JP2004340843A - Ion chromatography device and ion analytical method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the constitution of an ion chromatography device by enabling use of pure water as eluate. <P>SOLUTION: This ion chromatography device 10 has an ion exchanger 12 and a pair of electrodes 13 sandwiching the ion exchanger 12 in a separation column 11 where a sample liquid is injected. After analytical object ions in the sample liquid are captured by the ion exchanger 12, the pure water working as the eluate is introduced into the separation column 11, while applying a direct-current voltage to the electrodes 13. Hereby, the ions captured by the ion exchanger 12 are separated, developed, allowed to flow out from the separation column 11, and subjected to quantitative analysis by a subsequent ion detector 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ion chromatography apparatus and an ion analysis method, and more particularly, to an ion chromatography apparatus used for quantitative analysis of an ionic substance in a sample liquid, and an ion analysis method using the ion chromatography apparatus. .
[0002]
[Prior art]
Ion analyzers are used in the fields of water for power plants, cleaning water for precision processing such as semiconductor manufacturing, water for food processing, and environmental water quality analysis, in the fields of inorganic cations, inorganic anions, ionic organic matter ( Widely used for quantitative analysis of amino acids. As the ion analyzer, an ion chromatography device using an ion exchange resin stationary phase and an ion analyzer using electrophoresis in a capillary having an extremely small diameter are known.
[0003]
FIG. 12 shows a conventional ion chromatography apparatus. The ion chromatography apparatus 40 includes a sample liquid tank 41, a sample pump 43 for extracting a sample liquid from the sample liquid tank 41, an eluent tank 42, an eluent pump 44 for extracting an eluent from the eluent tank 42, and ions in the sample liquid. Column 45 for concentrating the sample, a separation column 46 for separating the ion-enriched sample solution for each ion, a suppressor 47 for removing background ions contained in the eluent, and an ion detector for measuring the amount of ions to be analyzed 48, and pipes and valves for connecting them.
[0004]
In order to quantitatively analyze ions in a sample liquid using the above-mentioned ion chromatography apparatus, first, the valves V1 and V5 are opened, the valves V2 and V4 are closed, and the sample liquid is sent by the sample liquid pump 43. The sample solution is passed from the downstream side of the concentration column 45. The ions to be analyzed in the sample liquid are adsorbed and captured by the ion exchanger packed in the concentration column 45, and the sample liquid after ion adsorption is discharged from the upstream side of the concentration column 45. This passage of the sample liquid is continued until the concentration of the ions to be analyzed adsorbed on the concentration column 45 becomes an amount necessary for setting the concentration in the predetermined ion concentration range.
[0005]
In parallel with the passage of the sample liquid, the valve V3 is opened, the eluent pump 44 is operated, and the eluent flows from the eluent tank 42 toward the separation column 46, the suppressor 47, and the detector 48, Stabilization with an eluent is performed as preparation for measurement. When the passage of the sample solution through the concentration column 45 is completed, the sample solution pump 43 is stopped, the valves V1, V3, and V5 are closed, the valves V2 and V4 are opened, and the eluate is supplied from the upstream side of the concentration column 45. Pass the liquid. Thereby, the analysis target ions adsorbed on the concentration column 45 are eluted by the eluent.
[0006]
The eluent containing the ions to be analyzed flows into the separation column 46, whereby the ions to be analyzed are separated and developed in the separation column 46, and separated into each ion component. The eluent containing the ions to be analyzed is passed through a suppressor 47 to reduce the background due to the eluent and improve the S / N ratio. Then, the eluent is introduced into an ion detector 48 to quantitatively analyze each ion component. To be detected.
[0007]
An ion analyzer using capillary electrophoresis is performed by, for example, electrophoresing ions in a capillary having a diameter of 100 μm or less. FIG. 13 shows the configuration of an ion analyzer using electrophoresis. This analyzer includes a pair of buffer (sample liquid) containers 52 and 54 in which electrodes 51 and 53 are inserted, a capillary 55 connecting the buffer containers 52 and 54, and a high voltage between the two electrodes 51 and 53. , And an ion detector 57 inserted in the middle of the capillary 55.
[0008]
The capillary 55 is filled with a buffer, and both ends of the capillary 55 are inserted into the buffer. The sample solution is injected into one buffer solution container 52 or 54 by pressurization, suction, a drop method or electrically. When a high voltage (10 to 30 kV) is applied between the electrodes 51 and 53 after the sample is injected, each ion component in the sample liquid moves in the capillary 55 at a speed based on the respective moving speed, and ion separation is achieved. Is done. As the ion detector 57, a UV detector or a photodiode array detector is used. Alternatively, an on-column detection method in which the capillary 55 is directly irradiated with ultraviolet rays is also used. Prior patent documents relating to the ion chromatography apparatus are shown below.
[0009]
[Patent Document 1]
JP-A-6-229994
[Patent Document 2]
JP 2001-74715 A
[Patent Document 3]
JP 2002-535618 A
[Patent Document 4]
JP 2002-509238 A
[Patent Document 5]
JP-T-2002-513912
[0010]
[Problems to be solved by the invention]
In the above-mentioned conventional ion chromatography apparatus, in order to achieve desired ion separation, it is essential to use an eluent containing ions that disturb the measurement of ions to be analyzed. A suppressor is used at the subsequent stage of the separation column to reduce the background ion concentration due to the eluent and analyze the analysis target ions with high sensitivity. However, the use of this suppressor complicates the configuration of the entire apparatus.
[0011]
In a continuous regeneration type suppressor using an ion exchange membrane, when the sample liquid flowing out of the separation column passes between the ion exchange membranes, the liquid that has flowed out earlier and the liquid that has flowed out later are mixed, There is also a problem that the ion separation once achieved in the separation column is impaired and the resolution is reduced.
[0012]
In an ion analyzer using a capillary electrophoresis method, application of a high voltage of 10 kV to 30 kV is required as an applied voltage. Therefore, handling of the device requires particular skill from the viewpoint of safety. In addition, when performing ion analysis industrially, the sample injection amount is as small as about several nL, and there is a problem in reproducibility.
[0013]
In view of the above, the present invention enables the use of an eluent having a low ion concentration as a background, so that a suppressor can be omitted, and a concentration column can be omitted relatively easily even in the case of analysis of trace ions. It is an object of the present invention to provide an ion chromatography apparatus which has a simple apparatus configuration, a high resolution, and can be easily handled because a relatively low voltage can be used.
[0014]
Still another object of the present invention is to provide an ion analysis method performed using the ion chromatography apparatus of the present invention.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the ion chromatography apparatus of the present invention has a sample liquid inlet and a sample liquid outlet, and accommodates an ion exchanger between the sample liquid inlet and the sample liquid outlet. A separation column;
Electric field applying means for applying an electric field between the end of the ion exchanger on the sample liquid inlet side and the end of the ion exchanger on the sample liquid outlet side,
Eluent supply means for supplying an eluent from or near the sample liquid inlet of the separation column,
An ion detecting means for detecting an analysis target ion in the liquid flowing out from the sample liquid outlet.
[0016]
In the ion chromatography apparatus of the present invention, ions to be analyzed in the sample liquid flowing from the sample liquid inlet are once captured (adsorbed) by the ion exchanger. Next, when the eluent is supplied by the eluent supply means while applying an electric field to the ion exchanger by the electric field application means, ions to be analyzed in the sample liquid are separated for each ion component, and the sample liquid outlet of the separation column is separated. Spill out of.
[0017]
The ions to be analyzed flowing out from the sample liquid outlet and separated for each ion component are quantitatively detected by the ion detecting means. By applying an electric field to the ion exchanger during the supply of the eluent, the elution of ions to be measured is accelerated, so that the ion concentration of the eluent can be reduced. It is not necessary to dispose all of the ion exchanger between the sample liquid inlet and the sample liquid outlet or between the pair of electrodes, and a part of the ion exchanger is provided between the inlet and the outlet or between the pair of electrodes. May be arranged between the electrodes.
[0018]
In a preferred embodiment of the present invention, the column container of the separation column has a capacity of 10¹⁴It is formed of a material having a volume resistivity of Ω · cm or more. In this case, it becomes easy to generate an effective electric field in the ion exchanger.
[0019]
In the ion chromatography apparatus of the present invention, when the ion to be analyzed is a cation, a cation exchanger is used as the ion exchanger, and when the ion to be analyzed is an anion, the ion exchanger is anion exchanger. Use an ion exchanger.
[0020]
It is preferable that the electric field applying means is constituted by a pair of electrodes sandwiching the ion exchanger. In this case, an ion chromatography apparatus having a simple configuration can be obtained, and handling is easy because a very high voltage is not required.
[0021]
Water having a low ion concentration can be used as an eluent. For example, water having an electric conductivity of 2 μS / cm or less and generally called deionized water, pure water or ultrapure water can be used, and in this case, a suppressor is not required.
[0022]
As the ion exchanger, it is preferable to use any one of an ion exchange membrane, an ion exchange resin, an ion exchange fiber, and an organic porous ion exchanger. These are ion exchangers conventionally used in ion chromatography devices.
[0023]
In order to analyze a sample solution having a low concentration of ions to be measured, it is preferable to further include a concentrator (concentration column) for concentrating ions in the sample solution at a stage preceding the separation column.
[0024]
The ion chromatography apparatus of the present invention (first ion chromatography apparatus) using a cation as an analysis target ion, and the ion chromatography apparatus of the present invention (second ion chromatography apparatus) using an anion as an analysis target ion Combine with
The separation column of the first ion chromatography device and the separation column of the second ion chromatography device are connected in series to flow the sample solution, and both ion exchangers capture ions corresponding to each other,
Each of the separation columns of the first and second ion chromatography devices is connected to a corresponding ion detector, and both ion detectors can independently detect ions. In this case, both cations and anions can be analyzed using the same sample solution.
[0025]
The ion analysis method of the present invention is an ion analysis method for analyzing ions to be measured in a sample liquid,
Let the ion exchanger capture the ions to be measured,
By applying an electric field having an electric field component in a direction parallel to the flow of the eluent to the ion exchanger while flowing the eluent through the ion exchanger, the trapped ions to be measured are separated from the ion exchanger. ,
The method is characterized in that the separated ions to be measured are analyzed.
[0026]
According to the ion analysis method of the present invention, the same advantages as those of the ion chromatography apparatus of the present invention can be obtained.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail based on embodiments of the present invention with reference to the drawings. FIG. 1 is a block diagram of an ion chromatography device according to the first embodiment of the present invention. The ion chromatography apparatus 10 includes a separation column 11 containing an ion exchanger 12 and a pair of electrodes 13 therein, and an ion detector that receives a sample liquid from a sample liquid outlet of the separation column 11 via a gas-liquid separator 14. 15, a power supply device 20 including a DC power supply 16 and a polarity switch 17, a sample liquid injection section 27 for injecting a sample liquid, a pure water tank 19 for storing pure water used as an eluent, and an eluent pump 33. And
[0028]
Each of the pair of electrodes 13 is arranged near the sample liquid inlet and the sample liquid outlet of the separation column 11 and with the ion exchanger 12 interposed therebetween. Each electrode 13 is configured as a mesh-like electrode, and a DC voltage is supplied between the two electrodes from a DC power supply 16 via a polarity switch 17. A sample liquid is injected from the sample liquid injection part 27 into the sample liquid inlet of the separation column 11. The sample liquid flows into the separation column 11 through the mesh of the electrode 13 on the sample liquid inflow side, and flows out of the separation column 11 through the mesh of the electrode 13 on the sample liquid outflow side. The operation of the eluent pump 33 causes the pure water tank 19 to supply pure water as an eluent. The ion detector 15 is composed of, for example, an electric conductivity detector, an electrochemical detector, or an ultraviolet detector. The gas-liquid separator 14 removes bubbles in the sample liquid and increases the detection accuracy of the ion detector 15.
[0029]
In order to detect cations using the ion chromatography apparatus, a cation exchanger is used as the ion exchanger 12. FIGS. 2A and 2B sequentially show the states of the cations analyzed by the ion chromatography apparatus of FIG. First, as shown in FIG. 4A, the polarity switch 17 connects the electrode 13 on the sample liquid inflow side to the negative electrode of the DC power supply 16 and connects the electrode 13 on the sample liquid outflow side to the positive electrode. As a result, an electric field E1 is generated inside the ion exchanger 12 from the sample liquid outflow side to the sample liquid inflow side.
[0030]
Next, the sample liquid is caused to flow into the separation column 11 from the sample liquid injection unit 27. The sample injection section 27 is constituted by, for example, a syringe or a liquid metering device. The cations to be analyzed in the flowing sample liquid are easily adsorbed and captured by the ion exchanger 12 in a state where the ion transfer speed is attenuated by the internal electric field E1 of the ion exchanger 12. In addition, the anion is accelerated by the internal electric field E1 of the ion exchanger 12 so that the ion transfer speed is accelerated, and the discharge of the anion from the separation column 11 is accelerated.
[0031]
Next, as shown in FIG. 2B, at the same time as the pure water forming the eluent flows into the separation column 11 from the pure water tank 19, the polarity switch 17 is switched to connect the electrode 13 on the sample liquid inflow side. The electrode 13 on the sample liquid outflow side is connected to the positive electrode of the DC power supply 16 and the negative electrode, respectively. As a result, an electric field E2 is generated inside the ion exchanger 12 from the sample liquid inflow side to the sample liquid outflow side. At the electrode 13 on the sample liquid inflow side, hydrogen ions are continuously generated by electrolysis of water, and cations to be measured are eluted from the ion exchanger 12 mainly by ion exchange with the generated hydrogen ions. Is also eluted from the ion exchanger 12 by the electric field E2 inside the ion exchanger 12. The eluted ions are separated (developed) according to the elution speed of each ion and the moving speed in the electric field, flow into the ion detector 15 (FIG. 1), and quantitative analysis of each ion is performed.
[0032]
In the above-described embodiment, an example in which a negative voltage is applied to the inflow-side electrode 13 and a positive voltage is applied to the outflow-side electrode 13 when the sample solution is introduced into the separation column 11 has been described. The voltage is not necessarily applied between the electrodes when the sample solution flows. Further, in the present embodiment, the detection of the cation is exemplified, but when the detection target ion is an anion, an anion exchanger is used as the ion exchanger, and the polarity of the electrode is the same as that of the above embodiment. Is reversed, and the injection of the sample liquid and the injection of the eluent are performed.
[0033]
FIG. 3 shows a modification of the first embodiment. Instead of installing the gas-liquid separator 14 in FIG. 1, a gas-liquid separation unit 21 constituting a part of the separation column 11 is provided on each of the sample liquid inflow side and the outflow side of the separation column 11. The gas-liquid separation unit 21 is provided to remove gas components generated by electrolysis near the electrode 13. Each gas-liquid separation unit 21 is connected to a vacuum device and removes gas components generated in the sample liquid. Other configurations are the same as those of FIG. 1 and some of them are not shown.
[0034]
FIG. 4 shows another modification of the first embodiment. Instead of the gas-liquid separator 14, the entire separation column 11 is provided in a degassing chamber 22. The generated gas is removed from the sample liquid by the degassing chamber 22.
[0035]
FIG. 5 shows another modification of the first embodiment. In the present modification, in consideration of the gas component being generated from the sample liquid in the vicinity of the electrode 13, the sample liquid inlet and the outlet are separated from the corresponding electrode 13 and arranged inside the ion exchanger 12. The outlet, in particular, is connected to the lower side of the separation column 11. This prevents the gas component from flowing into the ion detector 15 as much as possible.
[0036]
FIG. 6 shows the configuration of an ion chromatography device according to the second embodiment of the present invention. In the present embodiment, a sample liquid tank 18, a sample liquid pump 24, and a sample liquid / eluate liquid switching device 31 are used instead of the sample injection section 27 in the first embodiment. The sample liquid / eluent switching device 31 includes a sample injector 23 and a concentration column 25. By switching the flow path in the sample injector 23, a flow path of a solid line and a flow path of a dotted line can be selected. The sample liquid is sent from a sample liquid tank 18 by a sample liquid pump 24 constituting a metering pump, is introduced into a concentration column 25 via a solid line flow path in a sample injector 23, and a part is discharged to a drain. Is done.
[0037]
When a predetermined amount of the sample liquid is injected, the flow path in the sample injector 23 is switched to the dotted line side, and then the eluent pump 33 is operated to inject the eluent. The eluent is introduced into the concentration column 25 from the sample injector 23, and moves the sample solution containing the ions to be measured from the concentration column 25 to the separation column 11. The configurations of the separation column 11 and the subsequent ion detector 15 are the same as those of the first embodiment, and a detailed description thereof will be omitted.
[0038]
The ion chromatography apparatus of the present embodiment is used when quantitatively analyzing an ion having an extremely low concentration, and is an example in which a sample solution is concentrated by a concentration column 25 and introduced into a separation column 11. Note that a syringe may be used instead of the metering pump.
[0039]
FIG. 7 shows a modification of the above embodiment. A three-way valve 26 is used instead of the sample injector 23 in the second embodiment, and the injection of the sample liquid and the injection of the eluent into the separation column 11 are temporally switched. The concentration column 25 is provided between the three-way valve 26 and the separation column 11. When the concentration of the ion to be analyzed is relatively high, the concentration column 25 can be omitted.
[0040]
FIG. 8 shows the configuration of an ion chromatography device according to the third embodiment of the present invention. FIG. 9 shows the flow of the liquid in the sample liquid injection stage in this embodiment, and FIG. 10 shows the flow of the liquid in the chromatography separation stage. The present embodiment is applied to a case where the ions to be analyzed include both cations and anions, and it is possible to simultaneously analyze both ions using the same sample solution.
[0041]
As shown in FIG. 8, the ion chromatography apparatus 100 according to the present embodiment includes a cation detector 30A, an anion detector 30B, a sample liquid tank 18, a sample liquid pump 24, a three-way valve 26, and an eluent liquid tank 19. , And an eluent pump 33. The cation detector 30 includes a separation column 11A that houses a cation exchanger 12A and a pair of electrodes 13A, a power supply device 20A, and a cation detector 15A. The anion detector 30B includes a separation column 11B containing the anion exchanger 12B and a pair of electrodes 13B, a power supply 20B, and an anion detector 15B. These separation column, power supply device, and cation detector have the same configuration as the embodiment of FIG.
[0042]
As shown in FIG. 9, at the time of sample liquid injection, the three-way valve 26 is switched to the sample liquid side, the valve V6 is opened and the valve V7 is closed, and the sample liquid is serially passed through both the separation columns 11A and 11B. Shed. At this time, the polarity of the electrode is such that the liquid inflow side is a negative electrode and the liquid outflow side is a positive electrode in the separation column 11A of the cation detection section 30A, and the liquid inflow side is a positive electrode in the separation column 11B of the anion detection section 30B. Then, the liquid outflow side is made a negative electrode. The cations in the sample liquid are decelerated by the electric field inside the cation exchanger 12A, and are easily adsorbed and captured by the cation exchanger 12A. Anions in the sample solution are accelerated by the electric field inside the cation exchanger 12A, pass through the separation column 11A, and flow into the separation column 11B. The anions are decelerated by the electric field inside the anion exchanger 12B, and are easily adsorbed and captured by the anion exchanger 12B. When appropriate amounts of cations and anions have been captured, the injection of the sample solution is stopped.
[0043]
Next, as shown in FIG. 10, after reversing the polarity of the electrodes in each of the separation columns 11A and 11B, the three-way valve 26 is switched to the eluent side, the valve V6 is closed, and the valve V8 is opened to elute. The eluent (pure water) is injected by operating the liquid pump 33. The eluent is injected in parallel into the separation columns 11A and 11B, and flows through the respective ion detectors 15A and 15B. Each ion eluted from each ion exchanger 12A, 12B is quantitatively analyzed by the corresponding ion detector 15A, 15B. In the present embodiment, an example is described in which the sample liquid is first introduced into the cation exchanger 12A and then introduced into the anion exchanger 12B. Conversely, the sample liquid is introduced first into the anion exchanger 12B. May be introduced.
[0044]
In the second and third embodiments, the gas-liquid separator is omitted, but a gas-liquid separator may be provided. The gas-liquid separator is generally provided also in a conventional ion chromatography apparatus in order to prevent dissolved gas resulting from an eluent and an analysis sample from being defoamed by an ion detector. In each of the above embodiments, since a voltage is applied between the electrodes and pure water is used as the eluent, hydrogen gas and oxygen gas are generated at each electrode by electrolysis of water, and ion detection at the latter stage of the separation column is performed. In particular, it is particularly preferable to provide a gas-liquid separator or a gas-liquid separator because the device may become a noise source.
[0045]
As the separation column in the present invention, an anion exchange column or a cation exchange column is used. As the ion exchanger which is a packing material for the separation column, any of a surface functional type and a porous chemical bond type can be used. Examples of the shape of the ion exchanger include a membrane ion exchange membrane, a particulate ion exchanger, and an organic porous ion exchanger.
[0046]
Examples of the particulate surface-functional filler include those obtained by electrostatically or chemically bonding a nonporous substrate with a particulate ion exchanger. As the base material, sulfonated polystyrene, polystyrene or the like is used. Examples of the particulate porous chemical bonding type filler include porous silica gel and polyacrylate particles in which quaternary ammonium groups are chemically bonded.
[0047]
There are no particular restrictions on the type of material for the organic porous material, and examples thereof include styrene-based polymers, polyolefins, poly (halogenated olefins), nitrile-based polymers, (meth) acryl-based polymers, styrene-divinylbenzene copolymers, and vinylbenzyl. Chloride-divinylbenzene copolymer and the like. The polymer may be a homopolymer, a copolymer or a polymer blend. Among these organic polymer materials, a styrene-divinylbenzene copolymer, a vinylbenzyl chloride-divinylbenzene copolymer, etc. are mentioned as preferable materials in view of ease of ion exchange group introduction and high mechanical strength.
[0048]
As the organic porous ion exchanger used as a packing material for the separation column, an ion exchanger described in JP-A-2002-306976 can be used. The ion exchanger described in the publication has an open-cell structure having macropores and mesopores formed in the walls of the macropores. This open-cell structure has macropores that overlap with each other and have a mesopore serving as a common opening at the overlapping portion, and that portion has an open-pore structure. In the open pore structure, when a liquid flows, a flow path is formed in a bubble structure formed by macropores and mesopores.
[0049]
The macropores overlap with each other with 1 to 12 macropores, and 3 to 10 macropores. Therefore, the macropores have a three-dimensional network structure, and an ion exchange group is introduced into the open cell structure. I have. The material of the skeleton portion forming the open cell structure is an organic polymer material having a crosslinked structure. This polymer material contains, for example, 5 mol% or more of crosslinked structural units with respect to all the constituent units constituting the polymer material. By controlling the four factors of the organic porous ion exchanger, it is possible to obtain an organic porous ion exchanger according to the intended use.
[0050]
Since the separation column separates ions to be analyzed for each ion, high ion resolution is required. The separation column tends to have a longer flow path in order to increase the number of theoretical plates, and is a component that has the greatest effect on the pressure rise during liquid passage among the components of the ion chromatography apparatus. For this reason, it is preferable for the separation column to have a small pressure rise when the liquid is passed and to have the analysis time as short as possible. The organic porous ion exchanger used in the separation column has a mesopore radius of 0.01 to 50 μm, preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and W / R in an open-cell structure. The value is 0.5 or less, preferably 0.45 or less.
[0051]
The resolution of the separation column is remarkably improved by reducing the mesopore radius and the W / R value. When the mesopore radius is less than 0.01 μm, it becomes difficult to allow the liquid to flow due to an increase in pressure. When W / R exceeds 0.5, the resolution is reduced. The ion exchange capacity is 0.1 to 5000 μg equivalent / g dry organic porous ion exchanger, preferably 1 to 1000 μg equivalent / g dry organic porous ion exchanger, more preferably 10 to 500 μg equivalent / g dry organic porous ion. Exchanger.
[0052]
The ion exchange capacity affects the resolution of the separation column and the analysis time, which are in an opposite relationship. If the ion exchange capacity is small, the analysis time is short but the resolution is reduced. Conversely, if the ion exchange capacity is large, the resolution is high but the analysis time is long. Therefore, the ion exchange capacity is set in consideration of the balance between the two. The total pore volume is 1 to 50 ml / g, preferably 2 to 30 ml / g, and more preferably 5 to 20 ml / g. By increasing the total pore volume, the pressure during energization can be reduced. If the total pore volume is less than 1 ml / g, the pressure at the time of passage increases, and if it exceeds 50 ml / g, the strength of the organic porous ion exchanger is significantly reduced. By storing an organic porous ion exchanger having such properties in a separation column, a column having excellent separation performance can be obtained.
[0053]
As the organic porous ion exchanger housed in the separation column, an ion exchanger having a structure in which micropores, which are discontinuous pores having an average pore diameter of 5 to 800 nm, are formed on the inner wall of an open cell structure formed of mesopores and mesopores. May be. With a separation column containing such an ion exchanger, in addition to ion selectivity, the separation effect due to the size of the component to be measured can be synergistically utilized. For example, ion dissociation groups such as amino acids and proteins can be used. It has excellent resolution when separating and quantifying a mixed system of biologically related substances and inorganic low molecular ions having a similar ion selectivity.
[0054]
As the electrode, a metal, an alloy, a metal oxide, a material obtained by plating or coating any of them, a conductive material such as sintered carbon, or the like can be used. Examples of the shape of the electrode include a plate, a punched metal, and a mesh. The material of the electrode serving as the anode is preferably a conductive non-corrosive material which is excellent in acid resistance and is hardly oxidized. For example, Pt, Pd, Ir, β-PbO₂, NiFe₂O₄Etc. can be suitably used. Further, the material of the cathode is preferably excellent in alkali resistance, for example, Pt, Pd, Au, carbon steel, stainless steel, Ag, Cu, graphite, vitreous carbon, and the like.
[0055]
Regarding the arrangement of the electrodes, it is preferable that both the electrode and the ion exchanger are in contact with each other, since the applied voltage in the chromatographic separation step can be reduced. Although the applied voltage depends on the material and length of the ion exchanger, for example, a voltage value of about 100 V can be adopted.
[0056]
Column containers such as a separation column and a concentration column are not particularly limited, but various types having an inner diameter of about 1 to 6 mm and a length of about 1 cm to 25 cm are suitably used. As the material of the column container, an insulative plastic and glass which are inert to the eluent are used. Although the shape of the separation column is not particularly limited, for example, a columnar shape, a disk shape, a cylindrical shape, a donut shape, a capillary and the like are preferable for achieving uniform liquid flow. Further, the column container of the separation column is preferably formed of an insulating material.
[0057]
In a conventional separation column or concentration column, a filler, which is fine particles of the order of μm, is dispersed in a dispersion medium to form a slurry, and this slurry must be passed through a column container to form a uniform packed bed. Equipment and skill were required. However, the separation column in the present invention is obtained by filling an organic porous ion exchanger cut into a shape that can be inserted into a predetermined container, or by manufacturing the organic porous ion exchanger in a container. Thus, the ion exchanger can be packed much more easily and uniformly than a conventional column packed with a fine particle ion exchanger.
[0058]
As a method for producing an organic porous ion exchanger in a column container, a method in which a water-in-oil (W / O) emulsion is formed in the container, or an emulsion formed in another container is filled in a column container Later, a method of performing polymerization and introducing an ion exchanger may be mentioned. Although the shape of the container is not particularly limited, for example, a columnar shape, a disk shape, a capillary, and the like are preferable for achieving uniform liquid flow.
[0059]
The eluent (mobile phase) in the present invention is not particularly limited as long as it can move predetermined ions to be analyzed, and is variously selected and used depending on the type of stationary phase, the type of analysis ions, and the like. The eluent used in the above embodiment is preferably water, in particular, deionized water, pure water, ultrapure water, etc. In this case, a suppressor is not required. However, inorganic buffers, organic buffers, inorganic solutions, organic solutions and the like can also be used as the eluent in the present invention. When the ion-containing liquid is used as the eluent, the ion concentration can be variously selected. As the ion concentration in the eluent increases, the retention time of each analysis ion increases, so that separation and analysis are performed using this action.
[0060]
It is preferable to send the eluent in an amount equal to or more than the amount consumed for electrolysis when a voltage is applied to the electrodes at both ends of the ion exchanger accommodated in the separation column.
[0061]
The ion to be analyzed can be selected depending on the purpose and application, and may be only a plurality of types of anions, only a plurality of types of cations, or only amphoteric ions such as amino acids. Also, a mixture of these can be used.
[0062]
A guard column can be provided before the separation column, if necessary. The guard column is a small column installed before the separation column, if necessary, to protect the separation column from damage due to contamination of foreign matters. In the event of an abnormality, the column is protected and replaced by itself. The guard column is involved in ion separation similarly to the separation column during normal operation, and can be regarded as a part of the separation column provided for protection of the separation column body. Therefore, the same organic porous ion exchanger as the separation column can be used for the guard column.
[0063]
【Example】
An ion chromatography apparatus according to an embodiment of the present invention was prototyped, and quantitative ion analysis was performed using the apparatus.
Analyte ions
Sample solutions and eluents were prepared for cation analysis. The sample solution was mixed with a commercially available standard solution for ion chromatography, diluted with pure water, and used at a predetermined concentration. The ion concentrations in the sample solution were lithium ion 2 mg / l, sodium ion 6 mg / l, and ammonium ion 5 mg / l. As an eluent, ultrapure water of 18 MΩ · cm was used. An organic porous cation exchanger was used as the ion exchanger packed in the separation column.
[0064]
Preparation and sample liquid injection stage
First, the eluent was sent from the eluent tank by an eluent pump at a flow rate of 30 ml / min, passed through a separation column and an ion detector, and the relevant portion was stabilized by the eluent. Next, the three-way valve at the front stage of the separation column was switched to the sample solution sending side, and the sample solution was sent from the sample solution tank by the sample solution pump at a flow rate of 10 ml / min for 3 minutes. Thus, the sample was introduced into the ion exchanger of the separation column, and the respective ions contained in the sample solution were concentrated.
[0065]
Chromatographic separation stage
Next, the three-way valve at the front stage of the separation column was switched to the eluent liquid sending side, the eluent was supplied at a flow rate of 30 ml / min, and passed through the separation column and the detector. At this time, a DC voltage of 100 V was simultaneously applied between the two electrodes arranged in the separation column. Here, the polarity of the electrodes was such that the liquid inflow side electrode of the separation column was a positive electrode and the outflow side electrode was a negative electrode.
[0066]
In the separation column, separation is performed by ion exchange with hydrogen ions continuously generated at the electrode on the liquid inflow side of the separation column, and by electric attraction and electric repulsion between each ion and the electrode and ion exchanger. Each ion adsorbed and concentrated on the column was eluted and developed, separated into each ion component, and quantitatively detected by an ion detector. FIG. 11 shows the detected chromatogram. As can be understood from FIG.⁺Ion, Na⁺Ion, NH₄ ⁺The ions were effectively separated and detected.
[0067]
As described above, the present invention has been described based on the preferred embodiment. However, the ion chromatography apparatus and the ion analysis method of the present invention are not limited only to the configuration of the above-described embodiment. Various modifications and changes from the configuration described above are also included in the scope of the present invention.
[0068]
【The invention's effect】
According to the ion chromatography apparatus and the ion analysis method of the present invention, it is not necessary to prepare a special reagent as an eluent, for example, water can be used, so that a suppressor is not required, and the concentration of an ion to be analyzed is relatively low. Even when the temperature is low, ion analysis can be performed without providing a concentration column, so that the configuration of the entire apparatus is simplified. Further, both anions and cations can be analyzed using the same sample solution.
[Brief description of the drawings]
FIG. 1 is a block diagram of an ion chromatography apparatus according to a first embodiment of the present invention.
2 (a) and 2 (b) are schematic diagrams showing states at each stage of ion analysis in the ion chromatography apparatus of FIG. 1;
FIG. 3 is a partial block diagram of a modification of the first embodiment.
FIG. 4 is a partial block diagram of another modification of the first embodiment.
FIG. 5 is a partial block diagram of still another modified example of the first embodiment.
FIG. 6 is a block diagram of an ion chromatography device according to a second embodiment of the present invention.
FIG. 7 is a block diagram of a modification of the second embodiment.
FIG. 8 is a block diagram of an ion chromatography device according to a third embodiment of the present invention.
FIG. 9 is a block diagram showing a flow of a liquid in a sample liquid injection stage in the third embodiment.
FIG. 10 is a block diagram showing a flow of a liquid in a chromatographic separation stage in a third embodiment.
FIG. 11 is a graph showing the results of ion analysis by ion analysis according to an example of the present invention.
FIG. 12 is a block diagram of a conventional ion chromatography apparatus.
FIG. 13 is a block diagram of an ion analyzer using a conventional electrophoresis method.
[Explanation of symbols]
11: Separation column
12: Ion exchanger
13: Electrode
14: Gas-liquid separator
15: Ion detector
16: DC power supply
17: Polarity switch
18: Sample liquid tank
19: Pure water tank (eluent tank)
20: Power supply
21: Gas-liquid separation unit
22: Degas chamber
23: Sample injector
24: sample liquid pump
25: Concentration column
26: Three-way valve
27: Sample liquid injection part
30A: cation detector
30B: anion detector
31: Sample liquid / concentrate switching unit
33: Eluent pump

Claims (10)

A separation column having a sample liquid inlet and a sample liquid outlet, and containing an ion exchanger between the sample liquid inlet and the sample liquid outlet,
Electric field applying means for applying an electric field between the end of the ion exchanger on the sample liquid inlet side and the end of the ion exchanger on the sample liquid outlet side,
Eluent supply means for supplying an eluent from or near the sample liquid inlet of the separation column,
An ion chromatography apparatus comprising: ion detection means for detecting ions to be analyzed in the liquid flowing out from the sample liquid outlet. The ion chromatography device according to claim 1, wherein the column container of the separation column is formed of a material having a volume resistivity of 10 ¹⁴ Ω · cm or more. The ion chromatography apparatus according to claim 1, wherein the analysis target ion is a cation, and the ion exchanger is a cation exchanger. The ion chromatography apparatus according to claim 1, wherein the ion to be analyzed is an anion, and the ion exchanger is an anion exchanger. The ion chromatography device according to any one of claims 1 to 4, wherein the electric field applying unit is a pair of electrodes that sandwich the ion exchanger. The ion chromatography device according to any one of claims 1 to 5, wherein the eluent is water. The ion chromatography device according to claim 1, wherein the eluent is water having an electric conductivity of 2 μS / cm or less. The ion chromatography device according to any one of claims 1 to 7, further comprising a concentrating device for concentrating ions in the sample liquid at a stage preceding the separation column. Ion analysis for performing ion analysis using the ion chromatography device according to claim 3 (first ion chromatography device) and the ion chromatography device according to claim 4 (second ion chromatography device) The method,
The separation column of the first ion chromatography device and the separation column of the second ion chromatography device are connected in series to flow the sample liquid, and the ions corresponding to the two ion exchangers are captured,
An ion analysis method, wherein each of the separation columns of the first and second ion chromatography devices is connected to a corresponding ion detector, and both the ion detectors independently detect ions. In an ion analysis method for analyzing ions to be measured in a sample liquid,
Let the ion exchanger capture the ions to be measured,
While flowing the eluent through the ion exchanger, an electric field is applied to the ion exchanger to separate the trapped ions to be measured from the ion exchanger,
An ion analysis method characterized by analyzing the separated ions to be measured.

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