JP3721715B2 - Liquid chromatograph mass spectrometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid chromatograph mass spectrometer (hereinafter referred to as LC / MS), and more particularly to an interface between an LC / MS liquid chromatograph part and a mass spectrometer part.
[0002]
[Prior art]
In the liquid chromatograph mass spectrometer (LC / MS), the components separated in the liquid chromatograph part are ionized and introduced into the mass spectrometer part. Therefore, there is a need for an interface that ionizes the separated components. As an interface generally used for LC / MS, a method of performing ionization under atmospheric pressure such as an electrospray interface (ESI) or an atmospheric pressure chemical ionization interface (APCI) has recently been used. On the other hand, mass spectrometers provided at the subsequent stage of these interfaces are generally used under high vacuum conditions. Therefore, LC / MS based on the atmospheric pressure ionization method is usually arranged between an atmospheric pressure ionization chamber for ionizing a liquid introduced from the liquid chromatograph section under atmospheric pressure and a mass spectrometry chamber containing a mass spectrometer. An intermediate exhaust chamber is provided, and a vacuum exhaust system is provided in the intermediate exhaust chamber and the subsequent high vacuum exhaust chamber so that the vacuum state is gradually increased from the front side to the rear side. FIG. 1 shows a schematic configuration diagram of such a conventional LC / MS example. In the figure, 10 is a liquid chromatograph section, 20 is a mass analysis section, and 30 is an interface section. Reference numeral 31 denotes an electrospray probe of the ionization unit, which functions as an ionized sample introduction tube from the liquid chromatograph unit 10. 43 is an atmospheric pressure ionization chamber, 44 is an intermediate exhaust chamber that is roughly evacuated by an oil rotary pump (RP), 45 is a second intermediate exhaust chamber having a lens system for converging ions, 46 is a quadrupole rod or detection The mass spectrometric chamber has a built-in chamber, and is maintained at a higher vacuum than the intermediate exhaust chamber 44 by a turbo molecular pump (TMP). The second intermediate exhaust chamber 45 and the mass spectrometry chamber 46 may share a single vacuum exhaust pump. In addition, there is a case in which the second intermediate exhaust chamber 45 and the mass analysis chamber 46 are integrated without being partitioned by a partition wall.
[0003]
The atmospheric pressure ionization chamber 43 and the intermediate exhaust chamber 44 are partitioned by a partition wall 12 and a solvent removal unit 13 is provided. The desolvation unit 13 includes a heating unit block 32 including a heater (not shown) and a pipe 33 that passes through the heating unit block 32. The atmospheric pressure ionization chamber 43 and the intermediate exhaust chamber 44 communicate with each other only through the pipe 33. Has been. Therefore, when the intermediate exhaust chamber 44 is evacuated by the oil rotary pump (RP), part of the gas in the atmospheric pressure ionization chamber 43 flows in through the pipe 33.
[0004]
The pipe 33 is heated by the heating block 32 and functions as a desolvation means for promoting desolvation of the charged droplets generated by the electrospray probe 31. That is, a part of the charged droplet sprayed from the electrospray probe 31 flows into the pipe 33 due to the differential pressure between the atmospheric pressure ionization chamber 43 and the intermediate exhaust chamber 44 and is heated in the pipe 33, thereby removing the solvent. It is introduced into the intermediate exhaust chamber 44 while being promoted.
[0005]
The ions introduced into the intermediate exhaust chamber 44 are further introduced into the second intermediate exhaust chamber 45 and the mass analysis chamber 46 that are exhausted to a high vacuum, and are detected by the detector.
.
[Problems to be solved by the invention]
In such LC / MS, the gas from the atmospheric pressure ionization chamber is used for preventing contamination in the vacuum chamber after the intermediate exhaust chamber 43, protecting the detector, and extending the service life by reducing the load of the turbo molecular pump except during analysis. In order to block the inflow, it is desirable to attach a shutter mechanism to the pipe 33 between the atmospheric pressure ionization chamber and the intermediate exhaust chamber 44.
[0007]
However, in the conventional LC / MS, since the high pressure for ionization is applied to the atmospheric pressure ionization chamber, the end of the pipe 33 is used for safety or to prevent the solvent from scattering from the spray to unnecessary portions. A cover is attached in the vicinity of the. Therefore, for example, when a manual shutter is attached, it is necessary to remove the cover one by one when opening and closing, which not only makes the work complicated, but also adversely affects the reproducibility of the analysis. In addition, it may be possible to attach a mechanical mechanism that allows the shutter to be opened and closed from the outside of the cover, but the shape becomes complicated due to space limitations.
[0008]
Accordingly, an object of the present invention is to solve such a problem, and to provide an LC / MS having a shutter mechanism that can be used in a small space and can be opened and closed with a very simple structure.
[0009]
[Means for Solving the Problems]
The liquid chromatograph mass spectrometer (LC / MS) of the present invention, which has been made to solve the above problems, allows ions generated in an atmospheric pressure ionization chamber to pass through an intermediate exhaust chamber maintained in a vacuum state, and is subjected to mass spectrometry. In LC / MS, which is led into the room and detected by the detector in the mass spectrometry room, a pipe communicating between the partition walls between the atmospheric pressure ionization chamber and the intermediate exhaust chamber, a heating block for heating the pipe, and heating A shape memory alloy elastic member connected to the block and a shutter mechanism connected to the elastic member to open and close the pipe end.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the LC / MS of the present invention, the heating block and pipe of the desolvation section are heated to 200 ° C. to 300 ° C. during analysis, but are at room temperature except during analysis. By utilizing this heat, the shape memory alloy stretchable member is stretched. For example, the shape memory alloy extends at a high temperature during analysis, and the shutter is opened when the packing of the shutter mechanism connected thereto is separated from the end of the pipe. On the other hand, when the room temperature is reached, the shape memory alloy shrinks and the shutter is closed.
[0011]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a cross-sectional configuration diagram of the main part of the LC / MS showing one embodiment of the present invention. The parts not particularly shown in the LC / MS of the present invention are the same as those of the conventional example of FIG. 1, and therefore, the description thereof will be omitted by attaching the same reference numerals.
[0012]
As shown in the drawing, a heating block 32 is attached to the partition wall 12 between the atmospheric pressure ionization chamber 43 and the intermediate exhaust chamber 44, and a pipe 33 is provided so as to pass through the heating block 32. The atmospheric pressure ionization chamber 43 and the intermediate exhaust chamber 44 communicate with each other through the pipe 33. The atmospheric pressure ionization chamber side of the pipe 33 is bent downward, and the end 33 a of the pipe is in a direction perpendicular to the spray probe 31. This is in order to reduce the invasion of large charged droplets by preventing straight charged droplets sprayed from the spray probe 31 from flowing as they are. The heating block 32 is connected to a coil 50, which is a shape memory alloy-type elastic member, so that the heat of the heating block 32 is transmitted. The outer periphery of the coil 50 is surrounded by a guide 51, and the direction in which the coil 50 expands and contracts is defined as one direction, and the heat retaining action of heat conducted from the heating block 32 is also provided. A rod 52 and an arm 53 are connected to the other end of the coil 50, and a packing 54 is attached to the tip of the arm 53 so that the packing 54 faces the pipe end 33a. 52, the arm 53, and the packing 54 constitute a shutter. Then, the rod 52 slides with the expansion and contraction of the coil 50, whereby the packing 54 at the tip of the arm 53 opens and closes the end portion 33a.
[0013]
With such a configuration, when the heating block is heated to a high temperature for desolvation at the time of analysis, the coil 50 receives heat and extends, the packing 54 is separated from the end portion 33a via the rod 52 and the arm 53, and the pipe end is To be released.
On the contrary, when the heating block 32 returns to room temperature due to the end of the analysis, the coil 50 contracts and the packing 54 closes the end portion 33a.
In the present embodiment, the linear slide type is used, but the invention is not limited to this, and a lever type or a rotary type can be used depending on the shape of the shape memory alloy.
[0014]
【The invention's effect】
As described above, in the LC / MS of the present invention, the shutter mechanism is attached to the heating block by utilizing the fact that the heating block is heated only at the time of analysis and the shape memory alloy, and the pipe end is only at the time of analysis. Since a shutter that can be released is provided, a shutter with a small space can be obtained, and an external driving mechanism is not required. In addition, the cover can be attached so as to surround the shutter mechanism and the pipe end.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a conventional liquid chromatograph mass spectrometer.
FIG. 2 is a cross-sectional configuration diagram of a main part of a liquid chromatograph mass spectrometer which is an embodiment of the present invention.
[Explanation of symbols]
10: liquid chromatograph unit 12: partition wall 13: desolvation unit 20: mass analysis unit 30: interface unit 31: electrospray probe 32: heating block 33: pipe 33a: pipe end 43: atmospheric pressure ionization chamber 44: intermediate exhaust Chamber 46: Mass spectrometry chamber 51: Guide 52: Rod 53: Arm 54: Packing

Claims (1)

In a liquid chromatograph mass spectrometer that detects ions generated in an atmospheric pressure ionization chamber through a middle exhaust chamber maintained in a vacuum state and led into the mass analysis chamber, and is detected by a detector in the mass analysis chamber.
A pipe communicating between the partition walls between the atmospheric pressure ionization chamber and the intermediate exhaust chamber;
A heating block for heating this pipe;
A shape memory alloy stretchable member connected to the heating block;
A liquid chromatograph mass spectrometer comprising: a shutter mechanism connected to the expandable member and opening and closing a pipe end.

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