Analytical method for antimony ions, test tools used for analysis of pentavalent antimony ions, and test tools used for analysis of antimony ions by valence

Abstract

To provide a simple method for analyzing antimony.SOLUTION: A method of analyzing an antimony ion according to an embodiment includes: the step in which a first analysis solution or a second analysis solution is used, the first analysis solution contains trivalent antimony ions and pentavalent antimony ions, the second analysis solution is a mixed solution of a first acid and the first analysis solution, and the first analysis solution or the second analysis solution is mixed with a second acid to obtain a third analysis solution in which the pentavalent antimony ions are chlorinated and which contains [SbCl6]- ions; the step in which the third analysis solution is mixed with a first organic solvent, phase-separating the mixture into a fourth analysis solution as an organic phase and an aqueous phase, to obtain the fourth analysis solution; the step in which the fourth analysis solution is mixed with a coloring liquid containing rhodamine B to obtain a fifth analysis solution; and the step in which a concentration of the pentavalent antimony ions in the first analysis solution is evaluated from a color of the fifth analysis solution.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for analyzing antimony ions, a test tool used for analyzing pentavalent antimony ions, and a test tool used for analyzing antimony ions by valence. [Background technology]

[0002] In recent years, regulations on chemical substances have become stricter, and for companies that manufacture electrical and electronic equipment, it has become extremely important to manage the chemical substances contained in the constituent materials used in their products.

[0003] Antimony oxide is used as a fining agent for glass, a flame retardant for resins, etc. Since the toxicity of antimony varies depending on its valence, a method for analyzing antimony according to its valence is required.

[0004] Although X-ray fluorescence analysis can determine antimony concentration, it cannot evaluate antimony by valence, and therefore is not suitable for evaluating concentrations by valence.

[0005] Hydride generation inductively coupled plasma mass spectrometry (HG-ICP / MS) is used to analyze antimony by its valence. However, such equipment is large and not suitable as a screening method, so a screening method by valence that allows simple analysis is required. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-185730 A Summary of the Invention [Problem to be solved by the invention]

[0007] An embodiment of the present invention provides a simple method for analyzing antimony, a test tool used for analyzing pentavalent antimony ions, and a test tool used for analyzing antimony ions according to their valence. [Means for solving the problem]

[0008] In the embodiment, a method for analyzing antimony uses a first analytical solution or a second analytical solution, the first analytical solution contains trivalent antimony ions and pentavalent antimony ions, the second analytical solution is a solution in which a first acid and the first analytical solution are mixed, and the first analytical solution or the second analytical solution is and The pentavalent antimony ion is chlorinated by mixing a second acid. Ta [SbCl6] - The method includes the steps of obtaining a third analytical solution containing ions, mixing the third analytical solution with a first organic solvent to separate into a fourth analytical solution, which is an organic phase, and an aqueous phase to obtain a fourth analytical solution, mixing the fourth analytical solution with a coloring solution containing rhodamine B to obtain a fifth analytical solution, and evaluating the pentavalent antimony ion concentration in the first analytical solution from the color of the fifth analytical solution. The total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the first analytical solution is 0.00 mol / L or more and 0.1 mol / L or less. The total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the first acid is 0.00 mol / L or more and 0.1 mol / L or less. The total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the second acid is 0.00 mol / L or more and 0.1 mol / L or less. In the step of obtaining a fourth analysis solution, the stirred solution is allowed to stand at a temperature of 40° C. or more and 70° C. or less to cause phase separation. [Brief description of the drawings]

[0009] [Figure 1] 1 is a flowchart according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a test tool used for analyzing pentavalent antimony ions according to an embodiment. [Diagram 3] FIG. 2 is a spectrum diagram relating to evaluation of the valence of antimony according to an embodiment. [Figure 4] 1 is a flowchart according to an embodiment. [Diagram 5] An embodiment of a testing tool and a testing tool used for analyzing antimony ions by valence. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A preferred embodiment will be described in detail below with reference to the drawings. In the embodiment, unless otherwise specified, the conditions are those when carried out at 25° C. and atmospheric pressure (100 kPa). In the following steps, each solution may be used in its entirety or in part.

[0011] (First embodiment) As shown in the flow chart of the embodiment in FIG. 1, the analytical method of the first embodiment includes mixing a first analytical solution containing trivalent antimony ions and pentavalent antimony ions or a second analytical solution in which a first acid and the first analytical solution are mixed with a second acid to chlorinate the pentavalent antimony ions to form [SbCl6]. - The method includes a step (S01) of obtaining a third analytical solution containing ions, a step (S02) of mixing the third analytical solution with a first organic solvent and causing phase separation into a fourth analytical solution, which is an organic phase, and an aqueous phase, to obtain a fourth analytical solution, a step (S03) of mixing the fourth analytical solution with a color solution containing rhodamine B to obtain a fifth analytical solution, and a step (S04) of evaluating the concentration of pentavalent antimony ions in the first analytical solution from the color of the fifth analytical solution.

[0012] In the analysis method of the first embodiment, it is preferable to use a test tool 100 used for analyzing pentavalent antimony ions, which includes a first container 1 containing a first acid, a second container 2 containing a second acid, a third container 3 containing a first organic solvent, and a fourth container 4 containing a color developing solution. FIG. 2 shows a schematic diagram of the test tool 100 of the first embodiment. The schematic diagram of FIG. 2 also shows a simplified analysis procedure of pentavalent antimony ions using the test tool 100. In FIG. 2, the arrow from the first container 1 is shown by a dashed line because mixing of the first acid and the first analysis solution may be omitted.

[0013] The first container 1, the second container 2, the third container 3, and the fourth container 4 are preferably glass or synthetic resin containers. Each container may have a bottle shape or a tube shape. Each container has an opening. The opening is provided with a valve or a lid to prevent leakage of the solution. Each solution can be transferred to another solution using a pipette, a dropper, or a syringe.

[0014] The first analytical solution containing trivalent antimony ions and pentavalent antimony ions or the second analytical solution in which the first acid and the first analytical solution are mixed with the second acid to chlorinate the pentavalent antimony ions [SbCl6] - The step (S01) of obtaining a third analytical solution containing ions will be described. In other words, the step (S01) is performed by using a first analytical solution or a second analytical solution, the first analytical solution contains trivalent antimony ions and pentavalent antimony ions, the second analytical solution is a solution in which a first acid is mixed with the first analytical solution, and the first analytical solution or the second analytical solution is mixed with a second acid to chlorinate the pentavalent antimony ions to form [SbCl6]. - This results in a process of obtaining a third analysis solution containing ions.

[0015] In this process, trivalent antimony ions and pentavalent antimony ions contained in the first analytical solution, which is the subject of analysis, are chlorinated. The pentavalent antimony ions are chlorinated by mixing the first analytical solution containing trivalent antimony ions and pentavalent antimony ions or the second analytical solution in which the first acid and the first analytical solution are mixed with the second acid [SbCl6]. - The step (S01) of obtaining a third analysis solution containing ions may be abbreviated as step 1. Chlorinated antimony ions refer to antimony ions in which chloride ions are coordinated to antimony ions.

[0016] In the first step, a third analytical solution is obtained in which the pentavalent antimony ions contained in the first analytical solution are chlorinated without (substantially without) oxidizing the trivalent antimony ions contained in the first analytical solution to pentavalent antimony ions.

[0017] The first analysis solution is a solution containing trivalent antimony ions and pentavalent antimony ions. The first analysis solution is a solution obtained by dissolving a sample such as a resin or metal or by extracting antimony from the sample. In the embodiment, antimony in the sample to be analyzed can be evaluated.

[0018] The first analytical solution contains water in addition to antimony ions and acid. The first analytical solution may contain other metal ions in addition to antimony ions, acid, and water. The first analytical solution preferably does not contain at least one selected from the group consisting of gold, thallium, and gallium, which may interfere with the analysis of antimony ions, in an amount of 1% or more of the antimony ion concentration [mol %] of the first analytical solution, and more preferably does not contain any at all.

[0019] In the first step, the first analytical solution or a second analytical solution obtained by mixing the first analytical solution with the first acid is mixed with the second acid. The solution to be mixed with the second acid is the first analytical solution or the second analytical solution obtained by mixing the first acid with the first analytical solution.

[0020] In the first step, the first or second analytical solution preferably has a low pH because the chlorination of antimony ions does not proceed if the pH of the solution is high. If the pH of the first analytical solution is high, it is preferable to mix a first acid with the first analytical solution.

[0021] The pH of the first analytical solution is preferably 3 or less. There is no particular limit on the lower limit of the pH of the first analytical solution, and the pH of the first analytical solution is preferably -1 (minus one) or more and 3 or less. The first analytical solution having a pH higher than 3 is mixed with a second acid. When the pH of the first analytical solution is higher than 3, the first acid is mixed with the first analytical solution having a pH higher than 3 to obtain a second analytical solution having a pH of 3 or less. There is no particular limit on the lower limit of the pH of the second analytical solution, and the pH of the first analytical solution is preferably -1 or more and 3 or less.

[0022] When the first analytical solution contains one or more selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate, trivalent antimony ions in the first analytical solution are oxidized to pentavalent antimony ions. Experiments by the present inventors have revealed that nitric acid is also an oxidizing agent for trivalent antimony. In addition, cerium (IV) nitrate and cerium (IV) sulfate are known strong oxidizing agents.

[0023] Therefore, the total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate in the first analytical solution is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably, it is completely free of all of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate (0.00 mol / L).

[0024] The nitric acid concentration of the first analysis solution is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably contains no nitric acid at all (0.00 mol / L).

[0025] The cerium (IV) nitrate concentration in the first analysis solution is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no cerium (IV) nitrate is contained (0.00 mol / L).

[0026] The cerium (IV) sulfate concentration in the first analytical solution is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably contains no cerium (IV) sulfate at all (0.00 mol / L).

[0027] In the first embodiment, since the concentration of pentavalent antimony ions contained in the first analysis solution is evaluated, it is not preferable that the first analysis solution contains an acid that oxidizes trivalent antimony ions in the first analysis solution to pentavalent antimony ions. By performing the analysis without oxidizing trivalent antimony ions to pentavalent antimony ions, the second embodiment makes it possible to analyze antimony according to its valence. If the first analysis solution contains one or more selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate, some trivalent antimony ions will have changed in valence to pentavalent antimony ions, making it difficult to analyze antimony according to its valence.

[0028] The first acid can lower the pH of the first analysis solution without oxidizing trivalent antimony ions (without changing the valence to pentavalent antimony ions). If the pH of the first acid is low, a large amount of the first acid is used to lower the pH of the first analysis solution, and the concentration of antimony ions contained in the target solution will be low when evaluating the concentration of pentavalent antimony ions. Therefore, the pH of the first acid is preferably 3 or less, more preferably 1 or less.

[0029] The first acid is preferably one or more selected from the group consisting of hydrochloric acid, sulfuric acid, hydroperoxy acid, and perchloric acid, more preferably hydrochloric acid or sulfuric acid, and even more preferably hydrochloric acid and sulfuric acid. The first acid preferably contains hydrochloric acid of 2 mol / L to 12 mol / L and / or sulfuric acid of 2 mol / L to 18 mol / L. When hydrochloric acid or sulfuric acid is contained, the above-mentioned molar concentration may be satisfied by hydrochloric acid alone or sulfuric acid alone, or may be the sum of the molar concentrations of hydrochloric acid and sulfuric acid.

[0030] For the reasons mentioned above, the nitric acid concentration in the first acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no nitric acid is contained at all (0.00 mol / L).

[0031] For the reasons mentioned above, the concentration of cerium (IV) nitrate contained in the first acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no cerium (IV) nitrate is contained at all (0.00 mol / L).

[0032] For the reasons described above, the concentration of cerium (IV) sulfate contained in the first acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no cerium (IV) sulfate is contained at all (0.00 mol / L).

[0033] The mixing volume ratio of the first analytical solution to the first acid ([amount of first acid] / [amount of first analytical solution]) is preferably 1 or more and 100 or less, and more preferably 5 or more and 20 or less.

[0034] When the first acid contains multiple types of acids, one or more of the acids may be mixed separately with the first analysis solution. For example, when the second acid contains hydrochloric acid and sulfuric acid and is mixed with the first analysis solution, the first analysis solution may be mixed with sulfuric acid, and then the mixture of the first analysis solution and sulfuric acid may be mixed with hydrochloric acid.

[0035] In the first step, the temperature of the first analysis solution when the first analysis solution and the first acid are mixed is preferably 10°C or higher and 30°C or lower.

[0036] In the first step, the temperature of the first acid when the first analysis solution and the first acid are mixed is preferably 10°C or higher and 30°C or lower. In the first step, the temperature of the second analytical solution after mixing the first analytical solution with the first acid is preferably 10° C. or more and 30° C. or less. As long as the temperature of the second analytical solution is within the above-mentioned range, the temperatures of the first analytical solution and the first acid are not important.

[0037] In the first step, when the first analysis solution and the first acid are mixed, it is preferable to agitate the solution, for example by shaking.

[0038] A second acid is mixed with the first or second analyte solution to obtain a third analyte solution. The antimony ions in the third analyte solution are chlorinated. Specifically, the trivalent antimony ions in the third analyte solution are Sb 3- The pentavalent antimony ion exists as [SbCl6] - It exists as.

[0039] The second acid preferably contains at least hydrochloric acid. By containing hydrochloric acid in the second acid, the pH of the third analytical solution can be lowered or maintained at a low pH, and excess chloride ions can be supplied to the first analytical solution or the second analytical solution. In a solution having a low pH and containing excess chloride ions relative to antimony ions, the chlorination of trivalent antimony ions and pentavalent antimony ions proceeds and stabilizes.

[0040] In addition, the antimony ions in the first and second analytical solutions may also be partially chlorinated. By mixing the second acid with the first or second analytical solution, the hydrochloric acid (chloride ions) in the solution is ensured to be in excess, promoting the chlorination of the antimony ions and resulting in Sb 3- and [SbCl6] - exists steadily.

[0041] The second acid preferably contains at least one acid selected from the group consisting of sulfuric acid, hydroperoxide and perchloric acid in addition to hydrochloric acid.

[0042] The second acid preferably contains hydrochloric acid of 2 mol / L or more and 12 mol / L or less.

[0043] Of the acids contained in the second acid, the concentration (mol / L) of hydrochloric acid is preferably equal to or greater than the total concentration (mol / L) of acids other than hydrochloric acid, more preferably equal to or greater than twice the total concentration (mol / L) of acids other than hydrochloric acid, and even more preferably equal to or greater than five times the total concentration (mol / L) of acids other than hydrochloric acid.

[0044] When the second acid contains one or more selected from the group consisting of nitric acid, cerium nitrate, and cerium sulfate, trivalent antimony ions in the first analytical solution are oxidized to pentavalent antimony ions in the first step. In the first embodiment, since the concentration of pentavalent antimony ions contained in the first analytical solution is evaluated, it is not preferable for the second acid to contain an acid that oxidizes trivalent antimony ions in the first analytical solution to pentavalent antimony ions.

[0045] For the reasons described above, the total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the second acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no nitric acid, cerium (IV) nitrate, or cerium (IV) sulfate is contained at all (0.00 mol / L).

[0046] For the reasons mentioned above, the nitric acid concentration in the second acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no nitric acid is contained at all (0.00 mol / L).

[0047] For the reasons mentioned above, the concentration of cerium (IV) nitrate contained in the second acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no cerium (IV) nitrate is contained at all (0.00 mol / L).

[0048] For the reasons described above, the concentration of cerium (IV) sulfate contained in the second acid is preferably 0.00 mol / L or more and 0.1 mol / L or less, more preferably 0.00 mol / L or more and 0.02 mol / L or less, and even more preferably no cerium (IV) sulfate is contained at all (0.00 mol / L).

[0049] When the second acid includes multiple types of acids, one or more of the acids may be mixed separately with the first analysis solution or the second analysis solution. For example, when the second acid includes hydrochloric acid and sulfuric acid and is mixed with the first analysis solution, the first analysis solution may be mixed with sulfuric acid, and then the mixture of the first analysis solution and sulfuric acid may be mixed with hydrochloric acid.

[0050] The mixing volume ratio of the first analytical solution to the second acid ([amount of the second acid] / [amount of the first analytical solution]) is preferably 1 to 100, more preferably 5 to 20. Even if the concentration of antimony ions in the first analytical solution is unknown, sufficient chloride ions can be supplied to the first analytical solution by using a second acid in the above range.

[0051] The mixing volume ratio of the second analytical solution to the second acid ([amount of second acid] / [amount of second analytical solution]) is preferably from 1 to 100, and more preferably from 5 to 20. Even if the concentration of antimony ions in the second analytical solution is unknown, sufficient chloride ions can be supplied to the second analytical solution by using a second acid in the above range.

[0052] In the first step, the temperature of the first analysis solution when the first analysis solution and the second acid are mixed is preferably 10°C or higher and 30°C or lower.

[0053] In the first step, the temperature of the second acid when the first analysis solution and the second acid are mixed is preferably 10°C or higher and 30°C or lower.

[0054] In the first step, it is preferable that the temperature of the third analytical solution after mixing the first analytical solution with the second acid is 10° C. or more and 30° C. or less. As long as the temperature of the third analytical solution is within the above-mentioned range, the temperatures of the first analytical solution and the second acid are not important.

[0055] In the first step, when the first analysis solution and the second acid are mixed, it is preferable to agitate the solution, for example by shaking.

[0056] In the first step, the temperature of the second analytical solution when it is mixed with the second acid is preferably 10°C or higher and 30°C or lower.

[0057] In the first step, the temperature of the second acid when the second analysis solution and the second acid are mixed is preferably 10°C or higher and 30°C or lower.

[0058] In the first step, it is preferable that the temperature of the third analytical solution after mixing the second analytical solution and the second acid is 10° C. or more and 30° C. or less. As long as the temperature of the third analytical solution is within the above-mentioned range, the temperatures of the second analytical solution and the second acid are not important.

[0059] In the first step, when the second analysis solution and the second acid are mixed, it is preferable to agitate the solution, for example by shaking.

[0060] The step (S02) of obtaining a fourth analytical solution, which is a first organic phase, by mixing the third analytical solution with a first organic solvent and phase-separating the solution is described below. In this step, the third analytical solution is mixed with the first organic solvent, and the resulting solution is phase-separated into a fourth analytical solution, which is an organic phase, and an aqueous phase to obtain the fourth analytical solution. The step (S02) of obtaining a fourth analytical solution by mixing the third analytical solution with the first organic solvent and phase-separating the resulting solution into a fourth analytical solution, which is an organic phase, and an aqueous phase to obtain the fourth analytical solution is sometimes abbreviated to the second step.

[0061] Since chlorinated antimony ions are lipophilic, they can be separated by using the first organic solvent. When the third analytical solution is subjected to phase separation using the first organic solvent, it separates into the fourth analytical solution, which is an organic phase (first organic phase), and the first aqueous phase, which is an aqueous phase.

[0062] Chlorinated antimony ions are easily hydrolyzed, so [SbCl6] - From the viewpoint of improving analytical accuracy, it is preferable to extract the above-mentioned HSbCl6 molecules into the first organic phase.

[0063] The first organic solvent is preferably one or more selected from the group consisting of diisopropyl ether, diethyl ether, ethyl methyl ether, dibutyl ether, 1-octanol, chloroform, carbon tetrachloride, benzene, and hexane, more preferably one selected from the group consisting of diisopropyl ether, diethyl ether, ethyl methyl ether, and dibutyl ether, and even more preferably diisopropyl ether. By using these organic solvents, antimony ions can be extracted into the first organic phase as HSbCl6 molecules.

[0064] The first aqueous phase includes the first analysis solution, the first acid, the acid contained in the second acid, etc. Since the first aqueous phase is not the solution to be analyzed in the first embodiment, it is preferable to separate the first organic phase and the first aqueous phase into different containers or to remove the first aqueous phase. When the first aqueous phase includes an analyte other than antimony ions, the first aqueous phase can be used for another analysis.

[0065] In the second step, the temperature of the third analytical solution when it is mixed with the first organic solvent is preferably 10°C or higher and 30°C or lower.

[0066] In the second step, the temperature of the first organic solvent when the third analysis solution and the first organic solvent are mixed is preferably 10°C or higher and 30°C or lower.

[0067] In the second step, the temperature of the fourth analytical solution after mixing the third analytical solution with the first organic solvent is preferably 10° C. or more and 30° C. or less. As long as the temperature of the fourth analytical solution is within the above-mentioned range, the temperatures of the third analytical solution and the first organic solvent are not important.

[0068] In the second step, when the third analytical solution and the first organic solvent are mixed, it is preferable to stir the solution by shaking or the like. In the second step, it is preferable to stir vigorously. Therefore, the flow rate of the solution obtained by mixing the third analytical solution and the first organic solvent when mixing and stirring the third analytical solution and the first organic solvent is preferably 0.1 m / s or more and 1 m / s or less. It is preferable to stir the solution obtained by mixing the third analytical solution and the first organic solvent (solution A) at this flow rate multiple times, specifically 10 times or more and 50 times or less, in the up, down, left and right directions so that solution A hits the wall surface of the container containing the solution obtained by mixing the third analytical solution and the first organic solvent (solution A). The stirring time is preferably 0.5 minutes or more and 3 minutes or less. In the second step, the temperature of the solution obtained by stirring the third analytical solution and the first organic solvent is preferably 10 degrees Celsius or more and 30 degrees Celsius or less.

[0069] In the second step, the solution after stirring is preferably allowed to stand at a temperature of 40° C. or more and 70° C. or less for 0.5 to 3 minutes to cause phase separation of the solution.

[0070] From the viewpoint of suppressing hydrolysis of chlorinated antimony ions, the temperature of the third analytical solution is preferably 10° C. or more and 30° C. or less when moving from the first step to the second step, and the second step is preferably carried out within 10 minutes at this temperature. From the same viewpoint, it is not preferable to add an alkaline solution such as sodium hydroxide, chlorine gas, etc. to the third analytical solution during the process from the first step to the second step. From the same viewpoint, it is preferable to carry out the second step at a temperature of 10° C. or more and 30° C. or less and within 0 minutes to 10 minutes after the completion of the first step without adding anything to the third analytical solution except for unavoidable contamination.

[0071] The step (S03) of obtaining a fifth analytical solution by mixing the fourth analytical solution with a color developing solution containing rhodamine B will be described. In this step, the fourth analytical solution and the color developing solution are mixed. When the first analytical solution contains pentavalent antimony ions, the color of the fifth analytical solution changes. The step (S03) of obtaining a fifth analytical solution by mixing the fourth analytical solution with a color developing solution containing rhodamine B may be abbreviated as the third step.

[0072] The color developing solution is, for example, a sulfuric acid acidic solution in which 0.01 g to 1 g of rhodamine B is dissolved in 1 mL to 100 mL of sulfuric acid (0.1 mol / L to 2 mol / L).

[0073] When the fourth analytical solution is mixed with the coloring solution, the HSbCl6 molecules and rhodamine B form a complex, causing the fifth analytical solution to turn red. If the concentration of pentavalent antimony ions is high, the fifth analytical solution turns deep red, and if the concentration of pentavalent antimony ions is low, the fifth analytical solution turns light red. If the first analytical solution does not contain pentavalent antimony ions, the fifth analytical solution will not turn red. Sb 3+ does not turn red when mixed with rhodamine B. If the coloring solution has a high absorbance at around 550 nm, it becomes difficult to evaluate the concentration of pentavalent antimony ions in the next step. Therefore, it is preferable that the absorbance of the coloring solution at wavelengths of 530 nm to 570 nm is 0.01 to 3.

[0074] In the third step, the temperature of the fourth analytical solution when it is mixed with the color developing solution is preferably 10°C or higher and 30°C or lower.

[0075] In the third step, the temperature of the color developing solution when the fourth analysis solution and the color developing solution are mixed is preferably 10°C or higher and 30°C or lower. In the third step, the temperature of the fifth analytical solution after mixing the fourth analytical solution with the color developing solution is preferably 10° C. or more and 30° C. or less. As long as the temperature of the fifth analytical solution is within the above-mentioned range, the temperatures of the fourth analytical solution and the color developing solution are not important.

[0076] In the third step, when the fourth analysis solution and the color developing solution are mixed, it is preferable to agitate the solution by shaking, etc. The agitation in the third step is preferably performed by shaking vigorously, similarly to the agitation in the second step.

[0077] In the third step, the temperature of the fifth analytical solution during stirring is preferably 10°C or higher and 30°C or lower.

[0078] When moving from step 2 to step 3, the temperature of the fourth analytical solution is preferably 10° C. or higher and 30° C. or lower, and step 3 is preferably performed within 10 minutes at this temperature. From the viewpoint of preventing unintended oxidation of trivalent antimony ions, it is not preferable to add chlorine gas or the like to the fourth analytical solution in the process from step 2 to step 3. From the same viewpoint, it is preferable to perform step 3 at a temperature of 10° C. or higher and 30° C. or lower, and within 0 minutes to 10 minutes after step 2 is completed, without adding anything to the third analytical solution except for unavoidable contamination.

[0079] The step (S04) of evaluating the concentration of pentavalent antimony ions in the first analytical solution from the color of the fifth analytical solution will be described. In this step, the concentration of pentavalent antimony ions is evaluated from the color of the fifth analytical solution. The step (S04) of evaluating the concentration of pentavalent antimony ions in the first analytical solution from the color of the fifth analytical solution may be abbreviated as the fourth step.

[0080] When a coloring solution is added in the third step, the first analytical solution turns red if it contains pentavalent antimony ions. The concentration of pentavalent antimony ions is evaluated based on the color of the fifth analytical solution. Evaluation methods include a method of comparing the color of the fifth analytical solution with a color chart, or a method using an absorbance meter.

[0081] The method of comparing the color of the fifth analytical solution with a color chart is simple but suitable as a screening method because it does not require measuring equipment. Even when using a color chart, the absorbance at a wavelength of around 550 nm can be evaluated by the intensity of the red color.

[0082] The method using an absorbance meter evaluates the absorbance of the fifth analytical solution at a wavelength of 550 nm. The measurement wavelength is preferably 550 nm, but may be any wavelength between 530 nm and 570 nm, and preferably any wavelength between 540 nm and 560 nm. When an absorbance meter is used, a calibration curve is created in advance using an antimony standard solution, and the concentration of pentavalent antimony ions in the fifth analytical solution is evaluated. When a color chart is used, it is preferable to perform the evaluation taking into consideration how many times the first analytical solution is diluted with the fifth analytical solution.

[0083] In the analysis of antimony ions using Rhodamine B, cerium sulfate (IV) and other acids were added to the solution to be analyzed to convert the valence of trivalent antimony ions to pentavalent antimony ions, and then the analysis was performed. In this analysis, several strong acids, such as nitric acid, hydrochloric acid, sulfuric acid, and cerium sulfate (IV), were added when adjusting the solution, and no comparative study of the stage at which the valence of antimony ions occurs had been reported. Since cerium sulfate (IV) and cerium nitrate (IV) are strong oxidizing agents, it is expected that cerium sulfate (IV) and cerium nitrate (IV) are oxidizing agents that convert the valence of trivalent antimony ions to pentavalent antimony ions, but it was unclear whether these other acids also act as oxidizing agents for trivalent antimony ions, and they had not been paid attention to. Therefore, an evaluation was performed with and without treatment with cerium sulfate (IV) to determine what acids convert the valence of trivalent antimony ions to pentavalent antimony ions.

[0084] The following solutions were used for evaluation by cerium (IV) sulfate treatment: Sample A: 10μg / mL antimony (trivalent) solution (a solution in which 10μg of antimony trioxide (Sb(III)) in terms of metallic antimony is dissolved in 10mL of hydrochloric acid) Sample B: 10μg / mL antimony (pentavalent) solution (a solution in which 10μg of potassium pyroantimonate (Sb(V)) in terms of metallic antimony is dissolved in 10mL of pure water) Sample C: 10μg / mL antimony (trivalent + pentavalent) solution (a solution in which 5μg of antimony trioxide (Sb(III)) calculated as metallic antimony and 5μg of potassium pyroantimonate (Sb(V)) calculated as metallic antimony are dissolved in 10mL of pure water) Hydrochloric acid: 8 mol / L Sulfuric acid: 9mol / L Nitric acid: 16mol / L Cerium (IV) sulfate solution: 30 g / L (3.6 g of cerium (IV) sulfate tetrahydrate dissolved in 6 mL of sulfuric acid and water to make 100 mL) Rhodamine B solution: 0.02 g of Rhodamine B was dissolved in 6 mL of 6 mol / L sulfuric acid, and water was added to make 100 mL.

[0085] Test 1 3 mL of sample A, 5 mL of nitric acid, 5 mL of sulfuric acid, 10 mL of hydrochloric acid, and 7 mL of water were mixed (treatment 1). Cerium (IV) sulfate solution was added dropwise to the mixed solution until the color of the solution turned yellow, and 0.5 mL of cerium (IV) sulfate solution was added dropwise to the solution of treatment 1, and the solution was left to stand at room temperature for 5 minutes (treatment 2). Next, 20 mL of hydrochloric acid and 1 mL of cerium (IV) sulfate solution were added to the solution of treatment 2 (treatment 3). Next, 30 mL of diisopropyl ether was added to the solution of treatment 3, the solution was vigorously shaken for about 2 minutes, and the solution was left to stand to separate into an organic phase and an aqueous phase, and the aqueous phase was removed (treatment 4). 5 mL of rhodamine B solution was added to the organic phase, and the solution was vigorously shaken for 1 minute and left to stand (treatment 5). In test 1, it was observed that the transparent solution changed to red (coloration) by treatment 5.

[0086] Test 2 This was the same as Test 1, except that 3 mL of Sample B was used instead of 3 mL of Sample A. In Test 2, it was observed that the clear solution turned red (colored) after Treatment 5.

[0087] Test 3 This was the same as Test 1, except that 3 mL of Sample C was used instead of 3 mL of Sample A. In Test 3, it was observed that the clear solution turned red (colored) after Treatment 5.

[0088] A color reaction was observed in all of Tests 1 to 3. Since a color reaction was observed when HSbCl6 was present in the solution to which Rhodamine B solution was added in Treatment 5, it was found that the color reaction in Test 1 had caused a valence change from trivalent antimony ions to pentavalent antimony ions. In other words, it was found that a valence change had occurred in Treatment 1.

[0089] Test 4 The test was the same as Test 1 except that Treatment 2 was omitted. In Test 4, it was observed that Treatment 5 caused the transparent solution to turn red (coloration).

[0090] Test 5 The same as Test 2 except that Treatment 2 was omitted. In Test 5, it was observed that Treatment 5 caused the transparent solution to turn red (coloration).

[0091] Test 6 The same as Test 3 except that Treatment 2 was omitted. In Test 6, it was observed that Treatment 6 caused the transparent solution to turn red (coloration).

[0092] A color reaction was observed in all of Tests 4 to 6. Since a color reaction was observed when HSbCl6 was present in the solution to which Rhodamine B solution was added in Treatment 5, it was found that the valence of trivalent antimony ions was changed to pentavalent antimony ions even without the oxidation step in Treatment 2. In other words, it was found that a valence change occurred in Treatment 1.

[0093] Test 7 The same as Test 1, except that Treatment 2 was omitted and hydrochloric acid was not added in Treatment 3. In Test 7, it was observed that the transparent solution turned red (coloration) after Treatment 5.

[0094] Test 8 The procedure was the same as Test 2, except that Treatment 2 was omitted and hydrochloric acid was not added in Treatment 3. In Test 8, it was observed that the transparent solution turned red (colored) after Treatment 5.

[0095] Test 9 The same as Test 3, except that Treatment 2 was omitted and hydrochloric acid was not added in Treatment 3. In Test 9, it was observed that the transparent solution turned red (coloration) after Treatment 5.

[0096] A color reaction was observed in all of Tests 7 to 9. Since a color reaction was observed when HSbCl6 was present in the solution to which Rhodamine B solution was added in Treatment 5, it was found that the valence of trivalent antimony ions was changed to pentavalent antimony ions even without the oxidation step in Treatment 2. In other words, it was found that a valence change occurred in Treatment 1. Furthermore, it was thought that antimony ions were chlorinated by the addition of hydrochloric acid in Treatment 3, but since the color reaction occurred even without this hydrochloric acid, it is expected that the valence change and chlorination proceeded simultaneously in Treatment 1.

[0097] Test 10 The test was the same as Test 1 except that Treatments 2 and 3 were omitted. In Test 1, it was observed that Treatment 10 caused the transparent solution to turn red (color change).

[0098] Test 11 The procedure was the same as Test 2, except that Treatments 2 and 3 were omitted. In Test 11, it was observed that Treatment 5 caused the transparent solution to turn red (coloration).

[0099] Test 12 The same as Test 3 except that Treatment 2 and Treatment 3 were omitted. In Test 12, it was observed that Treatment 5 caused the transparent solution to turn red (coloration).

[0100] A color reaction was observed in all of Tests 10 to 12. Since a color reaction was observed when HSbCl6 was present in the solution to which Rhodamine B solution was added in Treatment 5, it was found that the valence of trivalent antimony ions was changed to pentavalent antimony ions even without the oxidation step in Treatment 2. In other words, it was found that a valence change occurred in Treatment 1. Furthermore, it was thought that antimony ions were chlorinated by the addition of hydrochloric acid in Treatment 3, but since the color reaction occurred even without this hydrochloric acid, it is expected that the valence change and chlorination proceeded simultaneously in Treatment 1.

[0101] Test 13 This was the same as Test 1, except that no nitric acid was added in Treatment 1, and Treatments 2 and 3 were omitted. In Test 13, Treatment 5 did not cause the clear solution to turn red.

[0102] Test 14 This was the same as Test 2, except that no nitric acid was added in Treatment 1, and Treatments 2 and 3 were omitted. In Test 14, Treatment 5 did not cause the clear solution to turn red.

[0103] Test 15 This was the same as Test 3, except that no nitric acid was added in Treatment 1, and Treatments 2 and 3 were omitted. In Test 15, Treatment 5 did not cause the clear solution to turn red.

[0104] No color reaction was observed in any of Tests 13 to 15. Since no change in the color of the solution could be confirmed, it is expected that at least chlorination did not progress in Treatment 1, where nitric acid was not added. Furthermore, since no color reaction was observed in any of Tests 13 to 15, it was not possible to determine from Tests 13 to 15 whether the presence or absence of nitric acid was a factor in the change in valence from trivalent antimony ions to pentavalent antimony ions.

[0105] Next, because Tests 1 to 15 showed that there was a possibility that trivalent antimony ions had changed to pentavalent antimony ions in Treatment 1, we performed an evaluation using X-ray Absorption Fine Structure (XAFS), which can obtain information on the valence of specific elements. When the acid used in Treatment 1 was changed, we evaluated which acid would (or would not) cause a change in the valence of antimony ions.

[0106] Test 16 An aqueous solution containing trivalent antimony ions was evaluated by XAFS. The XAFS spectrum (dotted line) between 30425 eV and 30525 eV is shown in Figure 3. The aqueous solution containing trivalent antimony ions in Test 16 contained 1 μg / mL Sb in terms of metallic antimony. 3+ In the XAFS spectrum of Test 16, a peak was confirmed at around 30474 eV due to trivalent antimony.

[0107] Test 17 The aqueous solution containing pentavalent antimony ions was evaluated by XAFS. The aqueous solution containing pentavalent antimony ions in Test 17 contained 1 μg / mL Sb in terms of metallic antimony. 5+ The XAFS spectrum (dashed line) between 30,425 eV and 30,525 eV is shown in Figure 3. In the XAFS spectrum of Test 17, a peak was confirmed near 30,480 eV due to pentavalent antimony.

[0108] Tests 18 to 21 were compared with the results of Test 16 and Test 17 to evaluate whether or not a valence change had occurred in the antimony ions. If the test results were similar to the XAFS spectrum of Test 16, no valence change had occurred. If the test results were similar to the XAFS spectrum of Test 17, a valence change had occurred. If the results were intermediate between the two, a partial valence change had occurred.

[0109] Test 18 The solution containing antimony ions was evaluated by XAFS. The aqueous solution containing antimony ions in Test 18 contained 1 μg / mL Sb in terms of metallic antimony (concentration after mixing with water and acid). 3+ Water, hydrochloric acid, sulfuric acid, and nitric acid are mixed into the solution containing antimony ions in Test 18. The hydrochloric acid concentration of the solution containing antimony ions in Test 18 is 1.5 mol / L, the sulfuric acid concentration is 1.5 mol / L, and the nitric acid concentration is 2.7 mol / L. The XAFS spectrum (solid line) between 30425 eV and 30525 eV in Test 18 is shown in Figure 3. In the XAFS spectrum of Test 18, a peak was confirmed between 30474 eV due to trivalent antimony and 30480 eV due to pentavalent antimony. Since a peak was confirmed between 30474 eV due to trivalent antimony and 30480 eV due to pentavalent antimony, it is considered that some of the trivalent antimony ions contained in the aqueous solution containing antimony ions in Test 18 changed in valence to pentavalent antimony ions.

[0110] Test 19 A solution containing antimony ions was evaluated by XAFS. The aqueous solution containing antimony ions in Test 19 was similar to the aqueous solution containing antimony ions in Test 18, except that the aqueous solution containing antimony ions in Test 19 did not contain nitric acid (water was increased instead of nitric acid). In the XAFS spectrum of Test 19, a peak was confirmed at around 30,474 eV due to trivalent antimony. The XAFS spectrum of Test 19 largely overlapped with the XAFS spectrum of Test 16. Since the XAFS spectrum of Test 19 largely overlapped with the XAFS spectrum of Test 16, it is considered that nitric acid acted as an oxidizing agent that changed the valence of trivalent antimony ions to pentavalent antimony ions.

[0111] Test 20 The solution containing antimony ions was evaluated by XAFS. The aqueous solution containing antimony ions in Test 20 was similar to the aqueous solution containing antimony ions in Test 18, except that the aqueous solution containing antimony ions in Test 20 did not contain sulfuric acid (water was increased instead of sulfuric acid). In the XAFS spectrum of Test 20, peaks were confirmed between 30474 eV due to trivalent antimony and 30480 eV due to pentavalent antimony. The XAFS spectrum of Test 20 largely overlapped with the XAFS spectrum of Test 18. Since the XAFS spectrum of Test 20 largely overlapped with the XAFS spectrum of Test 18, it is considered that nitric acid acted as an oxidizing agent that changed the valence of trivalent antimony ions to pentavalent antimony ions.

[0112] Test 21 The solution containing antimony ions was evaluated by XAFS. The aqueous solution containing antimony ions in Test 21 was similar to the aqueous solution containing antimony ions in Test 18, except that the aqueous solution containing antimony ions in Test 21 did not contain hydrochloric acid (water was increased instead of hydrochloric acid). In the XAFS spectrum of Test 21, a peak was confirmed between 30474 eV due to trivalent antimony and 30480 eV due to pentavalent antimony. The XAFS spectrum of Test 21 was largely overlapped with the XAFS spectrum of Test 18 and the XAFS spectrum of Test 20. Since the XAFS spectrum of Test 20 was largely overlapped with the XAFS spectrum of Test 18 and the XAFS spectrum of Test 20, it is considered that nitric acid acted as an oxidizing agent that changed the valence of trivalent antimony ions to pentavalent antimony ions.

[0113] From the results of Tests 18 to 21, the presence or absence of nitric acid caused differences in the XAFS spectrum. No differences in the XAFS spectrum were confirmed depending on the presence or absence of hydrochloric acid or sulfuric acid. From these results, it was found that when nitric acid is added to an aqueous solution containing trivalent antimony ions, the valence changes to pentavalent antimony ions. Therefore, in the first embodiment, it is preferable to carry out all steps under conditions that do not contain nitric acid, ammonium cerium (IV) nitrate, or cerium (IV) sulfate. The analytical method of the first embodiment includes mixing a first analytical solution containing trivalent antimony ions and pentavalent antimony ions or a second analytical solution in which a first acid and the first analytical solution are mixed with a second acid to chlorinate the pentavalent antimony ions to form [SbCl6]. - The method includes a step (S01) of obtaining a third analytical solution containing ions, a step (S02) of obtaining a fourth analytical solution by mixing the third analytical solution with a first organic solvent and causing phase separation into a fourth analytical solution which is an organic phase and an aqueous phase, a step (S03) of obtaining a fifth analytical solution by mixing the fourth analytical solution with a color developing solution containing rhodamine B, and a step (S04) of evaluating the concentration of pentavalent antimony ions in the first analytical solution from the color of the fifth analytical solution. By performing this analytical method, the concentration of pentavalent antimony ions in a solution can be simply and easily measured.

[0114] Second embodiment As shown in the flow chart relating to the embodiment of FIG. 4, the method for analyzing antimony according to the second embodiment includes a step (S05) of mixing the first or second analytical solution with a third acid to obtain a sixth analytical solution in which trivalent antimony ions are oxidized to pentavalent antimony ions, and a step (S06) of mixing the sixth analytical solution with a fourth acid to obtain the pentavalent antimony ions contained in the first analytical solution and the pentavalent antimony ions resulting from the oxidization of the trivalent antimony ions contained in the first analytical solution, which are chlorinated [SbCl6]. - The method includes a step (S06) of obtaining a seventh analytical solution containing ions, a step (S07) of mixing the seventh analytical solution with a second organic solvent and phase-separating it into an eighth analytical solution, which is a second organic phase, and an aqueous phase to obtain an eighth analytical solution, a step (S08) of mixing the eighth analytical solution with a color developing solution containing rhodamine B to obtain a ninth analytical solution, a step (S09) of evaluating the total concentration of trivalent antimony ions and pentavalent antimony ions in the first analytical solution from the color of the ninth analytical solution, and a step (S10) of evaluating the concentration of trivalent antimony ions contained in the first analytical solution by comparing the color of the fifth analytical solution with the color of the ninth analytical solution.

[0115] In the analysis step of the second embodiment, the valence of trivalent antimony ions is changed to pentavalent antimony ions to evaluate the total concentration of trivalent antimony ions and pentavalent antimony ions. Then, the concentration of trivalent antimony ions in the first analysis solution is evaluated using the evaluation result of the concentration of pentavalent antimony ions in the first analysis solution of the first embodiment.

[0116] The method for analyzing antimony according to the second embodiment performs both the analysis step according to the first embodiment and the analysis step according to the second embodiment (S05-S10). In the method for analyzing antimony according to the second embodiment, the analysis step according to the first embodiment and the analysis step according to the second embodiment may be performed in parallel, the analysis step according to the first embodiment may be performed first and the analysis step according to the second embodiment may be performed later, or the analysis step according to the second embodiment may be performed first and the analysis step according to the first embodiment may be performed later. When the analysis step according to the second embodiment is performed first and the analysis step according to the first embodiment is performed later, the step (S10) of evaluating the concentration of trivalent antimony ions contained in the first analytical solution by comparing the color of the fifth analytical solution with the color of the ninth analytical solution is performed after the step (S04) of evaluating the concentration of pentavalent antimony ions in the first analytical solution from the color of the fifth analytical solution according to the first embodiment and the step (S09) of evaluating the total concentration of trivalent antimony ions and pentavalent antimony ions in the first analytical solution from the color of the ninth analytical solution according to the second embodiment are performed.

[0117] In the analysis method of the second embodiment, it is preferable to use a test tool 200 used for analyzing antimony ions by valence, which includes a first container 1 containing a first acid, a second container 2 containing a second acid, a third container 3 containing a first organic solvent, a fourth container 4 containing a coloring solution, a fifth container 5 containing a third acid, a sixth container 6 containing a fourth acid, and a seventh container 7 containing a second organic solvent. FIG. 5 shows a schematic diagram of the test tool 200 of the second embodiment. The schematic diagram of FIG. 5 also shows a simplified analysis procedure for pentavalent antimony ions using the test tool 100. In FIG. 5, the arrow from the first container 1 is shown by a dashed line because the mixing of the first acid and the first analysis solution may be omitted.

[0118] When the second acid and the fourth acid are in the same solution, the second container 2 and the sixth container 6 are common. When the second container 2 and the sixth container 6 are common, the second container 2 or the sixth container 6 can be omitted.

[0119] When the first organic solvent and the second organic solvent are the same solution, the third container 3 and the seventh container 7 are common. When the third container 3 and the seventh container 7 are common, the third container 3 or the seventh container 7 can be omitted.

[0120] The first container 1, the second container 2, the third container 3, the fourth container 4, the fifth container 5, the sixth container 6, and the seventh container 7 are preferably glass or synthetic resin containers. Each container may have a bottle shape or a tube shape. Each container has an opening. The opening is provided with a valve or a lid to prevent leakage of the solution. Each solution can be transferred to another solution using a pipette, a dropper, or a syringe.

[0121] Description of the contents common to the first and second embodiments will be omitted below. In the first and second embodiments, a first analysis solution or a second analysis solution is used.

[0122] The first and second embodiments share the same treatment, except for the presence or absence of oxidation to change the valence of trivalent antimony ions to pentavalent antimony ions as shown in S05. In the treatments described in the first and second embodiments, the type, amount, temperature, time, stirring method, and other conditions of the solution used are the same for the common treatments, thereby improving the reliability of the evaluation of the trivalent antimony ion concentration in the second embodiment.

[0123] The step (S05) of mixing the first or second analytical solution with a third acid to obtain a sixth analytical solution in which trivalent antimony ions are oxidized to pentavalent antimony ions will be described. In this step, the valence of trivalent antimony ions contained in the first or second analytical solution to be analyzed is changed (oxidized) to pentavalent antimony ions. The step (S05) of mixing the first or second analytical solution with a third acid to obtain a sixth analytical solution in which trivalent antimony ions are oxidized to pentavalent antimony ions may be abbreviated as the fifth step.

[0124] When using a second analytical solution obtained by mixing the first analytical solution and the first acid, it is preferable that the first acid used in the first step of the first embodiment and the first acid used in the fifth analytical step of the second embodiment are the same acid and are used in the same amount.

[0125] In the second embodiment, the total concentration of trivalent antimony ions and pentavalent antimony ions contained in the first analysis solution is evaluated. Trivalent antimony ions do not undergo a color reaction with rhodamine B. In the second embodiment, in order to measure the concentration of antimony ions including trivalent antimony ions, the trivalent antimony ions are oxidized to pentavalent antimony ions in the fifth step.

[0126] In the fifth step, a third acid that oxidizes trivalent antimony ions in the first or second analytical solution to pentavalent antimony ions is mixed with the first or second analytical solution. The third acid preferably includes one or more acids selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate. More preferably, the third acid includes cerium (IV) sulfate. The third acid may further include one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, hydroperoxy acid, and perchloric acid.

[0127] Cerium (IV) nitrate is used, for example, as a solution in which cerium (IV) nitrate is dissolved in nitric acid. Cerium (IV) sulfate is used, for example, as a solution in which cerium (IV) sulfate hexahydrate is dissolved in sulfuric acid. The total concentration of the third acid, nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate, is preferably 0.02 mol / L or more and 1.0 mol / L or less, and more preferably 0.05 mol / L or more and 0.2 mol / L or less.

[0128] When the third acid contains nitric acid, the nitric acid concentration in the third acid is preferably 0.02 mol / L or more and 1.0 mol / L or less, and more preferably 0.05 mol / L or more and 0.2 mol / L or less.

[0129] When the third acid contains cerium (IV) nitrate, the concentration of cerium (IV) nitrate in the third acid is preferably 0.02 mol / L or more and 1.0 mol / L or less, and more preferably 0.05 mol / L or more and 0.2 mol / L or less.

[0130] When the third acid contains cerium sulfate, the concentration of cerium (IV) sulfate in the third acid is preferably 0.02 mol / L or more and 1.0 mol / L or less, and more preferably 0.05 mol / L or more and 0.2 mol / L or less.

[0131] The pH of the third acid is preferably 3 or less, more preferably 1 or less.

[0132] The mixed volume ratio of the first analytical solution to the third acid ([amount of third acid] / [amount of first analytical solution]) is preferably 1 to 100, more preferably 2 to 50. If the amount (volume) of the third acid relative to the amount (volume) of the first analytical solution is too small, oxidation of trivalent antimony ions to pentavalent antimony ions may be insufficient, making it impossible to perform an appropriate analysis.

[0133] The mixed volume ratio of the second analytical solution to the third acid ([amount of third acid] / [amount of second analytical solution]) is preferably from 1 to 100, and more preferably from 2 to 50. If the amount (volume) of the third acid relative to the amount (volume) of the second analytical solution is too small, oxidation of trivalent antimony ions to pentavalent antimony ions may be insufficient, making it impossible to perform an appropriate analysis.

[0134] When the third acid contains multiple types of acids, one or more of the acids may be mixed separately with the first analysis solution or the second analysis solution. For example, when the third acid contains nitric acid and sulfuric acid and is to be mixed with the first analysis solution, the first analysis solution may be mixed with sulfuric acid, and then the mixture of the first analysis solution and sulfuric acid may be mixed with nitric acid.

[0135] When cerium (IV) sulfate is used as the third acid, the cerium (IV) sulfate solution is added to the first or second analytical solution until the solution turns yellow, and then, preferably, 0.1 mL to 1.0 mL of the cerium (IV) sulfate solution is added to the yellow solution.

[0136] In the fifth step, the temperature of the first analysis solution when it is mixed with the third acid is preferably 10°C or higher and 30°C or lower.

[0137] In the fifth step, the temperature of the third acid when the first analysis solution and the third acid are mixed is preferably 10°C or higher and 30°C or lower.

[0138] In the fifth step, when the first analysis solution and the third acid are mixed, it is preferable to agitate the solution, for example by shaking.

[0139] In the fifth step, the temperature of the first analysis solution when the second analysis solution and the third acid are mixed is preferably 10°C or higher and 30°C or lower.

[0140] In the fifth step, the temperature of the third acid when the second analysis solution and the third acid are mixed is preferably 10°C or higher and 30°C or lower.

[0141] In the fifth step, when the second analysis solution and the third acid are mixed, it is preferable to agitate the solution, for example by shaking.

[0142] In the fifth step, it is preferable to perform the sixth step after 1 minute or more has elapsed since the first or second analytical solution is mixed with the third acid. If the sixth step is performed immediately after the third acid is added, the valence change of the trivalent antimony ion may not proceed sufficiently. Since the oxidation reaction proceeds relatively quickly when the third acid is added, it is preferable to perform the sixth step after 1 minute or more has elapsed since the first or second analytical solution is mixed with the third acid. There is no particular upper limit, but it is preferable to perform the sixth step after 1 minute or more and 10 minutes or less, and more preferably after 1 minute or more and 5 minutes or less.

[0143] By mixing the sixth analytical solution with the fourth acid, the pentavalent antimony ions contained in the first analytical solution and the trivalent antimony ions contained in the first analytical solution were oxidized, and the pentavalent antimony ions were chlorinated [SbCl6]. - The step (S06) of obtaining a seventh analytical solution containing ions will be described. In this step, the trivalent antimony ions contained in the first analytical solution, which is the subject of analysis, are converted to pentavalent antimony ions, and the pentavalent antimony ions contained in the first analytical solution are chlorinated. The sixth analytical solution is mixed with a fourth acid to obtain the pentavalent antimony ions contained in the first analytical solution and the trivalent antimony ions contained in the first analytical solution are oxidized to obtain the pentavalent antimony ions that have been chlorinated [SbCl6]. - The step (S06) of obtaining a seventh analysis solution containing ions may be abbreviated as a sixth step.

[0144] In the sixth step, the trivalent antimony ions contained in the first analytical solution (or the second analytical solution) are oxidized to pentavalent antimony ions, and both the pentavalent antimony ions contained in the first analytical solution (or the second analytical solution) are chlorinated [SbCl6] - A seventh analytical solution is obtained which comprises:

[0145] The explanation of the contents common to the fourth acid and the second acid will be omitted. The second acid can be used as the fourth acid. The fourth acid can be an acid solution different from the second acid.

[0146] The fourth acid is mixed with the sixth analytical solution to obtain a seventh analytical solution. The antimony ions in the seventh analytical solution are chlorinated. Specifically, the pentavalent antimony ions in the seventh analytical solution are [SbCl6] - It exists as.

[0147] The fourth acid preferably contains at least hydrochloric acid. By containing hydrochloric acid in the fourth acid, the pH of the sixth analytical solution can be lowered or maintained at a low pH, and excess chloride ions can be supplied to the third analytical solution. The chlorination of trivalent antimony ions and pentavalent antimony ions is preferably performed at a low pH, with excess chloride ions present relative to the antimony ions.

[0148] The fourth acid used in the sixth step may contain one or more selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate. Since the sixth analytical solution contains one or more selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate that oxidize trivalent antimony ions to pentavalent antimony ions, there is no adverse effect even if the fourth acid contains one or more selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate.

[0149] The fourth acid preferably includes, in addition to hydrochloric acid, one or more acids selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate.

[0150] The mixed volume ratio of the sixth analytical solution to the fourth acid ([amount of fourth acid] / [amount of sixth analytical solution]) is preferably 1 to 100, more preferably 5 to 20. If the amount (volume) of the fourth acid relative to the amount (volume) of the sixth analytical solution is too small, more specifically, if the amount of hydrochloric acid is too small, chlorination may be insufficient and appropriate analysis may not be performed.

[0151] In the sixth step, the temperature of the sixth analytical solution when it is mixed with the fourth acid is preferably 10°C or higher and 30°C or lower.

[0152] In the sixth step, the temperature of the fourth acid when the sixth analytical solution and the fourth acid are mixed is preferably 10°C or higher and 30°C or lower.

[0153] In the sixth step, when the sixth analytical solution and the fourth acid are mixed, it is preferable to agitate the solution, for example by shaking.

[0154] The step (S07) of mixing the seventh analytical solution with the second organic solvent and phase-separating it into the eighth analytical solution, which is the second organic phase, and the aqueous phase to obtain the eighth analytical solution will be described. In this step, the seventh analytical solution is mixed with the second organic solvent and phase-separated it into the eighth analytical solution, which is the second organic phase, and the aqueous phase to obtain the eighth analytical solution. The step (S07) of mixing the seventh analytical solution with the second organic solvent and phase-separated it into the eighth analytical solution, which is the second organic phase, and the aqueous phase to obtain the eighth analytical solution may be abbreviated as the seventh step.

[0155] The seventh step is similar to the second step, and the explanation of the contents common to the seventh step and the second step will be omitted.

[0156] Since the chlorinated antimony ions are lipophilic, the antimony ions can be separated by using the second organic solvent. When the seventh analytical solution is subjected to phase separation using the first organic solvent, it separates into the eighth analytical solution, which is an organic phase (second organic phase), and the second aqueous phase, which is an aqueous phase.

[0157] The second organic solvent is preferably one or more selected from the group consisting of diisopropyl ether, diethyl ether, ethyl methyl ether, dibutyl ether, 1-octanol, chloroform, carbon tetrachloride, benzene, and hexane, more preferably one selected from the group consisting of diisopropyl ether, diethyl ether, ethyl methyl ether, and dibutyl ether, and even more preferably diisopropyl ether. By using these organic solvents, antimony ions can be extracted into the second organic phase as HSbCl6 molecules. It is preferable to use the same organic solvent as the first organic solvent for the second organic solvent. By using the same organic solvent in the first and second embodiments, the analytical conditions become similar, and the reliability of the concentration evaluation is improved.

[0158] The amount (volume) of the second organic solvent used in step 7 is preferably 0.5 to 1.5 times the amount (volume) of the first organic solvent used in step 2. When evaluation using a color chart is performed in steps 4 and 9, evaluation based on color differences becomes easier if the liquid to be evaluated is diluted to the same extent with an organic solvent.

[0159] The second aqueous phase contains acids contained in the first analysis solution, the third acid, and the fourth acid. Since the second aqueous phase is not the solution to be analyzed in the second embodiment, it is preferable to separate the second organic phase and the second aqueous phase into different containers or to remove the second aqueous phase. When the second aqueous phase contains an analyte other than antimony ions, the second aqueous phase can be used for another analysis.

[0160] The step (S08) of obtaining a ninth analytical solution by mixing the eighth analytical solution with a color developing solution containing rhodamine B will be described. In this step, the eighth analytical solution and the color developing solution are mixed. When the first analytical solution contains trivalent antimony ions and / or pentavalent antimony ions, the color of the ninth analytical solution changes. The step (S08) of obtaining a ninth analytical solution by mixing the eighth analytical solution with a color developing solution containing rhodamine B may be abbreviated as the eighth step.

[0161] Step 8 is similar to step 3. Details common to step 8 and step 3 will be omitted.

[0162] When the eighth analytical solution is mixed with the coloring solution, the ninth analytical solution turns red due to the HSbCl6 molecules and rhodamine B. The coloring solution used in the eighth step is preferably the same as the coloring solution used in the third step. Using the same coloring solution improves the reliability of the evaluation of the antimony ion concentration.

[0163] The step (S09) of evaluating the total concentration of trivalent antimony ions and pentavalent antimony ions in the first analytical solution from the color of the ninth analytical solution will be described. In this step, the pentavalent antimony ion concentration is evaluated from the color of the ninth analytical solution. The step (S09) of evaluating the total concentration of trivalent antimony ions and pentavalent antimony ions in the first analytical solution from the color of the ninth analytical solution may be abbreviated as the ninth step.

[0164] Step 9 is similar to Step 4. Details common to Step 9 and Step 4 will be omitted.

[0165] When the coloring solution is added in the eighth step, the first analytical solution turns red if it contains trivalent antimony ions and / or pentavalent antimony ions. If the antimony ion concentration is high, the red color becomes deeper, and if the antimony ion concentration is low, the red color becomes lighter. Therefore, the total concentration of trivalent antimony ions and pentavalent antimony ions in the first analytical solution is evaluated from the color of the ninth analytical solution. Evaluation methods include a method of comparing the color of the ninth analytical solution with a color chart, or a method using an absorbance meter.

[0166] The step (S10) of evaluating the concentration of trivalent antimony ions contained in the first analytical solution by comparing the color of the fifth analytical solution with the color of the ninth analytical solution will be described. In this step, the color of the ninth analytical solution is compared with the color of the fifth analytical object, and the concentration of trivalent antimony ions contained in the first analytical solution is evaluated from the difference in color. The step (S10) of evaluating the concentration of trivalent antimony ions contained in the first analytical solution by comparing the color of the fifth analytical solution with the color of the ninth analytical solution may be abbreviated as the tenth step.

[0167] In the fourth step of the first embodiment, the concentration of pentavalent antimony ions (color of the fifth analytical solution) was evaluated, and in the ninth step of the second embodiment, the total concentration of trivalent antimony ions and pentavalent antimony ions (color of the ninth analytical solution) was evaluated. The two evaluation results are compared to evaluate the trivalent antimony ion concentration in the first analytical solution. When the antimony ions in the fifth and ninth analytical solutions are diluted to the same extent, the difference in color intensity between the two solutions represents the trivalent antimony ion concentration in the first analytical solution.

[0168] When comparing the fourth and ninth steps using a color chart, first, the dilution ratio of the fifth and ninth analytical solutions is taken into consideration. The difference in color between the two solutions is evaluated taking into consideration the amounts of the first and second organic solvents. The color of the ninth analytical solution becomes darker in proportion to the total concentration of trivalent antimony ions and pentavalent antimony ions contained in the first analytical solution. The color of the fifth analytical solution becomes darker in proportion to the concentration of trivalent antimony ions in the first analytical solution. The difference in color between the "color of the ninth analytical solution taking into consideration the dilution ratio" and the "color of the fifth analytical solution taking into consideration the dilution ratio" represents the concentration of trivalent antimony ions in the first analytical solution. If the difference in color between the "color of the ninth analytical solution taking into consideration the dilution ratio" and the "color of the fourth analytical solution taking into consideration the dilution ratio" is equal to or greater than a threshold value, it is preferable to measure the antimony ion concentration by valence using a precise method such as hydride generation inductively coupled plasma mass spectrometry (HG-ICP / MS).

[0169] When comparing the fourth and ninth steps using an absorbance meter, the fifth and ninth analytical solutions are measured in the same manner. In the fourth step, the pentavalent antimony ion concentration of the first analytical solution is evaluated (the concentration is determined). In the ninth step, the total concentration of the trivalent antimony ions and pentavalent antimony ions of the first analytical solution is evaluated (the concentration is determined). The trivalent antimony ion concentration is determined from the difference between the "total concentration of the trivalent antimony ions and pentavalent antimony ions of the first analytical solution" and the "pentavalent antimony ion concentration of the first analytical solution". If the determined trivalent antimony ion concentration is equal to or greater than a threshold value, it is preferable to measure the antimony ion concentration by valence using a precise method such as hydride generation inductively coupled plasma mass spectrometry (HG-ICP / MS).

[0170] According to the method described above, the antimony ion concentration can be evaluated by valence in a simple manner without using expensive equipment. Although the ion concentration by valence can be evaluated with high accuracy using hydride generation ICP mass spectrometry (HG-ICP / MS), which is expensive and requires complicated operations, it is not suitable for samples that are unlikely to contain trivalent antimony from an economical point of view and from the viewpoint of not being able to perform rapid analysis because the analysis is not easy. The method of the embodiment can evaluate trivalent antimony in a sample simply and in a short time, so it is suitable as a screening method for trivalent antimony. In addition, the analysis method of the embodiment can be performed at low cost, so it is an excellent analysis method from the viewpoint of economy.

[0171] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention.

Claims

1. A first analytical solution or a second analytical solution is used, the first analytical solution contains trivalent antimony ions and pentavalent antimony ions, the second analytical solution is a solution in which a first acid is mixed with the first analytical solution, and the first analytical solution or the second analytical solution is mixed with a second acid to chlorinate the pentavalent antimony ions [SbCl ６ ] － obtaining a third analysis solution comprising ions; mixing the third analytical solution with a first organic solvent and subjecting the resultant to phase separation into a fourth analytical solution which is an organic phase and an aqueous phase to obtain the fourth analytical solution; mixing the fourth analytical solution with a color developing solution containing rhodamine B to obtain a fifth analytical solution; and evaluating the concentration of the pentavalent antimony ions in the first analytical solution from the color of the fifth analytical solution; a total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the first analytical solution is equal to or greater than 0.00 mol / L and equal to or less than 0.1 mol / L; The total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the first acid is 0.00 mol / L or more and 0.1 mol / L or less; The total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate contained in the second acid is 0.00 mol / L or more and 0.1 mol / L or less; The method for analyzing antimony ions, in the step of obtaining the fourth analysis solution, the solution after stirring is allowed to stand at a temperature of 40° C. or higher and 70° C. or lower to cause phase separation.

2. the pH of the first analysis solution is greater than or equal to -1 and less than or equal to 3; 2. The method for analyzing antimony ions according to claim 1, wherein the pH of the second analysis solution is from −1 to 3.

3. 3. The method for analyzing antimony ions according to claim 1, wherein the first acid contains hydrochloric acid of 2 mol / L or more and 12 mol / L or less and / or sulfuric acid of 2 mol / L or more and 18 mol / L or less.

4. 4. The method for analyzing antimony ions according to claim 1, wherein the second acid contains hydrochloric acid having a concentration of 2 mol / L or more and 12 mol / L or less.

5. mixing the first or second analytical solution with a third acid to obtain a sixth analytical solution in which trivalent antimony ions are oxidized to pentavalent antimony ions; The sixth analytical solution is mixed with a fourth acid to oxidize the pentavalent antimony ions contained in the first analytical solution and the trivalent antimony ions contained in the first analytical solution, and the pentavalent antimony ions are chlorinated [SbCl ６ ] － obtaining a seventh analysis solution comprising ions; mixing the seventh analytical solution with a second organic solvent and subjecting the mixture to phase separation into an eighth analytical solution, which is a second organic phase, and an aqueous phase to obtain the eighth analytical solution; mixing the eighth analytical solution with a color developing solution containing rhodamine B to obtain a ninth analytical solution; evaluating the total concentration of trivalent antimony ions and pentavalent antimony ions in the first analytical solution from the color of the ninth analytical solution; and evaluating a concentration of trivalent antimony ions contained in the first analytical solution by comparing a color of the fifth analytical solution with a color of the ninth analytical solution, 5. The method for analyzing antimony ions according to claim 1, wherein the third acid includes at least one selected from the group consisting of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate.

6. 6. The method for analyzing antimony ions according to claim 5, wherein a total concentration of nitric acid, cerium (IV) nitrate, and cerium (IV) sulfate in the third acid is 0.02 mol / L or more and 1.0 mol / L or less.

7. A first container containing the first acid according to any one of claims 1 to 4; A second container containing the second acid according to any one of claims 1 to 4; A third container containing the first organic solvent according to any one of claims 1 to 4; A fourth container containing the color developing solution according to any one of claims 1 to 4; A testing tool used to analyze pentavalent antimony ions, including:

8. A first container containing the first acid according to any one of claims 1 to 4; A second container containing the second acid according to any one of claims 1 to 4; A third container containing the first organic solvent according to any one of claims 1 to 4; A fourth container containing the color developing solution according to any one of claims 1 to 4; a fifth vessel containing the third acid according to claim 5 or 6; a sixth container containing the fourth acid according to claim 5 or 6; a seventh container containing the second organic solvent according to claim 5 or 6; A testing tool used for the analysis of antimony ions, including those with different valence states.

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