JPS6240149A - Ion source for mass analysis device - Google Patents

Abstract

PURPOSE:To provide an ion source having a high sensitivity and capable of generating a large amount of sample ions, by ejecting a sample liquid from a nozzle in a low pressure chamber so as to cling to a porous member and permeate it to a high-vacuum-degree ion source chamber, and irradiating a primary particle ray upon the liquid on the chamber to ionize the liquid. CONSTITUTION:As the jet J of an outgoing liquid spurting from a nozzle 8 proceed toward a mesh 5 and clings thereto, the relatively easily evaporable solvent constituent of the outgoing liquid is evaporated first so that the concentration of a sample constituent is heightened. The concentration is more heightened if the temperature of the mesh 5 is raised beforehand. The liquid, the concentration of the sample constituent of which is thus heightened, is moved to an ion source chamber 1 through the mesh 5 by the pressure difference between a low pressure chamber 3 and the ion source chamber. The liquid having reached the surface of the mesh 5 on the ion source chamber 1 is irradiated with an argon atom beam A so that the liquid is ionized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ion source for a bulk analyzer that irradiates a sample with a primary particle beam and ionizes the sample by the impact of the beam.

[Prior Art] Recently, an ion source that uses a method in which a high-velocity neutral particle beam or ion beam is applied to a sample and ionizes the sample by the impact has been attracting attention. This ion source has the characteristic of being able to ionize samples with high mass.

In the ion source of the above method, the sample is usually introduced into the ion source by smearing it on the target, but this method of introduction is used when the effluent from a liquid chromatograph is continuously ionized. Can not. Therefore, in such a case, there is a method of spreading the effluent onto a belt and introducing it into the ion source as in JP-A-58-119148, or a method of atomizing the effluent as in JP-A-60-44. A method has been proposed in which a molecular linear sample is ejected through a skimmer and the molecular linear sample is attached to the surface of a target placed in a high vacuum ionization chamber 5 via a skimmer.

[Problems to be Solved by the Invention] However, the method disclosed in JP-A-58-119148 has drawbacks in its mechanism for introducing the belt while maintaining a vacuum within the ion source, and there is also the problem of contamination of the belt.

Furthermore, in the method of JP-A-60-44, the sample ejected from the atomizer must be introduced into the ionization chamber through a skimmer that has an extremely small diameter.
Even if you go from the atomizer to a very thin tip, it will not spread (
(in the form of molecular lines), the sample must be ejected in good direction.

It is extremely difficult to create such an atomizer, and even if it were possible, the amount of sample that can be introduced into the target via the skimmer is extremely small, making it difficult to achieve high sensitivity.

The present invention has been made in view of the above-mentioned problems, and
It is an object of the present invention to provide an ion source for a mass spectrometer that can eliminate these problems.

[Means for Solving the Problems] To achieve this object, the present invention provides an ion source chamber whose interior is kept at a high vacuum, and a low-pressure chamber which is placed inside the ion source chamber and whose interior is kept at a low vacuum. a porous member provided between the low pressure chamber and the ion source chamber; a nozzle disposed within the low pressure chamber for ejecting a sample liquid toward the porous member; and a nozzle disposed within the high vacuum ion source chamber. A particle beam generating section for irradiating a primary particle beam toward the porous member is characterized.

[Operation] The sample liquid ejected from the nozzle in the low pressure chamber adheres to the porous member. The sample liquid that has seeped out into the high-vacuum ion source chamber through this porous member is ionized by irradiation with the primary particle beam.

Hereinafter, one embodiment of the present invention will be explained in detail using the drawings.

[Example] FIG. 1 is a schematic diagram showing an example of an ion source implementing the present invention. In the figure, reference numeral 1 denotes an ion source chamber, the interior of which is maintained at a high vacuum of, for example, about 10@4 to 10' Torr by an oil diffusion pump 2. 3 is a low pressure chamber arranged in the ion source chamber 1, and the interior thereof is operated by an oil rotary pump 4 to
- It is maintained at a low vacuum of about Torr. 5 is a fully bent mesh that is fitted into a hole that communicates the ion source chamber 1 and the low pressure chamber 3 to partition them, 6 is an insulator for insulating this mesh from the surroundings, and 7 is an appropriate voltage applied to the mesh. This is a power source for applying voltage.

8 is a nozzle arranged in the low pressure chamber 3, to which the effluent from the liquid chromatograph 9 is supplied via the splitter 10, and this effluent is directed to the mesh 5 by the jet J.
erupts as.

Reference numeral 11 denotes a particle beam generator disposed in a high vacuum ion source chamber, and a generated primary particle beam, such as a high-speed argon atomic beam A, is irradiated onto the surface of the mesh 5 on the ion source chamber side. Reference numeral 12 denotes a focusing electrode that extracts sample ions I generated from the mesh surface by irradiation with the argon atomic beam A and focuses them toward a mass spectrometer (not shown).

In the configuration as described above, the nozzle 8 given a minute diameter
A jet J of effluent ejected from the mesh 5 flies toward the mesh 5 and adheres thereto. In this process, the solvent components contained in the effluent that are relatively easy to evaporate evaporate first, so that the concentration of the sample components is increased.

Furthermore, if the temperature of the mesh 5 is raised, the solvent component will evaporate from the effluent even after adhering to the mesh, and the concentration of the sample component will be further increased. The evaporated solvent components are exhausted by the oil rotary pump 4.

The effluent, in which the concentration of sample components is relatively increased in this manner, moves through the mesh toward the ion source chamber due to the pressure difference between the low pressure chamber 3 and the ion source chamber 1. The effluent that has arrived at the surface of the mesh on the ion source chamber side is ionized by irradiation with the argon atomic beam A. The generated sample ions I quickly leave the mesh surface due to the liberating voltage applied to the mesh, and the focusing electrode 1
2 to the mass spectrometer.

In the above example, a mesh was used as a member to partition the low-pressure chamber and the ion source chamber, but the mesh is not limited to the mesh. Due to the porous nature of the material, the outflow liquid is separated from the low-pressure chamber by ions due to the pressure difference between the low-pressure chamber and the ion source chamber. Any material that leaks into the source chamber can be used.

Further, during ionization, it is desirable that a matrix such as glycerin be present together with the sample components. For this purpose, glycerin may be mixed in advance into the solvent of the liquid chromatograph, or glycerin may be mixed into the effluent coming out of the liquid chromatograph.

Alternatively, as shown in FIG. 2, a nozzle 13 is added,
A jet of glycerin (dissolved in an appropriate solvent) is ejected from this nozzle 13 toward the mesh 5.
It may also be mixed with the effluent sent from the nozzle 8 above the effluent.

In addition, in order to increase the number of sample ions obtained and increase the sensitivity,
It would be better to increase the amount of effluent that adheres to the mesh 5 from the nozzle 8, but this will increase the amount of solvent vaporized in the low pressure chamber, so the number of oil rotary pumps used to exhaust the low pressure chamber may be increased. Needless to say, it is necessary to improve the exhaust capacity.

[Effects of the Invention] As described in detail above, according to the present invention, there is no M point unlike the belt method, there is no need for a skimmer because the nozzle is placed in a low pressure chamber, and there is no need for a skimmer to pass through the skimmer. Since the above problems are solved, a large amount of sample ions can be created and an ion source with excellent sensitivity can be realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic view showing an example of an ion source embodying the present invention, and FIG. 2 is a schematic side view of a main part showing another embodiment of the present invention. 1: Ion source chamber 2: Oil diffusion pump 3: Low pressure chamber 4: Oil rotary pump 5: Metal mesh 6: Insulator 7: Power supply 8: Nozzle 9: Liquid chromatograph 11: Particle beam generator port

Claims (3)

[Claims] (1) An ion source chamber whose interior is maintained at a high vacuum, a low pressure chamber located within the ion source chamber whose interior is maintained at a low vacuum, and a porous member provided between the low pressure chamber and the ion source chamber. a nozzle arranged in the low-pressure chamber to eject a sample liquid toward the porous member; and a particle beam generator arranged in the high-vacuum ion source chamber to irradiate a primary particle beam toward the porous member. An ion source for a mass spectrometer, comprising: (2) The ion source for a mass spectrometer according to claim 1, wherein the porous member is insulated from the surroundings and a desired voltage can be applied thereto. (3) The ion source for a mass spectrometer according to claim 2, wherein the porous member is formed of a metal mesh.