Sample analysis method and solution preparation device

Abstract

The present invention makes it possible, when using a calibration curve of an IC analysis device or the like to analyze the content of sulfur and / or halogen contained in a sample, to perform the analysis with good precision without the use of a reagent such as hydrazine or hydrogen peroxide.　In the present invention, when preparing an absorption liquid to introduce into an analysis device, an absorption tube comprising an electrode for electrolysis is used, electrolysis is performed on an absorption liquid accommodated in the absorption tube, thereby performing oxidation or reduction of a target component in the absorption liquid, and the absorption liquid is then introduced into the analysis device.　

Description

Sample analysis method and solution preparation device

[0001] The present invention relates to a method for analyzing the sulfur and / or halogen content of a sample using a calibration curve of an ion chromatograph analyzer or the like, and a solution preparation device used therefor.

[0002] In quantitative analysis of sulfur and halogens in a sample using ion chromatography (hereinafter also referred to as "IC"), the sample is thermally decomposed, and the gasified components to be analyzed are collected in an absorption liquid, which is then introduced into an IC analyzer as the solution to be analyzed.

[0003] When the sulfur compounds and halogen compounds gasified by combustion decomposition through the thermal decomposition are recovered in an absorption liquid and analyzed by an IC analyzer, all sulfite ions produced in the absorption liquid must be oxidized to sulfate ions, while free halogens and oxoacid ions must be reduced to halide ions before being introduced into the IC analyzer. A known method for oxidizing or reducing the ions contained in the absorption liquid is to add, to the absorption liquid, an oxidizing agent such as hydrogen peroxide and a reducing agent such as hydrazine hydrate (see, for example, Patent Document 1).

[0004] JP 2010-156568 A

[0005] The oxidizing agent hydrogen peroxide and the reducing agent hydrazine added to the absorption solution are highly reactive and toxic, making them extremely dangerous substances designated as deleterious and toxic. Therefore, they must be handled with great care, and storing the reagents requires a great deal of effort.

[0006] Furthermore, when an absorption solution containing hydrogen peroxide or hydrazine is measured using an IC analyzer, signals from these components appear on the chromatogram, interfering with the measurement of fluoride ions. Furthermore, these components may damage the column. Therefore, a method for preparing a solution that does not use these additives is desired.

[0007] In view of the problems of the conventional techniques, an object of the present invention is to enable accurate analysis of the sulfur and / or halogen content of a sample using a calibration curve of an IC analyzer or the like, without using reagents such as hydrogen peroxide or hydrazine.

[0008] The present inventors have realized that when preparing an absorption solution to be introduced into an IC analyzer, the above-mentioned treatment can be carried out by electrolysis as a means for oxidizing or reducing ions in the absorption solution without using highly toxic reagents such as hydrogen peroxide or hydrazine, and have completed the present invention.

[0009] More specifically, the inventors have found that the above-mentioned problems can be solved by preparing an absorption solution using an absorption tube equipped with electrodes for electrolysis, and electrolyzing the absorption solution contained in the absorption tube during or after the absorption of combustion decomposition gas, thereby oxidizing sulfite ions to sulfate ions and reducing free halogens or halogen oxoacid ions, thereby converting all sulfur compounds to sulfate ions and halogen compounds to halide ions, and then introducing the resulting solution into an IC analyzer, which led to the invention.

[0010] That is, in order to solve the above-mentioned problems, the sample analysis method of the present invention is characterized in that, when analyzing sulfur and / or halogens contained in a sample using an analytical device, sulfur compounds and halogen compounds produced by combustion and decomposition of the sample are recovered in an absorption liquid, and the sulfur compounds and halogen compounds contained in this absorption liquid are oxidized or reduced by electrolysis before being subjected to analysis.

[0011] The solution preparation apparatus of the present invention is characterized in that, when analyzing sulfur and / or halogens contained in a sample by ion chromatography, sulfur compounds and halogen compounds produced by combustion and decomposition of the sample are recovered in an absorption liquid contained in an absorption tube equipped with electrodes for electrolysis, and the sulfur compounds and halogen compounds contained in the absorption liquid are oxidized or reduced by electrolysis in the absorption tube before being subjected to analysis.

[0012] The sample analysis method and solution preparation device can be applied to the analysis of a sample by an IC analyzer, but the present invention can also be applied to other analyzers instead of an IC analyzer.

[0013] As mentioned above, electrolysis of the absorption solution is carried out in an absorption tube equipped with electrodes. The electrodes used for electrolysis can be made of platinum or a platinum alloy. The electrodes consist of a pair of anode and cathode, and a diaphragm made of a glass filter, ceramic filter, ion exchange membrane, or the like is installed between the two electrodes inside the absorption tube to divide the interior of the absorption tube via the diaphragm. One of the electrodes is positioned so that it comes into contact with the absorption solution into which the combustion decomposition gas is blown, and the other is installed in a counter electrode tank inside the absorption tube, separated by the diaphragm. The counter electrode tank contains an electrolyte so that electricity can be passed through it.

[0014] The electrode in contact with the absorbing solution switches polarity to act as an anode or cathode to oxidize or reduce the target component in the absorbing solution. When sulfite ions are oxidized to sulfate ions, a diaphragm is not required between the two electrodes.

[0015] An electrolyte is added to the absorption solution to allow electricity to flow. The electrolyte can be any component as long as it does not affect the measurement of the target component by IC, but it is preferable to use components that are used as IC eluents, such as hydroxides and carbonates.

[0016] According to the present invention, analytical work can be performed safely because dangerous and harmful reagents such as hydrogen peroxide and hydrazine are not used. Also, the laborious management of the reagents is not required. Furthermore, interference during measurement is eliminated, enabling highly accurate IC analysis.

[0017] 1 is a diagram showing a schematic configuration of one embodiment of a solution preparation apparatus for carrying out the reagent analysis method of the present invention. FIG. 2 is a diagram showing a schematic configuration of an absorption tube in FIG. 1. FIG. 3 is a chromatogram showing the analysis results of an absorption solution in which electrolysis was not performed in Example 2. FIG. 4 is a chromatogram showing the analysis results of an absorption solution in which electrolysis was performed in Example 2. FIG. 5 is a diagram showing the results of ion chromatographic measurement of a solution not containing hydrogen peroxide or hydrazine. FIG. 6 is a diagram showing the results of ion chromatographic measurement of a solution containing hydrogen peroxide. FIG. 7 is a diagram showing the results of ion chromatographic measurement of a solution containing hydrazine.

[0018] A preferred embodiment of the solution preparation apparatus of the present invention will be described below with reference to the drawings. Fig. 1 shows a schematic configuration of an apparatus for quantitatively analyzing sulfur and / or halogens contained in a sample using an IC analyzer, in which reference numerals 1 and 2 denote the solution preparation apparatus and the IC analyzer, respectively. The solution preparation apparatus 1 has a known configuration, except that an absorption tube 11 containing an absorption liquid is provided with a function for electrolyzing the absorption liquid, as will be described later.

[0019] In the illustrated apparatus configuration, a solution is prepared as follows: First, a sample is introduced into the sample port 4 from the sample inlet 3, and then transferred into the reaction tube 5, which is composed of an outer tube 5a and an inner tube 5b. The transferred sample is then heated and combusted in an electric furnace 6, which serves as a heating means. Appropriate amounts of oxygen and a carrier gas such as argon are supplied into the reaction tube 5 by flow rate regulators 7a and 7b, respectively. At the same time, water is supplied from a water pump 8a to supply sufficient water vapor into the reaction tube 5. The oxygen, inert gas, and water vapor are then introduced into the reaction volume region of the reaction tube 5.

[0020] The sample is thermally decomposed in the reaction tube 5 to generate a sample gas, which is then sent from the reaction tube 5 to the solution absorption tube 9, where it is absorbed in an absorbing liquid supplied by the water pump 8b, and this absorbing liquid is injected into the absorption tube 11 via the injection tube 10 and stored in the tube. The combustion of the sample, generation of the sample gas and its sending to the solution absorption tube 9, injection of the absorbing liquid, absorption into the sample gas, and injection into the absorption tube 11 are all controlled automatically by a control device consisting of a computer equipped with a predetermined control program.

[0021] An absorbing liquid is injected into the absorption tube 11, and electrolysis is carried out. A sample gas is blown into the tube, and oxidation or reduction is carried out. Once the combustion is complete, water is injected up to the liquid level sensor 12, and the volume of the absorbing liquid in the absorption tube 11 is made constant. The oxidized or reduced absorbing liquid is then introduced into the IC analyzer 2 via the sample injector 13, and the sulfur and halogen contents in the sample are analyzed. In the figure, reference numeral 8c denotes a pump for discharging the absorbing liquid from the absorption tube 11.

[0022] FIG. 2 shows a schematic configuration of an absorption tube 11 containing an absorbing solution. In the figure, the absorption tube 11 has a tank 11a in which an inlet tube 10, through which the sample gas delivered from the reaction tube 5 and the absorbing solution that has absorbed the sample gas are blown, comes into contact with the absorbing solution, and a counter electrode tank 11b containing an electrolytic solution. The two tanks are connected at their lower parts via a diaphragm 14. Inside the two tanks, an electrode pair 15a, 15b consisting of an anode and a cathode is installed, and the electrodes 15a, 15b are immersed in the absorbed solution and come into contact with the absorbed solution. An electrolyte solution is added to the tank 11a, into which the absorbed solution is injected from the inlet tube 10. The absorbed solution contained in the absorption tube 11 is electrolyzed by passing current through the electrode pair 15a, 15b. The polarity of the electrode 15b in the tank 11a, in which the inlet tube 10 comes into contact with the absorbed solution, is switched to act as the anode or cathode, thereby oxidizing or reducing the target component in the absorbed solution.

[0023] The effectiveness of the sample analysis method of the present invention was confirmed by quantitatively analyzing samples. (Example 1) Using p-bromoacetanilide (Br: 37.33%) as a sample, an absorption solution was prepared using the solution preparation apparatus shown in Figures 1 and 2. This was then introduced into a combustion ion chromatograph to analyze the bromine content in the absorption solution. Two types of absorption solution were prepared for analysis: one that underwent reduction treatment by electrolysis in an absorption tube, and one that did not undergo electrolysis. The bromine content of each was analyzed to confirm the difference in analytical results between the two absorption solution preparation methods. Electrolysis was performed by applying a voltage of 10 V to the electrode pair and flowing a current of approximately 10 mA through a tank containing the absorption solution and electrolyte. Electrolysis under these conditions allowed sulfite ions to be oxidized to sulfate ions in approximately 8 to 10 minutes. The analytical results are shown in Table 1.

[0024]

[0025] As shown in Table 1, even when the absorption solution prepared in the solution preparation apparatus was introduced directly into a combustion ion chromatograph for analysis, the recovery rate of bromine contained in the absorption solution was relatively high. However, it was confirmed that a recovery rate of nearly 100% could be obtained when the absorption solution was subjected to reduction treatment by electrolysis in the absorption tube.

[0026] Example 2 Using an ethanol solution of S-benzylthiuronium chloride (S: 136.6 μg / mL) as a sample, an absorption solution was prepared using the solution preparation apparatus in the same manner as in Example 1, and this was introduced into a combustion ion chromatograph to analyze the sulfur content in the absorption solution. Two types of absorption solution were prepared for analysis: one that was subjected to oxidation treatment by electrolysis in an absorption tube under the same conditions as above, and one that was not subjected to electrolysis. Analysis of the sulfur content was carried out for each solution, and the difference in the analytical results between the two absorption solution preparation methods was confirmed. The results are shown in Table 2. The chromatogram showing the analytical results of the absorption solution that was not subjected to electrolysis is shown in FIG. 3, and the chromatogram showing the analytical results of the absorption solution that was subjected to electrolysis is shown in FIG. 4.

[0027]

[0028] As shown in Table 2, it was confirmed that a 100% recovery rate could be obtained when the absorption solution was subjected to oxidation treatment by electrolysis in the absorption tube. Furthermore, as shown in Figure 3, a sulfite ion peak was eluted in the absorption solution without electrolysis, while as shown in Figure 4, the sulfite ion peak disappeared in the absorption solution with electrolysis, confirming that all the sulfite ions were oxidized to sulfate ions.

[0029] For reference, examples are shown in which hydrogen peroxide and hydrazine interfere with the measurement of fluoride ions. Figure 5 shows an example of ion chromatography measurement of a solution not containing hydrogen peroxide or hydrazine, Figure 6 shows an example of measurement of a solution containing hydrogen peroxide, and Figure 7 shows an example of measurement of a solution containing hydrazine. When hydrogen peroxide or hydrazine was added to an absorption solution and measured using an IC analyzer, signals derived from the components, as shown in Figures 6 and 7, appeared on the chromatography, and accurate analytical results could not be obtained. On the other hand, when the absorption solution was subjected to oxidation / reduction treatment by electrolysis, signals derived from the components did not appear, confirming that accurate measurement and analysis were possible.

[0030] The above-described and illustrated device configurations and configurations of components are merely examples, and the present invention is not limited to the configurations and configurations described and illustrated, and other appropriate configurations and configurations are possible. The present invention can be applied as a method and device for preparing solutions for various analytical devices, including IC analytical devices, that quantitatively analyze unknown components contained in samples using calibration curves.

[0031] REFERENCE SIGNS LIST 1 Solution preparation device, 2 IC analyzer, 3 Sample introduction device, 4 Sample port, 5 Reaction tube, 6 Electric furnace, 7a, 7b Flow rate regulator, 8a, 8b, 8c Pump 9 Solution absorption tube, 10 Injection tube, 11 Absorption tube, 12 Liquid level sensor 1, 13 Sample injector, 14 Diaphragm, 15a, 15b Electrode

Claims

1. When analyzing sulfur and / or halogen contained in a sample with an analyzer, the sulfur compound and halogen compound generated by pyrolyzing the sample are recovered in an absorption liquid, and the sulfur compound and halogen compound contained in the absorption liquid are oxidized or reduced by electrolysis and then subjected to analysis. A sample analysis method characterized by this.

2. The sample analysis method according to claim 1, wherein the analyzer is an ion chromatograph analyzer.

3. When analyzing sulfur and / or halogen contained in a sample by ion chromatography, the sulfur compound and halogen compound generated by pyrolyzing the sample are recovered in an absorption liquid contained in an absorption tube equipped with an electrode for electrolysis, and the sulfur compound and halogen compound contained in the absorption liquid are oxidized or reduced by electrolysis in the absorption tube and then subjected to analysis. A solution preparation device configured to be used.

4. The solution preparation device according to claim 3, wherein the oxidized or reduced solution is introduced into an ion chromatograph analyzer.

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