JPH11317192A - Ion source and mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent suction of a solution in a passage and the back flow of bubbles by spraying the flowing-out solution by a gas, to the tip part of a passage extending from a first vessel through a second vessel, and bringing the solution in the passage with the solution in the second vessel through a pore formed in the part piercing the second vessel of the passage. SOLUTION: Electrophoresis is made in a passage 3 between a first vessel 1 and a second vessel 4, and a solution atomizing gas carried into an ion source body 7 through a gas passage 9 and run out from an orifice 8. When the gas speed is high, the pressure of the terminal part of the passage 3 is lower than the atmospheric pressure near the level of the second vessel 4, and a solution 21 within the second vessel 4 is sucked to the passage through a pore 5 by this pressure difference, mixed with the electrophoresed solution carried from the first vessel 1, and sprayed by the gas running out from the orifice 8. The suction of the solution in an electrophoresis capillary by the atomizing gas can be suppressed to prevent reduction in resolution of electrophoresis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ion source and a mass spectrometer, and more particularly to an ion source particularly suitable for capillary electrophoresis and a mass spectrometer using this ion source.

[0002]

2. Description of the Related Art As is well known, capillary electrophoresis (CE) and liquid chromatography (LC) can separate a sample present in a solution, but it is difficult to identify the type of the separated sample. is there. On the other hand, a mass spectrometer (M
S) can identify the sample with high sensitivity, but cannot separate the sample in the solution. Therefore, when separating and analyzing a plurality of substances dissolved in a solvent such as water, a capillary electrophoresis / mass spectrometer (CE / MS) in which capillary electrophoresis is coupled to a mass spectrometer, or a liquid chromatograph Coupled to a liquid chromatograph / mass spectrometer (L
C / MS) is commonly used. For this CE / MS, for example, Analytical Chemistry (Analyt
ical Chemistry), 60, 436-441, 1988.

In order to analyze a sample separated by capillary electrophoresis or liquid chromatography with a mass spectrometer, it is necessary to convert sample molecules in a solution into gaseous ions. As a conventional technique for obtaining such ions, for example, an ion spray method is an analytical technique.
Chemistry (Analytical Chemistry) Vol. 59 (1987)
2642-2646, electrospray method is published by Journal of Phycal Chemistr
y) Volume 88 (1984) pp. 4451-4459, Atmospheric pressure chemical ionization method is used for Analytical Chemi
stry) 54 (1982) pp. 143-146.

[0004] Recently, as another ionization method different from the above-mentioned conventional methods, a sonic spray method capable of efficiently generating ions only by spraying a sample solution with a sonic gas,
For example, Analytical Chemis
try) 66, 4457-4559 (1994), Analytical Chemistry 67, 2878-2
882 (1995), and are proposed in JP-A-7-306193 and JP-A-8-62200. In this method, it is considered that fine charged droplets are generated by the flow of a sonic gas, and the solvent molecules are peeled off to generate ions.

Further, a method of continuously introducing a small amount of sample by gravity without using a liquid chromatograph or a liquid sending pump when introducing a sample into a mass spectrometer is described in JP-A-8-5624. I have. Further, a capillary electrophoresis / mass spectrometer that uses a sonic spray method as an ion source and does not require a pump for feeding a spray auxiliary solution is described in JP-A-9-243600.

[0006]

According to the sonic spray method, ions can be generated even when the salt concentration of the solution is high, so that the capillary electrophoresis / mass spectrometer (CE / M) can be used.
It is more suitable as an ion source of S) than other methods. However, the pressure near the tip of the capillary is depressurized by the high-speed gas flow flowing near the tip of the capillary, and the solution in the flow channel may be sucked by the pressure difference from the other end of the capillary. In an apparatus having a high solution flow rate such as a liquid chromatograph / mass spectrometer (LC / MS), the amount of the solution sucked by such a gas flow can be ignored, but when the solution flow rate is low such as CE / MS. Has a large effect, and there is a problem that the separation ability of CE is reduced.

Further, in the sonic spray method, since the potential of the sample solution must be grounded, an electrode must be provided in a flow path connecting the electrophoresis section and the ion source, and grounded. However, if an electrode is provided in a closed flow path, there is a problem that bubbles generated at the electrode flow back to the electrophoresis capillary and hinder migration.

In CE, a separation solution containing a nonvolatile salt is often used. However, since the solution containing the nonvolatile salt clogs the pores of the mass spectrometer, the CE /
Not available for MS.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, to prevent suction of a solution in an electrophoresis flow channel, and to prevent ions from flowing back into the electrophoresis flow channel. Is to provide a source.

Another object of the present invention is to provide an ion source which does not cause the pores of a mass spectrometer to be clogged even when a separating solution containing a high concentration of a nonvolatile salt is used.

[0011]

In order to solve the above-mentioned problems, an ion source according to the present invention comprises: a first container for containing a solution;
A second container for storing a desired solution, a channel (capillary) connected to the first container and extending through the second container, and supplying a gas near the tip of the channel. A means for spraying the solution flowing out of the flow path, a pore (pinhole) is formed in a portion of the flow path penetrating the second container, and the solution in the flow path is It is characterized in that it is in contact with the solution in the second container via the pore.

That is, a second container for storing a desired solution is provided between the first container for storing the solution and a portion for spraying the solution with gas, and a flow path connected to the first container includes: The gas extends through the second container to a portion where the solution is sprayed by the gas. Therefore, the flow path on the first container side (electrophoresis capillary) and the flow path on the spray side (ion source capillary) have a continuous structure in the second container.

In addition, a fine hole (pinhole) is formed in a portion of the flow passage penetrating the second container.
The solution in the second container and the solution in the flow path are in contact with each other through the pores.

Therefore, when a gas is flowed near the end of the flow path and the liquid is sprayed, the negative pressure generated by the gas supplied to the end of the flow path causes the gas to flow into the flow path on the ion source side. The solution in the second container is sucked, and the solution in the electrophoresis capillary is suppressed from being sucked. In addition, the solution introduced into the ion source is grounded via the solution in the second container, thereby preventing bubbles from entering the electrophoresis capillary. In addition, the contact between the solution in the flow path and the solution in the second container is performed through the pores formed in the flow path. Very few. Further, when the solution in the first container contains a non-volatile salt, the use of a low salt solution as the solution in the second container reduces the salt concentration. There is no risk of clogging.

It is preferable that the area inside the second container parallel to the liquid surface is larger than the area of the pores. When the area inside the second container parallel to the liquid surface is smaller than the area of the pores, the resistance in the second container becomes large, and the liquid hardly flows in the second container, and the gas is generated by the gas. When the liquid in the capillary is sucked by the negative pressure generated during spraying,
The liquid does not enter the capillary from the second container, and the liquid on the first container side is sucked.

By providing a means for applying a voltage to each of the solutions in the first and second containers, a desired voltage can be applied to the solutions in the first and second containers.

By grounding the solution in the second container, it is not necessary to provide an electrode in a closed flow path, and the liquid flows back to the electrophoresis capillary due to the generation of bubbles, thereby preventing electrophoresis. That is prevented. The first
And applying a desired voltage between the liquids in the second container,
Electrophoresis of the solution in the flow path between the first and second containers can be performed without any trouble.

The spraying of the solution is performed by flowing a gas near the end of the flow path to lower the air pressure near the end.

A first container for storing the mobile phase solution, an electrophoresis flow path (electrophoresis capillary) connected to the first container, a second container for storing a desired solution therein; A tube that penetrates through the second container and is immersed in the desired solution, a spray channel (ion source capillary) for spraying the introduced sample solution into the atmosphere,
An orifice into which the vicinity of the tip of the spray channel is inserted, and gas supply means for spraying the sample solution into the atmosphere from the tip, forming pores in the tube in the second container. Then, the electrophoresis flow channel and the spray flow channel may be inserted into both ends of the tube, and may be fixed to face each other with a predetermined interval.

Also in this case, the first and second electrodes are disposed in the first and second containers, respectively, and a means for applying a predetermined voltage between the first and second electrodes is provided. Good results are obtained.

Since the ion source according to any one of claims 1 to 7 is extremely excellent, both the mass spectrometer and the capillary electrophoresis / mass spectrometer having this ion source have extremely excellent characteristics. doing.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, one channel (capillary) 3 is made to penetrate through a second container 4, and one capillary can be used as an electrophoresis capillary and a spray capillary. In this case, one capillary 3 penetrates the second container 4 and the pores (pinhoes) 5 are
Is formed in the capillary 3 in the container 4 of FIG. Alternatively, one pipe 11 may be penetrated through the second container 4, and two flow paths 10 and 13 may be inserted from both ends of the pipe, and may be arranged to face each other with a predetermined interval. In this case, pores (pinholes) 12 are formed in the tube 11. In any case, the area of the pores 5 and 12 is preferably smaller than the area of the surface of the solution in the second container 4 which is in contact with the atmosphere.

As the mobile phase solution 20 in the first container 1, a solution containing a high concentration of a non-volatile salt can be used. In this case, a solution with a low salt concentration is used as the solution 21 in the second container 4, and the mobile phase solution 21 in the container 1 is diluted near the pinhole 5 to have a low salt concentration and then sent to the ion source. You can do so. In this way, even if the salt concentration of the mobile phase solution 21 in the container 1 is high,
There is no risk of clogging the pores of the mass spectrometer.

The solution 21 to be put in the second container 4 may be the same solution as the solution 21 in the first container 1 or a different kind of solution.

A voltage may be applied to the ion source body 7 to assist in charging the sample. The polarity of the voltage may be positive or negative.
However, when measuring positive ions, -1 kV to -2 k
A voltage of about V is preferably applied. The ion source body 7 may be grounded, or the electrode 2 may be grounded and a voltage may be applied to the electrode 6.

The area of the pores (pinholes) formed in the flow path or the pipe is preferably equal to or less than the cross-sectional area of the flow path or the pipe.

[0027]

<Embodiment 1> FIG. 1 is a diagram showing the structure of a first embodiment of the present invention. An electrode 2 is in contact with the mobile phase solution 20 placed in the container 1, and a voltage of several kV to several tens kV is applied to the electrode 2. The flow path (capillary) 3 through which the mobile phase solution 20 flows is a second container 4
To the ion source 7, the tip of which is inserted into the orifice 8.

As shown in FIG. 1, a pinhole 5 is formed in a portion of the flow path 3 passing through the second container 4, and the mobile phase solution in the flow path 3 passes through the pinhole 5. The solution 21 is in contact with the solution 21 in the second container 4 via the second container 4. The solution 21 in the second container 4 is grounded via the electrode 6.

In the flow path 3 between the container 1 and the second container 4,
Electrophoresis is taking place. On the other hand, the gas for solution spraying is
The gas enters the ion source body 7 from a gas supply source (not shown) provided outside through a gas flow path 9, and flows out of the orifice 8 into the atmosphere through the outer peripheral portion of the flow path 3. When the velocity of the gas is high, the pressure near the end of the flow path 3 drops, and a pressure difference is generated between the pressure near the liquid surface of the second container 4 which is the atmospheric pressure. The solution 21 is drawn into the flow channel 3 through the pinhole 5, further sent to the end of the flow channel 3 through the flow channel 3, and sprayed by the gas.

The solution electrophoresed in the channel 3 between the container 1 and the second container 4 is mixed with the solution in the second container 4 near the pinhole 5 and further flows through the channel 3. It is sent to the end of the road 3 and sprayed with gas. The sample dissolved in the electrophoresed solution is ionized by gas spray.

FIG. 5 shows the gas flow rate dependence of the ion intensity obtained by using the ion source of this embodiment. In the sonic spray method in which a solution is sprayed and ionized by a gas, the ionization efficiency is highest and the ionic strength is maximized when the velocity of the gas when flowing out of the orifice into the atmosphere is almost sonic. The flow rate of the gas introduced from the gas flow path to the ion source, which is required when the gas velocity is set to the sonic velocity, depends on the diameter of the orifice and the diameter of the capillary.

FIG. 5 shows the ion source of the present embodiment in which the diameter of the orifice is 280 μm and the diameter of the capillary is 50 μm.
m and the gas flow rate dependence of the ion intensity when the outer diameter is 150 μm. As is clear from FIG. 5, the ionic strength was maximum when the gas flow rate was about 2 liters / minute, and it was confirmed that the gas velocity could be made sonic if the gas flow rate was about 2 liters / minute. .

When the gas flow rate is 2 liters / minute,
FIG. 6 shows the dependence of the flow rate of the solution sucked into the capillary of the ion source on the inner diameter of the capillary. However, the length of the capillary was 60 cm. In FIG. 6, the black squares are the results of the actual measurement, and the white squares are the theoretical values calculated based on the measured values. Since the flow rate of the solution by electrophoresis is about 1 to 10 nanoliters / second, when the pinhole 5 is not formed in the flow path 3, if a capillary having an inner diameter of 50 to 100 μm often used in electrophoresis is used, suction It is expected that the flow rate and the flow rate of the electrophoresis will be about the same, and the resolution will decrease. However, in this embodiment,
Such an obstacle did not occur because the pinhole 5 was formed in the flow path 3.

Embodiment 2 FIG. 2 shows the configuration of a capillary electrophoresis / mass spectrometer according to a second embodiment of the present invention. One end of the electrophoresis capillary 10 having an outer diameter of 0.15 mm and an inner diameter of 0.05 mm is connected to the mobile phase solution 20 in the container 1.
The other end is inserted into a tube 11 having an outer diameter of 1.4 mm and an inner diameter of 0.15 mm penetrating the second container 4. A pinhole 12 having a diameter of 0.1 to 0.2 mm is formed in the tube 11, and a solution 21 is placed in the second container 4 so that the pinhole 12 is immersed. The mobile phase solution 20 in the electrophoresis capillary 10 is in contact with the solution 20 in the second container 4 via the pinhole 12. In this embodiment, the capillary 10 for electrophoresis and the capillary 13 for ion source have an outer diameter of 0.15.
mm and an inner diameter of 0.05 mm were used. As the tube 11, a tube made of a fluororesin having an outer diameter of 1.4 mm and an inner diameter of 0.15 mm and having a pinhole having a diameter of about 0.1 to 0.2 mm was used.

On the other hand, the outer diameter is 0.15 mm and the inner diameter is 0.05 m
One end of the ion source capillary 13 of m is also inserted into the tube 11, and the other end is inserted and fixed in the metal tube 14, and the metal tube 14 is fixed to the ion source body 7. The tip of the ion source capillary 13 is inserted into the orifice 9.

The gas introduced into the ion source body 7 through the gas flow path 9 flows along the outer periphery of the ion source capillary 13, flows out into the atmosphere through the orifice 8, and flows out of the ion source capillary 13. Spray the solution inside. The sample electrophoresed by the electrophoresis capillary 10 is placed near the pinhole 12 in the tube 11 in the solution 2 in the second container 4.
1 and is sucked by the gas flow, sent to the tip of the ion source capillary 13, sprayed, and ionized.

The ions generated in the atmosphere are introduced into the mass spectrometer 17 through the pores 16 and subjected to mass analysis. A plate 15 is disposed in front of the pores 16 to prevent the gas flow from cooling the periphery of the pores 16.

A voltage may be applied to the ion source body 7 to assist in charging the sample, or the ion source body 7 may be grounded. Further, the electrode 2 may be grounded and a voltage may be applied to the electrode 6.

When the mobile phase solution 20 in the container 1 is a solution containing a high-concentration nonvolatile salt, a low-salt solution is used as the solution 21 in the second container 4.
Can be diluted near the pinhole 5 to a low salt concentration before being sent to the ion source, with favorable results.

The tube 11 is preferably made of an inert material such as a fluororesin, but the surface may be inactivated by a chemical treatment to prevent the sample from adsorbing.

FIG. 7 shows an example of a chromatogram for measurement obtained by using the capillary electrophoresis / mass spectrometer of this example. That is, by using the capillary electrophoresis / mass spectrometer shown in FIG. 2, the sample solution 2 of gramicidin S is contained in the container 1 and the capillary 10 for electrophoresis.
0, and the second container 4 was filled with only the mobile phase solution 21 to which gramicidin S was not added.

First, gas was introduced into the gas flow path 9 without applying a voltage to the electrodes 2 and 6. In this state, since no electrophoresis occurred, only the mobile phase solution 21 in the second container 4 was sucked into the ion source capillary 13, and no gramicidin ion was observed. When a voltage was applied to the electrode 2 at the time indicated by the arrow (after about 7 minutes), electrophoresis occurred inside the electrophoresis capillary 10 and the gramicidin S solution was sent. Thus, the gramicidin S sample was sent to the ion source capillary 13 together with the mobile phase solution, and the ion intensity was increased and ions were observed.

When the application of the voltage is stopped after the voltage is applied for about 3 minutes, the electrophoresis is stopped, the sample is not sent, and only the mobile phase solution in the container 4 is sucked. The intensity rapidly decreased and no ions were observed, and the results confirmed the effect of the present invention.

Example 3 In this example, when a solution containing a high concentration of a non-volatile salt was used as a mobile phase solution,
This is an example of a capillary electrophoresis / mass spectrometer equipped with a plate for preventing a deposited salt from adhering to the vicinity of the pores, and will be described with reference to FIG.

As shown in FIG. 3, in the present embodiment, a plate 18 having a plurality of holes whose central axes are shifted from the holes 16 is provided in front of the holes 16 of the mass spectrometer 17. Therefore, the spray gas does not directly hit the pores 16 but first strikes the plate 18 and then the plate 1
Ions passing through the holes provided in 8 are taken into the holes 16. Therefore, the precipitated salt adheres to the plate 18 and the pore 1
No adhesion around 6. By installing the plate 18, it was possible to prevent the pores 16 from being clogged by the precipitated salt without diluting the mobile phase solution having a high salt concentration.

Further, a voltage may be applied by connecting the power supply 19 to the solution in the first container 1 and the solution in the second container 4. The polarity of the voltage may be either positive or negative.

At this time, a voltage may be applied to the ion source body 7 to assist the charging of the sample. The polarity of the voltage may be positive or negative. However, when measuring positive ions, -1
It is preferable to apply a voltage of about kV to −2 kV. The ion source body 7 may be grounded. Further, the electrode 2 may be grounded and a voltage may be applied to the electrode 6.

<Embodiment 4> FIG. 4 is a view showing details of the structure of the second container 4 used in the above-mentioned Embodiments 2 and 3. The tube 11 in which the pinhole 12 is formed penetrates through the second container 4, and the solution 21 is filled to a height at which the pinhole 12 is immersed. The capillary 13 and the electrophoresis capillary 10 are connected to the pinhole 1 in the tube 11.
2 are arranged so as to face each other, but face each other at a predetermined interval so as not to block the pinhole 12. Capillary 13 and capillary 1 for electrophoresis
The interval of 0 may be slightly larger than the diameter of the pinhole 12, or may be larger. By changing the interval or the diameter of the pinhole, the amount of liquid entering the tube 11 can be changed, and the degree of dilution of the mobile phase solution for electrophoresis can be adjusted to a desired value.

Example 5 FIG. 8 shows an example of an electrophoretic chromatogram of gramicidin S obtained by a capillary electrophoresis / mass spectrometer using the present invention. As the mobile phase solution, 15% ammonium acetate (50% aqueous methanol solution) was used. 2 picomoles (pmol) at the end of a 40 cm long, 50 μm inner diameter capillary for electrophoresis
Gramicidin S sample was introduced, and 5 k
Electrophoresis was performed by applying a voltage of V, and m / z = 571 was monitored. About 13 electrophoresed gramicidin S
Detected after minutes.

As a sample, 15 pmol of GABA was used.
FIG. 9 shows an electrophoresis chromatogram obtained when a mixed solution of 12 and 12 picomoles of dopamine was introduced. The separation conditions are the same as in FIG. GABA and dopamine ion m
M / z = 104 and 154 corresponding to / z were monitored. After about 13 minutes dopamine, after about 18 minutes GABA
Were detected respectively.

<Embodiment 6> This embodiment is an example in which acetic acid is used as the solution 21 in the second container 4 to improve the detection sensitivity. FIG. 10 shows an electrophoretic chromatograph of gramicidin obtained by the capillary electrophoresis / mass spectrometer of the present invention, which was the same as that used in Example 5. The mobile phase solution 20 in the first container 1 and the solution 21 in the second container 4 contain 15 mM ammonium acetate (5 mM).
0% methanol aqueous solution). 2 pmol at the end of an electrophoresis capillary with a length of 40 cm and an inner diameter of 50 μm
Of the gramicidin S sample, and the electrode 2 of the first container 1
Is applied with a voltage of 5 kV to perform electrophoresis, and m / z = 5
71 were monitored. The electrophoresed gramicidin S was detected after about 16 minutes.

FIG. 11 shows a case where 15 mM acetic acid (50% methanol aqueous solution) is used as the solution 21 in the second container 4. Other conditions are the same as those in FIG. In this case, electrophoresed gramicidin S was detected after about 20 minutes. Although the amount of the introduced sample was the same as that in the case of FIG. 10, the ion intensity of the peak was increased four times or more.

In the case of the sonic spray method, when an acid is added to a sample, the concentration of protons in the sample increases, so that sample ions to which protons are added are easily generated. Therefore,
When an acid is used as the solution 21 to be put in the second container 4,
Since the acid is mixed into the electrophoresed sample, the ionization efficiency of the sample is increased, and the effect of increasing the detected ionic strength is obtained. In this embodiment, acetic acid is used, but another type of acid such as trifluoroacetic acid may be used. Further, other than the acid, another solution capable of increasing the proton concentration in the sample may be used.

A mixed solution of 15 pmol of GABA and 12 pmol of dopamine was introduced as a sample.
FIG. 12 shows the same electrophoretic chromatograph as FIG. As the mobile phase solution 21 in the first container 1, 15 m
M ammonium acetate (50% methanol aqueous solution) was used, and other conditions were the same as those in FIG. M / z = 104 corresponding to the m / z of GABA and dopamine ions
And 105 were monitored, dopamine was detected after about 13 minutes, and GABA was detected after about 18 minutes and 18 minutes, respectively.

FIG. 13 shows that 15 mM acetic acid (50% aqueous methanol solution) was used as a solution to fill the second container.
The other conditions are the same as in FIG. Dopamine was detected after about 21 minutes, and GABA was detected after about 38 minutes. Although the amount of the introduced sample is the same as that in the case of FIG. 12, the intensity of the peak ion was increased seven times or more.

FIG. 14 shows an electrophoretic chromatogram of gramicidin S obtained by the capillary electrophoresis / mass spectrometer of the present invention. As the mobile phase solution 20 in the first container 1 and the solution 21 in the second container 4, 15 mM potassium phosphate (50% methanol aqueous solution) was used. A 2 pmol of gracimidine S sample was introduced into the end of an electrophoresis capillary having a length of 40 cm and an inner diameter of 50 μm, and a voltage of 5 kV was applied to the electrode 2 of the first container 1 to perform electrophoresis. M / z = 571 Was monitored. As a result, the amount of electrophoresed Glacimidin S was about 22%.
Detected after minutes. Typically, phosphates that are non-volatile
Although it cannot be used in a capillary electrophoresis / mass spectrometer, it can be used in the present invention. However, both solutions 20,
If a potassium phosphate solution is used for both, the detection ion sensitivity is low, and if analysis is performed for a long time, there is a risk that the pores of the capillary or the mass spectrometer may be clogged with the precipitated salt. Is good.

As the solution 21 to be put in the second container, 15
FIG. 15 shows the results when mM acetic acid (50% aqueous methanol solution) was used and the other conditions were the same as those in FIG. In this case, electrophoresed gramidicin S was detected after about 23 minutes. The amount of sample introduced was the same as in FIG. 14, but the ionic strength of the peak was more than 20 times higher.
Therefore, it has been recognized that by using an acid for the solution 21, even when a phosphate solution is used for the mobile phase solution 20, ionization can be efficiently performed, and practical analysis becomes possible. In this embodiment, acetic acid is used as the solution 21 in the second container 4, but another kind of acid such as trifluoroacetic acid may be used. Further, other than the acid, another solution that can increase the proton concentration in the sample solution may be used. Further, a solution for reducing the concentration of phosphoric acid in the mobile phase solution 20 may be used to prevent the pores of the capillary or the mass spectrometer from being clogged with the precipitated salt.

FIG. 16 shows an electrophoretic chromatogram of dopamine and GABA obtained by the capillary electrophoresis / mass spectrometer of the present invention. As a sample, 15p
A mixed solution of mol GABA and 12 pmol dopamine was introduced. 15 mM potassium phosphate (50% methanol aqueous solution) was used as the mobile phase solution 20 in the first container 1, and the other conditions were the same as those in FIG. Dopamine was detected after about 17 minutes, and GABA was detected after about 20 minutes. In addition, as in the case of FIG.
When 15 mM potassium phosphate (50% aqueous methanol solution) was used for both 0 and solution 21, detection was difficult with the same amount of sample as in FIG.

[0059]

As is apparent from the above description, according to the present invention, the solution in the capillary for electrophoresis is prevented from being sucked by the gas for spraying, so that the separation ability of electrophoresis is prevented from lowering. Is done. Further, no electrode is provided in the closed flow path, and an electrode is provided in a second container disposed between the ion source and the capillary for electrophoresis, and the ion source is supplied through the solution in the second container. Since the solution introduced into the capillary is grounded, bubbles are prevented from entering the electrophoresis capillary.

Further, by placing a solution having a low salt concentration in the second container, even when a mobile phase solution having a high salt concentration is used for electrophoresis, the salt is diluted before being introduced into the ion source. Therefore, the analysis can be performed without clogging the pores of the capillary or the mass spectrometer with the precipitated salt. Therefore, a mobile phase solution containing a non-volatile salt such as phosphoric acid, which cannot be used in a conventional capillary electrophoresis / mass spectrometer, can also be used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing the effect of the first embodiment of the present invention.

FIG. 6 is a diagram showing the effect of the first embodiment of the present invention.

FIG. 7 is an electrophoretic chromatogram showing the effect of the second example of the present invention.

FIG. 8 is an electrophoretic chromatogram showing the effect of the fifth embodiment of the present invention.

FIG. 9 is an electrophoretic chromatogram showing the effect of the fifth embodiment of the present invention.

FIG. 10 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

FIG. 11 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

FIG. 12 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

FIG. 13 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

FIG. 14 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

FIG. 15 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

FIG. 16 is an electrophoretic chromatogram showing the effect of the sixth example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st container, 2 ... electrode, 3 ... flow path, 4 ... 2nd container, 5 ... pore, 6 ... electrode, 7 ... ion source main body, 8 ... orifice, 9 ... gas flow path, 10 ... Capillary for electrophoresis, 11 ... tube, 12 ... pore, 13 ... capillary, 14
... Metal tube, 15 plate, 16 pore, 17 mass spectrometer, 18 plate, 19 power source, 20 mobile phase solution, 21 solution.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Toshi Huang 1-280, Higashi-Koigabo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Central Research Laboratory

Claims (10)

[Claims] 1. A first container for storing a solution, a second container for storing a desired solution, a flow passage connected to the first container and extending through the second container, Means for supplying gas near the tip of the path and spraying the solution flowing out of the flow path, wherein pores are formed in a portion of the flow path penetrating the second container; The ion source characterized in that the solution in the second container is in contact with the solution in the second container through the pores. 2. The ion source according to claim 1, wherein an area parallel to the liquid surface of the solution inside the second container is larger than an area of the pore. 3. The ion source according to claim 1, further comprising means for applying a voltage to each of the solutions in the first and second containers. 4. The ion source according to claim 1, wherein the solution in the second container is grounded. 5. Means for applying a desired voltage between said first and second containers and electrophoresing a solution in said flow path between said first and second containers. The ion source according to any one of claims 1 to 4, wherein: 6. The method according to claim 1, wherein the means for spraying the solution is a means for flowing a gas near an end of the flow path to reduce the air pressure near the end. An ion source according to claim 1. 7. A first container for storing a solution, a channel for electrophoresis connected to the first container, a second container for storing a desired solution therein, and the second container. A tube that penetrates and is disposed so as to be immersed in the desired solution, a spray channel for spraying the introduced sample solution into the atmosphere, and an orifice into which the vicinity of the tip of the spray channel is inserted. Gas supply means for spraying the sample solution from the tip into the atmosphere, wherein the tube in the second container has a pore formed therein, and the solution in the tube passes through the pore. Then, the ends of the electrophoresis capillary and the end of the spray capillary are inserted into the tube from both ends of the tube, and are fixed to face each other at a predetermined interval. An ion source characterized in that: 8. The apparatus according to claim 1, further comprising a first and a second electrode disposed in the first and the second containers, respectively, and means for applying a predetermined voltage between the first and the second electrodes. The ion source according to claim 6, wherein 9. A mass spectrometer comprising the ion source according to claim 1. Description: 10. A capillary electrophoresis / mass spectrometer having the ion source according to claim 1.