JP5612502B2 - ICP analyzer and analysis method thereof - Google Patents

Description

  The present invention relates to an inductively coupled plasma (hereinafter referred to as ICP) analyzer such as an inductively coupled plasma mass spectrometer (ICP-MS) and an inductively coupled plasma optical emission spectrometer (ICP-OES), and more particularly to plasma of an ICP analyzer. The present invention relates to an ICP analyzer characterized by a torch and a photometry unit and an analysis method thereof.

  FIG. 5 shows an example of a schematic configuration diagram of a conventional ICP analyzer. A plasma torch 51 that generates inductively coupled plasma, an induction coil 52 that applies a high-frequency voltage to the plasma torch 51, plasma light generated in the axial direction of the plasma torch 51, and a direction orthogonal to the axial direction of the plasma torch 51 A condensing unit 53 for taking in the generated plasma light, a fixed mirror 54 for the purpose of causing the light of the plasma generated in a direction perpendicular to the axial direction of the plasma torch 51 to enter the spectroscopic unit 56, and a spectroscope It is composed of a variable mirror 55 having a function of selecting either incident light from the plasma generation direction or light generated in a direction orthogonal to the generation direction.

  By driving the variable mirror 55, measurement is performed by switching between plasma light generated in the axial direction of the plasma torch 51 and plasma light generated in a direction perpendicular to the axial direction of the plasma torch 51 according to the analysis. (See Patent Document 1).

  As described above, the plasma light is condensed from two directions in the ICP analyzer for the following reasons.

  First, in the condensing from the axial direction, more light used for analysis near the central axis can be taken into the spectrometer. The plasma of the ICP analyzer has a donut structure, and the vicinity of the central axis in the plasma generation direction is a low temperature region, a high temperature region toward the periphery thereof, and then becomes a low temperature region again through the high temperature region. The sample is introduced in the direction of the central axis with respect to the center of the plasma of the donut structure. Therefore, there are many samples in the low temperature region of the plasma center, in other words, the measurement sensitivity is improved, so that there is an advantage of focusing in the axial direction. However, in the focusing method of the axial method, a large amount of other coexisting materials are taken together with the sample, so that it is easily affected by the analysis result. In addition, light emission from the plasma gas occurs at high temperatures near the central axis of the plasma. Yes Background for analysis.

  On the other hand, in the case of light collection from the lateral direction of the plasma, the closer to the central axis, the lower the probability of existence of the sample, and the less influence by other coexisting materials. is there.

JP 9-318537 A

However, the conventional ICP analyzer described above has the following problems.
That is, since the fixed mirror 54 and the variable mirror 55 for switching are provided for switching the condensing direction, it is necessary to adjust a plurality of mirrors, and it is necessary to provide drive mechanisms for these mirrors. In order to satisfy these requirements, an appropriate control mechanism is required, and there is a problem that the entire apparatus becomes complicated. Moreover, the cost for providing it also increases. Furthermore, from the viewpoint of the life of the apparatus, the plasma light capturing in the axial direction has a problem in that the life of the so-called detection part is shortened because the condensing part directly receives the heat.

  In this method, either plasma light generated in the axial direction of the plasma torch 51 or plasma light generated in a direction perpendicular to the axial direction of the plasma torch 51, at an arbitrary angle with high sensitivity. I could n’t. Therefore, since the light emitted from the sample introduced into the plasma cannot be taken in from a highly sensitive direction, the efficiency is still inferior.

In order to achieve the above object, the present invention provides the following means.
The present invention relates to a plasma torch in which an ICP analyzer according to the present invention introduces a plasma gas and an atomized sample, an induction coil for applying a plasma torch high-frequency voltage, and a plasma generated by the high-frequency voltage of the induction coil A condensing unit that collects light emitted from the sample excited by the light source, and an analysis processing unit that has a spectroscopic unit that divides the emission spectrum of the collected light. On the other hand, in order to adjust the plasma torch to an arbitrary angle, an angle adjusting mechanism capable of relatively moving the condensing unit and the plasma torch is provided.

  The angle adjusting mechanism is configured such that at least one of the plasma torch and / or the light converging unit is movable, and takes in light from an oblique direction of the plasma. In addition, the movable mechanism is a mechanism that can be relatively rotated by rotating either or both of the plasma torch tip and the condensing part of the detector in a linearly opposed position. It was.

  The ICP analyzer of the present invention and the measurement method thereof are high not only in the axial direction of the plasma light or in the lateral direction thereof but also in any direction with good sensitivity when the plasma light is taken into the light condensing part by the ICP analyzer. Can be implemented with efficiency. In addition, by preventing the plasma and the light condensing part of the plasma from facing each other in the axial direction, the load due to heating of the apparatus can be reduced, and the life of the apparatus can be extended.

It is the schematic which shows the whole ICP analyzer of this invention. 1 is a schematic diagram showing a first embodiment of a plasma torch and a detector relating to an ICP analyzer of the present invention. It is a schematic diagram which shows 2nd Embodiment of the plasma torch and detector in connection with the ICP analyzer of this invention. It is a schematic diagram which shows 3rd Embodiment of the plasma torch and detector in connection with the ICP analyzer of this invention. It is a block diagram which shows an example of the plasma torch periphery part of the conventional ICP analyzer.

  The outline of the ICP analyzer according to the present invention will be described below with reference to FIG. In the drawings, the dimensional ratio is appropriately changed for portions where the dimensional ratio is not important.

FIG. 1 is a schematic diagram of an apparatus for performing spectroscopic analysis as an ICP apparatus according to the present invention.
Gas for forming plasma (argon, nitrogen, helium, etc.) is supplied to the plasma torch 13 from the gas control unit 17. An upper portion of the plasma torch 13 is an opening, and an induction coil 12 is disposed around the outer periphery of the upper end. The gas supplied from the gas control unit 17 is excited by receiving power from the high frequency power source 16. Light is emitted and plasma 11 is generated from the opening above the plasma torch 13.

  The sample is atomized together with the carrier gas from the nebulizer 15, introduced into the vicinity of the center of the plasma 11 by the inner tube of the plasma torch 13 through the spray chamber 14, and excited to emit light.

  Light from the plasma 11 is taken from the light collecting unit 2 and guided to the spectroscopic unit 31. The output detected by the spectroscope 31 is input to the data calculation processing unit 33 and displayed on a monitor attached to the calculation processing unit 33. A commercially available personal computer (PC) can be used as the arithmetic processing unit 33.

  Control during measurement of the high-frequency power supply 16 and the spectroscope 31 is performed via the electronics console 32.

  The angle adjustment mechanism 4 adjusts the angle at which the light collecting unit 2 and the plasma torch 13 face each other so that the light from the plasma 11 can be taken in by the light collecting unit 2 from an arbitrary direction. The angle adjustment mechanism 4 can be controlled by a command from the arithmetic processing unit 33. As this method, the condensing unit 2 and / or the plasma torch 13 is rotated with respect to the center O as a trajectory on a circle indicated by a dashed line.

  Hereinafter, the adjustment of the facing angle between the light collector 2 and the plasma torch 13 will be described with an example.

(First embodiment)
First, a first embodiment of an ICP analyzer according to the present invention will be described with reference to FIG.
FIG. 2 shows an example of a schematic diagram of the configuration of the plasma torch 13 and the condenser 2 of the ICP analyzer of the present invention.

  As shown here, the condensing unit 2 is fixed in position, and is movable so that an arbitrary angular position can be taken with reference to the position where the plasma torch 13 faces the condensing unit 2 (A-A '). It has become.

  The movement is controlled by the angle adjusting mechanism 4, and the plasma torch 13 moves on the inductor 131a. In this case, the plasma torch 13 is driven integrally with the inductor 131a. It is assumed that the positional relationship between the plasma torch 131a and the induction coil 12 is not changed before and after the induction device 131a is driven. The plasma torch 13 may be installed by providing an installation section (not shown) that can be placed, and the installation section may be installed so as to be movable to the inductor 131a.

  The inductor 131a has a ¼ arc shape, and the plasma torch 13 with respect to the light condensing unit 2 includes the plasma axial direction (AA ′) to the plasma lateral direction (2A-2A ′). Arbitrary angles can be taken within the range of degrees. Therefore, the optimum angle can be set in consideration of the sensitivity due to the convenience of the sample or the lifetime of the apparatus. Specifically, the plasma torch 13 is attached to the inductor 131a by a fixing tool (not shown), and is fixed to the inductor 131a by, for example, a spring pressure. In this case, a rail-like member having a concavo-convex portion can be used as the main body portion of the inductor 131a. Moreover, the plasma torch 13 is detachable and attached at an arbitrary position.

  The angle adjusting mechanism 4 is divided into a driving part of the inductor and a fixed part. The drive part is a manual operation method in which the drive unit is manually operated, and an automatic operation method in which the arithmetic device 33 and the electronics console 32 are used as a control console, and a drive system such as a motor is controlled by a signal from the control device 33 and the electronic console 32. Any of these may be used. In the fixed portion, when a manual operation method is adopted, for example, a ball plunger or the like can be used to specify the angle of the plasma torch 13 for each stepwise arbitrary angle, for example, a screw presser is used. Thus, one of continuous angle adjustments can be selected. When adopting the automatic operation method, for example, a method for performing continuous angle adjustment using the number of pulses of the motor, for example, by specifying a stepwise arbitrary angle by installing a sensor for each arbitrary angle. A method etc. can be adopted.

(Second Embodiment)
FIG. 3 shows a schematic diagram of a configuration different from that of the first embodiment as the configuration of the plasma torch 13 and the condensing unit 2 of the ICP analyzer of the present invention.

  In the present embodiment, an arbitrary angle with the plasma torch 13 can be set by moving the condenser 2 on the inductor 311a with respect to the configuration of the first embodiment. The operations and effects in this embodiment are the same as those in the first embodiment.

  In this case, the inductor 311a is used to drive the spectroscopic unit 31 and is driven so as to adjust the positional relationship with respect to the fixed plasma torch 13.

  The angle adjusting mechanism is the same as that of the first embodiment except that the object to be driven is changed from the plasma torch 13 to the spectroscopic unit 31.

(Third embodiment)
FIG. 4 shows a third embodiment of the present invention. In the first and second embodiments, either the light collecting unit 2 or the plasma torch 13 is movable, but both are movable.

  In this case, the inductors 131b and 311b have a reference (C-C ') when the plasma torch 13 and the light condensing part 2 are arranged on a straight line facing each other, and both of them are either above or below the horizontal plane. It is provided on the surface side. Since both the plasma torch 13 and the condensing part 2 are movable, each movable range corresponds to the shape of a 1/8 arc, and the angle is relatively 0 (plasma generation axis direction) to 90 degrees (direct plasma lateral direction). Can be realized. Thus, by moving both the plasma torch 13 and the light converging unit 2 and controlling them by the angle adjusting mechanism 4, the movable range of the apparatus can be halved and the installation area can be reduced.

In this case, the inductors 131b and 311b are for driving the plasma torch 13 and the spectroscopic unit 31, respectively, and the respective angles can be controlled independently.
The angle adjustment mechanism is the same as that in the first embodiment.

  As described above, the ICP analyzer of the present invention is characterized in that the plasma torch and the condensing unit that takes in light from the plasma can be set at an arbitrary angle.

In the ICP analyzer of the present embodiment, the plasma torch 13 and the induction coil 12 are interlocked as shown in the embodiment, and the condensing unit 2 is shown integrally with the spectroscopic unit 31, but is not limited thereto. It is not a thing.
Moreover, although the case of the spectroscope was shown in this embodiment, you may use a mass spectrometer.

  In addition, the above-described inductor may be a movable rail or a guide groove, and may be any mechanism that can change the facing state between the plasma torch and the light collecting unit.

  In addition, the present invention is not limited to the contents described in the embodiment of the present invention, and the present invention is not limited as long as the configuration is suitable for the effects of the present invention (the plasma torch and the light converging unit are opposed to each other at an arbitrary angle). It belongs to the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Plasma light emission control part 2, 2a, 2b, 53 ... Condensing part 3 ... Analysis processing part 4 ... Angle adjustment mechanism 11 ... Plasma 12, 52 ... Induction coil 13, 13a, 13b, 51 ... plasma torch 14 ... spray chamber 15 ... nebulizer 18 ... sample 31, 31a, 31b ... spectroscopic part 131a, 131b, 311a, 311b ... inductor 33 ..Calculation device (computer)
54... Fixed mirror 55... Variable mirror 56.

Claims (4)

A plasma torch into which a plasma gas and atomized sample are introduced;
An induction coil for applying a high frequency voltage to the plasma torch;
A condensing unit that condenses light emitted from the sample excited by the plasma generated by the high-frequency voltage of the induction coil;
In an ICP analyzer comprising: an analysis processing unit having a spectroscopic unit that divides the emission spectrum of the collected light;
In order to adjust the plasma torch to an arbitrary angle with respect to the direction in which the light of the plasma is taken in by the light collecting part, an angle adjusting mechanism capable of relatively moving the plasma torch and the light collecting part,
The angle adjustment mechanism includes an installation unit in which the plasma torch and the light collecting unit are installed, a guide unit that guides the movement of the installation unit, and an angle detection mechanism that adjusts the arbitrary angle to detect the angle with the best sensitivity. ICP analyzer characterized by having.   2. The ICP analyzer according to claim 1, wherein the relative movement between the plasma torch and the light collecting unit in the angle adjusting mechanism is movable so that one or both of the plasma torch and the light collecting unit rotate. .   3. The ICP analyzer according to claim 1, wherein the angle adjustment mechanism further includes an arithmetic processing unit, and either or both of the plasma torch and the light collecting unit are independently driven by automatic control by the arithmetic processing unit. . A sample introduction step for introducing the plasma gas and the atomized sample into the plasma torch;
A plasma emission step of emitting plasma by applying a high-frequency voltage to an induction coil provided around the plasma torch; and
A condensing step for condensing light emitted from the sample excited by the plasma;
An analysis processing step of analyzing the emission spectrum by splitting the collected light;
In the analysis method by the ICP analyzer according to any one of claims 1 to 3 , comprising:
The condensing step arranges the plasma torch and the light condensing part condensing the light emitted from the sample in a straight line with respect to the direction in which the light emission of the plasma is taken in, and an arbitrary position between them is a rotation center As an analysis method using an ICP analyzer, one or both of the plasma torch and the light converging unit are driven to face each other at an arbitrary angle.

Images