JPH0542371Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a plasma torch for high-frequency inductively coupled plasma emission spectrometry (hereinafter referred to as ICP).

[Problems to be solved by conventional techniques and ideas]

ICP is widely used because it can accurately analyze many trace elements contained as impurities in the main components in solution state. The ICP device uses Ar gas or _N2 gas as a fuel gas, and generates a high-temperature plasma of several thousand degrees by heating this with high frequency. A sample solution is introduced into this plasma to make the elements in an excited state, and the The light produced when the energy level of an element falls to its ground state is now analyzed spectroscopically. Therefore, in IPC equipment, a quartz plasma torch is used as a plasma creation member to withstand high-temperature plasma.
This is structured such that a fuel gas pipe and a cooling gas pipe are arranged concentrically in order around a sample suction pipe on the outside thereof, and the tip surfaces of each of the three pipes become higher in order toward the outside. It was something I had.

However, when plasma is ignited, the plasma is often unstable, so the plasma swings and touches the tip of the plasma torch, that is, the tip of the cooling gas pipe, melting and deforming the tip, making ignition difficult. Inconveniences tend to occur in the analysis, such as not being able to obtain the normal shape of the plasma, or elements in the sample adhering to the inner wall of the tip of the cooling gas tube and weakening the tip, which can be expensive. The entire plasma torch had to be replaced, which was extremely uneconomical.

In view of the above-mentioned problems, the present invention provides a very economical plasma torch for high-frequency inductively coupled plasma emission analysis, which eliminates the need to replace the entire plasma torch even if the tip of the plasma torch melts and deforms or becomes brittle. The purpose is to

[Means and actions for solving problems]

A fuel gas pipe and a cooling gas pipe are placed concentrically in order around the sample suction pipe, and
In the plasma torch for high-frequency inductively coupled plasma emission analysis, which is configured such that the tip surfaces of the three tubes become higher in order as they go outward, the main body of the cooling gas tube is located at a position protruding from the tip surface of the fuel gas tube. The cap is separable from the tip at a ground-adjusted contact surface, and the tip is covered with a cylindrical cap that is slightly longer than the tip and has a flange and has a high-frequency coil wound around the outer periphery. By being fitted, if the tip of the plasma torch, that is, the tip of the cooling gas pipe becomes melted and deformed or becomes brittle, only the tip needs to be replaced.

〔Example〕

The present invention will be explained in detail below based on an embodiment shown in the drawings.

The drawing shows a longitudinal sectional view of an embodiment of the plasma torch of the present invention, in which 1 is a sample suction tube having an inlet 1a at the lower end and an outlet 1b at the upper end (tip);
2 is a fuel gas tube which is arranged concentrically outside the sample suction tube 1 and has an inlet 2a at the lower end and an outlet 2b at the upper end (tip) of the enlarged upper part;
3 is arranged concentrically on the outside of the fuel gas pipe 2, with an inlet 3a at the lower end and an outlet 3 at the upper end (tip).
cooling gas pipes each having b. The tip surfaces of the sample suction tube 1, the fuel gas tube 2, and the cooling gas tube 3 are configured to become higher in order toward the outside, and the tip surface of the cooling gas tube 3 is higher than the tip surface of the fuel gas tube 2. The portion (tip portion 3c) is replaceable. That is, the main body 3d of the cooling gas pipe 3
can be separated from the tip portion 3c at the contact surface 3e which is adjusted to fit in front of the tip surface of the fuel gas pipe 2. 4 is a cylindrical flanged cap that is slightly longer than the tip 3c and is fitted onto the tip of the cooling gas pipe 3; 5 is a high frequency coil wound around the outer circumference of the cap 4;

Next, how to use the plasma torch of the present invention will be explained.

First, place the tip 3c on the upper end surface of the main body 3d of the cooling gas pipe 3, rub it together so that there is no gap between the contact surfaces 3e (which would cause air to enter and extinguish the plasma), and then 3e Bring comrades into close contact. Next, the cap 4, around which the high-frequency coil 5 is wound in advance, is fitted onto the upper end of the main body 3d and the tip 3c of the cooling gas pipe 3, as shown, and the tip 3c is fixed to the upper end. Next, Ar gas is flowed into the fuel gas pipe 2 and the cooling gas pipe 3 to be ejected from the tip of the plasma torch, and after the gas flow is stabilized, a high frequency electromagnetic field is applied by the high frequency coil 5 and a Tesler discharger (not shown) is used. ignites and ionizes to form plasma. Then, according to the principle of atomization, the sample solution is sucked out from the outlet of the sample suction tube 1 by the flow of Ar gas, vaporized, and introduced into the plasma, and the light emitted at that time is used for spectroscopic analysis as in the conventional method. be done. At this time, if the ignition condition is poor and the plasma becomes unstable and touches the tip 3c and the tip 3c melts and deforms or becomes brittle, it is sufficient to replace only the tip 3c. Therefore, it is very economical because there is no need to replace the entire plasma torch as in the conventional method.
Further, the replacement work at that time is extremely easy as it is only necessary to remove the cap 4, replace the tip 3c, and then fit the cap 4 on again, which greatly contributes to the analytical work.

[Effect of idea]

As mentioned above, the plasma torch for high-frequency inductively coupled plasma emission analysis according to the present invention does not require replacing the entire plasma torch even if the tip of the plasma torch melts and deforms or becomes brittle, making it extremely economical and practical. It has important advantages.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of an embodiment of a plasma torch according to the present invention. 1...Sample suction tube, 2...Fuel gas pipe, 3...
Cooling gas pipe, 3c... tip, 4... cap,
5...High frequency coil.

Claims (1)

[Scope of utility model registration request] A fuel gas pipe and a cooling gas pipe are placed concentrically in order around the sample suction pipe, and
In the plasma torch for high-frequency inductively coupled plasma emission analysis, which is configured such that the tip surfaces of the three tubes become higher in order toward the outside, the main body of the cooling gas tube is located at a position protruding from the tip surface of the fuel gas tube. The cap is separable from the tip at a ground-adjusted contact surface, and the tip is covered with a cylindrical cap that is slightly longer than the tip and has a flange and has a high-frequency coil wound around the outer periphery. A plasma torch characterized by being fitted.