JPS63168956A - High-frequency induction coupling mass spectrometer - Google Patents

Abstract

PURPOSE:To generate the plasma easily, by positioning a shield plate between a high-frequency induction coil and a plasma torch, connecting the shield plate to the earth potential through a switch, generating a high-frequency induction coupling plasma in the condition that the switch is turned off, and turning on the switch after the plasma is generated. CONSTITUTION:When a switch 9 is turned off, argon gas is let flow in a plasma torch 1, and a high-frequency current is fed in a coil 2 to form a high-frequency magnetic field, a plasma 4 is generated easily and instantly. This is because the switch 9 is turned off, and the capacity coupling between the coil 2 and the plasma 4 is made larger. Since the plasma 4 has a specific high-frequency potential, a shield plate main 7a is connected to an earth 8 when the switch 9 is turned on, and the whole body of the shield plate 7 is made to have the earth potential. As a result, the shielding effect by the shield plate 7 is improved, and the capacity coupling of the coil 2 and the plasma 4 is made into the minimum. Therefore, the shielding is made rigid and the plasma is generated easily.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a high frequency inductively coupled plasma/mass spectrometer (Industrial Application Field) which combines a high frequency inductively coupled plasma and a mass spectrometer.
ductively coupled plasma-
Mass Spectomater, hereafter referred to as IcP-M
(abbreviated as SJ).

<Conventional technology> ICP-MS uses high-frequency inductively coupled plasma to excite a sample, guides the generated ions to a mass spectrometer through an interface consisting of a nozzle or skimmer, and electrolyzes ions with a specific mass. The device is configured to analyze the element to be measured in the sample by detecting the ions and precisely measuring the amount of the ions. FIG. 3 is an explanatory diagram of the main part configuration of a conventional example of such an ICP-MS, and in the figure, 1
For example, numeral 2 is a plasma torch with a triple tube structure having an outermost chamber 1g, an outer chamber 1b, and an inner chamber IC, 2 is a high-frequency induction coil wound around the torch 1, and 3 is a capacitor C, , C in the coil 2. , 4 is a high-frequency inductively coupled plasma, 5 is a nozzle, and 6 is a skimmer. In this figure, when the high frequency current is passed through the coil 2, a high frequency magnetic field is formed around the coil 2. When electrons or ions are planted in the argon gas in the plasma torch 1 near this high-frequency magnetic field,
Plasma 4 is instantaneously generated by the action of the high-frequency magnetic field, and the plasma has a constant high-frequency potential.

On the other hand, the plasma 4 and the high frequency induction coil 2 are capacitively coupled, and the plasma 4 has a high frequency potential. On the other hand, since the nozzle 5 and the skimmer 6 are normally connected to the ground and have a ground potential, discharge occurs between the tips of the nozzle 5 and the skimmer 6 and the plasma 4. In addition, the ions drawn from the plasma 4 into the skimmer 6 lose their ion characteristics obtained within the plasma 4 due to the influence of such discharge, which ultimately significantly reduces the analysis accuracy of ICP-MS. I learned to do it. In order to prevent such a decrease in analysis accuracy, after generating high-frequency inductively coupled plasma 4, the shield plate is slid in the direction of plasma torch 1, and the shield is inserted into the gap formed between the arc prevention tube and the plasma torch. ICP-MS was also devised (patent application 1986).
1-243923, application publication number undetermined).

<Problems to be Solved by the Invention> However, in the conventional example described above, there is a major drawback in that the more severe the shield provided between the plasma 4 and the coil 2, the more difficult the plasma 4 is to be generated. Ta.

Also, as in the above idea, inserting the shield plate after generating the plasma 4 is a problem with the configuration of the ICP-MS! j!
It becomes sloppy and about 6. This requires the difficult operation of inserting a shield plate through the vicinity of the plasma 4, which has a high temperature of 0[lO~+3Nfl@], which ultimately has the disadvantage of increasing production costs and making it more likely to cause failures.

The present invention has been made in view of the drawbacks of the conventional example, and its purpose is to provide an IcP- The goal is to provide MS.

Specific Means for Solving the Problems> A feature of the present invention for solving the above problems is that in IcP-MS, a shield plate is disposed between the high frequency induction coil and the plasma torch, and the shield plate is disposed between the high frequency induction coil and the plasma torch. The plate is connected to ground potential via an open/close switch, high-frequency inductively coupled plasma is generated with the switch open, and the switch is closed after the plasma is generated.

<Example> Hereinafter, the present invention will be described in detail using the drawings. 1st
The figure is an explanatory diagram of the main part configuration of the embodiment of the present invention, and in the figure, the third
The same symbols as in the figures are used with the same meaning, and redundant explanation will be omitted here. Further, 7 is a shield plate disposed on the outside of the plasma torch 1, and the shield plate main body 7@m
A flange portion 7C is provided at each end, and a notch portion 7b is provided along the entire length. 8 is a ground, and 9 is a switch for opening and closing the connection between the shield plate main body 71 and the ground 8. In the main part of the embodiment of the present invention having such a configuration, the switch 9 is first opened (off). In this state, argon gas is flowed into the plasma torch 1. coil 2
When a high frequency current is supplied into the coil 2, a high frequency magnetic field is formed around the coil 2. When electrons or ions are planted in the argon gas in the plasma torch 1 near this high-frequency magnetic field or ignited with a Tesla coil, etc.,
Plasma 4 is easily and instantaneously generated by the action of the high frequency magnetic field.

The reason why the plasma 4 is easily ignited is because the switch 9 is open and the capacitive coupling between the coil 2 and the plasma 4 is large. The plasma 4 thus generated has a constant high frequency potential. Then, when the switch 9 is closed (turned on), the shield plate main body 7a is connected to the ground 8, and the entire shield plate 7 comes to have a ground potential.

As a result, the shielding effect by the shield plate 7 is improved, and the capacitive coupling between the coil 2 and the plasma 4 is minimized. Therefore, the IcP-MS, the main part of which is shown in Figure 1,
Shielding is strict and plasma 4 is easily generated. Note that the present invention is not limited to the above-described embodiments, and can be modified in various ways. For example, the shield may be connected to a part of the coil 2 at the time of ignition and connected to the ignition raft ground. shall be.

FIG. 2 is an explanatory diagram of the overall configuration of an embodiment of the present invention. In the figure, the same symbols as in FIGS. 1 and 3 are used with the same meanings, and redundant explanation will be omitted here.

Further, 1h is an argon gas supply source, IOb is a gas regulator, 11 is a tank for storing a sample, 12 is a nebulizer that atomizes the sample to make an aerosol sample, 13 is a drive unit including a high-frequency power source 3, and 14 is a plasma torch. A housing for storing 15
17 is a vacuum pump that suctions and exhausts the inside of the forechamber 16 to, for example, 1 torr, 17 is a vacuum pump that suctions and exhausts the inside of the center chamber 18 to, for example, -'torr, and 19 is, for example, a quadrupole mass filter. 20 is a vacuum pump that suctions and exhausts the inside of the rear chamber 21; 22 is a secondary electron multiplier; 23 is a mass spectrometer detector;
is an arithmetic processing unit (for example, a microcomputer).

In the embodiment of the present invention having such a configuration, a gas regulator 1 is installed in the outermost chamber and 1b of the plasma torch 1.
Argon gas is supplied from a gas supply source 10@ via 0b. In addition, argon gas (supplied via the gas regulator IN) is supplied from the nebulizer 12 to the inner IC.
The aerosol sample is carried in by. On the other hand, coil 2
High frequency energy is supplied to the coil by the high frequency power supply 3 in the drive unit 13, and a high frequency magnetic field (not shown) is formed around the coil. Therefore, plasma 4 is generated by the action of the high frequency magnetic field. The ions in this plasma 4 are extracted into the skimmer 6 through the nozzle 5, and then
Ions of a specific mass are detected by mass spectrometer detector 19 . The detection signal is amplified by the secondary electron multiplier tube 22 and then sent to the arithmetic processing section 23, which finally provides an analysis value of the element to be measured in the sample.

<Effects of the Invention> According to the present invention as explained in detail above, plasma 4
An IcP-MS is realized in which the shield disposed between the coil 2 and the coil 2 is tightly secured to maintain a good shielding effect, and the plasma 4 can be easily generated and maintained normally.

[Brief Description of the Drawings] Fig. 1 is a perspective view of the main part of the embodiment of the present invention, Fig. 2 is an explanatory diagram of the overall structure of the embodiment of the present invention, and Fig. 3 is an explanatory diagram of the main part of the conventional example. It is. 1... Plasma torch, 2... High frequency induction coil,
3...High frequency power supply, 4...High frequency inductively coupled plasma, 7... Shield plate, 8... Earth, 9... Switch. Fig. 1 7, Shield effect 7a/Nund IL4-I Winter 3, Earth 9 Zwicke

Claims (3)

[Claims] (1) High-frequency energy is supplied to a high-frequency induction coil to form a high-frequency magnetic field to generate high-frequency inductively coupled plasma, the plasma is used to excite the sample to generate ions, and the ions are subjected to mass analysis via an interface. In an analyzer that detects and analyzes the element to be measured in the sample, a shield plate is disposed between the coil and the plasma torch that generates the plasma, and the shield plate is connected via an open/close switch. A high frequency inductively coupled plasma/mass spectrometer, characterized in that it is connected to a ground potential, the plasma is generated with the switch open, and the switch is closed after the plasma generation. (2) The high frequency inductively coupled plasma mass spectrometer according to claim 1, wherein the shield plate has a substantially cylindrical main body. (3) The shield plate according to claim 1 or 2, wherein the shield plate is a shield plate in which a flange is formed at one end and a notch is provided over the entire length. High frequency inductively coupled plasma/mass spectrometer.