JPH0644009Y2 - High frequency inductively coupled plasma mass spectrometer - Google Patents

Description

[Detailed Description of the Invention] <Industrial field of application> The present invention is a high frequency wave that prevents damage to the high frequency induction coil and the plasma torch when the high frequency inductively coupled plasma (argon plasma) causes an abnormal discharge. An inductively coupled plasma mass spectrometer.

<Prior Art> A high frequency inductively coupled plasma mass spectrometer excites a sample using high frequency inductively coupled plasma and guides the generated ions to a mass spectrometer through an interface consisting of a nozzle and a skimmer to electrically detect them. By precisely measuring the amount of ions, the element to be measured in the sample is analyzed with high accuracy. FIG. 2 is a diagram illustrating the configuration of a conventional example of such a high frequency inductively coupled plasma mass spectrometer.
In this figure, matching box 1 ^- on the outer tube 1b of the plasma torch 1 provided in the outermost tube 1c argon gas is supplied from an argon gas supply source 3 via a gas regulator 2, the inner tube 1a The sample in the sample tank 4 is atomized by the nebulizer 5 and then carried in by argon gas. A high-frequency current is applied to the high-frequency induction coil 6 wound around the plasma torch 1 by a high-frequency power source 10 and a high-frequency magnetic field (not shown) is formed around the coil 6. On the other hand, the inside of the fore chamber 11 sandwiched between the nozzle 8 and the skimmer 9 is sucked by the vacuum pump 12 to, for example, 1 Torr. Further, ion lenses 14a and 14b are provided in the center chamber 13, and the inside of the center chamber 13 has a first oil diffusion pump.
By 15 for example 10 ⁻⁴ Torr. The inside of the rear chamber 17 that has been sucked into the chamber and that houses the mass filter (for example, a quadrupole mass filter) 16 is, for example, 10 ⁻⁵
Torr. Have been sucked into. In this state, when electrons or ions are implanted in the argon gas in the vicinity of the high frequency magnetic field, high frequency induction plasma 7 is instantaneously generated by the action of the high frequency magnetic field. Ions in the plasma 7 are transferred to the nozzle 8
After passing through the skimmer 9 and small disk 14a and ion lens 1
After being converged between 4b and 14c, it is guided to the secondary electron multiplier 19 through the mass filter 16 and detected, and the detection signal is sent to the signal processing unit 20 to be calculated and processed. The elemental analysis value to be measured in the sample is obtained. Further, FIG. 3 is a perspective view showing a cutting structure of a conventional example in which a main part of a conventional high frequency induction plasma mass spectrometer is partially cut, and the same symbols as those in FIG. 2 have the same meanings. The redundant description used here is omitted. Also,
Reference numeral 21 is a spray chamber for removing droplets from the atomized sample sent from the nebulizer 5, 22a is a torch mounting bracket to which the plasma torch 1 is mounted and fixed, and 22b is spray chamber 21 to be fixed. It is a bracket for mounting the chamber. In essential parts of a conventional high frequency induction plasma mass spectrometer having such a configuration, a plasma torch 1 torch box 1 by the torch mounting bracket 22a ^- is fixed to the spray chamber 21 torch box 1 by chamber mounting bracket 22b ^- It is firmly fixed to.

<Problems to be Solved by the Invention> However, in the above conventional example, the high frequency induction coil is used.
6, the spray chamber 21 and the plasma torch 1 are only fixedly arranged in the torch box 1 ^- by brackets 22a, 22b. That the argon gas is filled for some reason in toward the high-frequency induction coil 6 and the ventilation of the wire mesh 23 abnormal discharge occurs, damaging the high-frequency induction coil 6 and a spray chamber 21, etc. ^- Therefore, torch box 1 There was a flaw.

The present invention has been made in view of the drawbacks of the conventional example, and an object thereof is to prevent damage to the high frequency induction coil or the plasma torch when the high frequency inductively coupled plasma (argon plasma) causes an abnormal discharge. Another object of the present invention is to provide a high-frequency inductively coupled plasma mass spectrometer that prevents the above.

<Means for Solving Problems> A feature of the present invention for solving the above problems is that a torch box in which a plasma torch for generating high frequency inductively coupled plasma is housed in a high frequency inductively coupled plasma mass spectrometer. A metal piece having a sharp tip is provided therein, and the metal piece is kept at the ground potential to guide the discharge generated in the torch box.

<Operation> The present invention operates as follows. That is, when the torch box is filled with argon gas for some reason, an abnormal discharge occurs inside the plasma torch. This discharge is directed to the metal piece that functions as a lightning rod, and is not guided to the high frequency induction coil or the wire mesh for ventilation. Therefore, even if an abnormal discharge occurs inside the plasma torch, the high-frequency induction coil and the ventilation wire mesh are not damaged.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. First
The drawing is a perspective view of a main part cutting structure in which a part of the main part of the present invention is cut, and the same symbols as those in FIG. 3 are used with the same meanings, and duplicate explanations are omitted here. To do. Also,
23 metal pieces that function as electrical earth potential the tip portion is formed at an acute angle, 24 a metal strip 232 torch box 1 ^- a fixing base for fixing via a mounting screw into.

In an embodiment of the present invention having such a configuration, the torch box 1 for some reason (for example, when the plasma torch 1 as cracked, etc.) ^- the argon gas within is filled, the plasma torch 1 ^- inside the Abnormal discharge occurs. However, this discharge is directed to the metal strip 23 if it were functioning as a lightning rod, said high frequency induction coil 6 and the ventilation of the wire mesh as in the conventional example (not shown usually, the torch box 1 ^-. Provided in the cover of the cover There is no such thing as a guide. Therefore, the plasma torch 1 ^- be inside abnormal discharge occurs, the like conventional above wire mesh of high-frequency induction coil 6 and ventilation as is not damaged.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the shape of the metal piece 23 may be needle-like.

<Effect of the Invention> According to the present invention as described in detail above, a metal piece having a sharp tip is provided in a torch box containing a plasma torch for generating high-frequency inductively coupled plasma. The discharge was generated in the torch box while maintaining the ground potential. Therefore, it is possible to realize a high frequency inductively coupled plasma mass spectrometer which prevents damages to the high frequency inductive coil, the plasma torch and the like when the high frequency inductively coupled plasma (argon plasma) causes an abnormal discharge.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cutting structure of an essential part of an embodiment of the present invention, FIG. 2 is an explanatory view showing an overall structure of a high frequency inductively coupled plasma mass spectrometer, and FIG. 3 is a perspective view showing a cutting structure of a conventional part. . 1 ...... plasma torch 1 ^- ... Torch box, 3 ...... argon gas supply source, 7 ...... inductively coupled plasma, 8 ... nozzle, 9 ... skimmer, 16 ... mass filter, 20 ... signal processing Part 21 …… Spray chamber, 22 …… Bracket, 23 …… Metal piece, 24 …… Fixing stand

Claims (1)

[Scope of utility model registration request] 1. An element to be measured in a sample is analyzed by introducing ions generated by exciting a sample using high frequency inductively coupled plasma to a mass spectrometer detector through an interface consisting of a nozzle and a skimmer and detecting the ions. In the analyzer described above, a metal piece having a sharp tip is provided in a torch box containing a plasma torch for generating the high frequency inductively coupled plasma, and the metal piece is kept at a ground potential in the torch box. A high-frequency inductively coupled plasma mass spectrometer, which is characterized in that it induces a discharge generated in.