate, 16: air heater, 17: pressure adjustment means, 18: outer shell chamber, 19: spring, 20: discharge wire, 21: charge imparting block, 22: connection block, 23: capillary connection portion, 24: housing, 25: analysis block, 26a: sample liquid, 26b: microdroplets, 26c: remaining sample liquid, 26d: solute particles, 27a, 27b: transport gas, 27c: heated gas, 27d: swirling air flow, 27e: transport gas, 27f: solute component, 27g: exhaust gas flow, 27h: air flow, 28: high voltage power supply, 29: variable power supply, 61: electric wire.

Claims (10)

An ion source for supplying ions of a solute component to an analysis block for analyzing a liquid sample containing the solute component,
A droplet generating unit for generating droplets of the liquid sample;
a heating and pressure adjusting gas supply block for heating the carrier gas flowing in from the droplet generating unit together with the droplets;
a charge imparting unit that imparts a charge to the solute component to ionize the solute component,
The heating and pressure adjusting gas supply block includes:
a sample transport pipeline disposed between the analysis block and the droplet generating unit;
a heating and pressure adjusting gas retention section configured to be in heat transferable contact with the sample transport pipe;
a gas heating unit that heats a predetermined gas to a predetermined temperature;
A pressure adjusting 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 droplets and the carrier gas are supplied to the sample transport pipeline from the droplet generating unit, and the predetermined gas heated from the heating and pressure adjusting gas retention unit is introduced from an upstream portion of the sample transport pipeline so as to swirl and envelop the droplets and the carrier gas;
an inner diameter of a flow path for the droplet, the carrier gas, and the predetermined gas from the upstream portion of the sample transport pipeline to the upstream portion of the capillary tube connection portion of the analysis block is substantially constant;
an inner diameter of the upstream portion of the sample transport pipeline is larger than an inner diameter of a portion of the droplet generating portion where the droplets and the transport gas are introduced;
The droplet generating unit has an ultrasonic vibration imparting unit,
The ion source according to claim 1 , wherein the droplets are generated by the ultrasonic vibration imparting unit. the droplet generating unit has a liquid flow path formed inside a pipe or a plate-like member,
the pipe or the plate-like member has micropores that communicate between an outside of the pipe or the plate-like member and the liquid flow path,
the ultrasonic vibration imparting unit is configured to impart ultrasonic vibration to the liquid sample flowing in the liquid flow channel;
The ion source of claim 2 , wherein the droplets are expelled from the micropore. The ion source of claim 1, wherein the droplet generating section is configured such that the droplets flow into the center of the sample transport pipe and the transport gas flows into the sample transport pipe so as to surround the flow of the droplets. The ion source according to claim 1, wherein the predetermined gas introduced from the heated and pressurized gas retention section into the sample transport pipeline is configured to flow in such a way as to surround the droplets and the flow of the transport gas. An ion source as described in claim 5, wherein the sample transport pipe has a larger flow passage cross-sectional area downstream of the position where the specified gas flows in than upstream of the position. The ion source of claim 1, wherein the charge imparting section is configured to be disposed between the analysis block and the heated and pressurized gas supply block. The ion source of claim 1, wherein the charge imparting section is disposed between the heating and pressure adjusting gas supply block and the droplet generating section. An ion source according to any one of claims 1 to 8;
An analysis device comprising the analysis block. the ion source and the analysis block are connected by the capillary connection;
10. The analysis device according to claim 9, wherein the ionized solute components are supplied to the analysis block through the capillary connection.

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