JPH0342611Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an atmospheric pressure ionization (API) ion source, etc.
The present invention relates to a mass spectrometer equipped with an ion source that performs ionization in a high pressure region.

In a mass spectrometer equipped with an API ion source, it is necessary to introduce ions produced by the ion source at atmospheric pressure into the mass spectrometer in a high vacuum. A configuration in which an aperture plate is arranged is known. In the figure 1
2 is an API ion source; 2 is a quadrupole mass spectrometer that performs mass spectrometry on ions generated by the API ion source;
3 and 4 are API ion source 1 and quadrupole mass spectrometer 2
In particular, the aperture plate 4 is used as a skimmer to reduce gases and unnecessary solvents flowing in from the atmosphere side. The interior of the quadrupole mass spectrometer 2 is evacuated by a vacuum pump 5, and the area sandwiched between the aperture plates 3 and 4 is evacuated by a vacuum pump 6.

In such a mass spectrometer, in order to efficiently introduce ions generated by the API ion source into the mass spectrometer and improve sensitivity, the diameter of the aperture formed in the aperture plate must be made as large as possible. . However, there is a limit to increasing the diameter of the aperture plate depending on the pressure difference. Therefore, as shown in FIG.
It is being considered to reduce the pressure difference that must be maintained per aperture plate and increase the diameter of the aperture by evacuating the area sandwiched by the aperture with a vacuum pump 8. However, when the number of aperture plates is increased to three, if the three apertures are misaligned, the ion loss increases accordingly, and there is no point in increasing the aperture diameter. Therefore, it is necessary to align the three apertures with their axes and also align them with the axis of the quadrupole mass spectrometer, but this requires adjusting each aperture plate by moving each aperture plate independently. As the number of sheets increases, it becomes much more difficult. Note that if the machining accuracy is extremely high, it is possible to omit such alignment, but since the diameter of the aperture is on the order of 100 μm, at present, where the upper limit of machining accuracy is about 50 μm, the misalignment that occurs can be ignored. It is not possible.

The present invention was devised in view of this point, and by providing a deflection electrode for deflecting ions in at least one of the regions sandwiched between the aperture plates, mass spectrometers can easily perform axis alignment. The purpose is to provide equipment.

The present invention consists of an ionization section with high pressure in the atmospheric pressure region, a mass spectrometry section with low pressure that introduces and analyzes the ions generated in the ionization section, and ions between the ionization section and the mass spectrometry section. a plurality of aperture plates arranged at intervals with the axes of the apertures aligned, means for evacuating a region sandwiched by the aperture plates; and a device passing through at least one of the regions sandwiched by the aperture plates. It is characterized by the provision of a deflection electrode that deflects ions. Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing an example of a mass spectrometer implementing the present invention. In FIG. 2, the API ion source 1 includes a glass cylinder 11, a corona discharge section 12 that creates carrier gas atoms or ions excited by corona discharge, and a sample placed in the flow of the excited carrier gas atoms or ions. It consists of a sample holding needle 13 for ionizing the sample, and the sample ions generated at the tip of the needle 13 are transferred to a quadrupole electrode 14, a lens electrode 15, and a vacuum container via aperture plates 3, 4, and 7. 16, etc., into a quadrupole mass spectrometer 2. The aperture plates 3, 4, and 7 are fixed to an insulating flange 17 that seals the end of the vacuum vessel 16, and a region 18 sandwiched between the aperture plates 3 and 4 is an exhaust pipe. 19 and also the aperture plate 4
The region 20 sandwiched between the aperture plate 7 and the aperture plate 7 is the exhaust pipe 2
1, each is connected to a rotary pump (not shown). Reference numeral 22 denotes a deflection electrode for deflecting ions and aligning their axes, and as shown in FIG. 3, which is a cross-sectional view taken along line A-A, it is composed of four electrodes 22a to 22d arranged facing each other across an ion path. An appropriate positive voltage is applied to each electrode from power supplies 23a to 23d.

In this embodiment having such a configuration, the aperture plates 3, 4, and 7 are attached to a single flange 17, so when attaching the three aperture plates to the flange in the atmosphere during the manufacturing process of the device, for example, the straight propagation of light is prevented. However, even if the axis is slightly misaligned, the direction of the ions can be deflected by the deflection electrode to ensure that the ions pass through the aperture plate 7. can do. Since this adjustment can be done electrically, the work is much easier than in the past, where the aperture plates had to be moved independently.

In addition, in this embodiment, in which a positive potential is applied to the four deflection electrodes for sample ions that normally have a positive charge, the deflection electrodes can have a converging lens effect, so that the sample ions that pass through the aperture plate 4 Ions that tend to diverge will head toward the aperture plate 7 in a converging state, resulting in an improvement in the ion passage efficiency. Needless to say, if the sample ions are negative, a negative potential may be applied to the deflection electrode.

In the above-mentioned embodiment, the deflection electrode was provided only in the region 20, but if it is also provided in the region 18, alignment can be performed with even more accuracy, and if applied to a device equipped with more aperture plates, it will be more effective. is even larger.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining the structure of a conventional example, FIG. 2 is a cross-sectional view showing an example of a mass spectrometer embodying the present invention, and FIG. 3 is a cross-sectional view taken along line A-A. 1: API ion source, 2: quadrupole mass spectrometer,
3, 4, 7: Aperture plate, 17: Flange, 1
9, 21: exhaust pipe, 22a to 22d: deflection electrode,
23a-23d: Power supply.

Claims (1)

[Scope of utility model registration request] An ionization section with high pressure in the atmospheric pressure region, a mass spectrometry section with low pressure that introduces and analyzes ions generated in the ionization section, and an aperture through which ions pass between the ionization section and the mass spectrometry section. a plurality of aperture plates arranged at intervals with their axes aligned; means for evacuating a region sandwiched by the aperture plates; and deflecting ions passing through at least one of the regions sandwiched by the aperture plates. A mass spectrometer characterized by being provided with a deflection electrode.