JP3109181U - Atmospheric pressure ionization mass spectrometer - Google Patents

Abstract

An atmospheric pressure ionization mass spectrometer having a high operating rate and improved maintainability is provided.
A tubular portion 31 made of a soft elastic material protruding toward the intermediate exhaust chamber 21 is provided on an isolation gate 13 provided on a partition wall 16 that defines an atmospheric pressure ionization chamber 15 and an intermediate exhaust chamber 21; The tubular portion 31 is configured such that the thin tube 11 is inserted, and an elastic pinching tool 32 that clamps the outer periphery of the tubular portion 31 is provided. With such a configuration, when the thin tube 11 is removed, the tubular portion 31 is tightened by the force of the elastic pinching tool 32 and the hole after the removal of the thin tube 11 is closed, so that the vacuum in the intermediate exhaust chamber 21 is maintained. As a result, the time for starting up the vacuum after maintenance becomes almost unnecessary, and the downtime of the apparatus is shortened. As a result, the operating rate is improved.
[Selection] Figure 1

Description

  The present invention relates to a mass spectrometer equipped with an atmospheric pressure ionization interface suitable for use as a liquid chromatograph mass spectrometer in combination with a liquid chromatograph.

  A mass spectrometer (hereinafter referred to as MS) may be used as a liquid chromatograph mass spectrometer (hereinafter referred to as LC / MS) in combination with a liquid chromatograph. That is, in LC / MS, components separated by liquid chromatography are introduced into MS for further mass analysis, but an interface for ionizing the separated components is necessary to perform mass analysis. As an interface generally used for LC / MS, a method of performing ionization under atmospheric pressure such as an electrospray interface or an atmospheric pressure chemical ionization interface has recently been used.

  A mass spectrometer provided in the latter stage of these interfaces is 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. 3 shows an example of a schematic configuration of such an LC / MS.
In the figure, 1 is a liquid chromatograph section, 20 is a mass analysis section, and 10 is an interface section for connecting the two.
The liquid eluted from the liquid chromatograph unit 1 is sprayed into the atmospheric pressure ionization chamber 15 from the nozzle 14 in the interface unit 10, and the sample component molecules contained in the eluate are ionized. The generated ions are guided to the intermediate exhaust chamber 21 evacuated roughly through the narrow tube 11, collected by the converging lens 24, and sent to the second intermediate exhaust chamber 22 of higher vacuum, where it is converted into a beam by the ion lens 25. Then, it is introduced into the mass analysis chamber 23 maintained at a higher vacuum and sent to the central space of the quadrupole filter 26 composed of four rod electrodes. A voltage obtained by superimposing an AC voltage and a DC voltage is applied to the quadrupole filter 26, and only ions having a specific mass number (more precisely, a mass-to-charge ratio) corresponding to this voltage pass through the quadrupole filter 26. It passes through and reaches the ion detector 27. In the ion detector 27, a current corresponding to the number of ions that have reached is taken out as an output signal.

A narrow tube 11 is provided in the partition wall 16 defining the atmospheric pressure ionization chamber 15 and the intermediate exhaust chamber 21, and the atmospheric pressure ionization chamber 15 and the intermediate exhaust chamber 21 communicate with each other only through the narrow tube 11. It is configured. Therefore, a part of the gas in the atmospheric pressure ionization chamber 15 flows into the intermediate exhaust chamber 21 evacuated through the thin tube 11.
The thin tube 11 is heated by the heating block 12 and functions as a desolvation unit for promoting desolvation of the charged droplets generated in the atmospheric pressure ionization chamber 15. That is, a part of the charged droplets sprayed from the nozzle 14 flows into the narrow tube 11 by the differential pressure between the atmospheric pressure ionization chamber 15 and the intermediate exhaust chamber 21 and is heated, thereby promoting the intermediate exhaust while promoting the desolvation. It is introduced into the chamber 21.

  Since the non-volatile components in the sample or inorganic salts precipitated from the mobile phase solvent adhere to and accumulate inside the thin tube 11, it is necessary to periodically remove and perform maintenance such as cleaning and replacement. In order to shorten the downtime of the apparatus at the time of this maintenance, there is one in which an isolation gate 13 is provided on the partition wall 16 so that the thin tube 11 can be inserted and removed without dropping the vacuum. The isolation gate 13 is generally a port for taking in and out an object through a vacuum bulkhead, but here the thin tube 11 is inserted into the isolation gate 13 so as to be detachable, and automatically when the thin tube 11 is removed. The mouth is configured to close.

  A conventional example of such a self-closing isolation gate 13 is shown in FIG. In this configuration, the isolation gate 13 and the heating block 12 are integrally formed. In FIG. 4, the left side of the partition wall 16 is maintained at atmospheric pressure and the right side is maintained at a rough vacuum, and the narrow tube 11 is inserted into the heating block 12. Yes. In this state, the ball 33 is pushed up by the thin tube 11, but when the thin tube 11 is pulled out to the left in the figure, the ball 33 falls by the force of the spring 34 to close the hole generated after the pulling out of the thin tube 11. (For example, refer to Patent Document 1). Reference numeral 35 denotes a cover for preventing contamination by droplets sprayed into the atmospheric pressure ionization chamber 15.

JP 2002-198006 A

The self-closing isolation gate shown in FIG. 4 has a problem in that it is difficult to achieve both the smooth movement of the ball and the blockage, and a slight instability remains in the opening and closing operation. That is, if the fit between the ball and the surrounding wall is made dense, the occlusion is improved, but the movement of the ball becomes worse, and the ball does not fall after removal of the thin tube, or the resistance when inserting the thin tube is large. Such a problem occurs. Conversely, if the ball is loosely fitted, the movement of the ball becomes smooth, but the gas flow cannot be completely stopped even when the ball is dropped.
The present invention has been made in view of such circumstances, and devised a self-closing isolation gate that allows easy insertion and removal of capillaries and that can reliably close the hole after removal of capillaries. An object of the present invention is to provide an improved atmospheric pressure ionization mass spectrometer with high availability.

  In order to solve the above problems, the present invention provides a tubular portion made of a soft elastic material protruding toward the intermediate exhaust chamber in an isolation gate provided on a partition wall defining the atmospheric pressure ionization chamber and the intermediate exhaust chamber. The tubular portion is configured so that a thin tube can be inserted therethrough, and an elastic pincer that clamps the outer periphery of the tubular portion is provided. With such a configuration, when the thin tube is removed, the tubular portion is tightened by the force of the elastic pinching tool and the hole after the thin tube is removed is closed, so that the vacuum in the intermediate exhaust chamber is maintained.

  Since the present invention is configured as described above, the reliability of the opening and closing operation of the isolation gate is increased, and the vacuum in the vacuum chamber is reliably maintained even after the contaminated tubule is removed for maintenance. The time for starting up the vacuum after maintenance becomes almost unnecessary, the downtime of the apparatus is shortened, and as a result, the operating rate is improved.

FIG. 1 shows an embodiment of the present invention. This figure shows only the isolation gate 13 and its periphery, and the overall configuration of the MS using this is the same as in FIG. 2A shows a state in which the narrow tube 11 is inserted through the isolation gate 13, that is, a normal use state, and FIG. 3B shows a state in which the thin tube 11 has been removed for maintenance. Is the atmospheric pressure ionization chamber 15, and the right side is the intermediate exhaust chamber 21.
As shown in the figure, the isolation gate 13 fixed to the partition wall 16 has a disc shape made of a soft elastic material such as silicon rubber, and its central portion protrudes to form a tubular portion 31. This tubular portion A thin tube 11 is inserted into the tube 31. A groove 31 a is provided on the outer periphery of the tubular portion 31, and the elastic pinching tool 32 fitted in the groove 31 a sandwiches the tubular portion 31.

The present embodiment configured as described above operates as follows.
First, in the state of FIG. 1A, that is, in a normal use state, the rear end portion of the thin tube 11 heated by the heating block 12 is inserted into the tubular portion 31, and the elastic clamping tool 32 is inserted from the outside of the tubular portion 31. Since the outer surface of the narrow tube 11 and the inner surface of the tubular portion 31 are in close contact with each other, the atmospheric pressure ionization chamber 15 and the intermediate exhaust chamber 21 communicate with each other only through the inside of the narrow tube 11. Thus, the original function of guiding the ions to the vacuum system while desolvating them can be achieved.
Next, as shown in FIG. 1B, when the thin tube 11 is taken out together with the heating block 12, the tubular portion 31 is tightened by being pinched by the elastic pinching tool 32, and the hole after the thin tube 11 is removed is closed. The communication between the atmospheric pressure ionization chamber 15 and the intermediate exhaust chamber 21 is cut off.
When the thin tube 11 is inserted again, it is only necessary to push in the elastic pinching tool 32 while expanding it by applying a little force.

The shape of the elastic clamping tool 32 is, for example, as shown in FIG. This is a kind of retaining ring called “clip ring”. The figure (A) is produced by punching an elastic metal plate, and (B) is produced by bending an elastic metal wire such as a piano wire. It is functionally equivalent to (A) and can be easily obtained in the market. In addition, a type that can be said to be a (A) (B) eclectic type combining sheet metal and wire is also conceivable.
Moreover, if it is a pinching tool using elasticity, even if it is a shape different from FIG. 2, it may be applicable to this invention.

  In FIG. 1, the periphery of the isolation gate 13 protrudes in an annular shape to form an outer ring portion 36. The outer ring portion 36 surrounds and protects the elastic pinching tool 32, but a groove (not shown) is provided on the inner wall of the outer ring portion 36 so that the elastic pinching tool 32 is held by the groove. You may comprise. A configuration in which the outer ring portion 36 is omitted is also possible.

  The MS according to the present invention may be used not only as an LC / MS but also as an ICP / MS in combination with, for example, ICP (ion coupled plasma emission spectroscopy).

It is a figure which shows one Embodiment of this invention. It is a figure which shows the shape of the components used by one Embodiment (FIG. 1) of this invention. It is a figure which shows schematic structure of LC / MS. It is a figure which shows an example of the conventional isolation gate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid chromatograph part 10 Interface part 11 Narrow tube 12 Heating block 13 Isolation gate 14 Nozzle 15 Atmospheric pressure ionization room 16 Partition 20 Mass analysis part 21 Intermediate exhaust room 22 Second intermediate exhaust room 23 Mass analysis room 24 Converging lens 25 Ion Lens 26 Quadrupole filter 27 Ion detector 31 Tubular portion 31a Groove 32 Elastic pinching tool 33 Ball 34 Spring 35 Cover 36 Outer ring portion

Claims (1)

A sample is ionized in an atmospheric pressure ionization chamber, and ions generated are introduced into an intermediate exhaust chamber evacuated through a thin tube, and further introduced into a subsequent vacuum chamber for mass separation. In the atmospheric pressure ionization mass spectrometer in which the capillary tube is detachably provided via an isolation gate provided on a partition wall defining the intermediate exhaust chamber, the isolation gate protrudes toward the intermediate exhaust chamber An atmospheric pressure characterized by comprising a tubular portion made of a soft elastic material that is configured to be inserted into the tubular portion through the thin tube, and having an elastic pinching tool for pinching the outer periphery of the tubular portion. Ionization mass spectrometer.

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