JP2007205898A - Icp analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically discriminate the kind of the plasma torch mounted on an ICP analyzer. <P>SOLUTION: The ICP analyzer is equipped with an impedance adjusting part for matching the impedance of an induction coil with the outputs impedance of a power supply part so as to minimized the reflected power at the time of lighting of plasma, a set value memory part in which a set value at the time of matching is preserved at every kind of the plasma torch and a discrimination means for discriminating the kind of the plasma torch mounted on the ICP analyzer on the basis of the set value at the time of matching due to the impedance adjusting part and the standard set value preserved in the set value memory part. In order to automatically prevent the melt loss of the torch and the damage of the peripheral part of the torch, it is desirable to stop the supply of power to the induction coil in a case that the kind of the torch set to the control part is different from the kind of the actually mounted torch. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ICP analyzer using an ICP light source that causes plasma emission or ionization of a liquid sample, such as an ICP (Inductively Coupled Plasma) emission analyzer or an ICP mass spectrometer.

  An ICP emission spectrometer is included in a sample by measuring the wavelength and intensity of the atomic spectrum by spectroscopically analyzing the light that is introduced into the plasma and emitted when the excited sample atoms transition to a low energy level. Elemental qualitative or quantitative determination is performed (for example, see Patent Document 1).

  FIG. 3 shows a schematic configuration diagram of a conventional general ICP emission analyzer. This ICP emission analyzer includes a plasma torch wrapped around an induction coil, a power supply unit that supplies high-frequency power to the induction coil, an impedance adjustment unit, a sample introduction unit, a gas flow rate control unit, a spectrometer, a detector, data It consists of a processing unit, a control unit, and the like.

  When analyzing a sample using an ICP emission spectrometer, the plasma is turned on as follows before the sample is introduced; cooling gas and auxiliary gas (usually from the gas flow control unit to the plasma torch) In either case, Ar is used), and a predetermined high frequency power is applied to the induction coil while supplying a predetermined flow rate, and spark discharge is used to light the high frequency induction plasma. By introducing the atomized sample into the plasma, excitation light emission of the sample molecules occurs.

  When the plasma is turned on, the impedance when the induction coil side is viewed from the high-frequency power supply device side (hereinafter simply referred to as “the impedance of the induction coil”) changes greatly.

  Here, in order to efficiently supply power to the plasma, a process of matching the impedance of the high-frequency power supply and the impedance of the induction coil is performed (in the present specification, simply referred to as “impedance matching” or simply “matching”). Refers to the matching between the impedance of the high frequency power supply and the impedance of the induction coil). Since the impedance of the high-frequency power supply is normally designed to be 50Ω, impedance matching is performed so that the impedance of the induction coil viewed from the power supply device side is also 50Ω. By properly performing this impedance matching, the incident power is injected into the plasma with the highest possible efficiency (ie, the reflected power is minimized). This impedance matching is generally performed by increasing or decreasing the capacity of the variable capacitor in the matching circuit of the impedance adjusting unit.

  By the way, in ICP analysis, it is common to use different plasma torches with different shapes depending on the type and application of the sample to be measured. For example, a high salt torch has a wider shape near the outlet than a standard torch in order to prevent deposition of deposited salt. In addition, the organic solvent torch is expected to have a large internal volume in anticipation of the volatile content of the sample in the torch. On the contrary, the internal volume of the torch for suppressing consumption of the analysis gas is small. In this way, the torch has a different shape and internal volume for each type, and the appropriate values of the incident power and the gas flow rate differ accordingly.

  After the plasma torch is attached or replaced, the operator needs to set the type of torch currently attached to the ICP analyzer. Conventional ICP analyzers do not have a function to identify the actually installed torch, so if the operator makes a mistake in this setting, the incident power and gas amount suitable for a different type of torch are not obtained. As a result, the temperature of the torch was excessively increased, and there was a possibility that it was melted by heat. In addition, the torch not only melts down, but there is a possibility that surrounding parts may be damaged by the heat.

  For example, the type of torch set in the control unit of the ICP analyzer is applied if the internal volume is a standard size torch while actually mounting a small-sized torch with a small internal volume. Since the high frequency power is too large, the temperature of the torch rises and the torch melts. In addition, if the torch type set in the control unit is a small-sized torch while a standard-size torch is installed, the cooling gas flow rate will be insufficient and the torch temperature will rise. Then the torch melts down.

Japanese Patent Laid-Open No. 10-253540

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ICP analyzer that can automatically identify the type of torch that is mounted.

An ICP analyzer according to the present invention, which has been made to solve the above problems,
A plasma torch into which a plasma forming gas is introduced, an induction coil arranged around the plasma torch, and a power supply unit that generates high-temperature plasma in the plasma torch by applying high-frequency power to the induction coil And a control unit that controls high-frequency power, gas flow rate, etc. according to the type of plasma torch set in advance,
a) an impedance adjustment unit that matches the impedance of the induction coil and the output impedance of the power supply unit so that the reflected power during plasma lighting is minimized;
b) a set value storage unit in which standard set values, which are set values at the time of impedance matching, are stored for each type of plasma torch;
c) a torch identifying unit for identifying a type of plasma torch mounted on the ICP analyzer based on a set value at the time of matching by the impedance adjusting unit and a standard set value stored in the set value storage unit; ,
It is characterized by providing.

  In addition, the ICP analyzer according to the present invention is preferably configured such that the type of plasma torch preset for the control unit of the ICP analyzer is different from the type of plasma torch identified by the identifying means. It is preferable to further include power supply control means for stopping the operation of the power supply unit.

  The ICP analyzer according to the present invention can be applied to various analyzers using an ICP light source, such as an ICP emission spectroscopic analyzer and an ICP mass spectrometer.

  According to the ICP analyzer of the present invention, it is possible to automatically identify the type of plasma torch installed in the ICP analyzer, so the type of torch set in the ICP analyzer and the actual torch installed. When the type of torch used is different, it is possible to prevent problems caused by improper incident power being applied to the torch or by introducing an inappropriate flow rate of gas. .

  And a control unit for stopping the operation of the power supply unit when the type of plasma torch set in advance for the control unit of the ICP analyzer is different from the type of plasma torch identified by the identification unit. In addition, if the structure is equipped, the torch can be surely prevented from being melted, and damage to the equipment in the periphery of the torch can be prevented in advance, so it is highly safe to use the ICP analyzer. Sex can be secured.

Hereinafter, an ICP analyzer according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the main part of the ICP analyzer of this embodiment. The ICP analyzer of the present invention includes a plasma torch 1 that can be attached and detached, an induction coil 2 that is wound around the plasma torch 1, a power supply unit 4 that supplies high frequency power (incident power 21) to the induction coil 2, An impedance adjustment unit 3 and a control unit 5 are provided. A set value storage unit 7 storing standard set values (described later) for each type of plasma torch is connected to the control unit 5 so as to be accessible. The control unit 5 further includes a torch identification unit 6 that is a function realized by the CPU of the control unit 5 executing a predetermined program (the torch identification unit 6 is configured in hardware by a circuit or the like). May be good).
The spectroscope, detector, data processing unit, etc. (see FIG. 3), which are other components of the ICP analyzer, are not shown in FIG.

  The control unit 5 is usually composed of a CPU that performs various calculations, a storage device such as a memory, a hard disk, and the like, and controls the flow rate of gas (cooling gas, auxiliary gas, carrier gas) supplied from the gas flow rate control unit 9 and timing of introduction. , Performing the control of the amount and timing of the sample supplied from the sample introduction unit 8, and performing various controls such as control of power supply to the power supply unit 4. In the control unit 5, the type of plasma torch to be used is set in advance by an operator.

As described above, the impedance adjustment unit 3 matches the impedance of the high frequency power supply and the impedance of the induction coil by increasing or decreasing the capacity of the variable capacitor. As a result, the reflected power 22 is minimized and the incident power 21 is maximized.
The matching circuit of the impedance adjusting unit is usually composed of a semi-fixed variable capacitor, and the impedance is matched by appropriately changing only the capacitance of the other variable capacitor. However, the ICP analyzer of the present invention has this configuration. It is not limited to. The impedance adjustment unit 3 may adjust the impedance on the induction coil 2 side, or may adjust the impedance on the power supply unit 5 side.
The impedance adjusting unit 3 also has a function of outputting a set value that is various values (such as the capacitance of a capacitor) of the matching circuit at the time of impedance matching.

  Hereinafter, embodiments of plasma torch identification processing by the ICP analyzer according to the present invention will be described. In the ICP analyzer according to the present invention, first, impedance matching is performed by the impedance adjusting unit 3 when the plasma is turned on. The set value at this time (at the time of matching) is output to the control unit 5.

The torch identification unit 6 of the control unit 5 that has received the set value from the impedance adjustment unit 3 compares the set value with the standard set value stored in the set value storage unit 7. This standard set value is a standard set value of the impedance adjusting unit 3 obtained when impedance matching is performed under substantially the same conditions as in the case where the plasma torch identification process is performed by the ICP analyzer according to the present invention. That is.
That is, since the standard set value stored in the set value storage unit 7 differs depending on the type of plasma torch, the torch actually attached to the ICP analyzer is currently set according to the set value output from the impedance adjustment unit 3. Can be identified. At this time, it is not necessary for the set value and the standard set value to be exactly the same, and it is desirable to set a predetermined tolerance.

As a result of identification by the torch identification unit 6, when the type of torch set in the control unit 5 is the same as the type of torch actually attached to the ICP analyzer, the control unit 5 continues. Introduce sample and start analysis. Alternatively, a predetermined message indicating that the torch is set correctly is displayed on a display unit (not shown).
On the other hand, if the type of torch set in the control unit 5 and the type of torch actually mounted on the ICP analyzer are different, the control unit 5 displays a predetermined error message on a display unit (not shown). Is displayed or a warning sound is emitted to notify the operator that the setting is incorrect. The operator can immediately know from the error message and warning sound that the setting of the torch in the control unit 5 is wrong (or the type of the torch attached is wrong), so the torch is excessive. It is possible to take appropriate measures such as stopping the supply of electric power before the torch is melted and the surrounding parts are damaged by heating.

  However, the operator may not be aware of the error message or warning sound, or may not be able to take appropriate action quickly. Therefore, safety can be further improved by providing the power supply control unit 10 in the control unit as shown in FIG. The power supply control unit 10 is a function realized by the CPU of the control unit 5 executing a predetermined program. Of course, the power supply control unit 10 may be configured by a predetermined circuit or the like.

  In the case of this configuration, when it is determined that the type of torch set in the control unit 5 by the torch identifying unit 6 is different from the type of torch actually attached to the ICP analyzer, power supply is performed. The control unit 10 transmits a control signal instructing to stop power supply to the induction coil 2 to the power supply unit 4 (or by stopping the output of the control signal, Stop supplying.) As a result, overheating of the torch can be prevented without any operator intervention.

  In the above embodiment, the torch is identified before the sample is introduced into the torch. However, the torch may be identified after the sample is introduced.

  In the above embodiment, the torch identification unit 6 and the power supply control unit 10 are included in the control unit 5, but these may be provided outside the control unit 5.

  The ICP analyzer according to the present invention has been described above. However, each of the above-described embodiments is merely an example, and modifications and modifications as appropriate within the spirit of the present invention are included in the scope of the claims of the present application. Obviously.

The principal part block diagram of the ICP emission spectroscopy apparatus which concerns on this invention. The principal part block diagram of the other Example of the ICP emission spectroscopy apparatus which concerns on this invention. 1 is a schematic configuration diagram of a conventional ICP emission spectrometer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plasma torch 2 ... Inductive coil 3 ... Impedance adjustment part 4 ... Power supply part 5 ... Control part 6 ... Torch identification part 7 ... Set value memory | storage part 8 ... Sample introduction | transduction part 9 ... Gas flow rate control part 10 ... Power supply control part 21 ... Incident power 22 ... Reflected power

Claims (4)

A plasma torch into which a plasma forming gas is introduced, an induction coil arranged around the plasma torch, and a power supply unit that generates high-temperature plasma in the plasma torch by applying high-frequency power to the induction coil And a control unit that controls high-frequency power, gas flow rate, etc. according to the type of plasma torch set in advance,
a) an impedance adjustment unit that matches the impedance of the induction coil and the output impedance of the power supply unit so that the reflected power during plasma lighting is minimized;
b) a set value storage unit in which standard set values, which are set values at the time of impedance matching, are stored for each type of plasma torch;
c) a torch identifying unit for identifying a type of plasma torch mounted on the ICP analyzer based on a set value at the time of matching by the impedance adjusting unit and a standard set value stored in the set value storage unit; ,
ICP analyzer characterized by comprising.   d) a power supply control unit for stopping the operation of the power supply unit when the type of plasma torch set in advance for the control unit is different from the type of plasma torch identified by the identification unit; The ICP analyzer according to claim 1, further comprising: A plasma torch into which a plasma forming gas is introduced, an induction coil arranged around the plasma torch, and a power supply unit that generates high-temperature plasma in the plasma torch by applying high-frequency power to the induction coil And a control unit that controls high-frequency power, gas flow rate, etc. according to the type of plasma torch set in advance,
At the time of plasma lighting, the impedance adjustment unit matches the impedance of the induction coil and the output impedance of the power supply unit so that the reflected power is minimized,
The type of the plasma torch mounted on the ICP analyzer is identified based on the set value of the impedance adjustment unit at the time of impedance matching and the standard set value for each type of plasma torch stored in advance. ICP analyzer plasma torch identification method. The type of the plasma torch identified by the plasma torch identification method of the ICP analyzer according to claim 3 is different from the type of the plasma torch set in advance for the control unit. A method of controlling an ICP analyzer, characterized in that the operation is stopped.

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