JPH0634547A - Method for icp emission spectrochemical analysis - Google Patents

Abstract

PURPOSE:To enable accurate determination of the position of a peak wavelength of an element to be analyzed and thereby to obtain a precise result of analysis when an ICP emission spectrochemical analysis is conducted by using a monochromator. CONSTITUTION:On the occasion when an aerosol is produced by subjecting a solid sample S1 to discharge evaporation by a direct solid nebulizer 4 and this aerosol is introduced into a plasma torch 2, a standard liquid sample S1 containing the same elements as the solid sample S1 is atomized by an atomizing means 6 provided separately from the direct solid nebulizer 4 and is introduced into the plasma torch 2 at the same time. Light emitted by excitation by this plasma torch 2 is separated into its spectral components by a monochromator 8 and thereby a peak wavelength is determined for each element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ICP emission spectroscopic analyzer, and more particularly to a direct solid
The present invention relates to a technique in which a nebulizer discharges and vaporizes and introduces it into a plasma torch.

[0002]

2. Description of the Related Art Generally, when a monochromator is used as a spectroscope in an ICP emission spectroscopic analyzer, it takes time to analyze multiple elements simultaneously as compared with a polychromator, but it takes a long time for analysis, but an arbitrary wavelength position. Since there is a large degree of freedom, such as the ability to select, when detecting trace elements, it is possible to select the peak wavelength at a position that is not affected by the peak wavelength of the element of the main component and perform the analysis. It has advantages such as obtaining an analysis result with a good S / N ratio.

When performing quantitative analysis of a specific element to be analyzed using this monochromator, in order to remove the influence of temperature drift, mechanical backlash, etc., wavelength scanning is performed in advance and the element is analyzed. After determining the position of the peak wavelength of, the monochromator is set to the position of the peak wavelength and the integrated intensity is measured.

On the other hand, as a method for performing ICP emission spectroscopic analysis on a solid sample, conventionally, direct solid
There is a technique in which a solid sample is vaporized by a nebulizer (DSN) and the resulting aerosol is introduced into a plasma torch. That is, in this DSN, a spark discharge is caused between a solid sample and an electrode to evaporate the solid sample into an aerosol, and the aerosol is introduced into a plasma torch by a carrier gas to excite and emit light. .

When such a DSN is used, it is possible to introduce a high-concentration aerosol directly into the plasma torch, so that the analytical sensitivity is high and the trace elements can be analyzed.

[0006]

By the way, when a solid sample is spark-discharged by the DSN and vaporized, a pulse-shaped discharge is generated, so that the aerosol introduced into the plasma torch is also likely to be coarse and dense. Therefore, the monochromator is used. The peak intensities detected after the spectroscopic analysis at 5 also fluctuate to some extent.

Therefore, it may be difficult to accurately determine the position of the peak wavelength of the element to be analyzed, which is required before the quantitative analysis using the monochromator.

The present invention has been made in view of the above problems, and when the ICP emission spectral analysis is performed using a monochromator, the peak wavelength of the element to be analyzed can be accurately determined, and the accuracy can be improved. The challenge is to obtain good quantitative analysis results.

[0009]

The ICP emission spectroscopic analysis method according to the present invention is characterized in that a solid sample is vaporized by a direct solid nebulizer to generate an aerosol, and the aerosol is introduced into a plasma torch. The standard liquid sample containing the same element as the solid sample was
Atomizing means provided separately from the solid nebulizer atomizes and introduces it into the plasma torch at the same time, and the peak wavelength is determined for each element by dispersing the light excited and emitted by this plasma torch with a monochromator. It is a thing.

[0010]

When the above means is adopted, the aerosol obtained by vaporizing the solid sample by discharge and the aerosol obtained by atomizing the standard liquid sample are simultaneously introduced into the plasma torch. In this case, since the aerosol based on the standard liquid sample contains the same element as the aerosol based on the solid sample, the spectrum at the peak wavelength position of the element obtained by spectroscopy with the monochromator is relative to the peak based on the solid sample. The peaks based on the standard liquid sample are superposed, and the overall peak height appears larger than that of the solid sample alone. Therefore, the peak wavelength of the element can be accurately determined.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an apparatus for applying the ICP emission spectral analysis method of the present invention.

In the figure, 1 is a high-frequency coil, 2 is a plasma torch, and 4 is a direct solid nebulizer (D) which discharges and vaporizes a solid sample s ₁ to generate an aerosol.
SN), 6 is an atomizing means for atomizing the standard liquid sample s ₂ , 8 is a monochromator, and 10 is a photometric processing device.

The plasma torch 2 is arranged coaxially with the high frequency coil 1 so that the aerosol based on the solid sample s ₁ and the aerosol based on the standard liquid sample s ₂ can be introduced simultaneously with the coolant gas and the plasma gas. It has a quadruple pipe structure.

The DSN 4 has a hollow block 12,
An electrode 14 made of W or the like is inserted into the block 12 to face the solid sample s ₁ placed in a state of closing the upper opening of the block 12, and the electrode 14 is supported by an insulating material 16. At the same time, a high voltage is applied, while the block 12 is grounded. And this block 12
A gas introduction pipe 18 of a carrier gas such as Ar is connected to the plasma torch 2, and is further connected to the plasma torch 2 via a carrier pipe 20.

Meanwhile, atomizing means for atomizing the standard liquid sample s ₁ 6 includes a nebulizer 22 for nebulizing a standard liquid sample s ₁ by ejecting the carrier gas, the aerosol obtained by atomizing with this nebulizer 22 uniform And a chamber 24 for converting the plasma torch 2 to the plasma torch 2 via a carrier pipe 26.

In this example, the monochromator 8 is of a Zerniter type, and is composed of a condenser lens 30, an entrance slit 32, an exit slit 34, reflection mirrors 36 and 38, a plane diffraction grating 40, a photomultiplier tube, and the like. The detector 42 of FIG.

The photometric processing device 10 is composed of a CPU in this example, controls the wavelength selection of the monochromator 8 and photometrically processes the spectrum of each element dispersed by the monochromator 8 for data processing.

Next, the method of the present invention to which this ICP emission spectral analyzer is applied will be described.

When performing quantitative analysis on the element to be analyzed, it is necessary to determine the position of the peak wavelength of the element in advance.

In order to determine the peak wavelength of the element to be analyzed, first, the solid sample s ₁ is placed on the block 12 of the DSN 4 and spark discharge is generated between the electrode 14 and the electrode 14 at a predetermined frequency. , The solid sample s ₁ is vaporized to generate an aerosol. This aerosol is introduced into the gas introducing pipe 18
It is introduced into the plasma torch 2 via the carrier tube 20 by the carrier gas from.

When the aerosol from the DSN 4 is introduced into the plasma torch 2, a standard liquid sample
s _{2 is} also atomized by the atomizing means 6. That is, the standard liquid sample s ₂
As the solid sample s ₁ , an element containing the same element as the analysis target element is prepared in advance, and this standard liquid sample s ₂ is atomized in the chamber 6 by jetting a carrier gas, and the aerosol obtained by this is atomized. Is introduced into the plasma torch 2 via the carrier tube 26.

As a result, the aerosol obtained by vaporizing the solid sample s ₁ by discharge vaporization and the aerosol obtained by atomizing the standard liquid sample s ₂ are simultaneously introduced into the plasma torch 2 and excited and emitted. As a result, the spectrum at the peak wavelength position of the element to be analyzed obtained by spectral analysis with the monochromator 8 has the peak based on the standard liquid sample s ₂ superimposed on the peak based on the solid sample s ₁ .

For example, when the solid sample s ₁ alone is spark-discharged by the DSN 4 and vaporized, a pulsed discharge is generated, and therefore the aerosol introduced into the plasma torch 2 is likely to be coarse and dense, and therefore the monochromator is used. As shown in Fig. 2 (a), the peak intensity detected by spectral analysis in 8 has a large fluctuation in peak intensity, and in particular, in the case of trace elements, the value of peak intensity is also relatively small. It is difficult to determine the position of λ ₀ .

On the other hand, as shown in FIG. 2B, when only the standard liquid sample s ₂ is atomized by the atomizing section 6, the aerosol is relatively stably introduced into the plasma torch 2, Moreover, since the concentration of the element to be analyzed can be increased and prepared, the peak intensity detected after being dispersed by the monochromator 8 is stable and large as shown in FIG. 2 (b). The peak intensity is shown.

Therefore, when an aerosol obtained by vaporizing the solid sample s ₁ by discharge and an aerosol obtained by atomizing the standard liquid sample s ₂ are simultaneously introduced into the plasma torch 2, the monochromator 8 splits the spectrum. The spectrum of the element to be analyzed obtained as shown in Fig. 2 (c) is
_The peak based on the standard liquid sample s ₂ is superimposed on the peak based on ₁ , and the peak height as a whole appears larger than in the case of the solid sample s ₁ alone (the case of FIG. 2A). Therefore, the position of the peak wavelength λ ₀ of the element can be accurately determined. That is, in this case, the S / N ratio is deteriorated by the amount of the standard liquid sample s ₂ superposed, but the certainty is increased in determining the peak wavelength λ ₀ .

After the peak wavelength λ ₀ of the specific element to be analyzed is determined in this way, when the quantitative analysis of the element of the solid sample s ₁ is subsequently performed, the following procedure is performed.

First, a calibration curve of the standard liquid sample s ₂ relating to the element to be analyzed is prepared in advance, and the data of this calibration curve is stored in the tobacco memory or the like of the photometric processing device 10. Next, for the plasma torch 2, in the same manner as above, the solid sample
The aerosols of s ₁ and standard liquid sample s ₂ are introduced at the same time to perform integrated photometry, and the photometric processing device 10 quantifies the element using a calibration curve. In this case, if the concentration of the element contained in the standard liquid sample s ₂ is known in advance, in the photometric processing device 10, if the calculation process for subtracting the element concentration of the standard liquid sample s ₂ from the quantitative result is performed, the solid sample The concentration of the element contained in s ₁ is determined.

[0028]

According to the present invention, the position of the peak wavelength of the element to be analyzed can be accurately determined when carrying out ICP emission spectral analysis using a monochromator, so that an accurate analysis result can be obtained. Like

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus for applying an ICP emission spectral analysis method of the present invention.

FIG. 2 is an explanatory diagram showing a method for determining a peak wavelength of an element to be analyzed.

[Explanation of Codes] 2 ... Plasma torch, 4 ... Direct solid nebulizer (DSN), 6 ... Atomizing means, 8 ... Monochromator,
s ₁ ... solid sample, s ₂ ... standard liquid sample.

Claims (1)

[Claims] 1. A direct solid nebulizer discharges and vaporizes a solid sample to generate an aerosol, and when the aerosol is introduced into a plasma torch, a standard liquid sample containing the same element as the solid sample is replaced with the direct liquid sample. The atomizing means provided separately from the solid nebulizer atomizes and introduces it into the plasma torch at the same time, and the light excited and emitted by this plasma torch is dispersed by a monochromator to determine the peak wavelength for each element. An ICP emission spectroscopic analysis method characterized by the following.