JPH0460299B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion source for a mass spectrometer that irradiates a sample with a primary particle beam and ionizes the sample by the impact, and particularly relates to an ion source for a mass spectrometer that ionizes the sample with a primary particle beam. It provides an effective ion source when a sample solution is directly introduced into the ionization chamber and ionized.

[Prior Art] As a method for directly introducing a sample solution separated by a liquid chromatograph into a mass spectrometer, a structure shown in FIG. 3 is used.

In the figure, 1 is the mass analysis section of the mass spectrometer, 2 is the ionization chamber, 3 is a group of slits that accelerate and focus the ions generated in the ionization chamber 2, 4 is the particle beam generator, and 5 is the liquid Chromatograph, 6
is an introduction tube for introducing the sample solution separated by the liquid chromatograph 5 into the ionization chamber 2.
As this introduction tube, for example, a fused silica tube with an inner diameter of about 40 μm is used. In addition, as shown in FIG. 4, which is an enlarged sectional view of the introduction tube 6 inserted into the ionization chamber 2, the tip of the introduction tube is covered with a stainless steel tube 7, and a glass tube (such as stainless steel) is placed on the outside of the stainless steel tube 7. (It may be a metal tube) 8 is covered. A porous member 9 is attached so as to close the opening of the introduction pipe. As this porous member, for example, a filter (frit) made by sintering stainless steel powder is used. Incidentally, an appropriate voltage is applied to the stainless steel tube 7 from a repeller power supply 10.

In this configuration, the sample solution separated by the liquid chromatograph 5 is sequentially introduced into the ionization chamber 2 through the introduction tube 6, seeps out onto the surface of the porous member 9 attached to the tip of the introduction tube, and is transferred to the particle beam generator. It is ionized by being irradiated with the primary particle beam B from 4. The generated ions are pushed out of the ionization chamber 2 by a repeller voltage applied to the stainless steel tube 7, introduced into the mass spectrometer 1, and subjected to mass spectrometry.

[Problems to be Solved by the Invention] When introducing the sample solution from the liquid chromatograph into the ion source online in this way and sending the sample solution to the surface of the porous member 9 for ionization, the It is desirable that all the sample components are ionized one after another and no sample components sent earlier remain, but in reality, as shown by the symbol S in FIG. It is impossible to avoid the accumulation of the result,
The sample component S accumulated at the lower end of the porous member is also irradiated with the primary particle beam B, and the ions generated thereby are introduced into a mass spectrometer and subjected to mass analysis. Therefore, the sample components sent later and the sample components sent earlier are simultaneously ionized and subjected to mass spectrometry, which adversely affects the analysis.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is an object of the present invention to provide an ion source that can absorb sample components that have not been ionized on the primary particle beam irradiation surface and quickly remove them from the surface. It is something.

[Means for Solving the Problems] In order to achieve the above object, the present invention introduces an introduction tube into the ionization chamber, and passes the sample liquid through the introduction tube to the irradiation surface provided at the tip of the introduction tube. In an ion source for a mass spectrometer that ionizes a sample liquid by irradiating a primary particle beam onto the irradiation surface, the sample liquid accumulated on the irradiation surface is moved out of the primary particle beam irradiation area using capillary action. It is characterized in that a suction member for suctioning is provided on the outer circumference of the irradiation surface.

Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

[Example] Fig. 1 is an enlarged sectional view of essential parts showing one embodiment of the present invention, Fig. 2 is an enlarged view taken in the direction of arrow A in Fig. 1, and Fig.
The same reference numerals as in the figures and FIG. 4 indicate the same components.

That is, in this embodiment, an elongated plate 11 is used as an absorbing member, and the side surface of this plate is brought into contact with the lower surface of the porous member 9, and the capillary phenomenon occurs in the minute gap formed by the contact. It is characterized in that it is configured to absorb sample components by utilizing. The plate 11 is attached to the glass tube 8 by bending its middle portion.
Further, the upper end of the plate 11 on the side that is in contact with the porous member 9 is arranged so as to be located outside the area C where the primary particle beam B irradiates the surface of the porous member 9, as shown in FIG. be.

By doing this, sample components that have not been ionized on the surface of the porous member can be forcibly absorbed by the capillary phenomenon that occurs at the contact portion between the porous member 9 and the plate 11, so that the porous member It is possible to prevent unionized sample components from accumulating on the surface of the sample. In addition, the sample components that have been sucked fall down along the plate and are collected in the intermediate portion D thereof. Here, projecting portions 12a and 12b (12b not shown) are provided on both sides of the intermediate portion D of the plate 11, respectively, to prevent the absorbed sample components from leaking into the ion source.

It should be noted that the above description is an example of the present invention, and many modifications can be made in implementing the present invention. For example, in the above explanation, a plate was used to generate capillary phenomenon, but the invention is not limited to this, and it is possible to arrange a large number of thin wires on the surface of a porous member and contact them, or to use a metal mesh, sponge, etc. to form a porous member. It may be brought into contact with the surface and absorbed. At this time, if these absorption members are irradiated with the primary particle beam, the sample introduced first will be ionized, so it is better to surround the absorption members with a cover.

Furthermore, the porous member and the glass tube portion may be heated in order to promote the evaporation of the solvent component in the sample container that seeps out from the porous member and to increase the amount of generated ions.

In addition, a porous member was attached so as to close the irradiation surface, that is, the opening, which is irradiated with the primary particle beam of the introduction tube introduced into the ionization chamber. This is not necessarily necessary, but the opening of the introduction tube can be used as the irradiation surface.
The sample liquid held on this irradiation surface may be directly irradiated with the primary particle beam to sequentially ionize the sample components that are sent.

In addition, although the above example shows the case where the liquid chromatograph and the ion source are connected online,
The present invention is not limited to this, and the same method can be applied to off-line analysis of a single sample component.

[Effects] As detailed above, according to the present invention, the sample liquid sent to the primary particle beam irradiation surface provided at the tip of the introduction tube can be absorbed, so that the sample liquid that has not been ionized is deposited on that surface. It is possible to prevent the sample liquid from accumulating, and it is possible to prevent the sample liquid sent earlier and the sample liquid sent later from being ionized together, and it is possible to improve analysis accuracy. At the same time, the amount of sample liquid introduced into the ionization chamber can be increased, and sensitivity can be improved.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part showing an embodiment of the present invention, FIG. 2 is an enlarged view taken in the direction of arrow A in FIG. 1, and FIGS. 3 and 4 are diagrams for explaining a conventional example. . 1: mass spectrometry section, 2: ionization chamber, 3: slit group, 4: particle beam generator, 5: liquid chromatograph, 6: introduction tube, 7: stainless steel tube, 8: glass tube, 9: porous member, 10: Repeller power supply, 1
1: plate body, 12a: overhang part.

Claims (1)

[Claims] 1 A mass for introducing an introduction tube into the ionization chamber, supplying a sample liquid through the introduction tube to an irradiation surface provided at the tip of the introduction tube, and ionizing the sample liquid by irradiating the irradiation surface with a primary particle beam. An ion source for an analyzer, characterized in that a suction member is provided on the outer periphery of the irradiation surface for sucking the sample liquid accumulated on the irradiation surface out of the primary particle beam irradiation area using capillary phenomenon. Ion source for analyzers.