JPH0388250A - Mass sorting ion source box - Google Patents

Abstract

PURPOSE:To guide high mass quantity material to an MS guide port of a mass analyzer in an ionizing chamber and improve the analysis sensitivity for the high mass quantity material by providing the MS guide port in a curved surface properly apart from a sample gas jet port. CONSTITUTION:An MS guide port 2B is provided in an inner wall of a curved surface of an ionizing chamber properly apart from a jet port of a vaporizer probe 1, so that gas of a high mass quantity moving close to the wall surface passes around the MS guide port 2B. A repeller electrode is provided at a close position facing the guide port 2B, so ions of a high mass quantity are guided to MS effectively. The measuring precision of the high mass ions can thus be increased at the MS.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mass fractionating ion source box used in a mass spectrometer or the like.

(Prior art) The ion source box of a conventional liquid chromatograph mass spectrometer (LC/MS) is shown in Fig. 2.The sample liquid flowing out from the LC is gasified by a paperizer probe 1 and then jetted into an ionization chamber 2A. do. The sample gas injected into the ionization chamber collides with accelerated electrons emitted from the electron gun 3 and is ionized. The ionized sample molecules are diffused in the ionization chamber, and the force of the electric field by the repeller electrode 4 pushes the diffused ions toward the mass spectrometer (MS), and the pushed ions pass through the MS introduction hole 2B. However, since sample ions with a large mass number are difficult to accelerate, a small amount of sample ions with a large mass number are introduced into the mass spectrometer, and when analyzing high-mass substances. However, there was a problem in that the measurement sensitivity decreased.

<Problems to be Solved by the Invention> An object of the present invention is to improve measurement sensitivity for analysis of high-mass substances.

(Means for Solving the Problem) In the ion source box, the wall surface facing the ejection port of the paperizer probe is curved concavely when viewed from the paperizer side, and the nozzle axis of the paperizer probe is brought into contact with the curved wall surface. M is arranged on the curved wall surface appropriately away from the spout of the paper riser 10-p.
An S introduction hole is provided, and a repeller electrode is provided inside the curved wall surface at a position opposite to the MS introduction hole, so as to exhaust air from the opposite side of the paperizer probe to the MS introduction hole. did.

(Function) According to the configuration of the present invention, the sample gas is ejected from the tangential direction of the concave curved surface, and the gas flow macroscopically flows along this curved surface. In this flow, a boundary layer is formed along the concave curved surface based on the viscosity of the gas flow. However, because the ion source box is evacuated, the flow is quite different from the aerodynamic flow at atmospheric pressure, and the boundary layer is thicker. The boundary layer is a field where the momentum of gas particles in the direction perpendicular to the wall surface is diffused. Along with the diffusion of momentum, gas particles, or substances, also diffuse, but the diffusion rate is faster than that of heavier particles. In other words, in the boundary layer, the sample gas with lower mass diffuses more easily, and therefore, the sample gas with lower mass diffuses away from the curved surface faster than the sample gas with higher mass. The higher the mass of the sample gas, the slower the diffusion rate and the longer it stays in the boundary layer. Therefore, the higher the inertia of the sample component gas, the higher the inertia.
It has a higher rate of movement along a curved surface for a longer time than a sample component gas with a lower mass, and the ratio of heavier components in the boundary layer increases as it moves away from the paperizer jet port along the wall surface. Therefore, by providing the MS inlet on a curved surface appropriately away from the sample gas outlet, high-mass substances can be efficiently guided to the MS inlet of the ionization chamber. In this step, the pressure inside the ion source box is reduced and the boundary layer is thick, so the diameter of the MS inlet can be made smaller than the thickness of this boundary layer, and the repeller can also be placed within the boundary layer, so ions due to mass can be reduced. You will be able to make a selection.

(Example) FIG. 1 shows an example of the present invention.
is a paperizer probe that gas-ionizes the sample flowing out from the LC and gasifies the liquid into the ionization chamber 2A and jets it out. 3 is an electron gun that ionizes the sample gas by colliding electrons with the sample gas ejected into the ionization chamber 2A. Reference numeral 2 denotes an ion source box, and an ionization chamber 2A is provided by rigging the inner wall of the side facing the paperizer probe 1 with a curved surface. place,
The sample gas is ejected at high speed along the curved wall surface of the ionization chamber 2A. The sample gas ejected at high speed moves farther along the wall surface as the gas has a higher mass number due to the inertial action explained in the action section. An MS introduction hole 2B is provided on the inner wall of the curved surface of the ionization chamber (in this example, at the midpoint of the curved surface) at an appropriate distance from the ejection port of the paperizer probe 1, so that the high-mass gas moving near the wall surface can be
It is made to pass near the MS introduction hole 2B. A propeller electrode 4 is provided in the vicinity of the introduction hole 2B, and the MS
High-quality I ions passing near the introduction hole 2B are accelerated in the MS direction, and high-mass ions are efficiently introduced into the MS.
S is used to increase the measurement accuracy of high-mass ions.

The repeller electrode 2B is provided so as to be slidable in the ring direction so that the distance from the introduction hole 2B can be adjusted.1 The distance from the introduction hole 2B is adjusted depending on the diffusion state of the high mass sample gas to be analyzed. An exhaust port 2C is provided on the opposite side of the paperizer probe 1, and the exhaust port 2C is connected to a rotary pump 5 to discharge residual sample gas that has not passed through the MS introduction hole 2B from the two ionization chambers. 6 is the lens,
The sample gas that has passed through the MS introduction hole 2B is converged and guided to the MS.

(Effects of the Invention) According to the present invention, by selectively and efficiently introducing high-mass substances into the MS, the analysis sensitivity of high-mass substances is improved, and thereby the analysis accuracy is also improved. Additionally, by suppressing the entry of low-mass ions into the MS, the amount of carrier material ions introduced is reduced, and contamination of the MS by carriers is also reduced.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention, and FIG. 2 is a configuration diagram of a conventional example. 1... Paperizer probe, 2... Ion source box, 2A... Ionization chamber, 2B... MS introduction hole, 2C... Exhaust port, 3... Electron gun, 4... Repeller Electrode, 5... rotary pump, 6... lens.

Claims (1)

[Claims] The wall surface facing the spout of the paperizer probe is curved concavely when viewed from the paperizer side, the nozzle axis of the paperizer probe is arranged so as to be in contact with the curved wall surface, and the nozzle axis of the paperizer probe is arranged to be in contact with the curved wall surface. An MS introduction hole is provided in the curved wall surface that is separated from the curved wall surface, a repeller electrode is provided at a position opposite to the MS introduction hole inside the curved wall surface, and a side opposite to the jet port of the paperizer probe with respect to the MS introduction hole is provided. A mass fractionating ion source box characterized by exhausting air from the