JPH1164318A - Method for determining element contained in liquid chemical - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a trace element contained in a liquid chemical used in the field of electronic industry at a level of 10 wt.ppt can be determined accurately. SOLUTION: In a method for determining element contained in liquid chemical, at least one kind of trace element selected from among zinc, germanium, zirconium, cadmium, tin, and antimony contained in a liquid chemical is determined. The method comprises a first step of collecting a sample from the liquid chemical in a container, a second step of adding sulfuric acid and/or phosphoric acid to the sample, and a third step of obtaining a concentrated residue by evaporating the sample by heating the container containing the sample. The method also comprises a fourth step of obtaining an aqueous solution by dissolving the residue in water or an acidic solution by adding the water or acidic solution to the residue, and a fifth step of carrying out quantitative analysis on the aqueous solution for determining the element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining an element in a liquid drug. More specifically, the present invention relates to a method for quantitatively analyzing at least one element selected from the group consisting of zinc, germanium, zirconium, cadmium, tin and antimony, which is present in a liquid chemical, wherein the liquid is used in a pre-analysis step. Eliminates the serious problem that some of the elements in the chemicals are lost due to scattering or insolubilization, etc., so that, for example, very small amounts of 100 wt. TECHNICAL FIELD The present invention relates to a method for quantifying an element in a liquid drug capable of accurately quantifying the element.

[0002]

2. Description of the Related Art Chemicals used in the electronics industry require high-purity chemicals in which impurity elements are reduced as much as possible. In particular, as the degree of integration of semiconductors increases, high-purity chemicals with fewer impurity elements are required. Therefore, it is important to accurately determine the impurity elements in these high-purity chemicals. Heretofore, as a method for quantifying impurity elements in high-purity chemicals, for example, high-purity chemicals are heated and concentrated in a container, and then quantified by inductively coupled plasma mass spectrometry, atomic absorption spectrometry, inductively coupled plasma emission spectrometry, or the like. Methods are known. However, the conventional method has not always been satisfactory in that accurate quantification at a level of 100 weight ppt or less is performed. In particular, there is a serious problem that some of the elements in the liquid chemical are lost due to scattering, insolubilization, and the like in the pretreatment step of the analysis.

[0003]

Under these circumstances, the problem to be solved by the present invention is to solve the problems of zinc, germanium, zirconium, cadmium,
This is a method for quantitatively analyzing at least one element selected from the group consisting of tin and antimony, and in the pretreatment step of analysis, a serious problem that some of the elements in the liquid chemical are lost due to scattering or insolubilization. Accordingly, the present invention provides a method for quantitatively determining an element in a liquid chemical capable of accurately determining an ultra-trace element having a level of 100 wt. Ppt or less present in a liquid chemical used in the electronics industry, for example. It exists.

[0004]

That is, the present invention is a method for quantitatively analyzing at least one element selected from the group consisting of zinc, germanium, zirconium, cadmium, tin and antimony, which is present in a liquid chemical. Thus, the present invention relates to a method for quantifying an element in a liquid chemical, comprising the following [first step] to [fifth step]. [First step]: a step of collecting a liquid medicine to be analyzed in a container [Second step]: A step of collecting the liquid medicine collected in the first step
Step of adding sulfuric acid and / or phosphoric acid [Third step]: heating the container containing the liquid chemical after the second step, evaporating and concentrating the liquid to obtain a concentrated residue [Fourth step]: Third step Step of adding water or an acidic aqueous solution to the concentrated residue obtained in the above to obtain an aqueous solution in which the concentrated residue is dissolved [Fifth step]: a step of performing quantitative analysis of the above-mentioned elements in the aqueous solution obtained in the fourth step

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Liquid chemicals to be analyzed in the present invention are not particularly limited. One of the liquid chemicals that can fully enjoy the excellent effects of the present invention is a liquid chemical for electronic industrial chemicals. be able to.

[0006] Specific examples of liquid chemicals include aqueous hydrogen peroxide,
Examples include hydrochloric acid, nitric acid, aqueous ammonia or pure water or a mixture thereof. In this case, it is preferable that each content of each element to be analyzed present in the chemical is not more than 100 weight ppt.

The elements analyzed by the present invention are zinc,
At least one element selected from the group consisting of germanium, zirconium, cadmium, tin and antimony.

The first step of the present invention is a step of collecting a liquid chemical to be analyzed in a container. As the container, a beaker made of quartz or fluororesin, an Erlenmeyer flask, an evaporating dish, and the like are preferable. It is better to use quartz if the liquid chemical is hydrochloric acid, nitric acid, aqueous hydrogen peroxide, pure water, that is, from acidic to neutral, and to use fluorine resin if the aqueous ammonia is alkaline, but it is limited to this. Not something. PTFE and PFA are particularly recommended as the fluororesin. In particular, when a synthetic quartz beaker, an Erlenmeyer flask, and an evaporating dish are used, contamination from the heating vessel can be further prevented, and more accurate quantification can be performed. It is not always necessary that the entire container is made of quartz or fluororesin, and it is sufficient that the inner surface of the container that comes into contact with the liquid is processed with quartz or fluororesin. The amount of the liquid chemical to be collected is not particularly limited, but from the viewpoint of easiness of operation, 10 to
Preferably, it is 2000 g.

The second step of the present invention is a step of adding sulfuric acid and / or phosphoric acid to the liquid chemical collected in the first step. Sulfuric acid and phosphoric acid may be added alone or as a mixture. The concentrations of sulfuric acid and phosphoric acid to be added are not particularly limited. In the case of 96% by weight sulfuric acid or 85% by weight phosphoric acid, 0.005%
Preferably it is ~ 0.1 ml. If the amount is too small, some of the elements in the liquid drug are lost during the third step,
The accuracy of the analysis may be lost, while if the amount is too large, impurities in the sulfuric acid or phosphoric acid may interfere with the quantification.

The third step of the present invention is a step of heating the container containing the liquid chemical after the second step, evaporating and concentrating the liquid to obtain a concentrated residue. The heating is usually performed on a hot plate installed in a clean draft. The heating temperature is not particularly limited, but it is usually preferable to carry out the heating at 60 to 250 ° C. from the viewpoint of economic analysis time. The atmospheric pressure of the heat concentration is not particularly limited.

The fourth step of the present invention is a step of adding water or an acidic aqueous solution to the concentrated residue obtained in the third step to obtain an aqueous solution in which the concentrated residue is dissolved. That is, after cooling the concentrated residue obtained in the third step, water or an acidic aqueous solution is added, and the acidic aqueous solution is preferably a nitric acid aqueous solution.
The amount of water or acidic aqueous solution is usually about 1 to 50 g.

The fifth step of the present invention is a step of quantitatively analyzing the above-mentioned elements in the aqueous solution obtained in the fourth step. Quantitative analysis is usually performed by inductively coupled plasma mass spectrometry (Induct
actively Coupled Plasma Mass Spectrometry, Inductively Coupled Plasma Ato
mic Emission Spectrometry or atomic absorption method (Atomic
Absorption Spectrometry). The element concentration may be calculated by any of an absolute calibration method using an external standard, an internal standard method and a standard addition method.

The most important feature of the present invention resides in that sulfuric acid and / or phosphoric acid is used in the second step when the specific element contained in the liquid chemical is quantitatively analyzed with high accuracy. This makes it possible to extremely efficiently prevent the loss of elements due to the evaporation and concentration of the liquid due to the heating performed in the subsequent third step, and perform accurate quantitative analysis.

In practicing the present invention, all of the above elements may be measured simultaneously, or only a specific element selected from these elements may be determined. Further, other elements other than the above elements can be measured in parallel.

[0015]

Next, the present invention will be described by way of examples. Note that “ppt” is “weight ppt”.

Example 1 300 g of ultrapure water was placed in a synthetic quartz Erlenmeyer flask.
Was added to the ultrapure water in an amount corresponding to 10 wt. Ppt, 0.01 ml of 96 wt% sulfuric acid was added thereto, and the mixture was heated on a hot plate installed in a clean draft to obtain a sample. The water was evaporated. The evaporation residue was dissolved in 3% nitric acid, the whole was adjusted to 5 ml, and quantified by inductively coupled plasma mass spectrometry. Table 1 shows the recovery rate ((quantified amount / added amount) × 100) from the obtained quantitative value. It was found that all six tested elements could be quantitatively recovered and analyzed.

Example 2 A test was conducted in the same manner as in Example 1 except that the amount of 96% by weight sulfuric acid was changed to 0.03 ml. Table 1 shows the obtained results. It was found that all six tested elements could be quantitatively recovered and analyzed.

Example 3 300 g of ultrapure water was placed in a synthetic quartz Erlenmeyer flask.
Was added to the ultrapure water in an amount corresponding to 10 wt. Ppt, 0.01 ml of 85 wt.% Phosphoric acid was added thereto, and the mixture was heated on a hot plate installed in a clean draft to obtain a sample. Water was evaporated. The evaporation residue was dissolved in 3% nitric acid, the whole was adjusted to 5 ml, and quantified by inductively coupled plasma mass spectrometry. Table 1 shows the recovery rate ((quantified amount / added amount) × 100) from the obtained quantitative value. It was found that all the five tested elements except for antimony could be quantitatively recovered and analyzed. Antimony was not quantified because antimony was present in the phosphoric acid used in the test.

Example 4 A test was conducted in the same manner as in Example 1 except that the amount of 85% by weight phosphoric acid was changed to 0.03 ml. Table 1 shows the obtained results. It was found that all the five tested elements except for antimony could be quantitatively recovered and analyzed. Antimony was not quantified because antimony was present in the phosphoric acid used in the test.

Comparative Example 1 300 g of ultrapure water was placed in a synthetic quartz Erlenmeyer flask.
Was added to the ultrapure water in an amount corresponding to 10 wt. Ppt, and heated on a hot plate installed in a clean draft to evaporate the water of the sample. The evaporation residue was dissolved in 3% nitric acid, the whole was adjusted to 5 ml, and quantified by inductively coupled plasma mass spectrometry. Table 1 shows the recovery rate ((quantified amount / added amount) × 100) from the obtained quantitative value.

Example 5 50 g of ultrapure water was placed in an evaporating dish made of synthetic quartz, and the elements shown in Table 2 were added to the ultrapure water in an amount corresponding to 50 weight parts per weight (ppt). .01 ml was added and heated on a hot plate set in a clean draft to evaporate water of the sample. The evaporation residue was dissolved in 3% nitric acid, the whole was adjusted to 5 ml, and quantified by inductively coupled plasma mass spectrometry. Table 2 shows a recovery rate ((quantified amount / added amount) × 100) from the obtained quantitative value. It was found that all six tested elements could be quantitatively recovered and analyzed.

Example 6 A test was conducted in the same manner as in Example 2 except that the amount of 96% by weight sulfuric acid was changed to 0.03 ml. Table 2 shows the obtained results. It was found that all six tested elements could be quantitatively recovered and analyzed.

Example 7 As high purity chemicals, 35% aqueous hydrogen peroxide, 20% hydrochloric acid,
68% nitric acid was placed in a synthetic quartz beaker in the amount shown in Table 3, and 0.01 ml of 96% by weight sulfuric acid was added thereto, and the mixture was heated and evaporated on a hot plate installed in a clean draft. Dissolve the evaporation residue with 3% nitric acid,
, And quantified by inductively coupled plasma mass spectrometry. Table 3 shows the obtained results. It was found that this method allows extremely high-precision quantification of any high-purity chemical.

Example 8 30% ammonia water was placed in a PTFE beaker in the amount shown in Table 3, and 0.01 ml of 85% by weight phosphoric acid was added.
It was heated and evaporated on a hot plate installed in a clean draft. The evaporation residue was dissolved in 3% nitric acid, the whole was adjusted to 5 ml, and quantified by inductively coupled plasma mass spectrometry. Table 3 shows the obtained results. It was found that high-purity aqueous ammonia could be quantified with high accuracy by this method.

[0025]

[Table 1] The addition amount of each element in Table 1 is 10 weight parts per weight.

[0026]

[Table 2] The addition amount of each element in Table 2 is 50 weight ppt.

[0027]

[Table 3]

[0028]

As described above, according to the present invention, there is provided a method for quantitatively analyzing at least one element selected from the group consisting of zinc, germanium, zirconium, cadmium, tin and antimony, which is present in a liquid chemical. It eliminates the serious problem that some of the elements in the liquid chemical are lost due to scattering, insolubilization, etc. in the pretreatment step of the analysis. It is possible to provide a method for quantifying an element in a liquid chemical, which can accurately determine an ultra-trace element at a weight level of ppt.

Claims (6)

[Claims] 1. A method for quantitatively analyzing at least one element selected from the group consisting of zinc, germanium, zirconium, cadmium, tin and antimony, which is present in a liquid chemical, comprising the following [first step] to [ Fifth step]
For the determination of elements in liquid chemicals containing [First step]: a step of collecting a liquid medicine to be analyzed in a container [Second step]: A step of collecting the liquid medicine collected in the first step
Step of adding sulfuric acid and / or phosphoric acid [Third step]: heating the container containing the liquid chemical after the second step, evaporating and concentrating the liquid to obtain a concentrated residue [Fourth step]: Third step Step of adding water or an acidic aqueous solution to the concentrated residue obtained in the above to obtain an aqueous solution in which the concentrated residue is dissolved [Fifth step]: a step of performing quantitative analysis of the above-mentioned elements in the aqueous solution obtained in the fourth step 2. The method according to claim 1, wherein the liquid chemical to be analyzed is a liquid chemical for electronic industrial chemicals. 3. The method according to claim 1, wherein the liquid chemical to be analyzed is aqueous hydrogen peroxide, hydrochloric acid, nitric acid, aqueous ammonia, pure water, or a mixture thereof. 4. A liquid chemical to be analyzed is aqueous hydrogen peroxide, hydrochloric acid, nitric acid, ammonia water or pure water or a mixture thereof, and the content of each element to be determined present therein is 100 weight parts per weight (ppt). The method of claim 1, wherein: 5. The method according to claim 1, wherein the container in the first step is made of quartz or fluororesin. 6. The method according to claim 1, wherein the quantification performed in the fifth step is performed by inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry, or atomic absorption spectrometry.