JPH112622A - Mass spectrograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mass spectrograph capable of highly speedy and highly accurate analysis. SOLUTION: This mass spectrograph is formed of a glass or silicon substrate 1 provided with a sample solution introducing opening 9, a sample solution disposing opening 10, and buffer solution introducing openings 7 and 8, and electrophoresis passages 5 and 6 for separating a sample solution and a capillary 2 connected to the end of the electrophoresis passages which couples the electrophoresis passages to an ion generating part 15 are integrally formed in the substrate 1. By this, it is possible to minimize time loss in separating a sample solution, to simplify the introduction of the sample solution into the capillary 2, and to provide a mass spectrograph capable of highly sensitively identifying separated substances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass spectrometer, and more particularly to a method for separating and analyzing a mixed solution containing a bio-related substance, an environment-related substance or a complex thereof at high speed and with high sensitivity. The present invention relates to a coupling device (hereinafter, referred to as CE / MS) between a capillary electrophoresis device (hereinafter, referred to as CE) and a mass spectrometer (hereinafter, referred to as MS).

[0002]

2. Description of the Related Art Conventionally, mass spectrometers with a high scanning speed have been used.
Although there was a quadrupole mass spectrometer, the resolution, sensitivity, and stability were not always sufficient. Therefore, online coupling of CE / MS has been proposed for analysis of natural products, biological components, drugs and metabolites. Since the CE / MS is separated in an electric field in the CE and the separated sample components are ions, the CE / MS is well compatible with an ionization method such as electrospray of the MS, and various techniques have been proposed. Have been.

[0003] For example, analytical chemistry
60 (1988) Sections 436 to 441 (Anal
ytical Chemistry 60 (1988)
pp 436-441) describes a CE / MS technology in which CE and MS are combined.

In the CE, a small amount of a mixed sample solution is introduced into one end of a quartz capillary filled with a buffer solution. The inner diameter of the quartz capillary is 0.1 m
m and the length is 1 m. An inlet of the quartz capillary is in contact with a buffer solution, an electrode is provided in the buffer solution, and a voltage is applied to the solution from the electrode. By applying a high voltage of about 30 kV to both ends of the quartz capillary, sample separation in the mixed sample solution is performed. In addition, silver is vapor-deposited at the end of the quartz capillary, and a voltage can be applied to the solution existing at the end of the capillary from the outside.

Further, the separated component is MS
At the inlet, they are converted into gaseous ions under atmospheric pressure by electrospray ionization (electrostatic spraying). A high voltage of about 5 kV is applied to the end of the capillary for the ionization. The ions generated under atmospheric pressure are
It is introduced into a vacuum system through a sampling orifice (pore) of the MS and mass-separated. The mass analysis unit of the MS performs mass scanning periodically, and the data processing unit records the obtained mass spectrum. The separated substance is identified from the obtained mass spectrum.

Further, another Analytical Chemistry 65 (1993) from paragraphs 2637 to 2642 (A
analytical Chemistry 65 (19
93, p2637-2642), 70mm x 80m
There is a description of CE using a rectangular glass substrate of m. On the glass substrate, grooves for electrophoresis paths (12 μm × 5
0 μm) is formed and the migration length is 24 mm. Since the electrophoresis length is short, the time required for electrophoresis is about 5 seconds, and high-speed separation is realized. Further, since the length of the migration path is short, the voltage applied to both ends of the migration path is about 10 kV, which is about 1/3 of the above 30 kV.

[0007] The separated substance in the mixed sample solution is
It is detected as a temporal change in fluorescence intensity by the laser-induced fluorescence method. Also, a groove for introducing a sample is provided on the glass substrate in addition to the groove for electrophoresis, so that the sample solution can be easily introduced into the electrophoresis path.

[0008]

The above-mentioned analytical
Chemistry 60 (1988) Sections 436-44
Item 1 (Analytical Chemistry
60 (1988) pp 436-441), a long quartz capillary was used for electrophoresis, so that the electrophoresis time of the sample solution required about 30 minutes. Therefore, there is a problem that it takes time to separate the sample solution, and real-time analysis is impossible. Furthermore, there is a problem that it is not easy to introduce the sample solution into the capillary, and it is difficult for a beginner to handle the sample solution unless a complicated device is used.

Also, Analytical Chemistry 6
5 (1993) Paragraphs 2637 to 2642 (Ana
Lytical Chemistry 65 (199
3) The conventional technique described in pp. 2637-2642) has a problem that the size of the excitation light source, the luminous intensity and the concentration are proportional, and the like, and it is difficult to identify the separated separated substance with high sensitivity. Yes. Furthermore, the above CE and M
In the case of bonding with S, there is a problem in that an unnecessarily long time loss occurs because a predetermined length is absolutely required for the bonding portion, and high throughput analysis cannot be performed. Furthermore, when the separation by the CE is insufficient, the analysis by the MS becomes useless, and there is a problem that an expensive MS is inefficient.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and eliminates unnecessary time loss by directly connecting the CE and the ion generator of the MS, thereby enabling high-speed separation of a sample solution. It is easy to introduce the sample solution into the capillary, high throughput, high efficiency,
It is another object of the present invention to provide a mass spectrometer capable of rapidly identifying the separated substance with high sensitivity.

[0011]

In order to achieve the above object, a mass spectrometer according to the present invention comprises a glass substrate or a silicon substrate provided with a sample solution inlet, a sample solution outlet, and a buffer solution inlet. A separation unit configured to separate a sample solution provided on the substrate, an ion generation unit configured to generate gaseous ions by a capillary from the separated sample solution, and mass separation of the generated gaseous ions. In a mass spectrometer configured from a mass spectrometer, using an electrophoresis apparatus for the separation unit,
The capillary of the ion generating section is connected to the end of the electrophoresis apparatus, and these are integrally formed in the substrate.

In the mass spectrometer described in the preceding paragraph, the capillary is made of quartz and has a concentric cross section. In any of the mass spectrometers described in the preceding paragraph, an electrode is provided at an inlet and a waste port of the sample solution and a buffer inlet so that a voltage can be applied to the electrode. The mass spectrometer according to any one of the preceding items, wherein the capillary length is 0.1 m or less. The mass spectrometer according to any one of the preceding items, wherein a solution inlet is provided in the migration path. In any one of the mass spectrometers described in the preceding paragraph, a detection unit that detects the separated sample solution is provided at a predetermined position on either the electrophoresis path or the capillary. The mass spectrometer according to any one of the preceding items, wherein a concentration section for concentrating the sample solution is provided at a front stage of the electrophoresis path.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mass spectrometer according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of one embodiment of a mass spectrometer according to the present invention,
FIG. 2 is a plan view of the separation unit and the ion generation unit in the mass spectrometer of FIG. 1, and FIG. 3 is a cross-sectional view of the separation unit and the ion generation unit of FIG.

First, a schematic configuration of the mass spectrometer according to the present embodiment will be described. This mass spectrometer provides a device that combines a mass spectrometer with a capillary electrophoresis device in which the ends of a short migration path formed on a substrate are formed in a capillary shape in order to realize high-speed separation analysis. And
Separation is carried out by a capillary electrophoresis apparatus, and a mass spectrometer is used for identification of separated substances. In FIG. 1, in the mass spectrometer according to the present embodiment, a sample solution separated by a substrate 1 is introduced into a capillary 2. At the end of the capillary 2, gaseous ions 3 are generated from the separated solution. At least a part of the gaseous ions 3 is introduced into the mass spectrometer 4 and subjected to mass separation, and the sample components are identified from the obtained mass spectrum.

FIGS. 2 and 3 show a separation unit and an ion generation unit in the mass spectrometer of FIG. As shown in FIGS. 2 and 3, buffer cells 7 and 8 filled with a buffer solution are provided on a quartz glass substrate 1 formed by providing a small rectangular projection on one side of a square. Migration path 5
Is provided to connect between the two buffer cells 7 and 8, and the M / S
It extends to the side. In addition, the shape of the substrate 1 is a square in which a small protruding portion is provided on one side. However, the shape is not limited to this, and any shape may be used as long as the above configuration is possible. Absent.

Further, the electrophoresis path 5 is provided with two electrophoresis paths 6a and 6b which are branched in opposite directions at two places near the buffer cell 8, respectively. And
A sample solution introduction cell 9 and a sample solution waste cell 1 are provided at ends of the two electrophoresis paths 6a and 6b opposite to the branch side, respectively.
0 is provided. Although not shown, the cross section of the migration path 5 has a square shape of 20 μm × 50 μm, and the length is about 30 mm.

Each of the cells 7, 8, 9, and 10 has:
Electrodes 11, 12, 13, and 14 are provided, respectively, so that a voltage can be applied to the solution of each of the cells 7, 8, 9, and 10. One end of a quartz capillary 2 is inserted into an extension end on the M / S side of the migration path 5 connected to the buffer cell 7, and is fixed with an adhesive. The concentrating unit 3 is provided upstream of the sample solution introduction cell 9.
0 is provided, and is connected to the sample solution introduction cell 9 via a channel 30a. Note that the concentration unit 30 may be provided outside the substrate 1.

Further, a small rectangular projecting portion on one side of the rectangular substrate is connected to an ion generating portion 15 for generating gaseous ions. The ion generator 15 is provided in a housing 20 having a cavity therein, and a gas inlet 24 in an upper portion.
And an orifice 21 on the front side on the MS side. The capillary 2 connected to the buffer cell 7 is inserted into the orifice 21 so that the center axis of the capillary 2 and the center axis of the orifice 21 coincide with each other.
The substrate 1 is placed and fixed on the support section 23, and the migration path 5 and the capillary 2 are positioned and fixed.

At the end of the electrophoresis path 5, a sensor 25 for confirming the separation of the sample solution is provided.
It is sent to S and is linked. The sensor 2
Reference numeral 5 may be provided at the entrance of the capillary 2. Further, a nitrogen gas is introduced from a gas inlet 24 above the ion generator 15 and is injected from the orifice 21 together with the sample solution.

The nitrogen gas pressure in the ionization generating section 15 is
Since the pressure is 2 to 7 atmospheres, a rubber packing 22 is used between the ion generating unit 15 and the substrate 1 to seal gas leakage. Since the substrate 1 is formed by laminating a plurality of quartz glasses, the migration paths 5 and 6 have a completely closed structure. One end of the substrate 1 opposite to the side on which the ion generation unit 15 is disposed is provided with the electrodes 11 to 14.
Are provided with terminals 16 to 19 for applying a voltage, respectively, and a voltage can be supplied from the outside by a socket-like terminal member via electric wiring indicated by a broken line in the figure.

The capillary 2 can be formed integrally with the substrate 1, and a power supply for supplying a voltage is installed on the substrate 1 to integrate all the devices. You can also. The quartz capillary 2 has an inner diameter of 50 μm, an outer diameter of 150 μm, and a length of 10 mm.

Referring to FIG. 3, the functions of the separation unit and the ion generation unit configured as described above will be described. On the substrate 1, a small amount of the sample solution introduced into the sample solution introduction cell 9 moves toward the sample solution waste cell 10 due to the potential difference generated by the voltage applied between the electrodes 13 and 14. When the moving sample solution is positioned on the migration path 5 between the buffer cells 7 and 8, the application of the voltage to the electrodes 13 and 14 is stopped. In this case, when the sample solution to be introduced is dilute, the sample is extracted and concentrated in the concentrating unit 30 with, for example, a solvent such as hexane.

Next, in order to cause the concentrated sample solution to undergo electrophoresis, about 10 k
When a voltage of about V is applied, the sample solution is separated and introduced into the quartz capillary 2. The electrode 1
1 is the ground potential. The separation of the sample solution is confirmed by the sensor 25, an output signal is sent to the control unit of the M / S, the ion generation unit 15 is started in conjunction with it, and nitrogen gas is introduced from the gas inlet 24. Here, if the sample solution has not been separated, the analysis at the M / S is stopped by appropriate means.

The function of the ion generator 15 will be described in detail. For example, ion generation is performed by a sonic spray ionization method. In this sonic ionization method, a sample solution is sprayed by a sonic gas flow flowing coaxially with the capillary 2 at the end of the capillary 2 to generate fine charged droplets.

The gaseous ions 3 are generated from fine charged droplets in the spray gas. It is known that the ionic strength depends on the gas flow velocity, and the ionic strength becomes maximum at the speed of sound. The orifice 21 and the capillary 2
When the distance to the end of the liquid is longer than a certain value, the gas flow velocity is widely distributed, and the size of the generated droplet cannot be reduced on average. As a result, the ion generation efficiency decreases.

Further, a voltage may be applied to the ion generator 15 in order to increase the ion generation efficiency. Gaseous ions 3 formed in the ionization section 15
Is introduced into the M / S and mass separated. In the case of using a non-concentric one, the ion generation unit 15 cannot increase the ion generation efficiency and does not realize high-sensitivity analysis.

Depending on the ion species to be analyzed, it is also possible to use another method such as atmospheric pressure chemical ionization (hereinafter referred to as APCI) or electrospray ionization (hereinafter referred to as ES) as the ionization method. .
In the ES, a high voltage of about 3 to 5 kV is applied to the electrode 11. A liquid cone is formed from the end of the capillary 2, and charged droplets are discharged from the tip of the cone. Since the ions are generated from fine charged droplets, if the cross section of the capillary 2 is not concentric, the intensity of the generated ions is not reproducible and is not practical. Unless a capillary having a concentric cross section is used, a stable cone is not formed, and the ion generation efficiency is low.

On the other hand, in the APCI, it is not necessary to apply a voltage to the ion generator 15. Orifice 2 for corona discharge
1 and the spray gas is introduced into the plasma generated by corona discharge. Ionization of neutral molecules generated in the spray gas is realized by an ion-molecule reaction with ions generated in the plasma. Unless a concentric capillary is used, it is difficult to form fine droplets. For this reason, it is preferable to use concentric capillaries because the efficiency of generating neutral molecules is reduced and high sensitivity analysis is not realized as a result.

[0029]

As described above in detail, according to the configuration of the mass spectrometer according to the present invention, a short migration path is formed on a substrate, an introduction cell is provided in the migration path, and ion generation is performed in this migration path. Since the parts are combined, unnecessary time loss is minimized, introduction of the sample solution into the capillary is easy, and high throughput. Further, it is possible to provide a mass spectrometer capable of rapidly identifying a separated substance with high sensitivity. In addition, since a concentration section is provided in the preceding stage of the migration path, high sensitivity analysis can be performed by concentrating a dilute sample solution, and M / S efficiency can be improved by confirming the separation of the sample solution with a detector. Can be planned.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of a mass spectrometer according to the present invention.

FIG. 2 is a plan view of a separation unit and an ion generation unit in the mass spectrometer of FIG.

FIG. 3 is a sectional view of a separation unit and an ion generation unit in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Capillary, 3 ... Gaseous ion, 4 ...
Mass spectrometer, 5, 6 migration path, 7, 8 buffer cell, 9 sample cell introduction cell, 10 sample waste cell,
11, 12, 13, 14 ... electrodes, 15 ... ion generation unit,
16, 17, 18, 19: terminal, 21: orifice, 2
2 rubber packing, 23 support, 24 gas inlet, 25 sensor, 30 concentrator

Continued on the front page (72) Inventor Hideaki Koizumi 1-280 Higashi Koikebo, Kokubunji-shi, Tokyo Inside Central Research Laboratory, Hitachi, Ltd.

Claims (7)

[Claims] A separating unit configured to separate a sample solution provided on the substrate, comprising a glass substrate or a silicon substrate provided with an inlet for a sample solution, a waste port for the sample solution, and a buffer solution inlet; In a mass spectrometer including an ion generation unit that generates gaseous ions by a capillary from the separated sample solution, and a mass analysis unit that performs mass separation of the generated gaseous ions, an electrophoresis apparatus is provided in the separation unit. Wherein the capillary of the ion generating section is connected to the end of the electrophoresis apparatus, and these are integrally formed in the substrate. 2. The mass spectrometer according to claim 1, wherein the capillary is made of quartz and has a concentric cross section. 3. The mass spectrometer according to claim 1, wherein an electrode is provided at an inlet, a waste port, and a buffer inlet of the sample solution so that a voltage can be applied to the electrode. Characteristic mass spectrometer. 4. The mass spectrometer according to claim 1, wherein said capillary length is 0.1 m or less. 5. The mass spectrometer according to claim 1, wherein a solution inlet is provided in the electrophoresis path. 6. The mass spectrometer according to any one of claims 1, 2, 3, 4, and 5, wherein the separated sample solution is detected at a predetermined position on the electrophoresis path or the capillary. A mass spectrometer characterized by providing a detection unit for performing mass spectrometry. 7. The mass spectrometer according to claim 1, wherein a concentration section for concentrating the sample solution is provided at a front stage of the electrophoresis path. Mass spectrometer.