JP2000214093A - Inductively coupled plasma emission spectrochemical analyzing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a positional relationship constant even when a force is applied to a torch by setting a torch branch pipe clip which enables a torch branch pipe to be fitted by rotating the torch centering a center axis of the torch. SOLUTION: The inductively coupled plasma emission spectrochemical analyzing apparatus is provided with a torch branch pipe clip 9 for holding, e.g. a plasma gas feed pipe 10 of a torch 12. A gap of the torch branch pipe clip 9 has an equal size to an outer diameter of the plasma gas feed pipe 10. The plasma gas feed branch pipe 10 is fitted by rotating the torch 12 about a center axis of the torch after setting the torch to a torch-fixing tool 7. The fixed torch 12 is accordingly prevented from moving back and forth in a direction of the center axis. A positional relationship in the direction of the center axis between an XYZ stage 14 and the torch 12 is kept constant. Unless a position of the XYZ stage 14 changes, a positional relationship between a plasma 2 formed to a leading end of the torch 12 and a sampling cone 1 or the like is constant at all times, and therefore measurement results of good reproducibility can be obtained.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for holding a torch of an inductively coupled plasma analyzer. 2. Description of the Related Art A conventional inductively coupled plasma analyzer is shown in FIG.
As shown in FIG. 4, the sample is introduced into the torch 12 for generating the plasma 2, and the sample is emitted or ionized by the plasma 2. Then, the emitted light is separated into spectrum light of each wavelength and detected by a photodetector (not shown), or the ionized sample is detected by a mass spectrometer (not shown), thereby forming a sample. Perform qualitative and quantitative analysis of contained elements. Usually, the torch 12 is formed of a coaxial triple cylindrical tube, and a sample introduced from a sample supply unit (not shown) connected to the torch 12 passes through the innermost tube 6 of the triple cylindrical tube. Is introduced into the plasma 2. Innermost tube 6 of torch 12
An intermediate pipe 5 is disposed radially outside of the intermediate pipe 5, and auxiliary gas is supplied to the intermediate pipe 5 through an auxiliary gas supply branch pipe 11 provided radially inward of the intermediate pipe 5 so as to communicate with the inside of the intermediate pipe 5. Passed through. Further, an outermost tube 4 is disposed radially outside the intermediate tube 5, and a plasma gas supply branch pipe 10 provided radially inside the outermost tube 4 so as to communicate with the inside of the outermost tube 4. Then, the plasma gas is passed through the outermost tube 4. On the XYZ stage 14, a matching box 13 for adjusting the transmission of high-frequency power is fixed, and the matching box 13 has an induction coil 3 for flowing high-frequency power around the tip of the torch 12. Is provided. The torch fixture 7 is further attached to the XYZ stage 14, and the torch 12 is held by tightening the torch fixture 7 from the outside in the radial direction of the outermost cylindrical tube 4 with the tightening screw 8. In the case of an emission spectrometer of the inductively coupled plasma analyzer, plasma generated at the tip of the torch 12 is used.
The light emitted from the sample by 2 enters a spectroscope (not shown) via an incident optical system (not shown) such as a condenser lens or an entrance slit. The spectroscope separates the light into spectral light of each wavelength, and the light is analyzed by a photodetector. On the other hand, in the case of a mass spectrometer among the inductively coupled plasma analyzers, a plasma
A sampling cone 1 through which the sample ionized by 2 passes is provided, and the sample is analyzed by a mass spectrometer (not shown) after passing through the hole of the sampling cone 1. Here, since the emission intensity and ionization rate of the sample in the plasma 2 differ depending on the site in the plasma 2, when the positional relationship between the plasma 2 and the incident optical system or the sampling cone 1 changes, it is led to the photodetector. The light intensity and the amount of the ionized sample guided to the mass spectrometer change, and even if the same sample is measured, the sensitivity greatly differs. Therefore, when attaching the torch 12 to the torch fixture 7, the torch 12 is fixed so as not to move from the torch fixture 7, and the position of the XYZ stage 14 to which the torch fixture 7 is fixed is controlled from a personal computer. The positional relationship between the torch 12 and the incident optical system or the sampling cone 1 is adjusted. In the above-mentioned prior art, the torch 12 is held by tightening the torch fixture 7 from the radially outer side of the cylindrical outermost tube 4 of the torch 12. As shown in Fig. 5, the torch fixing device sandwiches two plates with a V-shaped groove from both sides of the torch 12, and the central axis of the cylindrical torch 12 is formed due to the V-shaped groove. Is held so as not to shift. However, the holding method described above has insufficient holding force in the center axis direction of the torch 12 and reproducibility of the detached position. Therefore, when a load such as the weight of a sample supply unit (not shown) connected to the torch 12 is applied to the torch 12, or before and after the torch 12 is detached from the torch fixture 7, the position of the torch 12 changes. There was something. Therefore, if the positional relationship between the torch 12 held on the XYZ stage 14 via the torch fixture 7 and the incident optical system and the sampling cone 1 is constant even though the position of the XYZ stage 14 has not changed. Did not. In such a case, even if the same sample is measured under the same measurement conditions, the same sensitivity cannot be obtained, and the torch is not used.
12 It was not possible to compare the measured results before and after desorption. [0009] The present invention solves the above-mentioned problems, and the torch 12 can be provided even when a force is applied to the torch 12 or when the torch 12 is detached.
It is necessary to obtain an inductively coupled plasma analyzer that can maintain a constant positional relationship between the laser beam, the incident optical system, and the sampling cone 1, and can obtain a highly reproducible measurement result in the same sample under the same conditions. Aim. [0010] In order to achieve the above object, an inductively coupled plasma analyzer adopted by the present invention has a torch branch pipe clip, and rotates the torch about a central axis of the torch. Thereby, the branch pipe of the torch can be fitted into the torch branch pipe clip. The torch branch pipe clip of the inductively coupled plasma analyzer of the present invention is fixed to the XYZ stage, and the gap between the torch branch pipe clips has the same size as the outer diameter of the branch pipe. Does not move back and forth in the direction of the torch center axis. Further, even when the torch is rotated around the torch center axis, the position of the torch center axis is fixed by the V-shaped groove-shaped torch fixing tool, so that the torch is always kept at the same position. The position of the center axis of the torch and the position of the torch in the direction of the center axis of the torch are always the same with respect to the torch fixture fixed to the XYZ stage, so that the position of the torch is maintained unless the position of the XYZ stage changes. , And the positional relationship with the incident optical system and the sampling cone is always kept constant.
Therefore, the positional relationship between the torch and the incident optical system or the sampling cone can be kept constant even when a force is applied to the torch or when the torch is attached or detached, and the measurement results with good reproducibility when measuring the same sample under the same conditions Can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to FIGS. Note that in FIGS. 1 to 3, FIG.
Components described in 5 and having almost the same function may not be described here. The torch 12 is made of a triple cylindrical quartz tube, and gas (eg, argon gas) is supplied from the plasma gas supply branch pipe 10 to the tip of the torch 12 via the outermost tube 4, and high frequency power (eg, , A frequency of 27.12 MHz and a power of 1.6 kW) to form a plasma 2. Reference numeral 11 denotes an auxiliary gas supply branch pipe, and auxiliary gas is supplied to the tip of the torch 12 through the intermediate pipe 5. The sample that reaches the torch 12 via a sample supply unit (not shown) is supplied to the tip of the torch 12 through the innermost tube 6 among the triple tubes of the torch 12, and is ionized by the plasma 2. The ionized sample is the sampling cone
It passes through hole 1 and is analyzed by a mass spectrometer (not shown). Here, since the ionization rate of the sample differs depending on the site in plasma 2, plasma 2 and sampling cone 1
Is changed, the amount of the ionized sample passing through the hole of the sampling cone 1 changes, and even if the same sample is measured, the sensitivity greatly differs. Therefore, in order to obtain the optimum sensitivity, the plasma 2 formed at the tip of the torch 12 and the sampling cone
Need to adjust the position with 1. At this time, since the position of sampling cone 1 is fixed, the torch fixture
The optimum position of the torch 12 is adjusted by moving the XYZ stage 14 to which the torch 12 is fixed via the computer 7 under the control of a personal computer. The adjusted position of the XYZ stage 14 is stored in the personal computer, and the XYZ stage 14 can be returned to the stored position at any time.
If the position is shifted after the adjustment, the position of the plasma 2 formed at the tip of the torch 12 and the sampling cone 1 will be shifted, and even though the XYZ stage 14 is at the adjusted optimum position, No sensitivity will be obtained. The torch fixture 7 fixed to the XYZ stage 14 has a V-shaped groove as shown in FIG.
Since the two plates are sandwiched from both sides of the torch 12, even when the torch 12 held by the torch fixing device 7 is rotated around the torch center axis, the position of the torch The positional relationship between the XYZ stage 14 and the center axis of the torch is always kept constant. After the torch 12 is attached to the torch fixture 7, the plasma gas supply branch pipe 10 of the torch 12 can be fitted by rotating the torch around the torch center axis as shown in FIG. Since the gap between the torch branch pipe clips 9 is the same as the outer diameter of the plasma gas supply branch pipe 10 as shown in FIG. 3, the fixed torch 12 does not move back and forth in the torch center axis direction. The positional relationship between the stage 14 and the torch 12 in the direction of the torch center axis is always kept constant. Since the position of the torch center axis and the position of the torch 12 in the direction of the torch center axis are always the same with respect to the XYZ stage 14, the torch 12 is formed at the tip of the torch 12 unless the position of the XYZ stage 14 changes. The positional relationship between the plasma 2 and the sampling cone 1 is always kept constant. Therefore, when a force is applied to the torch 12 or the attachment / detachment of the torch 12, the positional relationship between the plasma 2 and the sampling cone 1 does not change, and a highly reproducible measurement result can be obtained by measuring the same sample under the same conditions. be able to. In the above description, the torch branch pipe clip 9 fitted into the plasma gas supply branch pipe 10 has been described. However, it is apparent that the torch branch pipe clip 9 fitted into the auxiliary gas supply branch pipe 11 also has the effect of the present invention. Further, in the above description, the inductively coupled plasma mass spectrometer constituted by the sampling cone 1 and the mass spectrometer (not shown) has been described, but the inductively coupled plasma mass spectrometer constituted by the incident optical system and the spectroscope (not shown) has been described. It is clear that the plasma emission spectrometer also has the effects of the present invention. That is, the invention of the present application is directed to a coaxial multiple cylindrical tube, wherein branch pipes respectively communicating with the inside of each cylindrical tube constituting the multiple cylindrical tube are directed radially inward of each cylindrical tube. In an inductively coupled plasma analyzer including a torch arranged in each case and a torch fixture for holding the torch, the torch is rotated by rotating the torch about an axis of the multiple cylindrical tubes. , Equivalent to plasma gas supply branch 10 or auxiliary gas supply branch 11)
An inductively coupled plasma analyzer having a torch branch pipe clip into which a torch can be fitted. According to the present invention, there is provided an inductively coupled plasma analyzing apparatus having a torch branch pipe clip, and attaching the torch to a torch fixture and then rotating the torch around a torch center axis. Since the structure is such that the tube can be fitted into the torch branch tube clip, the following effects are obtained. (1) The fixed torch does not move back and forth in the torch center axis direction, and the positional relationship between the XYZ stage and the torch in the torch center axis direction is always kept constant. (2) The positional relationship between the XYZ stage and the torch does not shift when a force is applied to the torch or when the torch is attached or detached. (3) Since the positional relationship between the XYZ stage and the torch is always constant, as long as the position of the XYZ stage is the same, the positional relationship between the plasma formed at the tip of the torch and the incident optical system and the sampling cone is always constant. Will be kept. (4) Since the positional relationship between the plasma and the incident optical system or the sampling cone is always constant, the sensitivity of the same sample is always kept constant under the same conditions, and measurement with good reproducibility can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross section of an inductively coupled plasma analyzer according to an embodiment of the present invention. FIG. 2 is a front view of an inductively coupled plasma analyzer according to an embodiment of the present invention. FIG. 3 is a top view of an inductively coupled plasma analyzer according to an embodiment of the present invention. FIG. 4 is a schematic cross section of a conventional inductively coupled plasma analyzer. FIG. 5 is a front view of a conventional inductively coupled plasma analyzer. [Description of Signs] 1 Sampling cone 2 Inductively coupled plasma 3 Induction coil 4 Outer tube 5 Intermediate tube 6 Inner tube 7 Torch fixture 8 Clamping screw 9 Torch branch pipe clip 10 Plasma gas supply branch 11 Auxiliary gas supply branch 12 Torch 13 Matching box 14 XYZ stage 15 XYZ stage moving direction

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yoshitomo Nakagawa             1-8 Nakase, Mihama-ku, Chiba-shi, Chiba             Iko Instruments Inc. (72) Inventor Osamu Matsuzawa             1-8 Nakase, Mihama-ku, Chiba-shi, Chiba             Iko Instruments Inc. F term (reference) 2G043 AA01 EA08 GA11 GB01 GB05                       GB19 JA01

Claims (1)

Claims: 1. A coaxial multiple cylindrical pipe, wherein a branch pipe communicating with the inside of each cylindrical pipe constituting the multiple cylindrical pipe is radially inward of each of the cylindrical pipes. In an inductively coupled plasma analyzer equipped with a torch and a torch fixture holding the torch, the branch pipe is rotated by rotating the torch about the axis of the multiple cylindrical pipe. An inductively coupled plasma analyzer having a torch branch tube clip that can be fitted.