JP2015034716A - Hydride generation analysis method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for reducing disturbance of transition metal and rapidly and accurately measuring a target element in liquid chromatographic separation-hydride generation analysis for a sample containing arsenic, antimony, selenium, tin, or the like.SOLUTION: A hydride generation analysis method controls so that feeding of boron hydride sodium solution is stopped by using switching means within a prescribed period while feeding of acid solution to a sample after the sample passes through a separation column 4.

Description

  The present invention relates to a hydride generation analysis method and apparatus, and more particularly to an analysis method and apparatus for generating and measuring hydride after separating a sample containing arsenic, antimony, selenium, tin and the like for each chemical form.

  Arsenic, antimony, selenium, tin, and the like are required to be removed from wastewater and electrolyte according to the regulations of water quality standards and wastewater standards. These components are generally known to improve selectivity and sensitivity by forming hydrides and analyzing them. In addition, since the behavior differs for each valence, analysis by valence is required.

For example, arsenic (As) in solution is trivalent and pentavalent, but only pentavalent can be removed by the iron coprecipitation method of wastewater treatment, so it is required to grasp the state of arsenic. ing.
In recent years, there has been an increasing need to collect even a small amount of arsenic, particularly in factory wastewater, and accordingly, there is a demand for an accurate and rapid arsenic valence separation method and analysis method.

Antimony (Sb) in the solution is mainly trivalent and pentavalent. Antimony in the copper electrolyte is associated with the formation of airborne slime and affects the purity of electrolytic copper. For this reason, the analysis according to the valence of antimony in the copper electrolyte is an important item in operation management.
In recent years, antimony regulations regarding factory wastewater and the like have been examined, and 0.02 mg / L is currently set as an item to be monitored. Co-precipitation separation with iron is effective for removing antimony, but the behavior differs between trivalent and pentavalent, so it is considered that analysis by valence is necessary.

  The selenium (Se) in the solution is mainly tetravalent and hexavalent. Selenium contained in the wastewater is separated and removed by iron coprecipitation, but only tetravalent can be removed by this method. For this reason, the analysis method according to the valence of selenium is an important item in wastewater treatment at factories and mines.

As described above, in order to manage the concentrations of these components, analysis by valence is essential. It is known that arsenic and antimony have different solvent extraction behaviors when their valences are different.
For example, Patent Document 1 discloses valence separation of arsenic (III) and arsenic (V) and / or antimony (III) and antimony (V) by an extraction method, and further quantitative analysis thereof by inductively coupled plasma emission spectrometry. (ICP-OES) or the hydrogen compound separation ICP-OES method, specifically, among trivalent and pentavalent arsenic (and / or trivalent and pentavalent antimony) present in the aqueous phase, Using a specific extractant, trivalent arsenic (and / or antimony) is transferred to the organic phase, and trivalent arsenic (and / or antimony) is made ready for ICP-OES analysis by back extraction with nitric acid, A technique is described in which pentavalent arsenic and antimony are subjected to ICP-OES analysis by performing the same operation after reducing the extraction residue directly or trivalently. .

  In addition, tetravalent selenium can be separated by iron coprecipitation, iron-yttrium coprecipitation, tellurium coprecipitation, etc., and therefore, analysis by valence using this method has been performed for a long time. First, tetravalent selenium is separated by iron coprecipitation, iron-yttrium coprecipitation, or tellurium coprecipitation, and tetravalent selenium is measured by a measuring method such as ICP-OES. Separately, hexavalent selenium is calculated by measuring and subtracting all selenium in the solution.

  Non-Patent Document 1 describes a method for separating and quantifying tetravalent selenium by tellurium coprecipitation. However, it is also described that a reducing agent such as L-ascorbic acid is necessary for quantitatively recovering tetravalent selenium.

  However, the solvent extraction method and the coprecipitation separation method not only require skill but also many operations require a long time. Further, when there are disturbing components, an operation for removing them in advance is required, but it is very difficult to operate without changing the valence of the target component. For this reason, there is a need for an analysis method that is simple and accurate, in a short period of time, with high accuracy and less interference.

Further, regarding morphological analysis by valence of arsenic using a high performance liquid chromatograph apparatus (hereinafter sometimes referred to as HPLC), Patent Document 2 discloses a pH (3 (specific range) of trivalent and pentavalent arsenic). To 8), that is, trivalent arsenic has no valence of H ₃ AsO ₃ , pentavalent arsenic becomes H ₂ AsO ₄ ⁻ or HAsO ₄ ²⁻ , pH 3 A technique is described in which an arsenic-containing sample adjusted to ˜8 is passed through an anion exchange resin to adsorb only pentavalent arsenic to the resin.

  Non-Patent Document 2 describes a technique in which an ion exchange column is used to separate trivalent antimony by a method such as complexing with thiourea.

JP 2000-317205 A JP 2006-284374 A

Yukito Kashiwagi; 2nd Tsukuba University Technical Staff Technical Presentation (2003) Sayama, T., Fukaya, T., Kuno, Y .; Analytical Chemistry, 7, 569-573 (1995)

  Usually, after a hydride is generated, a method using an analyzer such as an atomic absorption photometer, ICP-OES, or ICP-MS is strongly affected by interference such as copper, nickel, iron, cobalt, platinum, and palladium. That is, the deposit of the above metal is generated on the flow path after adding sodium borohydride, and this preferentially decomposes sodium borohydride to inhibit the hydrogenation of arsenic, antimony, selenium, tin, etc. ing. Therefore, it is necessary to remove these precipitates up to about several mg / L in advance.

However, none of the above prior art can avoid the effects of these contaminating components.
In view of the above problems, an object of the present invention is to reduce the influence of impurities in the analysis of a sample containing arsenic, antimony, selenium, tin, etc. using a hydride generation method, and realize an accurate and rapid analysis. It is in.

  As one aspect for solving the above-described problems, the present invention provides an analyzer that analyzes at least one of arsenic, antimony, selenium, and tin in a sample as a target element and analyzes each by valence. A liquid feeding section for feeding the eluent, a sample injection section for injecting the sample into the flow path of the sent eluent, and a separation column for separating the injected sample for each sample component A separation section, an acidic solution feeding means for feeding an acidic solution to a sample that has passed through the separation column, a sodium borohydride solution feeding means for feeding a sodium borohydride solution, and the borohydride A hydride reaction section that is arranged upstream of the sodium solution feeding means and that switches the feeding of the sodium borohydride solution, and generates a hydride of the target element in the sample; A control unit that controls the hydride analysis unit that analyzes the generated hydride, and the separation unit, the hydride reaction unit, and the hydride analysis unit, wherein the control unit includes the acidic solution An apparatus characterized by controlling the switching means so as to stop the feeding of the sodium borohydride solution for a predetermined period during feeding the liquid, and a method using the apparatus .

  According to the present invention, in the hydride generation analysis using arsenic, antimony, selenium, tin and the like as target samples, the influence of interference of impurities such as copper, nickel, iron, cobalt, platinum, palladium and the like is reduced. Realize highly accurate and efficient analysis. For this reason, useful operation management can be performed about processing of arsenic, antimony, selenium, and a tin containing sample solution, such as copper electrolyte, plating solution, and drainage.

The block diagram which shows the 1st example of the analyzer which concerns on embodiment of this invention. The block diagram which shows the 2nd example (example connected with the control apparatus) of the analyzer which concerns on embodiment of this invention. The graph which shows the analysis result according to the valence of antimony in the copper electrolyte under the conditions according to Example 1 of the present invention. The graph which shows the result (chromatogram) which analyzed trivalent and pentavalent arsenic on the conditions which concern on Example 2 of this invention. The graph which shows the influence of the arsenic collection | recovery rate in a copper containing sample solution and copper concentration based on Example 2 of this invention. The graph which shows the result (chromatogram) which analyzed the tetravalent and hexavalent selenium on the conditions which concern on Example 3 of this invention. The graph which shows the relationship of the selenium collection | recovery rate in a copper containing sample solution and copper concentration based on Example 3 of this invention. The block diagram which shows the example of the conventional analyzer. The chart figure which shows the switching timing of the valve | bulb 15 which concerns on embodiment of this invention.

Examples of an analysis apparatus according to an embodiment of the present invention and an analysis method using the apparatus will be described below with reference to the drawings. As a matter of course, the present invention is not limited to the embodiments described below.
This embodiment is an example in which a sample is separated into components by a high performance liquid chromatograph apparatus, then a hydride is generated, and a sample solution containing arsenic, selenium, antimony, tin or the like is analyzed by atomic absorption spectrophotometry or the like. To

  FIG. 1 is a configuration diagram illustrating a first example of an analyzer according to an embodiment of the present invention. The eluent held in the eluent tank 1 is sent to the injector 3 by the liquid feed pump 2. The injector 3 includes an inlet for a sample solution containing the target component, and injects the sample solution into the eluent flow path. The injected sample solution is mixed with the eluent and sent to the separation column 4 together.

  The separation column 4 includes a reverse phase column, an ion exchange column, and the like, and separates the target component according to the valence in the process of passing the target component-containing sample solution and the eluent sent from the injector 3. Specifically, arsenic and antimony are trivalent and pentavalent, selenium is tetravalent and hexavalent, and tin is bivalent and tetravalent. The target component is separated according to valence by an eluent whose composition is adjusted to have different retention times.

  The liquid discharged from the separation column 4 is sent to the mixing coil 8. A tube pump (perista pump) 7 is connected to the inlet of the mixing coil 8 so that an acidic solution is sent in a constant amount.

The acidic solution tank 5 stores a mixed solution of 6M hydrochloric acid for hydrogenation and 1.8M to 4.5M hydrobromic acid or 9M to 12M hydrochloric acid. It is mixed with the solution in the acidic solution tank 5. Subsequently, in the line 9, the liquid in the sodium borohydride solution tank 6 is mixed and then sent to the hydrogenation reaction coil 10. Here, sodium borohydride solution tank 6 stores sodium borohydride (NaBH ₄ ) and sodium hydroxide (NaOH) solutions.

Although the hydrogenation reaction starts immediately after the sodium borohydride solution is mixed, the hydrogenation reaction coil 10 is used to sufficiently react the mixed solution sent from the line 9. The gas-liquid mixed fluid that has passed through the hydrogenation reaction coil 10 is sent to the gas-liquid separator 11. In the gas-liquid separator 11, among the reactants sent from the hydrogenation reaction coil 10, the hydride is placed on an inert carrier gas 12 such as nitrogen (N ₂ ) gas or argon (Ar) gas, and an atomic absorption photometer. 13. Further, the portion other than the hydride is liquid and is sent to the waste liquid tank 14.
The atomic absorption photometer 13 is equipped with a heat absorption cell, and heats the hydride sent from the gas-liquid separator 11 to measure the absorbance of the target component atoms and perform quantitative analysis.

Here, the valve 15 sends the sodium borohydride solution for the hydrogenation reaction, stops the liquid feeding, sends air instead of the solution, or switches the liquid feeding.
FIG. 9 is a chart showing the switching timing of the valve 15 according to the embodiment of the present invention. Here, the reaction solution A represents an acidic solution in the acidic solution tank 5, and the reaction solution B represents a solution in the sodium borohydride solution tank 6.

  As shown in this figure, before the sample is injected from the injector 3, the valve 15 keeps the air side or the flow of the liquid in a stopped state. At this time, the line 9 and the hydrogenation reaction coil 10 are connected to the eluent. 1, only the acid solution 5 for hydrogenation and the air sucked from the valve 15 are flowing. As a result, the line 9 and the reaction coil 10 are cleaned to remove precipitates that hinder the hydrogenation of the target component.

  Then, the valve 15 is switched to the sodium borohydride solution tank 6 and connected to the sodium borohydride solution tank 6 1 to 10 minutes before the target component elutes from the separation column 4, preferably 2 to 5 minutes before. The tube pump 7 is turned on. Thereafter, the solution in the sodium borohydride solution tank 6 is fed, and a hydrogenation reaction starts in the line 9 and the hydrogenation reaction coil 10.

  If the eluent component contains a component that easily foams, gas-liquid separation by the gas-liquid separator 11 may be insufficient. In this case, do as follows. The flow rate of the tube pump 7 is temporarily reduced to about 30 to 90% 2 minutes before the target component is eluted from the column 4, preferably 3 to 5 minutes before. Thereafter, the valve 15 is switched to the sodium borohydride solution 6. When the hydrogenation reaction starts in the line 9 and the hydrogenation reaction coil 10 and bubbles come out in the gas-liquid separator 11, the flow rate of the tube pump 7 is restored. This is because when the normal flow rate is maintained, the hydrogenation reaction starts suddenly when the sodium borohydride solution reaches the line 9 and the reaction coil 10, and the liquid in the line 9 and the hydrogenation reaction coil 10 is gas-liquid. It pushes out to the separator 11. When this happens, the liquid overflows in the gas-liquid separator 11 and the liquid is lifted up to the atomic absorption photometer 13. The lifted liquid not only contaminates the heat absorption cell of the atomic absorption photometer 13 but also the piping connecting the gas-liquid separator 11 and the atomic absorption photometer 13, so that it is difficult to continue the measurement. End up.

If it takes time to switch between the sodium borohydride solution 6 and the air by the valve 15, it is desirable to take a long time until the target component is eluted from the column 4. This is because immediately after the sodium borohydride solution 6 is flowed and hydrogen is generated, the baseline is not stable for about 1 to 2 minutes as shown in FIG.
Although these operations can be performed manually by a user, it is desirable to use automatic control via a control device when processing a large amount of samples.

  FIG. 2 is a configuration diagram showing a second example (an example of connection with a control device) of the analyzer according to the embodiment of the present invention. That is, the sample is automatically injected into the separation column 4 by the autosampler 18 or the like using the injector 3, and the valve 15 is switched and the flow rate of the tube pump 7 is controlled until the peak of the first target component appears. Then, the above washing operation is performed. After the cleaning operation, after the detection of the peak of the target component of one sample is completed for the sample to be analyzed, the next sample is injected and the cleaning operation is performed until the peak of the target component appears. Try to repeat the cycle. The control device 16 can select a personal computer, a system controller, or the like. The signal line 17 is selected from cables that can be used for communication of each device.

  FIG. 3 is a graph showing the analysis results by valence of antimony in the copper electrolyte under the conditions according to Example 1 of the present invention. In FIG. 3, the result of a present Example, the comparative example 1, and the comparative example 2 is shown. Details of the analysis conditions at this time will be described. Column: Wakopak Navi C30-5 (6 mmφ250 mm + 150 mm), eluent: 3 mM tetra-n-propylammonium hydroxide + 100 mM tartaric acid + sodium dihydrogen phosphate (pH 5.1), flow rate: 1 mL / min, injection amount: 10 μL The solution of trivalent antimony 130 mg / L, pentavalent antimony 250 mg / L, copper concentration 70 g / L, nickel concentration 20 g / L, sulfuric acid concentration 150 g / L was diluted 100 times with 0.1 M tartaric acid. 20 μL of the solution was injected into the column. After separation, a mixture of 6M hydrochloric acid and 1.8M hydrobromic acid was introduced at 0.9 mL / min and mixed, followed by 0.9 mL of 1% sodium borohydride / 0.4% sodium hydroxide solution. / Min to produce antimony hydride. This gas-liquid mixed fluid was introduced into a gas-liquid separator, and the gas phase was introduced into a heat absorption cell of an atomic absorption apparatus with nitrogen gas, and the absorbance was measured. The background Zeeman method was used for background correction. The solution of sodium borohydride stopped once before the start of the first injection and resumed before the peak of pentavalent antimony appeared.

Both injections of pentavalent and trivalent antimony are eluted by one injection. Therefore, in this example, the elution results for three injections are shown.
As is apparent from the chromatogram obtained by the present example shown in the upper part of FIG. 3, even when a copper electrolyte is injected, measurement can be continuously performed until the second sample injection without causing a decrease in sensitivity. I understand that. In the third injection, a slight decrease in sensitivity is observed. In such a case, the sensitivity can be restored by performing the washing operation by stopping and restarting the feeding of the sodium borohydride solution as described above.
Moreover, when the liquid feeding of the sodium borohydride solution was stopped and when air was fed instead, almost the same effect was obtained.

  Next, Comparative Example 1 will be described. In this example, the measurement was performed in the same manner as in Example 1 except that the acid added after separation by the separation column 4 was 1.2 M hydrochloric acid. The obtained chromatogram is shown in the lower part of FIG. 3, and it can be seen that not only the sensitivity is greatly lowered, but also the sensitivity is lowered as the second and third injections are performed.

  Next, Comparative Example 2 will be described. In this example, measurement was performed in the same manner as in Example 1 except that the acid added after separation by the separation column 4 was 6M hydrochloric acid. The sodium borohydride solution was stopped once before the first sample injection was started, and resumed before the pentavalent antimony peak appeared. The obtained chromatogram is shown in the middle part of FIG. 3, but it can be seen that the sensitivity is greatly inferior to that of Example 1 although the sensitivity is less compared with that of Comparative Example 1. It can also be seen that the sensitivity decreases with the second and third injections.

  FIG. 4 is a graph showing the results (chromatogram) of analyzing trivalent and pentavalent arsenic under the conditions according to Example 2 of the present invention. Details of the analysis conditions at this time will be described. Column: Wakopak Navi C30-5 (6 mmφ × 150 mm), eluent: 4 mM tetra-n-butylammonium hydrogen sulfate + 20 mM citric acid (pH 2.4), flow rate: 1 mL / min, injection volume: 10 μL, trivalent And pentavalent arsenic was measured. The acidic solution, sodium borohydride, equipment, etc. were the same as in Example 1. As an example of a chromatogram, a case where a liquid containing only trivalent arsenic 3.3 mg / L and pentavalent arsenic 6.7 mg / L is measured will be closed.

  FIG. 5 is a graph showing the effects of arsenic recovery and copper concentration in a copper-containing sample solution according to Example 2 of the present invention. When the total concentration of arsenic is in the range of 0.1 to 15 mg / L, using a sample solution containing copper, the total recovery of the measured values of trivalent arsenic and pentavalent arsenic, and the copper concentration in the sample solution I investigated the relationship. The sodium borohydride solution stopped feeding after the pentavalent arsenic peak appeared, and resumed before the trivalent arsenic peak appeared. As shown in FIG. 5, it can be seen that according to this example, the copper concentration is hardly affected.

  Next, Comparative Example 3 will be described. A conventional apparatus having no valve 15 is used between the sodium borohydride solution tank 6 and the tube pump 7 shown in FIG. 8, and the acid added after separation in the column is 1.2 M hydrochloric acid, borohydride. Measurement was performed in the same manner as in Example 1 except that sodium was continuously fed. When the copper concentration is low, the recovery rate is a numerical value close to 100%, but it can be seen that the recovery rate greatly decreases as the copper concentration increases.

FIG. 6 is a graph showing the results (chromatogram) of analyzing tetravalent and hexavalent selenium under the conditions according to Example 3 of the present invention. Details of the analysis conditions at this time will be described. Column: Wakopak Navi C30-5 (6 mmφ × 150 mm), eluent: 4 mM tetra-n-propylammonium hydroxide + 100 mM tartaric acid + 5 mM sodium sulfate (pH 2.4), flow rate: 1 mL / min, injection amount: 10 μL, Tetravalent and hexavalent selenium was separated. After separation, a mixture of 6M hydrochloric acid and 1.8M hydrobromic acid was mixed in at a rate of 0.9 mL / min, and irradiated with ultraviolet light with a 4 W sterilization lamp for about 1.5 minutes. Was reduced to tetravalent. Subsequently, 1% sodium borohydride / 0.4% sodium hydroxide solution was mixed at 0.9 mL / min to generate selenium hydride. This gas-liquid mixed fluid was introduced into a gas-liquid separator, and the gas phase was introduced into a heat absorption cell of an atomic absorption apparatus with nitrogen gas, and the absorbance was measured. The background Zeeman method was used for background correction.
As an example of the chromatogram, a case where a liquid containing tetravalent selenium 4.3 mg / L, hexavalent selenium 2.8 mg / L, and copper 17 mg / L was measured was shown.

  FIG. 7 is a graph showing the relationship between the selenium recovery rate and the copper concentration in the copper-containing sample solution according to Example 3 of the present invention. When the total concentration of selenium is in the range of 0.01 to 20 mg / L, measure the tetravalent and hexavalent selenium of the liquid containing copper, and sum the measured values of the tetravalent and hexavalent selenium. Asked. Then, the influence of the copper concentration on the recovery rate was examined. As shown in FIG. 7, according to Example 3, it can be seen that the selenium recovery rate is maintained at almost 100% without being affected by the copper concentration.

  Next, Comparative Example 4 will be described. 10 μL of a sample in which copper was added to a 0.1 mg / L tetravalent selenium solution was injected, and 1.2 M acid was mixed at 0.9 mL / min without being separated by the separation column 4, followed by 1% hydrogen. Sodium borohydride / 0.4% sodium hydroxide solution was mixed at 0.9 mL / min to generate selenium hydride, and the concentration was measured. The recovery rate was calculated from the measured values, and the plotted results are shown in FIG. As shown in this figure, it can be seen that the sample is not separated by the separation column 4 greatly affects, and the recovery rate is greatly reduced only by coexistence of several mg / L of copper.

As described above, in the embodiment according to the present invention, after the elution concentration of the target component is sufficiently lowered from the separation column 4 and the measurement is finished, the valve 15 of the sodium borohydride solution supply line is rotated to perform hydrogenation. The feeding of the sodium boron solution was stopped and air was sent instead.
After passing air for 1 to 10 minutes, preferably 2 to 5 minutes, by switching the valve and flowing the sodium borohydride solution, analysis by valence of the target component can be performed without interference.

Of course, since the same effect can be obtained even if the supply of the sodium borohydride solution is stopped or replaced with water, the valve may be set at a position where the flow of the liquid stops, or water is used instead of air. May be.
The effect of flowing air is that liquid and air are mixed in the hydrogenation reaction coil, and the amount of liquid flowing into the gas-liquid separator can be reduced when sodium borohydride is flowed next. is there. This makes it difficult for the liquid in the gas-liquid separator to overflow, and troubles such as the liquid being lifted up by the atomic absorption photometer can be reduced.

  There are no particular limitations on the conditions for performing analysis by valence of arsenic, selenium, antimony, etc. in a sample by HPLC. However, a reversed-phase column with a modified silica gel surface is excellent in durability, and thus is suitable for the purpose of stably measuring an electrolytic solution such as a copper electrolytic solution, waste water, etc., which is a subject of the present invention over a long period of time.

  In the separation by HPLC, the retention times of the target components arsenic, selenium, antimony, etc. are lengthened, and the retention times of the transition metal ions eluted earlier are made different. By using this method in combination with the above-described method for reducing the interference of transition metal ions, the interference of transition metal ions can be eliminated to a negligible level. The following are examples of separation conditions for arsenic and antimony.

As the reverse phase column, a commonly used ODS type can be used, but a C28 or C30 type is desirable for improving the separation. The particle diameter of the column packing material may be 5 to 10 μm, or a particle diameter of 3 μm may be used if higher resolution is desired.
If HPLC analysis using a reverse phase column is used, it is resistant to contaminants and stable over a long period of time, allowing separation and analysis of target components by valence. In addition to being less susceptible to the effects of coexisting transition metals, not only the analysis of samples with relatively low interfering components, such as wastewater and river water, but also trace purposes in solutions with high concentrations of interfering components such as copper electrolytes. Component analysis can be performed.
However, when separation is insufficient with a reverse phase column, an ion exchange column may be used. In the case of using an ion exchange column, it is desirable to consider measures such as retention capacity and contaminant removal treatment and take measures to extend the life of the column.

  When antimony was used as an analysis target, a mixed liquid of n-propylammonium hydroxide and tartaric acid was effective as an eluent. The concentration of n-propylammonium hydroxide is 1 to 20 mM, preferably 2 to 10 mM.

  The pH of the eluent is preferably 5-8. When the column length to be used is short, the pH is in the range of 6 to 8, and conversely when it is long, the pH is in the range of 5 to 7. In any case, the pH is selected so that separation is sufficient and tailing is suppressed. By setting such pH, not only can trivalent and pentavalent antimony be separated more effectively, but also pentavalent antimony can be prevented from changing to trivalent in the column. If necessary, a base such as sodium hydroxide can be used to adjust the pH.

  Further, since the pH of the eluent is 5 to 8, it is necessary to prevent precipitation of copper hydroxide or the like when a metal hydroxide such as a copper electrolyte is used. For this purpose, oxycarboxylic acid is added. As the oxycarboxylic acid, tartaric acid is preferably used when the column temperature is 30 to 60 ° C. If this is citric acid, pentavalent may be easily changed to trivalent, and measurement of pentavalent antimony may be difficult. On the other hand, when the column temperature can be sufficiently separated at 20 to 40 ° C., trivalent antimony tailing can be suppressed by using citric acid.

  The concentration of oxycarboxylic acid in the eluent is required to be 20 mM or more in order to prevent precipitation of metal ions in the sample. Further, if the concentration is too high, the life of the parts of the HPLC apparatus is shortened, so 200 mM or less is preferable. Within this range, select conditions that allow sufficient separation of trivalent and pentavalent antimony. Usually, it is preferably used in the range of 20 to 100 mM.

  Further, when separating arsenic by valence, trivalent and pentavalent arsenic can be separated sufficiently effectively by using tetra-n-butylammonium ions. In this case, since the retention time varies due to sulfate ions or the like, a salt such as hydrogen sulfate ion, sulfate ion, or chloride ion is used as the counter ion from the viewpoint of reducing the influence of disturbance. Thereby, it can apply to the analysis method which reduced the influence of disturbance.

  In addition, when a metal hydroxide such as a copper electrolyte is used, citric acid is added to prevent precipitation of copper hydroxide and the like. The amount of addition is set to 5 to 100 mM, preferably 10 to 50 mM, because if the concentration is too high, the efficiency of arsenic separation by valence decreases.

  In order to more effectively separate trivalent and pentavalent arsenic, the pH of the eluent is preferably set to 2.2 to 4.0. By setting such pH, it is possible to increase the resolution and further increase the retention time of pentavalent arsenic in the column, so that it can be applied to an analysis method that is not easily disturbed. If necessary, a base such as sodium hydroxide can be used to adjust the pH.

As described above, according to the present invention, the analysis by the valence of the target component becomes possible, which is advantageous in the following points.
(1) Since the form of arsenic and antimony in the copper electrolyte greatly affects the generation of floating slime and greatly affects the quality of electrolytic copper, trivalent and pentavalent antimony can be measured quickly and accurately. , Can greatly contribute to operational management.
(2) Antimony in wastewater is an item to be monitored, but antimony coprecipitation separation differs in removal efficiency depending on the valence. For this reason, it can also contribute to drainage management.
(3) The removal efficiency of selenium in waste water varies depending on its valence. For this reason, it can contribute to drainage management.
(4) In the conventional method, the removal operation of the interfering component is complicated, and the measurement of a sample that requires a lot of time and labor for measurement (analysis) of a copper electrolyte or the like is greatly facilitated by the present invention.

DESCRIPTION OF SYMBOLS 1 ... Eluent tank 2 ... Liquid feed pump 3 ... Injector 4 ... Separation column 5 ... Acidic solution tank 6 ... Sodium borohydride solution tank 7 ... Tube pump 8 .... Mixing coil 9 ... Line 10 ... Hydrogenation reaction coil 11 ... Gas-liquid separator 12 ... Inert carrier gas 13 ... Atomic absorption photometer 14 ... Waste liquid tank 15 ... Valve 16 ... Control device 17 ... Signal line 18 ... Autosampler

Claims (8)

An analyzer for analyzing at least one of arsenic, antimony, selenium, and tin in a sample as a target element,
A liquid feeding section for feeding an eluent;
A sample injection section for injecting the sample onto the flow path of the sent eluent;
A separation column that separates the injected sample for each sample component;
To the sample that passed through the separation column,
An acidic solution feeding means for feeding an acidic solution;
A sodium borohydride solution feeding means for feeding a sodium borohydride solution; a switching means arranged on the upstream side of the sodium borohydride solution feeding means for switching the feeding of the sodium borohydride solution; A hydride reaction section for producing a hydride of a target element in the sample,
A hydride analyzer for analyzing the generated hydride,
A control unit that controls the separation unit, the hydride reaction unit, and the hydride analysis unit,
The controller is
In order to stop the feeding of the sodium borohydride solution for a predetermined period while feeding the acidic solution,
An analyzer characterized by controlling the switching means. The analyzer according to claim 1,
The hydride analyzer includes a detector for detecting the generated hydride,
The controller is
After feeding the acidic solution, the feeding of the sodium borohydride solution is stopped for a predetermined period before the peak of the hydride is detected by the detector.
An analyzer characterized by controlling the switching means. The analyzer according to claim 1,
The hydride analyzer is
An analyzer characterized by being one of an atomic absorption photometer, an inductively coupled plasma emission spectrometer, and an inductively coupled plasma mass spectrometer. The analyzer according to claim 1,
The separation unit is
An analyzer characterized by being a liquid chromatograph. An analysis method for analyzing at least one of arsenic, antimony, selenium, and tin in a sample as a target element and analyzing each by valence,
A separation step of feeding an eluent, injecting the sample onto the flow path of the sent eluent, and separating the injected sample for each sample component;
A hydride reaction step of mixing a sample that has passed through the separation column, an acidic solution, and a sodium borohydride solution to generate a hydride of a target element contained in the sample;
A hydride analysis step of analyzing the generated hydride,
In the hydride reaction step,
An analysis method, wherein the feeding of the sodium borohydride solution is stopped by a switching means for a predetermined period during feeding of the acidic solution. The analysis method according to claim 5,
In the hydride analysis step,
An analysis method, wherein the feeding of the sodium borohydride solution is stopped for a predetermined period after the feeding of the acidic solution and before the detector detects the peak of the hydride. The analysis method according to claim 5,
In the hydride analysis step,
An analysis method comprising analyzing the hydride using any one of an atomic absorption photometer, an inductively coupled plasma emission spectrometer, and an inductively coupled plasma mass spectrometer. The analysis method according to claim 5,
In the separation step,
An analysis method comprising separating the sample using a liquid chromatograph.