JPH06109639A - Method for emission spectral analysis - Google Patents

Abstract

PURPOSE:To stabilize the spectrum occurring from a sample by monitoring the emission intensity of plasma, and as it changes, controlling the output to the light source gas of a high frequency wave generating device, so that the emission intensity of a plasma gas element becomes constant. CONSTITUTION:A high frequency induction coil 4A is supplied with power from a high frequency power source 4B, and makes the gas, introduced into a plasma area P, to be a plasma state, to excite the element contained in a sample with the plasma. The excited element releases its energy as light when it becomes inactive, and the light is diffracted at a spectral part 5 as a bright line spectrum for analysis at a light measuring part 6. Thus, based upon wave length and intensity of spectrum, qualitative and quantitative analyses of elements can be made. Here the spectrum intensity of plasma gas element is monitored, and its fluctuation information is inputted in a high frequency control part 7, and the spectrum intensity is controlled to be constant, for the plasma temperature to be keep constant. Thus, a sample is determined with less measurement error.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emission spectroscopic analysis method, and more particularly, to an emission spectroscopic analysis method for exciting a sample in ICP and quantifying the sample by the intensity of an emission line spectrum generated by the excited sample. A sample solution for elemental analysis is dissolved in a solvent to prepare a sample solution, and the sample solution is made into mist-like sample droplets, and a gas for inductively coupled plasma (ICP) generation is turned into plasma by a high frequency generator. The present invention relates to an emission spectroscopic analysis method in which a sample for analysis contained in the sample droplet is guided into plasma, the spectrum generated by the excited sample is measured, and the sample is quantified.

[0002]

2. Description of the Related Art Hitherto, as a method of emission spectroscopic analysis of this kind, a calibration solution in which samples are prepared into solutions having various concentrations and an internal standard element other than the analysis element is added to each of the solutions at a constant ratio. After clarifying the relationship of the emission intensity ratio between the internal standard element and the concentration of the analytical element, quantitatively analyze a sample for analysis in which the internal standard element is added at a fixed ratio, There is an ICP emission spectroscopic analysis method for quantifying the sample using a so-called internal standard method in which the analysis result is calibrated from the relationship of the emission intensity ratio which has been clarified.

[0003]

However, even when the above-mentioned conventional emission spectroscopic analysis method is used, when a sample for analysis is dissolved in a solvent and atomized sample droplets are introduced into plasma. However, there is a problem that the plasma emission intensity fluctuates, and this plasma emission intensity fluctuation appears as a measurement error with respect to the spectral intensity of each of the analysis element and the internal standard element, and the state of the variation varies from element to element. The ratio also fluctuates. That is, the measurement error due to the fluctuation of the plasma emission intensity could not be calibrated, and a measurement error of about 0.5% occurred in the quantitative analysis.

Therefore, in view of the above situation, it is an object of the present invention to provide an emission spectroscopic analysis method capable of reducing a measurement error due to fluctuations in plasma emission intensity and quantifying a sample with higher measurement accuracy.

[0005]

The feature of the present invention for attaining this object is to monitor the emission intensity of a plasma gas element and to output the output to the gas of the high frequency generator in accordance with the variation of the emission intensity of the plasma. Is to stabilize the emission spectrum of the sample by controlling so that the emission intensity of the sample becomes constant, and it is better to calibrate the measurement error by the above-mentioned internal standard method. The effects are as follows.

[0006]

Function: A sample for elemental analysis is dissolved in a solvent to prepare a sample solution, and the sample solution is made into mist-like sample droplets, and the sample droplets are introduced into plasma. Therefore, the acidity of the sample solution, It has been known that the particle size and flow velocity of the sample droplets easily vary due to liquidity such as viscosity and surface tension, and this variation causes a measurement error. Since the change in the amount of solvent introduced in the plasma is accompanied by the change in the amount of solvent, it is considered that the measurement error was caused by the change in the temperature of the plasma. Because it is difficult to directly control the plasma temperature because it is compatible with temperature changes, it is possible to control the plasma temperature by controlling the emission intensity of the plasma gas element to be constant. One in which it is possible to reduce the error.

That is, the variation of the emission intensity of the plasma gas element is monitored, the degree of the variation of the emission intensity is detected, and the output to the light source gas of the high frequency generator is controlled so that the emission intensity of the plasma gas element becomes constant. By controlling, even if the amount of solvent introduced into the plasma fluctuates, the temperature of the plasma fluctuates with the fluctuation of the solvent amount, and the emission intensity of the plasma gas element that changes with the fluctuation of the temperature is also controlled. Since the plasma emission intensity will be controlled to return to the original value after detection, the emission intensity of the plasma gas element will be kept constant, that is, the plasma temperature will be kept constant. As a result, the energy state of the plasma is stabilized, and as a result, the amount of energy that the sample for analysis receives from the plasma is stabilized, and Generated spectral intensity is stabilized.

If the solvent for dissolving the sample is water, it is highly versatile for various samples. Furthermore, by calibrating the measured value using the internal standard method, the amount of solvent introduced into the plasma can be reduced. Since the measurement error due to factors other than the fluctuation can be calibrated at the same time, more accurate and stable spectrum intensity can be obtained.

[0009]

As described above, since the spectrum intensity generated from the sample for analysis is stabilized, a stable measurement result can be obtained and the measurement accuracy can be improved. In other words, more accurate quantitative analysis became possible. As a result, highly accurate analysis can be performed without using an analytical method such as a gravimetric method or a volumetric method, so that it becomes possible to more easily and accurately quantify a sample for analysis.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the emission spectroscopic analysis apparatus used in the emission spectroscopic analysis method of the present invention is a nebulizer 1 for making a sample solution into a mist-like sample droplet, and to make the particle size of the sample droplet small to some extent and uniform. Spray chamber 2, a torch 3 for guiding a homogeneous sample drop to a plasma region, a high-frequency generator 4 for converting a light source gas into plasma, a spectroscopic unit 5 for spectrally dispersing a spectrum generated from a plasma light source, and a spectroscopic result is analyzed. It comprises a photometric unit 6 and a high frequency control unit 7. In addition,
Although not shown, a gas control unit for controlling the flow rate of the argon gas sent to the nebulizer and the torch for stable plasma generation and a data processing unit for outputting the analyzed photometric result are provided.

The nebulizer 1 has a sample solution introducing tube 1
A and a carrier gas introducing pipe 1B connected from the gas control unit are coaxial ejection pipes, and the carrier gas introduced by the gas control unit is a negative pressure when passing through the tip portion 1a of the nebulizer 1. Atomize the solution. As a result, the solution sample becomes a mist and becomes fine particle sample drops suitable for spectrum measurement. Although argon gas is usually used as the carrier gas, any component that can be used as plasma, such as helium or nitrogen, may be used, and the carrier gas is not limited to this.

The spray chamber 2 is a spray chamber 2
A rectifying partition 2B provided in the spray chamber 2A, which is composed of A, a rectifying partition 2B, a sample droplet introducing tube 2C, and a drain collecting path 2D, and further particles suitable for spectrum measurement among the sample droplets generated from the nebulizer 1 Only the sample droplets having a small diameter are guided to the sample droplet introducing pipe 2C, and the sample droplets having a relatively large particle size which are not suitable for the spectrum measurement are collected in the drain collecting passage 2D made of a water sealed tube. With these configurations, the particle size of the sample droplet becomes constant,
Since the amount of solvent introduced into the plasma region is stable, the plasma temperature is stable and more accurate measurement is possible.

The torch 3 is formed by a quartz triple tube, and a light source gas introducing pipe 3B connected by a gas control unit is provided outside the sample introducing pipe 3A continuous with the sample drop introducing pipe 2C, and a gas is further provided outside thereof. The structure is such that a cooling gas introduction pipe 3C connected from the control unit is provided. With these configurations, by introducing the light source gas and the cooling gas into the light source gas introduction pipe and the cooling gas introduction pipe, respectively, from the gas control unit, the sample droplet can be guided to the plasma region P above the torch. . The light source gas and the cooling gas introduced from the gas control unit are of the same quality as the carrier gas.

The high frequency generator 4 includes a water cooled high frequency induction coil 4A above the torch 3 and a high frequency power source section 4B.
The high frequency induction coil 4A is connected to the high frequency induction coil 4A by supplying electric power from the high frequency power source unit 4B.
It has the function of turning the gas introduced into the plasma into plasma and exciting the elements contained in the sample by the plasma. Further, the high frequency power supply unit 4B is composed of a high frequency oscillator and a tuning coupling device, and is configured to stably supply power to the high frequency induction coil.

Since the excited element emits its energy as light when it is deactivated, the emitted light can be observed as an emission line spectrum. That is, in the spectroscopic unit, the emission line spectrum is diffracted by the spectroscopic unit 5 and analyzed by the photometric unit 6 to determine the qualitative of the element from the wavelength of the emission line spectrum and the quantification of the element contained in the sample from the intensity of the emission line spectrum. You can Here, since the high frequency controller 7 for monitoring the spectral intensity of the plasma gas element and transmitting the variation information to the high frequency oscillator is provided, the spectral intensity of the plasma can be controlled to be constant and the spectral intensity By controlling the temperature to be constant, the plasma temperature is kept constant, whereby the spectrum intensity obtained from the sample can be stably obtained, and the sample can be quantified with a small measurement error.

Further, in the case of performing quantitative analysis, analysis is performed using a standard sample in which a fixed amount of yttrium, which is an internal standard element, is added to a solution of each of the analyzed elements in various concentrations. After clarifying the relationship between the concentration of the element and the emission intensity of the internal standard element in advance, use a calibration curve that shows the relationship between the emission intensity of the analytical element contained in the sample and the emission intensity of the internal standard element. The accurate quantification can be performed by calibrating the emission intensity of the analysis element.
Needless to say, yttrium, which is an internal standard element, is used because it is not included in the test, but it can be replaced with calcium or the like. If a calibration curve is obtained from the relationship between the emission intensity ratio of the internal standard elements and the emission intensity of the analytical element, it will be introduced into the plasma due to the change in the particle size of the sample droplet caused by the difference in viscosity and specific gravity of the sample solution. Even if the number of atoms of the analysis element changes, the ratio with the number of atoms of the internal standard element does not change. Therefore, the emission intensity of the analysis element can be calibrated more accurately, and more accurate quantitative analysis can be performed.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an emission spectroscopic analyzer used in the emission spectroscopic analysis method of the present invention.

[Explanation of symbols]

 4 High frequency generator

Claims (3)

[Claims] 1. A sample solution is prepared by dissolving a sample for elemental analysis in a solvent, and the sample solution is formed into a mist-like sample droplet, which is then inductively coupled plasma (ICP) by a high frequency generator (4). An emission spectroscopic analysis method in which a gas for generation is introduced into plasma and the sample for analysis contained in the sample droplet is excited, and the spectrum generated by the excited sample is measured to quantify the sample. In, the emission spectrum of the plasma is monitored, and the output to the light source gas of the high frequency generator is controlled so that the emission intensity of the plasma gas element becomes constant in accordance with the fluctuation of the emission intensity, and the emission spectrum from the sample is controlled. Method for stabilizing emission of light. 2. The emission spectroscopic analysis method according to claim 1, wherein the solvent is water. 3. The sample is prepared in various concentration solutions,
After making a calibration solution by adding an internal standard element other than the analytical element to each of these solutions at a constant ratio, and clarifying the relationship between the emission standard of the internal standard element and the analytical element concentration, A sample for analysis, to which the internal standard element is added at a constant ratio, is quantitatively analyzed by the emission spectroscopic analysis method according to claim 1, and the analysis result is calibrated from the relationship of the emission intensity ratio which has been clarified in advance. Emission spectroscopy method.