JP6459128B2 - Analysis method of selenium by valence - Google Patents

Description

  The present invention relates to a method for quantifying selenium (Se) in a solution by valence.

  Selenium is handled as a raw material, a by-product, or an exempted substance in various manufacturing processes such as semiconductor devices and glass products, flue gas desulfurization processes in thermal power plants, and petroleum refining processes. Currently, precipitation methods, ion exchange membrane methods, activated carbon adsorption methods, etc. are known as methods for removing selenium and selenium compounds from wastewater. Needed to process. As used herein, the valence is a number indicating the oxidation state of an atom. In a selenium compound that can exist in an aqueous solution, generally, a tetravalent selenium [Se (IV); for example, selenite compound] and + 6valent selenium [Se (VI); for example, selenate compound] is known. Since selenium is an element that may be harmful to human health, as described above, in addition to wastewater, it is required to quantify a small amount of selenium contained in drinking water, river water, seawater, groundwater, etc. by valence. It has been.

As a method of quantifying selenium for each valence, Patent Document 1 discloses selenite ion (SeO ₃ ^2- ) and selenate ion in a sample by ion exchange chromatography packed with a strongly acidic anion exchange resin. (SeO ₄ ²⁻ ) was separated from the sample, and sulfuric acid was added. Then, by an inductively-coupled plasma mass spectrometry (ICP-MS) apparatus, the value of selenium was determined for each retention time in ion exchange chromatography. For each number, a method for counting selenium atoms is shown. In what was described in Patent Document 1, as an eluent in ion exchange chromatography, for example, a 0.0001 to 0.003 mol / L aqueous solution of 1,3,5-benzenetricarboxylic acid adjusted to pH 6.6 was used. It has been.

JP-A-11-2623

  Since the method described in Patent Document 1 separates Se (IV) and Se (VI) by ion exchange, there is a problem that it is difficult to apply to a sample having a high salt concentration, such as seawater or wastewater. This is because the use of a cation type stationary phase exchange group results in a decrease in selenium separation ability due to binding of anions such as chloride ions in a high salt concentration sample to the stationary phase. In addition, the method of Patent Document 1 cannot be said to have sufficient detection sensitivity, and has a problem of using an eluent containing high-concentration organic carbon that places a load on the apparatus.

  An object of the present invention is to provide a method for quantifying selenium by valence, using an eluent containing no organic carbon, having sufficient detection sensitivity, and applicable to a sample having a high salt concentration. There is.

  There exists an inductively coupled plasma mass spectrometer (ICP-MS) as an apparatus which performs quantification with high sensitivity. The solution introduced into ICP-MS for this highly sensitive determination is generally an aqueous nitric acid solution, but when an aqueous nitric acid solution is used as the eluent, it has been difficult to separate selenium compounds by valence. As a result of studying this point, the present inventors have used an aqueous solution containing nitric acid and sulfate as an eluent, and further used ICP-MS as a detector using ion exclusion chromatography as liquid chromatography. As a result, it was discovered that selenium compounds can be quantified by valence, and the present invention was completed. That is, according to the present invention, a method for quantifying selenium contained in a sample solution by valence is obtained by passing an aqueous solution containing nitric acid and sulfate through an ion exclusion column having an anionic exchange group as an eluent. Injecting the sample liquid into the exclusion column and separating the selenium compound in the sample liquid by valence, and introducing the liquid flowing out from the ion exclusion column into the inductively coupled plasma mass spectrometer and quantifying selenium. Have.

  As will be apparent from the examples described later, according to the present invention, an eluent obtained by adding a small amount of sulfate to an aqueous nitric acid solution that has been frequently used in high-sensitivity quantitative analysis using ICP-MS has been used. By this, it becomes possible to quantify a small amount of selenium compound in the sample solution by valence without imposing a load on the apparatus. In addition, by using ion exclusion chromatography instead of ion exchange chromatography, that is, by using an ion exclusion column, selenium can be quantified without any trouble even when the salt concentration in the sample solution is high. .

It is a figure explaining the principle of ion exclusion chromatography. It is a figure which shows an example of a structure of the apparatus for enforcing the determination method according to the valence of selenium of one Embodiment of this invention. (A), (b) is a graph which shows the result of Example 1. FIG. (A), (b) is a graph which shows the result of Example 2. FIG. (A), (b) is a graph which shows the result of Example 3. FIG. It is a graph which shows the result of Example 4. 10 is a graph showing the results of Example 5. (A), (b) is a graph which shows the result of Example 6. FIG.

  Next, modes for carrying out the present invention will be described with reference to the drawings.

  In the selenium quantification method for each valence based on the present invention, selenium compounds in a sample solution are separated by valence using ion exclusion chromatography using an ion exclusion column. First, the principle of ion exclusion chromatography will be described. FIG. 1 shows the principle of ion exclusion chromatography.

  If, for example, an H-type strongly acidic cation exchange resin is used as the stationary phase 11 in the liquid chromatography, a large number of pores 12 are formed on the surface of the stationary phase 11 and the outermost surface of the stationary phase 11. Is modified with a strongly acidic anion group 13 such as a sulfo group. Let us consider a case where a neutral chemical species 21, a weakly acidic chemical species 22, and a strongly acidic chemical species 23 flow along with the liquid as the mobile phase. Then, due to the negative charge possessed by the strongly acidic anion group 13, a chemical species having a larger negative charge in the mobile phase (a chemical species having a smaller pKa) is subjected to larger static electricity elimination and is eluted sooner. Further, the penetrating power into the pores 12 is determined by the magnitude of the negative charge, and the penetrating power into the pores 12 increases as the negative charge amount decreases, that is, the pKa increases. As a result, the elution time of the neutral chemical species 21 becomes longer, and the elution time becomes shorter as the pKa has a smaller chemical species. In ion exclusion chromatography, in general, the contribution of chemisorption from the mobile phase to the stationary phase by ion exchange can be ignored. Eventually, in ion exclusion chromatography using a strongly acidic cation exchange resin, it is generally considered that the smaller the anion (anion), the lower the pKa.

  The acid dissociation index (pKa) of selenic acid and selenious acid, which are representative compounds of selenium, is as shown below.

_{^{HSeO 4 - ⇔ H + + SeO}} 4 2- pKa 2 = 1.66
H ₂ SeO ₃ ⇔ H ⁺ + HSeO ₃ ⁻ pKa ₁ = 2.75
_{^{HSeO 3 - ⇔ H + + SeO}} 3 2- pKa 2 = 8.50
The above-described ion exclusion chromatography is a method of chromatography using an ion exchange resin, and even when a high-concentration coexisting sample such as a sodium chloride solution typified by seawater is an analytical sample, Since a strongly acidic anion group is used as an exchange group in the above, and chloride ions do not bind to the stationary phase, it is considered that the resolution does not decrease. However, even by ion exclusion chromatography, as will become clear from the examples described later, separation by valence of selenium cannot be realized by a normal method using dilute nitric acid as an eluent. Therefore, in the method according to the present invention, an aqueous solution containing nitric acid and sulfate is used as an eluent, and separation and quantification of selenium according to the valence are made possible.

  FIG. 2 shows an example of the configuration of an apparatus for performing quantitative analysis for each valence of selenium by the method according to the present invention. The eluent stored in the eluent tank 31 is supplied to the injector 33 by the pump 32. The injector 33 is a six-way valve type that is usually used for sample injection in high performance liquid chromatography. The injector 33 is also supplied with a sample solution containing a selenium compound from a sample bottle 34 via a sample pump 39. Both ends of the sample loop 35 are connected to the injector 33, and a guard column 36 and a separation column 37, both of which are ion exclusion columns, are connected in series in this order to the outlet of the injector 33. The injector 33 directly loads the eluent from the pump 34 through the ion exclusion column while introducing the sample liquid from the sample bottle 34 into the sample loop 35 and the eluent from the pump 34 through the sample loop 35. It is possible to switch between the injection mode for passing through the ion exclusion column via the ion exclusion column. The outlet of the separation column 37 is connected to the sample inlet of an inductively coupled plasma mass spectrometer (ICP-MS) apparatus 38. Here, the ICP-MS apparatus 38 is used as a selenium element detector in ion exclusion chromatography using an ion exclusion column comprising a guard column 36 and a separation column 37.

When quantifying selenium by valence using such an apparatus, an aqueous solution containing nitric acid and sulfate is used as an eluent, the injector 33 is set to the load mode, and the pump 32 and the injector 33 are used. The sample solution is introduced into the sample loop 35 through the injector 33 while the eluent is continuously passed through the guard column 36 and the separation column 37. Next, the injector 33 is switched to the injection mode so that the eluent passes through the sample loop 35, and the sample liquid in the sample loop 35 is kept in the guard column while maintaining the state in which the eluent passes through the ion exclusion column. 36 to be injected. As a result, a sample solution collected in a certain amount in the sample loop 35 is injected into the guard column 36 and subsequently into the separation column 37. At this time, according to the principle of ion exclusion chromatography described above, selenic acid flows out from the outlet of the separation column 37 prior to selenious acid, and the selenium compound in the sample solution is separated by valence. It will be. Then, the liquid from the outlet of the separation column 37 is guided to the ICP-MS apparatus 38, and atomic ions of selenium (for example, ⁷⁸ Se ⁺ ) are detected and counted in the mass analyzer of the ICP-MS apparatus. By counting the count value in the ICP-MS device according to the elapsed time from the time when the sample liquid is injected in the injector 33 (the time when the mode is switched from the load mode to the inject mode) and obtaining a chromatogram, Quantification of selenium by valence was performed.

Examples of ion exclusion columns used in the present invention include:
(1) Shimadzu Shim-pack (registered trademark) SCR series (for example, SCR-102H: length 300 mm, inner diameter 8 mm, particle diameter 7 μm, stationary phase is sulfo group),
(2) SH1011 and SH1821 manufactured by Shodex (for example, SUGAR SH1011: size 8 mm × 300 mm, particle size 6 μm, functional sulfo group),
(3) Kdex-811 (for example, RSpak KC-811: size 8 mm × 300 mm, particle size 6 μm, functional group sulfo group) manufactured by Shodex,
(4) TSKgel (registered trademark) OApak-A and OApak-P (for example, TSKgel (registered trademark) OApak-A: particle diameter 5 μm, functional group carboxymethyl group, base polymer (methacrylate type)) manufactured by Tosoh Corporation
(5) TSKgel (registered trademark) SCX (particle diameter 5 μm, functional group sulfo group, base polymer (styrene-based)) manufactured by Tosoh Corporation,
(6) ICSep series manufactured by Transgenomic (for example, ICSep ION-300: pressure resistance 7 MPa, particle diameter 7 μm, functional group sulfo group, counter ion H ⁺ , crosslinking rate 6%),
(7) Dionex IonPac ion exclusion column series (for example, Dionex IonPac ICE-AS1: size 9 × 250 mm, or Dionex IonPac ICE-AS6: size 9 × 250 mm, functional group sulfo group and carboxy group) manufactured by Thermo Fisher
Etc. In particular, it is preferable to use a strongly acidic cation exchange resin having a stationary phase, and the strongly acidic cation exchange resin preferably has a hydrogen (H) ion form. In FIG. 2, the ion exclusion column is divided into a guard column 36 at the front stage and a separation column 37 at the rear stage, but it is not always necessary to provide the guard column. When each of the ion exclusion column products exemplified above is used as the separation column 37, a guard column suitable for the ion exclusion column product is often designated. May be used. In general, the guard column 36 and the separation column 37 are filled with the same type of stationary phase.

  Next, the eluent used in the present invention will be described. In the present invention, an aqueous solution containing nitric acid and sulfate is used as the eluent. The pH of the eluent is preferably 1 or more and 5 or less. When the pH exceeds 5, the separation of Se (IV) and Se (VI) in the ion exclusion column tends to be poor. If the pH is less than 1, the strong acidity may cause adverse effects on the ion exclusion column, the ICP-MS apparatus, and the pump for feeding the eluent. As the sulfate contained in the eluent, for example, one or more compounds selected from the group consisting of an alkali metal sulfate, an alkaline earth metal sulfate, and ammonium sulfate are preferably used. The alkali metal here refers to each element of Li, Na, K, Rb, and Cs, and the alkaline earth metal refers to each element of Be, Mg, Ca, Sr, and Ba. Specifically, for example, sodium sulfate, calcium sulfate, ammonium sulfate and the like can be used as the sulfate. The concentration of sulfate in the eluent is preferably 0.002 mmol / L or more and 100 mmol / L or less. However, even if the sulfate concentration is increased above a certain value, the improvement in the selenium valence separation performance has reached its peak, rather, each peak in the chromatogram tends to widen and the measurement sensitivity tends to decrease. Since there is a risk of clogging at the ICP-MS introduction part, it is more preferable to set the concentration of sulfate in a low concentration region such as 1 mmol / L or less.

  Furthermore, in the present invention, arsenic (As) can be quantified by valence simultaneously with selenium. As is well known, arsenic is highly toxic, and when comparing trivalent arsenic (As (III) and + pentavalent arsenic (As (V)), the trivalent arsenic is more toxic. Therefore, it is required to be able to quantify arsenic by valence with high detection sensitivity, and since selenium and arsenic often coexist in wastewater and environmental samples, selenium and arsenic are simultaneously classified by valence. It is useful to be able to measure.

  As arsenic compounds that can exist in an aqueous solution, generally, + 3-valent selenium [As (III); for example, arsenous acid compound] and + 5-valent arsenic [As (V); for example, arsenic compound] are known. Yes. The acid dissociation index (pKa) of arsenic acid and arsenous acid is as shown below.

H ₃ AsO ₄ ⇔ H ⁺ + H ₂ AsO ₄ ⁻ pKa ₁ = 2.3
H ₂ AsO ₃ ⁻ ⇔ H ⁺ + HAsO ₄ ²⁻ pKa ₂ = 6.8
HAsO ₄ ²⁻ ⇔ H ⁺ + AsO ₄ ³⁻ pKa ₂ = 11.6
H ₃ AsO ₃ ⇔ H ⁺ + H ₂ AsO ₃ ⁻ pKa = 9.28
When quantifying selenium and arsenic in a sample solution by valence at the same time for a sample solution containing selenium and arsenic, the same ion exclusion column (guard column 36 and separation column 37) and eluent as above are used. The sample solution is introduced into the guard column 36, the solution from the outlet of the separation column 37 is guided to the ICP-MS device 38, and the selenium atomic ion (for example, ⁷⁸ Se ⁺ ) And arsenic atomic ions (generally ⁷⁵ As ⁺ ) are detected and counted. Then, the count value in the ICP-MS device is divided into selenium and arsenic according to the elapsed time from the time when the sample liquid is introduced in the injector 33, and the chromatogram is obtained, thereby obtaining selenium and arsenic in the sample liquid. Quantification by each valence was performed.

  As will be described later, according to the present embodiment, as an eluent, for example, an aqueous solution containing 10 mmol / L of nitric acid and a low-concentration sulfate of about 1 mmol / L or less is used. This means that dilute nitric acid, which is the sample condition with the best analytical performance (detection sensitivity, stability, etc.) in the MS apparatus, can be used. The eluent contains sulfate, which is a non-volatile salt, in addition to nitric acid, but its concentration can be very low, such as 1 mmol / L. The influence on the ionization rate of selenium that affects the detection sensitivity is also small. In addition, since the salt concentration in the eluent is low, it is possible to eliminate the influence of salt precipitation at the liquid contact portion of the pump or injector even in the liquid chromatograph device including the ion exclusion column. Therefore, according to the method of the present embodiment, a small amount of selenium can be stably and accurately quantified by valence without adversely affecting the device.

  Next, the present invention will be described in more detail with reference to examples. In each example, the apparatus having the configuration shown in FIG. 2 was used. However, the sample bottle 34 and the sample pump 39 are not provided, and the sample liquid is introduced into the injector 33 by a microsyringe. Conditions common to the embodiments will be described below.

In each example, a sample solution containing Se (IV), Se (VI), As (III) and As (V) is used. These sample solutions are selenous acid (H ₂ SeO ₃ ) manufactured by Kanto Chemical Co. as Se (IV), selenic acid (H ₂ SeO ₄ ) manufactured by Kanto Chemical Co., As (III) as Se (VI) SPEC-As5 manufactured by SPEX was used as an arsenic standard solution manufactured by Kanto Chemical Co., Inc. (As), and these were mixed to a predetermined concentration and diluted with ultrapure water. As nitric acid used as one component of the eluent, one having a specific gravity of 1.42 (high purity reagent Ultrapur-100 manufactured by Kanto Chemical Co., Inc.) was used. The eluent was prepared by diluting nitric acid and added sulfate with ultrapure water.

As the ion exclusion column, SCR-102H manufactured by Shimadzu Corporation was used for the separation column 37. This is a column having an inner diameter of 8 mm and a length of 30 cm filled with an H-type strongly acidic cation exchange resin based on a hard styrene-divinylbenzene copolymer and having a functional group as a sulfo group. As the guard column 36, SCR102H (inner diameter 6 mm, length 5 cm) manufactured by Shimadzu Corporation having a stationary phase similar to that of the separation column 37 was used. As an ICP-MS apparatus, Agilent 7500ce is used, which has a high frequency output of 1550 W, a carrier gas flow rate of 0.75 L / min, a makeup gas flow rate of 0.3 L / min, and a hydrogen (H ₂ ) gas flow rate of 3 mL / min. I drove under conditions. To detect selenium and arsenic simultaneously, ⁷⁸ Se ⁺ ions are used to detect selenium, ⁷⁵ As ⁺ ions are used to detect arsenic, and detection ions are switched at high speed in the mass spectrometer. did.

  The flow rate of the eluent by the pump 32 was 1.5 mL / min. The sample loop 35 used was 50 μL, so that the amount of sample liquid injected in one operation was 50 μL.

[Example 1]
Sample liquid containing 50 μg / L of Se (IV) in terms of selenium atoms, 50 μg / L of Se (VI), 50 μg / L of As (III) in terms of arsenic atoms, and 50 μg / L of As (V) Using sodium sulfate (Na ₂ SO ₄ ) as the sulfate contained in the eluent, changing the sodium sulfate concentration in the eluent, and chromatographing selenium and arsenic for each changed sodium sulfate concentration Got gram. The nitric acid concentration in the eluent was fixed at 10 mmol / L. The results are shown in FIG. Even when the sodium sulfate concentration in the eluent was changed within the range shown in FIG. 3, the pH of the eluent was constant at 2.1.

  As shown in FIG. 3A, regarding selenium, when no sodium sulfate was added to the eluent, almost no selenium peak was observed. In an eluent containing 0.0035 mmol / L or more of sodium sulfate, Se (IV) and Se (VI) were separated, and these could be quantified separately. The higher the sodium sulfate concentration, the larger Se (IV) and Se (VI) and the sharper the peak. From these results, it was found that for the determination of selenium by valence, it is effective to add sulfate to the eluent mainly composed of dilute nitric acid.

  On the other hand, as shown in FIG. 3B, for arsenic, As (III) and As (V) were well separated regardless of the amount of sodium sulfate. In terms of the sharpness of the peak, better results were obtained when sodium sulfate was added. Regarding arsenic, it is considered better to add sulfate for separation by valence.

[Example 2]
A sample solution having the same composition as in Example 1 was used, sodium sulfate was used as the sulfate contained in the eluent, the sodium sulfate concentration in the eluent was fixed at 0.7 mmol / L, and the nitric acid concentration was changed. Thus, the pH of the eluent was changed, and chromatograms for selenium and arsenic were obtained for each pH. The results are shown in FIG.

As shown in FIG. 4A, for selenium, the closer the pH is to 2, the greater the separation of Se (VI) peak and Se (IV) peak on the chromatogram. This is because the pKa _{2 of} selenic acid is 1.66 while the pKa _{1 of} selenious acid is 2.75, and this difference in pKa greatly contributes to the difference in ion exclusion effect. It is believed that there is. From this result, it was found that the pH of the eluent is preferably 5 or less.

  As shown in FIG. 4B, with regard to arsenic, the peak of As (III) and the peak of As (V) were largely separated on the chromatogram without depending on the pH.

[Example 3]
Using a sample solution having the same composition as in Example 1, it was examined how the chromatographs of selenium and arsenic differ when the type of sulfate added to the eluent is varied. As sulfates, sodium sulfate, ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), and calcium sulfate (CaSO ₄ ) were used. As a comparative example, the case where sodium chloride (NaCl) was added to the eluent instead of sulfate was also examined. The concentration of nitric acid in the eluent was fixed at 10 mmol / L, and the concentration of sulfate was also unified at 0.5 mmol / L in terms of sulfate ion (SO ₄ ²⁻ ). When sodium chloride was added, the concentration was 0.5 mmol / L. The results are shown in FIG.

  As can be seen from FIG. 5 (a), for selenium, if the volume molar concentration of sulfate in the eluent is the same as the sulfate ion, Se (IV) and Se (VI) are used regardless of the type of sulfate. ) And were successfully separated and quantified. On the other hand, when sodium chloride was used, the selenium peak itself could not be recognized. This indicates that it is preferable to add sulfate regardless of the type for quantification of selenium by valence.

  As can be seen from FIG. 5 (b), for arsenic, As (III) and As (V) can be well separated and quantified regardless of the type of sulfate, and the eluent contains sulfate. Even when sodium chloride is contained, As (III) and As (V) can be separated.

[Example 4]
Using a sample solution having the same composition as in Example 1, the sulfate added to the eluent was ammonium sulfate, and the concentrations thereof were 0.7 mmol / L and 70 mmol / L, and selenium was obtained at these concentrations. The nitric acid concentration in the eluent was 10 mmol / L. The results are shown in FIG. As can be seen from FIG. 6, when the sulfate concentration is extremely high, each peak of Se (IV) and Se (VI) spreads so that they overlap each other. It can be seen that the concentration of sulfate in the eluent is preferably about 1 mmol / L or less, since it is difficult to quantitatively separate the peaks when the peak overlap is large.

[Example 5]
FIG. 7 shows the selenium chromatogram and the arsenic chromatogram obtained by superimposing and displaying the selenium chromatogram obtained when the sodium sulfate concentration in the eluent in Example 1 is 0.7 mmol / L. At the same time, it can be seen that selenium and arsenic can be quantified by valence.

[Example 6]
Sample solutions having different concentrations of selenium compound and arsenic compound were prepared, and both selenium and arsenic were quantified by valence simultaneously to obtain a calibration curve. At the same time, the repeatability was also determined. An eluent containing 10 mmol / L nitric acid and 0.7 mmol / L sodium sulfate was used. A calibration curve for selenium is shown in FIG. 8 (a), and a calibration curve for arsenic is shown in FIG. 8 (b). The coefficient of variation (CV) indicating repeatability is 4.3% for Se (IV), 4.6% for Se (VI), 3.5% for As (III), and As (V). It was 0.8%. As a result, the measurement lower limit of the measurement described in this specification is 5 μg / L for Se (IV), 5 μg / L for Se (VI), 1 μg / L for As (III), and As (V). It is estimated to be 1 μg / L. It was also confirmed that the reproducibility by the method of the present invention was good.

[Example 7]
About the real sample, the quantitative analysis according to valence was simultaneously performed with respect to selenium and arsenic. As samples, JSAC 0302-3, a river water certified reference material distributed by the Japan Analytical Chemical Society (certified value of total selenium is 5.0 ± 0.2 μg / L, certified value of total arsenic is 5.2 ± 0.1 μg) / L) Two types of factory wastewater (factory wastewater A and factory wastewater B) were used. Table 1 shows the water quality of factory wastewater A and factory wastewater B. The total arsenic concentration shown in Table 1 is based on an inductively coupled plasma-atomic emission spectrometry (ICP-AES) method.

  The results quantified by valence are shown in Tables 2 and 3. Table 2 shows the results for selenium, and Table 3 shows the results for arsenic. The 10 μg / L added sample is a measured value after adding selenium or arsenic corresponding to 10 μg / L to the sample according to valence, and after adding the measured value of the original sample and the equivalent of 10 μg / L. From the measured values, the recovery rate was calculated for selenium or arsenic. Also, the sum of the measured values of Se (IV) and Se (VI) or As (III) and As (V) in this embodiment is shown as a measured value meter (this is referred to as [a]), and the authentication value Or the value of total selenium or total arsenic by ICP-AES is [b], and [a] / [b] is shown in the rightmost column of the table.

  Based on the results of Example 7, the method of the present invention can be used for quantification of selenium by valence of environmental samples such as river water or samples containing a large amount of various ions and metal components such as industrial wastewater. It was confirmed that it was effective.

Claims (6)

A method for quantifying selenium contained in a sample solution by valence,
The sample solution is injected into the ion exclusion column while passing an aqueous solution containing nitric acid and sulfate as an eluent through an ion exclusion column having an anionic exchange group, and the selenium compound in the sample solution is separated by valence. And the stage of
Introducing a liquid flowing out from the ion exclusion column into an inductively coupled plasma mass spectrometer to quantify selenium;
Having a method.   The method according to claim 1, wherein the pH of the eluent is 1 or more and 5 or less.   The method according to claim 1, wherein the sulfate is one or more compounds selected from the group consisting of an alkali metal sulfate, an alkaline earth metal sulfate, and ammonium sulfate.   The method according to any one of claims 1 to 3, wherein a concentration of the sulfate in the eluent is 0.002 mmol / L or more and 100 mmol / L. Injecting the sample liquid containing arsenic in addition to selenium into the ion exclusion column, and separating the arsenic compound contained in the sample liquid according to valence simultaneously with the selenium compound,
The method according to any one of claims 1 to 4, wherein selenium and arsenic are simultaneously quantified in the inductively coupled plasma mass spectrometer.   The method according to claim 1, wherein the ion exclusion column includes a strongly acidic cation exchange resin as a stationary phase.

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