JPS5837541A - Automatic analyzing method for flameless atomic absorption - Google Patents

Abstract

PURPOSE:To make an infinitesimal analysis without carrying out pretreatment such as extraction, by injecting a sample solution for plural times in one measuring cycle of absorbance measurement. CONSTITUTION:Atomizing is carried out through the following processes, injection 1 of a solution to the atomizing part of a high-temperature reactor drying 1 sample solution injection 2 drying 2-sample solution injection n drying n incineration atomizing or sample solution injection 1 drying 1 incineration 1-sample solution injection n drying n incineration n atomizing. Further, the absorption intensity of light having a certain specific wavelength due to atomic vapor is detected by using a hollow cathode lamp, a spectroscope and a detector during these processes and the density of a metal to be measured is measured. Hereby, the density of the atomic vapor in an effective light flux 31 of atomic absorption measurement is increased because a dried or incinerated sample 33 exisits within a comparatively narrow domain in a graphite tube 32.

Description

[Detailed description of the invention] The present invention is widely applied in fields such as environmental measurement, medicine/occupational health/public health, petrochemical industry, metal/metallurgy industry, non-metal industry, food/fishery industry, electronic industry, etc. This paper relates to an automatic flameless atomic absorption spectrometry analysis method for trace analysis.

In the field of electronics industry, especially in the research and development of devices using semiconductor materials and optoelectronic materials, and in the manufacturing of products, trace amounts of component elements and impurity elements are analyzed in order to control the performance of the target device. There is a need. For example, analysis of trace impurities such as Fe*CumAl+Cr and Si in compound semiconductors such as Si semiconductors and GaAs is an important issue.

In particular, analysis of trace impurities in Cr t 51 in GmAs has become an important theme. There are various methods for analyzing such trace impurities, one of which is flameless atomic absorption spectrometry. It is something like this:

Substances exposed to high temperatures dissociate into atomic vapors. In this case, the atoms are at an older energy level and at a lower energy level. Atomic absorption spectrometry is
This takes advantage of the properties of atoms at low energy levels. When an atom at a lower energy level is given a certain amount of energy, it absorbs it and transfers it to a higher energy level. In atomic absorption spectrometry, it can be expressed as light energy. The amount of light energy is related to the wavelength.

Therefore, only light of a certain wavelength is absorbed by an element, and the strength of that absorption is proportional to the density of the atomic vapor, that is, the concentration in the original substance. An atomic absorption spectrophotometer performs analysis using this principle.

An atomic absorption photometer consists of a light source (hollow cathode lamp) that emits light at a wavelength corresponding to the energy level absorbed by atoms, a high-temperature furnace as an atomization unit that creates atomic vapor, and a spectrometer that selects light at the required wavelength. It consists of a detector, an electric control unit that controls the high temperature furnace, a gas control unit that controls the flame, and an electric processing unit that processes signals.

(Fig. 1) Next, Fig. 2 shows the process of atomic absorption from the light source to the detector and the process of the quantitative method.

In FIG. 2(a), the lamp emits a line spectrum of the element to be measured, and the black areas represent specific wavelengths (resonance lines).

As shown in FIG. 2(b), the sample in the high-temperature reactor atomization section absorbs energy at the resonance line, and the line spectrum other than the resonance line passes through as is.

As shown in Fig. 2(C), the spectrometer functions to pass only the light near the resonance line.

In FIG. 2(d), the receiver detects only the magnitude of the resonance line, which has been reduced by absorption of elements in the sample.

In Figure 1, considering the case where the line width of the light source lamp is extremely small and cheap, log Yu'-= ABS = K, f, N, J
, Iν, the metal concentration to be measured is proportional to the absorbance. It is also understood that in order to increase the analysis sensitivity, it is better to select a resonance line with a large f value or to increase l.

Note that actual calibration curves rarely exhibit linearity over a wide concentration range due to various influences of spectral lines.

In the conventional method, this flameless atomic absorption automatic analysis has been carried out by a process of sample solution injection, drying, and ashing and monoatomization. In this process, the analysis sensitivity for trace component elements and impurity elements is as shown in Figure 3(a), when the graphite tube 3 is within the effective luminous flux 31 during atomic absorption measurement.
It depends on the atomic vapor density coming out of the sample 33 in 2.

As shown in FIG. 3(b), in the conventional method, when a large amount of sample is injected to increase the absorbance, the dried or incinerated sample 33 is injected into the graphite furnace tube in one go. exist in a wide area, and even if atomized in such a state, the atomic vapor density within the effective luminous flux was low. For this reason, it was insufficient in terms of trace analysis.

The present invention involves sample solution injection, heating of the atomization section (drying, ashing,
By controlling both operations (atomization) completely independently by computer, within one absorbance measurement cycle,
A key feature of this method is that it enables multiple injections of sample solutions to perform microanalysis that is lower than conventional methods without pretreatment such as extraction. That is, the method of the present invention includes sample solution injection (1)
- Drying (1) - Sample solution injection (2) → Drying (2) →...
...→Sample solution injection (n) -Drying (,)→Ashing-mono-atomization process or sample solution injection (1)→Drying (1)→Ashing (1)--Sample Solution injection (n)
The process is as follows: → drying (n) → ashing (n) → atomization.

Through the process of the present invention, as shown in FIG. 3(c), the dried or incinerated sample 33 exists in a relatively narrow area, so the density of the atomic vapor coming out from there is It comes to exist in the effective light beam 31 in a high state.

Next, one embodiment of the present invention will be described. Figure 4 shows the atomic absorption measurement data when absorbance was measured using the conventional method, and Figure 5 shows the atomic absorption measurement data when the sample solution was injected 1, 2, 3, and 5 times using the method of the present invention. This is atomic absorption measurement data. The sample solution used was GaAs O,2f/
l Ome (distilled water + acid) (solution A) and ('GaA
s Q, 2y + Cr O, 1ttP ), / 10 m
l (distilled water + acid) (solution B), the amount of sample solution injected at one time is 20 μl, drying is 45A1, ashing is 16
0A.

Atomization was performed by heating with a current of 310A. It can be seen from FIG. 4 that the method of the present invention is superior to the conventional method.

Next, another embodiment of the present invention will be described. Figure 6 shows a total of 100 μl for 5 times of 20 μl each and 2 times of 50 μl for a total of 100 μl using the aforementioned solution B.
This is atomic absorption measurement data when the injection of 100% was performed by the method of the present invention. From now on, if we assume the amount of Prime Minister's intake iooμl, it will be 20μ7 rather than 50μl/time x 2 times? / times×
It turns out that 5 times is more effective. This is shown in Figure 3 (C
), by injecting a small amount (5 to 20 le) of the sample solution into the same location with good reproducibility, during atomization,
This is because the atomic vapor density within the effective light flux of atomic absorption measurement can be increased.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the principle of the high temperature furnace method, and FIG. 2 is a diagram of the atomic absorption measurement process. Fig. 8 is a diagram showing the atomization density state, Fig. 4 is a diagram showing absorbance data by the conventional measurement method, Fig. 5 is a diagram showing absorbance data by the method of the present invention, and Fig. 6 is a diagram showing the absorbance data by the method of the present invention. This is a diagram showing absorbance data when a 100 μl solution was divided into two and five times, dried and ashed, and then atomized and measured. In the figure, 31 shows the effective light flux during atomic absorption measurement, 32 shows the graphite tube, and 33 shows the sample after incineration. Agent Patent Attorney Satoshi Tsukasa 1'42.71Figure 72

Claims (1)

[Claims] (1) In flameless atomic absorption automatic analysis, a sample solution is injected multiple times within one absorbance measurement cycle to analyze trace amounts of component elements and impurity elements. Law.