JPH05232094A - Ion chromatography measuring method and its device - Google Patents

Abstract

PURPOSE:To improve analytic sureness and realize simple measuring by removing coexisting opposition electric charge ions at the front step of an enrichment column. CONSTITUTION:The 1st and 2nd six-way valves 20, 21 are set at the route of a solid line. A sample solution 10 is delivered by means of a liquid delivering pump 14 to a positive ion removing column 17 via the valve 20, and only positive ions in the solution 10 are adsorbed and removed therein, and the solution 10 containing negative ions alone is delivered to a negative ion enrichment column 18 via valves 20, 21. Negative ions are adsorbed therein, and the enrichment of negative ions is conducted by continuing to let the solution 10 flow for a fixed time. The solution 10 that has passed the column 18 is discharged from a waste liquid drain 24 via the valve 21. During this time, an eluate 11 is delivered to a negative ion separation column 19 and the inside of it is washed. After the solution 10 is enriched for a fixed time, valves 20, 21 are switched over to the route shown by dotted lines. The eluate 11 is delivered to the column 18 through the valve 21, and enriched negative ions are conducted with elution and delivery to the column 19 via the valve 21 is carried out. The separation of this is conducted at the column 19 and delivery to a detection portion 23 is carried out, and analysis is conducted therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion chromatography measuring method and an apparatus therefor, and in particular, trace anions in water containing cations (or tens of ppm anions) of several ppm level ( (Or cation) impurities.

[0002]

2. Description of the Related Art For environmental measurement of water quality, pure water used in semiconductor processes, etc., it is necessary to measure the amount of trace anions at a ppb (10 ^-9 ) level in water.

Conventionally, such an analysis has been standardized to be measured by using ion chromatography, and an apparatus having a structure as shown in FIG. 10 is used.

This device is a device for measuring a minute amount of anions, and includes a sample solution 1, an eluent 2, a sample solution delivery pump 3,
The eluent feed pump 4, anion concentration column 5, anion separation column 6, hexagonal valve 7 and the like are included.

The sample solution 1 passes through the solid line path in the circumferential frame of the hexagonal valve 7 and then passes through the concentration column 5 to adsorb and concentrate only anions, and is drained from the drain 8. The case where the hexagonal valve 7 is at the position indicated by the solid line A will be referred to as A mode. In this way, the sample solution 1 is allowed to flow for a fixed time (fixed amount) to concentrate a trace amount of anions.

As described above, after the anion contained in the fixed amount of the sample solution 1 is concentrated, the hexagonal valve 7 is switched to the path of the dotted line B. In this B mode, eluent 2
Passes through the path of the dotted line B of the hexagonal valve 7 and passes through the concentration column 5
The anions that have been adsorbed and concentrated on the column are eluted, separated by the separation column 6, and sent to the detection unit 9 for predetermined analysis.

Although the measurement of anions in the presence of cations has been described above, the same applies to the measurement of trace amounts of cations in the reverse coexistence of anions. Anion concentration column and anion separation column are respectively used as a cation concentration column and a cation concentration column. Analysis can be performed in place of the ion separation column.

[0008] However, in the above conventional method, when measuring a small amount of anions in a sample solution 1 coexisting cation number ppm (10 ^-6) above, in particular fluorine ions (F ^-) and chlorine ions (Cl ^- ) Etc., the concentration column 5
The anion concentration efficiency (amount of adsorbed anions / amount of anions in the sample solution that flowed in) was decreased, and the measured value of anions was lower than the actual value. The analysis accuracy was significantly reduced, depending on the ion concentration.

Also, when measuring cations in a sample solution in which anions coexist at several tens of ppm or more, the concentration efficiency of the cation concentration column decreases, and the same phenomenon as described above is observed.
The analysis accuracy was significantly reduced.

[0010]

As described above, in the conventional method of concentrating a certain amount of the ions to be measured in the sample solution in the concentration column and then separately measuring the ions to be measured in the separation column, When the measured ion is a small amount of anion or cation and the non-measured ion is a cation or anion having opposite charges, the concentration efficiency of the measured ion in the concentration column is opposite. However, there is a problem in that the degree of the decrease is also affected by the concentration of the oppositely charged ions, and as a result, the analytical accuracy of the measured ions is significantly deteriorated.

In order to improve such problems, the following method is used. For example, when the measured ion in the sample solution is a small amount of anion and a cation that is not the measured ion coexists, a standard solution to which the same concentration of cation as the coexisting cation in the sample solution is added Can be prepared to obtain a calibration curve, which can be used to measure anions. However, with this method,
It is necessary to prepare a standard solution every time the coexisting cation concentration changes, which is troublesome and adds a random error.

As described above, when the ion in the sample solution is measured by ion chromatography, when the sample solution contains an ion having a charge opposite in polarity that coexists with the ion to be measured, the coexisting ion However, there is a problem in that the accuracy of analysis is reduced due to the influence of, and the method of using a standard solution to which coexisting ions are added is troublesome. It is an object of the present invention to provide an ion chromatography measurement method and an apparatus therefor, which can solve these problems, improve the analysis accuracy, and perform simple measurement.

[0013]

The ion chromatography measurement method according to claim 1 of the present invention is such that when the ion to be measured is an anion and an ion other than the ion to be measured is a cation, or the ion to be measured is When measuring ions in a sample solution by ion chromatography when ions other than the ions to be measured are cations and anions other than the ions to be measured, measure the ions to be measured after removing the ions other than the ions to be measured. And an ion chromatography measurement method characterized by:

Further, in the ion chromatograph apparatus according to claim 2 of the present invention, a removal column for removing ions other than the ions to be measured is provided in front of the ion concentration column to be measured and the ion separation column to be measured, and the removal column is provided. The apparatus for carrying out the measuring method according to claim 1, further comprising: a unit for flowing a regeneration liquid to regenerate and a unit for flowing deionized water to wash the removal column.

[0015]

[Function] The phenomenon that the measured ion concentration column is affected by the charged ions of the opposite polarities coexisting with the measured ion in the sample solution and the concentration efficiency of the measured ion is lowered was found by trial.

Therefore, in the present invention, after the coexisting oppositely charged ions in the sample solution are removed by the removal column, the concentration of the measured ions is concentrated by the concentration column and the measured ions are separated by the measured ion separation column. taking measurement.
As a result, the concentration efficiency of the measured ion concentration column is improved and becomes a constant value, and the analysis accuracy is significantly improved.
Further, unlike the prior art, it is not necessary to prepare a standard solution to which coexisting oppositely charged ions are added in response to the concentration of the oppositely charged ions, so that the measurement can be performed more easily.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This figure is a flow chart of the ion chromatograph apparatus of the present invention when measuring a trace amount of anionic impurities in water containing cations.

The apparatus comprises a sample solution 10, an eluent 11, a regenerant 12, a pure water 13, a sample solution delivery pump 14, an eluent delivery pump 15, a regenerant and pure water delivery pump 16, cation removal. The column 17, an anion concentration column 18, an anion separation column 19, a first hexagonal valve 20, a second hexagonal valve 21, a three-way valve 22 and pipes connecting them are provided. Reference numeral 23 is a detection unit including a suppressor and a detector, and reference numerals 24 and 25 are drains for waste liquid.

Next, an example of a measuring method using the ion chromatograph having the above-mentioned structure will be described.

First, the first six-way valve 20 and the second six-way valve 21 are set in the paths (referred to as A mode) indicated by solid lines in the circumferential frame. The sample solution 10 is a liquid feed pump 1
4, it is sent to the cation removal column 17 via the solid line path of the first hexagonal valve 20. Cation removal column 1
In 7, only cations in the sample solution are adsorbed and removed. The sample solution containing only the ions to be measured is the first and second
Is sent to the anion concentration column 18 through the solid line paths of the hexagonal valves 20 and 21 of FIG. Anion concentration column 18
Then, the anions in the solution are adsorbed, and the sample solution is continuously flowed in the above state for a certain period of time (that is, a certain volume) to concentrate the ions to be measured. The sample solution that has passed through the concentration column 18 is discharged from the waste liquid drain 24 through the solid line path of the second hexagonal valve 21.

During the A mode, the eluent 11 is sent by the liquid feed pump 15 to the anion separation column 19 through the solid line path of the second hexagonal valve 21 to wash the inside of the separation column 19.

After concentrating the sample solution 10 for a certain period of time, the first and second hexagonal valves 20 and 21 are switched to the paths of dotted lines (referred to as B mode). The eluent 11 passes through the dotted line path of the second hexagonal valve 21 by the liquid delivery pump 15, enters the anion concentration column 18, elutes the anions that have been adsorbed and concentrated in the column, and then the second hexagonal valve 21. Then, it enters the anion separation column 19 via the other dotted line path, is separated, and is sent to the detection unit 23 for analysis.

During the B mode, the regenerant and pure water feed pump 16 is operated, and the regenerant 12 passes through the solid line path of the three-way valve 22 and the dotted line path of the first hexagonal valve 20,
The solution is sent to the cation removal column 17. The cations adsorbed on the cation removal column 17 are removed by the regenerant. The used regenerating liquid is discharged from the waste liquid drain 25 through another dotted line path of the first hexagonal valve. After flowing the regeneration liquid 12 for a certain period of time, the three-way valve 22 is switched to the path indicated by the dotted line. The pure water 13 is sent to the cation removal column 17 by the liquid feed pump 16 via the dotted line path of the three-way valve 22 and the dotted line path of the first hexagonal valve 20.
The removal column 17 is washed.

Next, ammonium ion (NH ₄ ⁺ ) was used as a coexisting cation, and its concentration was used as a parameter (10 ppm, 1 ppm,
0.1 ppm, 0 ppm), and trace amounts of fluorine ions (F ⁻ ) and chlorine ions (Cl) in coexisting solutions of NH ₄ ^{+ at} various concentrations.
^- ) Calibration curve was measured. The results are shown in FIGS. 2 to 5. 2 and 3 show the results of measurement using the conventional apparatus shown in FIG. 10, and FIGS. 4 and 5 show the results of measurement using the apparatus of the present invention shown in FIG. 2 and 4
Shows the calibration curve of F ion, and FIGS. 3 and 5 show the calibration curve of Cl ion. The horizontal axis represents the concentration of measured ions (ppb), and the vertical axis represents the peak height of the waveform actually measured by the detector.

In FIGS. 2 and 3 using the conventional apparatus, NH
There is a decrease in the measured peak value due to the coexistence of ₄ ⁺ ,
With the increase of NH ₄ ⁺ concentration, the degree of decrease is large,
The calibration curve shows a more gradual slope. Therefore, in the conventional apparatus, the analysis accuracy is extremely low unless the coexisting NH ₄ ⁺ concentration is taken into consideration. In order to measure the anion concentration accurately, it was necessary to prepare a standard solution containing the same concentration of cations as the sample solution.

On the other hand, in FIGS. 4 and 5 in which the same sample was measured using the apparatus of the present invention, the slope of the calibration curve is constant regardless of the NH ₄ ⁺ concentration in the solution.

That is, in the apparatus of the present invention shown in FIG. 1, since the cations in the sample solution are removed by the cation removal column and then the anions are concentrated, a decrease in the anion concentration efficiency of the concentration column is prevented. Therefore, the apparatus of the present invention can easily and accurately measure a trace amount of anions without using a cation-added standard solution.

In the above embodiment, the case where the ions to be measured are negative ions and the ions other than the ions to be measured are positive ions have been described. In the above description, when the anion and the cation are exchanged with each other, that is, when the measured ion is a cation and the ion other than the measured ion is an anion, the ion chromatograph apparatus uses the cation. The apparatus may be provided with an anion removal column in front of the concentration column and the cation separation column, and an anion removal column regenerant and a pure water channel for washing the anion removal column.

In the flow charts of the conventional apparatus shown in FIG. 10 and the apparatus of the present invention shown in FIG. 2, the respective apparatuses having the constituents of cations instead of anions and anions instead of cations are used. A calibration curve measurement as shown in FIGS. 2 to 5 was performed. The results are shown in FIGS. 6 to 9. 6 and 7 are obtained by using the conventional apparatus, FIGS. 8 and 9 are obtained by using the apparatus of the present invention, and FIGS.
Is the result of calibration curve measurement of trace ammonium ion (NH ₄ ⁺ ) in F ^- coexisting solution at each concentration, with F ion as coexisting anion and its concentration as parameter (30 ppm, 10 ppm, 0 ppm) 7 and 9 show that Cl ion is a coexisting anion and the concentration thereof is a parameter (50 ppm, 30 ppm,
0 ppm), and trace amounts of NH ₄ ^{+ in} each concentration of Cl ^- coexisting solution
Is the result of calibration curve measurement.

According to the calibration curve measurement results shown in FIGS. 6 to 9, as in the case of FIGS. 2 to 5, in the conventional apparatus, the concentration efficiency of the cation concentration column was significantly reduced due to the influence of coexisting anions. Although the analysis accuracy is low, the apparatus of the present invention removes the coexisting anions in the previous stage, so that the slope of the calibration curve is always constant without being affected by the coexisting anions, and high-accuracy analysis results can be obtained. ..

[0031]

The concentration efficiency of the ion concentration column to be measured is
It decreases due to the influence of ions having opposite charges coexisting with the ion to be measured, but in the present invention, since coexisting opposite charges ions are removed in the preceding stage of the concentration column,
The problem that the analysis accuracy is lowered due to the influence of the coexisting ions is also solved, and the labor for preparing the standard solution to which the coexisting ions are added can be omitted. According to the present invention, it is possible to provide an ion chromatography measurement method and an apparatus therefor which can improve the analysis accuracy and can perform the measurement easily.

[Brief description of drawings]

FIG. 1 is a flow chart of components in an ion chromatograph device according to an embodiment of the present invention.

FIG. 2 Trace F in NH ₄ ⁺ coexisting solution using conventional equipment
^- the measurement results of the calibration curve.

FIG. 3 Trace amount C in NH ₄ ⁺ coexisting solution using a conventional device
l ^- is a measurement result of the calibration curve.

FIG. 4 is a measurement result of a calibration curve of a small amount of F ^{− in} an NH ₄ ⁺ coexisting solution using the device of the present invention.

FIG. 5 is a measurement result of a calibration curve of a trace amount of Cl ^{− in} an NH ₄ ⁺ coexisting solution using the device of the present invention.

FIG. 6 Trace amount of NH ₄ in F ⁻ coexisting solution using a conventional apparatus
^This is the measurement result of the ⁺ calibration curve.

FIG. 7: Trace amount NH in Cl ^- coexisting solution using a conventional apparatus
It is the measurement result of the ₄ ⁺ calibration curve.

FIG. 8: Trace NH in F ⁻ coexisting solution using the device of the present invention
It is the measurement result of the ₄ ⁺ calibration curve.

FIG. 9: Trace N in Cl ^- coexisting solution using the device of the present invention
It is a measurement result of a calibration curve of H ₄ ⁺ .

FIG. 10 is a flow diagram of components in a conventional ion chromatograph device.

[Explanation of symbols]

 10 Sample Solution 11 Eluent 12 Regeneration Liquid 13 Pure Water 14-16 Liquid Delivery Pump 17 Cation Removal Column 18 Anion Concentration Column 19 Anion Separation Column 20 First Six-way Valve 21 Second Six-way Valve 22 Three-way Valve 23 Detector 24 , 25 drain

Claims (2)

[Claims] 1. A sample solution when the ion to be measured is an anion and an ion other than the ion to be measured is a cation, or when the ion to be measured is a cation and an ion other than the ion to be measured is an anion. A method for measuring ions in a sample by ion chromatography, which comprises measuring ions to be measured after removing ions other than the ions to be measured. 2. A removal column for removing ions other than the ions to be measured is provided before the ion concentration column to be measured and the ion separation column to be measured, and a means for regenerating a regeneration liquid by flowing through the removal column and the removal column. An ion chromatograph device for carrying out the measuring method according to claim 1, further comprising a means for flowing pure water to wash.