JPH11281621A - Mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable operation even with a high rate of flow by arranging the center axis of a spray capillary at an inclined angle with respect to the center axis of an ion introducing pore. SOLUTION: By inclining the center axis of a spray capillary 11 with respect to the center axis of an ion introducing pore 15a, only droplets of especially small particle diameter present in the periphery of a jet among droplets generated by electrostatic spraying are captured from the ion introducing pore 15a. In the case where the axis of the ion introducing pore 15a is in parallel with the axis of the spray capillary 11, a jet generated from the spray capillary 11 rebounds off a counter electrode 12 to destabilize the stream. In the case of not being in parallel, the jet flows along the counter electrode 12 to stabilize the stream and to improve the stability of ionic strength observed at a mass analyzing part 6. The angle between the center axes of the spray capillary 11 and the ion introducing pore 15a is regulated between at 10 degrees and 90 degrees according to the rate of flow of a sample solution introduced to an ion source as the optimal angle differs according to the flow of rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus in which a liquid chromatograph and a mass spectrometer which are particularly important for separating and analyzing non-volatile substances such as proteins are combined, that is, an interface in a liquid chromatograph / mass spectrometer.

[0002]

2. Description of the Related Art At present, in the field of analysis, development of liquid chromatograph / mass spectrometer is regarded as important. Liquid chromatographs are excellent at separating mixtures but cannot identify substances, whereas mass spectrometers are sensitive and have excellent ability to identify substances, but the analysis of mixtures is difficult. Therefore, a liquid chromatograph / mass spectrometer using a mass spectrometer as a detector of the liquid chromatograph is very effective for analyzing a mixture.

For reference, FIG. 14 is a block diagram showing the entire configuration of a conventional liquid chromatograph / mass spectrometer. The sample solution eluted from the liquid chromatograph is introduced into the ion source through the pipe 2. The ion source is controlled by a power source 4 for the ion source via a signal line 5a. Ions related to the sample molecules generated by the ion source are introduced into the mass spectrometer and subjected to mass analysis. The mass spectrometer is evacuated to a vacuum by an exhaust system. The mass-analyzed ions are detected by the ion detector 8, and the detection signal is sent to the data processing device via the signal line 5b.

Although the principle of a liquid chromatograph / mass spectrometer is simple as described above, a liquid chromatograph handles a sample in a solution, whereas a mass spectrometer handles ions in a high vacuum. The incompatibility makes the development of this method very difficult. Several methods have been developed to solve this problem. Among them, a promising one is a spray ionization method in which an eluate from a liquid chromatograph is sprayed, and sample molecules contained in the generated droplets are ionized and taken into a mass spectrometer.

As an example of the spray ionization method, the electrostatic spray method described in Analytical Chemistry 59 (1987) 2642, Vol. 59, p. 2642, 1987 will be described. FIG. 15 is a sectional view showing the structure of a liquid chromatograph / mass spectrometer provided with an electrostatic spray ion source. The sample solution eluted from the liquid chromatograph 1 is introduced into the spray capillary 11 via the pipe 2 and the connector 10. The spray capillary 11 and the counter electrode 1
When a voltage of several kV is applied between the sample solution 2 and the sample solution, a so-called electrostatic spraying phenomenon occurs in which the sample solution is in a cone state at the tip of the spray capillary 11 and microdroplets are generated from the tip. In the electrostatic spraying method, a spray gas outlet 13 is provided, and
A gas such as nitrogen is flowed from around to promote the vaporization of the microdroplets. Further, a gas such as nitrogen is blown from the vaporizing gas jet port 14 provided on the counter electrode 12 side toward the generated microdroplets, thereby promoting the vaporization of the microdroplets. The ions generated through the above process are directly introduced into the vacuum from the ion introduction pore 15 and subjected to mass analysis in the mass analyzer 6 under a high vacuum.

In US Pat. No. 4,935,624, the position of the spray tubing is independent of the process when heating and spraying the sample solution, and the tubing is moved 9 degrees from the orifice plate.
There is a statement that it may be 0 °. However, there is no description suggesting the remarkable effect obtained by inclining the center line of the spray capillary with respect to the center line of the pore when the capillary is not heated. In addition, Japanese Patent Application Laid-Open No. Hei 3-23505
5 shows that spraying is performed by dividing the spray nozzle into two. However, the appropriate direction of the liquid is perpendicular to the central axis of the pore, and the ion discharge is performed using an electrode, which is completely different from the present invention.

[0007]

The conventional method has the following problems. The flow rate of the sample solution that can be introduced into the electrostatic spray ion source is limited to about 10 microliters per minute. If a flow rate exceeding this flow rate is introduced into the ion source, ions cannot be observed stably. This is because as the flow rate of the sample solution increases, the diameter of the droplet generated by electrostatic spraying increases, and it becomes difficult to vaporize the droplet and extract ions contained in the droplet. On the other hand, the flow rate of a commonly used liquid chromatograph is from 200 microliters per minute to 1000 microliters per minute. This incompatibility between the flow rates of the liquid chromatograph and the electrostatic spray ion source made it impossible to directly couple the liquid chromatograph and the electrostatic spray ion source. Conventionally, a method has been adopted in which a sample solution eluted from a liquid chromatograph is separated using a splitter, and only a small part of the sample solution is introduced into an electrostatic spray ion source. FIG. 16 shows a configuration diagram in which a liquid chromatograph and an electrostatic spray ion source are connected using a splitter. The sample solution eluted from the liquid chromatograph
a into the splitter 16. The sample solution is divided by the splitter 16 and only a part is
Although the solution is introduced into the ion source 3 by b, most of the solution is discharged from the pipe 2c.

However, in the configuration shown in FIG. 16, a splitter having a high separation ratio, such as 1/100, must be used. A splitter with a high splitting ratio is difficult to operate stably, and the observed ion intensity is not stable. Furthermore, if the flow rate in the pipe 2b for introducing the sample solution into the ion source 3 is small, the pipe 2
The problem of diffusion in b cannot be ignored. Therefore, there has been a demand for the development of an electrostatic spray ion source that can be operated stably even at a high flow rate so that the liquid chromatograph can be directly connected to the electrostatic spray ion source without using a splitter.

An object of the present invention is to provide an electrostatic spray ion source capable of introducing a sample solution at a high flow rate, thereby directly connecting a liquid chromatograph and the electrostatic spray ion source to stably. To be usable.

[0010]

In order to stably operate an electrostatic spray ion source even at a high flow rate, a sample solution sent from a liquid chromatograph is introduced into one end of a spray capillary. An electrostatic spray ion source for generating ions by electrostatically spraying from the other end of the spray capillary, an ion introducing pore for introducing the generated ions into a vacuum section, and a mass for mass analyzing the introduced ions. In a mass spectrometer provided with an analysis unit, the central axis of the spray capillary is inclined with respect to the central axis of the ion introduction pore, and is arranged to have a predetermined angle. More specifically, toward the jet generated by electrostatically spraying the sample solution from the spraying capillary, the solvent molecules are removed from the direction opposite to the direction in which the central axis of the spraying capillary is inclined with respect to the central axis of the ion introduction pore. A gas (cross flow gas) is blown to lower the partial pressure to accelerate the vaporization of the droplets and to push the atomized droplets back toward the ion introduction pores. In addition, the droplet generated by the electrostatic spray is moved from 50 degrees Celsius to 2 degrees.
It is introduced into the vacuum part through the ion introduction pore heated to 50 degrees. The electrode having the iontophoretic pores is heated independently of the other parts of the electrospray ion source. Furthermore, a mechanism for measuring the flow rate of the sample solution is provided, and according to the measured flow rate, the angle of the spray capillary, the position of the spray capillary, the flow rate of the gas for spraying, the flow rate of the cross flow gas, and the temperature of the ion introduction pore are determined. A mechanism for controlling at least one of them is provided. Further, a mechanism for measuring the electric conductivity of the sample solution is provided, and a mechanism for controlling a voltage applied to the spray capillary according to the electric conductivity of the sample solution is provided.

Since the center axis of the spray capillary is inclined with respect to the center axis of the ion introduction pore, only the small droplets having a particularly small particle size among the fine droplets generated by electrostatic spraying are selectively used. Into the vacuum section and mass spectrometric analysis. Since it passes through the heated ion introduction pores, the vaporization of the droplets in the ion introduction pores is promoted. A mechanism for measuring the flow rate of the sample solution is provided, and according to the flow rate, the angle of the spray capillary, the position of the spray capillary, the flow rate of the gas for spraying, the flow rate of the cross flow gas, and the temperature of the ion introduction pore are controlled. Since a mechanism to measure the electric conductivity of the solution is provided and the voltage applied to the spray capillary is controlled according to the electric conductivity,
By directly connecting the liquid chromatograph and the electrostatic spray ion source,
Even if a sample solution with a high flow rate of several hundred microliters per minute is introduced, a liquid chromatograph / mass spectrometer capable of stably observing ions becomes possible. Further, a sample solution sent from the liquid chromatograph is introduced into one end of a spray capillary, and an electrostatic spray ion source for electrostatically spraying from the other end of the spray capillary to generate ions. In a mass spectrometer provided with an ion-introducing pore for introducing into a vacuum section and a mass-analyzing section for mass-analyzing the introduced ions, a tip of the spray capillary is a predetermined distance from the ion-introducing pore. Wherein the tip of the spray capillary is within a predetermined distance from the center axis of the ion introduction pore, and the ion introduction pore passes through the center axis of the spray capillary and the tip of the spray capillary. And a straight line parallel to the central axis of the line makes a predetermined angle.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to FIGS. FIG. 1 shows an electrostatic spray ion source according to a first embodiment of the present invention. The sample solution eluted from the liquid chromatograph is introduced into the spray capillary 11 via the pipe 2 and the connector 10. The angle of the central axis of the spray capillary 11 is set to
5a can be inclined with respect to the central axis. The angle described here means an angle formed by a central axis of the spray capillary 11 and a straight line passing through the tip of the spray capillary 11 and parallel to the center axis of the ion introduction pore 15a. In addition, the position of the tip of the spray capillary 11 can be moved with respect to the ion introduction pore 15a. Spray capillary tip and ion introduction pore 15
If the distance between a and a is too short, discharge is likely to occur,
If the distance is too far, the ions cannot be observed strongly.
Preferably between 0 mm. The deviation of the tip of the thin tube 11 from the central axis of the ion introduction pore 15a is preferably between 0 mm and 20 mm. The sample solution is electrostatically sprayed by applying a high voltage between the spraying tube 11 and the counter electrode 12, and simultaneously spraying the spraying gas from the spraying gas outlet 13 facilitates spraying. The atomizing gas may be heated.

The protective electrode 17 is provided to shield the influence of an external electric field. When a voltage is applied between the protective electrode 17 and the counter electrode 12 using a power supply 18a, ions generated by electrostatic spraying are applied. Can be drifted in the direction of the ion introduction pore 15a. Further, the electrode 17 may be replaced with an insulating material, and an electric field may be concentrated between the tip of the spray capillary 11 and the counter electrode 12. The obtained ions are supplied to the ion introduction pore 15a, the differential exhaust portion 19, and the ion introduction pore 15
b, it is taken into the mass spectrometry unit 6 and subjected to mass analysis. A drift voltage of several tens of volts is applied between the ion introduction pore 15a and the ion introduction pore 15b by the power supply 18b. This drift voltage has the effect of improving the transmittance of ions and causing the ions with solvent molecules attached to collide with the residual gas in the differential pumping section 19 to remove the solvent molecules from the ions. The counter electrode 12 having the ion introduction pore is provided with a heater 20 on either the atmospheric pressure side or the intermediate pressure side.
When the gas adiabatically expands through 5a, the temperature is lowered to prevent the solvent molecules from aggregating again, and at the same time, dirt inside and around the ion introduction pore 15a is reduced.

As shown in FIG. 1, by tilting the angle between the spray capillary 11 and the central axis of the ion introduction pore 15a, the droplets generated by electrostatic spraying are present at the outer peripheral portion of the jet. Only droplets having a particularly small particle size can be taken in from the ion introduction pore 15a. In addition, when the axis of the ion introduction pore 15a and the axis of the spray capillary 11 are parallel, the jet generated from the spray capillary 11 rebounds at the counter electrode 12, and the flow becomes unstable. When the axis of the introduction pore 15a is not parallel to the axis of the spray capillary 11, the jet flows along the counter electrode 12, so that the flow is stable and the stability of the ion intensity observed by the mass spectrometer 6 is improved. did. Since the optimum angle between the spray capillary 11 and the central axis of the ion introduction pore 15a varies depending on the flow rate of the sample solution to be introduced into the ion source, it is adjusted between 10 ° and 90 ° according to the flow rate. .

The cross flow gas 21 is applied to the jet containing the fine droplets obtained by the electrostatic spraying from a direction opposite to the direction in which the spraying capillary 11 is inclined, so that a sufficient ion intensity can be obtained even at a high flow rate. Obtainable. This cross flow gas 21 may be heated. The cross flow gas 21 includes
The effect of accelerating the vaporization of the droplets by lowering the partial pressure of the solvent molecules and the atomization of the droplets into the ion-introduced pores 1
There is an effect of pushing back in the direction of 5a. The type of the cross flow gas is preferably a rare gas, a nitrogen gas, an oxygen gas, a carbon dioxide gas, a SF ₆ gas, or a mixed gas of these gases.

FIG. 2 shows a second embodiment in which a vaporizing gas outlet 14 is provided on the counter electrode 12 side, and a vaporizing gas is sprayed on the droplets together with the cross flow gas 21 to further promote the vaporization of the droplets. In the case of the structure shown in FIG. 2, a heater 20c is attached to the counter electrode 12, and particles having a large particle diameter near the center of the jet flow are destroyed by being applied to the counter electrode 12, and the heater 20c is present at the outer peripheral portion of the jet flow. By taking only the droplets having a small particle diameter into the vacuum from the ion introduction pore 15a, the angle between the axis of the spray capillary 11 and the central axis of the ion introduction pore 15a is not necessarily 10 ° to 90 °.
Instead, high flow rates can be introduced into the ion source at angles less than 10 °.

When a sample solution with a high flow rate is sprayed, the jet stream hits the ion introduction pores 15a to locally cool the periphery of the ion introduction pores 15a, so that the droplets are not sufficiently vaporized and mass analysis is possible. In some cases, the amount of ions may decrease. In order to avoid this, as in the third embodiment shown in FIG. 3, the electrode 22 with the ion-introducing pores and the ion-introducing pore supporting electrode 23 are thermally separated using the heat insulating portion 24.
The electrode 22 with the ion introducing pores is independently heated by the heater 20a. The heater 20a is preferably made of ceramic so as not to disturb the electric field. If the temperature of the ion introduction pore is too low, it is difficult to obtain ions, and if the temperature is too high, a sample such as a protein which is easily thermally dissociated may be decomposed. In such a case, a thermometer such as a thermocouple 25 is connected to the electrode 22 having the ion introducing pores, and the calorific value of the heater 20a is controlled so as to keep the temperature at an appropriate temperature, thereby obtaining ions stably. Can be. It is desirable that the temperature of the electrode 22 with the ion introduction pores is about 50 to 250 degrees. Among the droplets generated by the electrostatic spraying, the droplet having a large particle size existing in the central portion of the jet flows is brought into contact with the ion introduction pore supporting electrode 23 heated by the heater 22b and disappears. The potential of the electrode with ion introduction pores 22 may be the same as the potential of the ion introduction pore support electrode 23, or may be independently changed using the power supply 18c. In addition, the ion introduction pore supporting electrode 23 is a part which supports the electrode 22 with ion introduction pores.

FIG. 4 shows a fourth embodiment in which a droplet is taken through a long heated ion-introducing pore in order to more effectively vaporize the droplet. The microdroplets generated by the electrostatic spraying are introduced into the differential exhaust unit 19 through the long ion introduction holes 15c heated by the heater 20a. When the droplet passes through the long ion introduction pore 15c, thermal energy is obtained, and the vaporization of the droplet is promoted. As long as the length of the ion introduction pore 15c is limited to vaporization of the droplet, the longer the length, the more effective. However, as the length becomes longer, it becomes more difficult to clean the inside of the ion introduction pore. Therefore, the length of the ion introduction pore 15c is 10 to 1000 times the inner diameter of the ion introduction pore 15c.
Double is preferred. In the structure shown in FIG. 1, FIG. 2, FIG. 3, and FIG. 4, when it is difficult to move the position of the spray capillary tip 11 with respect to the ion introduction pore 15, as shown in FIG. Position the capillary tip 11 at the ion-introducing pore 1
5 by changing the angle of the spray capillary 11 relative to the center axis of the ion introduction pore 15 around this fixed point, the flow rate of the sample solution that can be introduced into the spray capillary 11 is set to It can be set widely from microliters to hundreds of microliters per minute.

FIG. 6 is an enlarged view of the vicinity of the ion introduction pore of the electrostatic spray ion source shown in FIG. Vacuum sealing is performed by an O-ring 26. Since the droplets having a large particle diameter disappear by touching the ion introduction pore supporting electrode 23 having a large heat capacity, the heat transfer between the ion introduction pore supporting electrode 22 and the ion introduction pore supporting electrode 23 is deteriorated. If this is not the case, the temperature of the ion introduction pore 15c will not suddenly change even if the heat insulating portion 24 shown in FIG. 6 is not particularly provided. As shown in FIG. 7, the electrode 22 with the ion introducing pore and the electrode 23 for supporting the ion introducing pore are provided.
Are independent structures, and the gas layer 27 generated in the gap between the electrodes
May be used for heat insulation. In the case of the structure shown in FIG. 7, the electrode 22 with the ion-introducing pores is heated by the heater 20b attached to the electrode 23 for supporting the ion-introducing pores. .

The electrodes 22 having long ion-introducing pores shown in FIGS. 4, 6 and 7 are manufactured by making holes in a metal block. As shown in FIG. 8, the ion introducing thin tube 32 may be embedded in the metal block 28, and the metal block 28 and the ion introducing thin tube 32 may be brought into thermal contact by means such as brazing. As shown in FIG. 9, the heater 20a is attached to the ion-introducing pore electrode 22 so that the heater 20a attached to the ion-introducing pore electrode 22 does not disturb the gas flow.
a may be embedded. Further, as shown in FIG. 10, the electrode 22 with the ion introducing pores may have a sharp tip.

FIG. 11 shows the relationship between the flow rate of the sample solution introduced into the electrostatic spray ion source and the observed ion intensity, measured using the electrostatic spray ion source shown in FIG. As a sample solution, a cytochrome C solution as a protein (concentration: 10 to ⁶ mol / l (liter), water / methanol / 5% acetic acid) was used to observe 15-valent ions with protons added to the sample molecules. The measurement was performed with the angles formed by the spray tubule and the central axis of the ion introduction pore being 0, 30, and 45 degrees. The ion intensity represents a relative intensity based on the intensity observed when 50 microliters per minute is introduced into the ion source. The flow rate of the solution introduced into the ion source is 50 per minute.
In the case of microliter, even if the angle between the spray capillary and the central axis of the ion introduction pore was changed, the observed ion intensity hardly changed within the range of the experimental error. However, when the angle was 0 degree, the observed ionic strength decreased as the flow rate of the solution was increased. By disposing the spray capillary 11 in a direction inclined by 45 degrees from the central axis of the ion introduction pore 15c and taking in the droplet through the heated long ion introduction pore 15c, the flow rate of the sample solution is reduced to 5 / min.
Changing from 0 microliters to 200 microliters per minute hardly changes the observed ion intensity. At this time, the diameter of the ion introduction pore was 0.25 mm, the length of the ion introduction pore was 30 mm, the temperature was about 100 degrees, and the flow rate of the spray gas was 1.5 liters per minute.

When the flow rate of the sample solution is 50 microliters / minute, the flow rate of the cross flow gas is 0 / minute.
Ions were strongly observed in the range of 1 to 4 liters per minute for ２2 liters, 100 to 150 microliters per minute, and 3 to 5 liters per minute for 200 microliters per minute. In this way, the sample solution is sprayed from the direction inclined from the central axis of the ion introduction pore, and the droplet is introduced into the vacuum through the heated spray capillary, and further, the cross flow gas is used to introduce the droplet into the ion source. Even when the flow rate of the sample solution was increased, strong ions were observed.

As a result of the present invention, strong ions were observed even when a flow rate of several hundred microliters per minute was introduced into the electrostatic spray ion source. As a result, direct connection between the liquid chromatograph and the electrostatic spray ion source became possible.

Further, as is apparent from FIG. 11, the angle between the spraying capillary tube having the highest ionic strength and the central axis of the ion introduction pore differs depending on the flow rate of the sample solution introduced into the ion source. Therefore, as shown in FIG. 12, a flow meter is arranged in the middle of the pipe 2 connecting the liquid chromatograph and the ion source, and a signal from the flow meter is sent to the ion source control unit via the signal line 5c, and the ion source is controlled. By the control unit,
(1) the angle of the central axis of the spray capillary relative to the central axis of the ion introduction pore; (2) the distance from the ion introduction pore at the tip of the spray capillary; (3) the flow rate of the gas for spraying; By automatically controlling any one of the conditions (5), the temperature of the ion introduction pore, and a plurality of conditions, the highest ion intensity can always be obtained.

The optimum value of the voltage applied to the spray capillary for electrostatically spraying the sample solution differs depending on the composition of the sample solution to be introduced into the electrostatic spray ion source, especially the electric conductivity of the solution. As shown in FIG. 13, a device 31 for measuring the electric conductivity of the solvent is provided in a part of the flow path for introducing the solvent into the ion source 3, and the signal is sent to the ion source power supply via the signal line 5 d. By automatically adjusting the voltage applied to the spray capillary, ions can be stably obtained.

[0026]

According to the present invention, only droplets having a particularly small particle size among droplets generated by electrostatic spraying can be introduced into the vacuum section. Even if a liquid solution is connected directly to a liquid chromatograph and an electrostatic spray ion source, and a sample solution with a flow rate several tens of times that of the conventional solution is introduced, stable liquid ion chromatography
A mass spectrometer becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electrostatic spray ion source according to a first embodiment of the present invention, in which a central axis of a spray capillary and a central axis of an ion introduction hole are inclined.

FIG. 2 is a sectional view of an electrostatic atomization ion source according to a second embodiment of the present invention, which sprays a vaporizing gas together with a cross-flow gas onto droplets.

FIG. 3 is a cross-sectional view of an electrostatic spray ion source according to a third embodiment of the present invention, in which a heater is used to independently heat an electrode with ion-introducing pores.

FIG. 4 is a cross-sectional view of a mass spectrometer according to a fourth embodiment of the present invention, which captures a droplet through a heated long iontophoretic pore.

FIG. 5 shows a fifth embodiment of the present invention, in which the tip of a spray capillary is arranged on the central axis of an ion introduction pore, and the center axis of the spray capillary and the ion introduction pore are centered on the tip of the spray capillary. FIG. 2 is a cross-sectional view of an electrostatic spray ion source that makes an angle formed with a central axis of the electrostatic spraying ion source variable.

FIG. 6 is an enlarged sectional view of an ion-introduced portion of a fourth embodiment.

FIG. 7 is an enlarged cross-sectional view of an ion-introduced portion in which an electrode with an ion-introducing pore and an electrode for supporting an ion-introducing pore are formed as independent structures.

FIG. 8 is a cross-sectional view of an electrode having long ion introduction pores manufactured by embedding a spray capillary in a metal block.

FIG. 9 is a cross-sectional view of an electrode with an iontophoretic pore in which a heater is embedded.

FIG. 10 is a cross-sectional view of an electrode with a sharp ion injection pore.

FIG. 11 is a view showing the relationship between the flow rate of a sample solution introduced into an ion source and the observed ion intensity, measured using the electrostatic spray ion source of the fourth embodiment.

FIG. 12 is a configuration diagram for measuring a flow rate of a sample solution and controlling an ion source.

FIG. 13 is a configuration diagram for measuring the electric conductivity of a sample solution and controlling an ion source.

FIG. 14 is a block diagram showing a configuration of a conventional liquid chromatograph / mass spectrometer.

FIG. 15 is a sectional view showing the structure of a conventional liquid chromatograph / mass spectrometer equipped with an electrostatic spray ion source.

FIG. 16 is a diagram showing a configuration in which a liquid chromatograph and an electrostatic spray ion source are connected using a conventional splitter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid chromatograph, 2, 2a, 2b, 2c ... Piping, 3 ... Ion source, 4 ... Ion source power supply, 5a, 5b,
5c, 5d: signal line, 6: mass spectrometer, 7: exhaust system, 8: ion detector, 9: data processing device, 10: connector, 11: spray tube, 12: counter electrode, 13: gas jet for spray Outlet, 14 ... Gas-emission port for vaporization, 15, 15
a, 15b, 15c: ion introduction pore, 16: splitter, 17: protective electrode, 18a, 18b, 18c: power supply, 19: differential exhaust unit, 20, 20a, 20b, 20c
... heater, 21 ... cross-flow gas, 22 ... electrode with ion introduction pores, 23 ... ion introduction pore support electrode, 24 ...
Insulation part, 25 ... Thermocouple, 26 ... O-ring, 27 ... Gas layer,
28: metal block, 29: flow meter, 30: ion source control unit, 31: electric conductivity measuring device, 32: ion introduction capillary.

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[Procedure amendment]

[Submission date] February 24, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (9)

[Claims] 1. An electrostatic spray ion source for introducing a sample solution into one end of a spray capillary, and electrostatically spraying the sample solution from the other end of the spray capillary to generate ions.
An ion introduction pore formed in the counter electrode for introducing the generated ions into the vacuum section, and a mass analysis section for performing mass analysis on the ions introduced into the vacuum section, the center of the spray capillary. The axis is inclined by a predetermined angle with respect to the center axis of the ion introduction pore, and a means for flowing a predetermined cross-flow gas to the pore side of the other end of the spray capillary is provided. Mass spectrometer. 2. A portion extending from the other end of the central axis of the spray capillary to the introduction pore side is in contact with a portion of the counter electrode separated by a predetermined distance from the ion introduction pore. The mass spectrometer according to claim 1, wherein: 3. The mass spectrometer according to claim 1, further comprising means for ejecting an atomizing gas near the other end of the atomizing capillary. 4. The method according to claim 1, wherein the cross-flow gas flows in a direction in which the spray capillary is inclined from a direction opposite to a direction in which the spray capillary is inclined. Mass spectrometer as described. 5. A protection electrode is disposed on the spray capillary side of the counter electrode so as to face the counter electrode, and the cross-flow gas flows through a gap between the counter electrode and the protection electrode. The mass spectrometer according to any one of claims 1 to 4, wherein: 6. The mass spectrometer according to claim 1, further comprising means for heating said cross flow gas. 7. The mass spectrometer according to claim 1, further comprising means for heating the counter electrode. 8. The cross flow gas according to claim 1, wherein the cross flow gas is a single gas or a mixed gas of a rare gas, a nitrogen gas, an oxygen gas, an oxygen dioxide gas and an SF ₆ gas. Mass spectrometer. 9. The mass according to claim 1, wherein an angle between a central axis of the spray capillary and a central axis of the ion introduction pore is 10 ° to 90 °. Analyzer.