JP6711188B2 - Ion chromatograph switching suppressors - Google Patents

Description

The present invention relates to an ion chromatograph equipped with a suppressor means used for separation and analysis of ionic species.

In ion chromatography that separates and analyzes ionic species in liquid samples, a functional unit called a suppressor is installed between the separation column and the detector to reduce the background signal derived from the strong electrolyte in the eluent used. The connection has been made conventionally. The suppressor converts the strong electrolyte in the eluent into a weak electrolyte or water by utilizing an ion exchange reaction, thereby reducing the electric conductivity which becomes a background signal. The ion exchange reaction uses an ion exchange material having an ion exchange group immobilized on the surface of an insoluble carrier in the form of particles, gel, slurry, film, fiber or the like.

Since the ion exchange material in the suppressor has a limited ion exchange capacity, the ion exchange capacity decreases as the ion exchange reaction with the ions in the eluate progresses. As a solution to this problem, a method has been reported in which multiple switchable suppressor columns are provided, one of which is placed in the analysis flow path from the separation column while the other suppressor column is treated with a regenerant liquid or the like. (For example, Patent Document 1). According to this method, even if the ion exchange capacity of the suppressor decreases as the analysis progresses, the suppressor column can be replaced with a regenerated suppressor column by a simple switching operation.

In addition, there is a device that uses two or more valve switchable suppressor chambers filled with a slurry ion-exchange resin, and uses one for measurement while the other automatically discharges/fills the ion-exchange resin. It is disclosed (for example, Patent Document 2). When the ion exchange capacity of the suppressor is reduced or after the measurement has been performed an arbitrary number of times, the flow path is switched from the chamber containing the ion exchange resin in use to the chamber containing the new ion exchange resin to continue the measurement. It becomes possible.

US Pat. No. 6,153,101 JP-A-2002-48774

In the suppressor replaced as described above, the detector signal fluctuates due to fluctuations in the liquid property inside the suppressor at the beginning of use, so the detector signal will stabilize for a certain period of time (hereinafter, stabilization time). May be required. The composition of the eluent used for analysis (hereinafter referred to as "analytical eluent") differs from the liquid used to store or wash the ion-exchange material in the suppressor column, so each time the flow path is changed when the suppressor column is replaced. There has been a problem that when the liquids having different liquid properties flow into the eluent for analysis, the electrical conductivity fluctuates and the detector signal fluctuates.

Further, when the suppressor column is switched during the measurement, it is necessary to switch the timing at a timing that does not affect the detection of the target ion species in the sample, which poses a problem in using the ion chromatograph. It is an object of the present invention to provide an ion chromatograph that suppresses fluctuations in the detector signal due to switching of suppressor columns.

As a result of extensive studies to achieve the above object, the present invention has been completed.

That is, the present invention is an ion chromatograph for detecting a ionic species by introducing a sample and an eluent into an analysis flow path communicating at least a separation column, a suppressor means and a detector, wherein the suppressor means has a background electric conductivity. A plurality of chambers capable of holding an ion exchange material for reducing the flow rate, and the plurality of chambers can be switched between a channel position communicating with the analysis channel and one or more channel positions not communicating with the analysis channel. A means for equilibrating the ion exchange material in the chamber with an eluent is connected to a flow path position that is not connected to the analysis flow path.

The means for equilibrating the ion exchange material with the eluent is not limited as long as it is a means for passing the eluent used for chromatographic separation through the ion exchange material in the chamber provided in the suppressor means. As the eluent used for equilibration, it is preferable to use a solvent that minimizes fluctuations in the background signal during chamber switching, that is, an eluent having the same composition as the eluent that was flowing immediately before chamber switching. .. If chamber switching is performed before sample injection, it is preferable to use an eluent having the same composition as the eluent that is flown immediately before sample injection. In the present invention, "equalize the ion exchange material with an eluent" means to replace the liquid holding the ion exchange material in the chamber provided in the suppressor column in a wet state or a suspended state with the eluent. Means an operation.

In addition to the means for equilibrating the ion exchange material with the eluent, the ion exchange material in the chamber is connected to the means for equilibrating the ion exchange material with the eluent at a flow path position not communicating with the analysis flow path. A regenerant supply means for regenerating the ion exchange material may be connected to the same or different flow path position as the existing flow path position. According to this configuration, the suppressor chamber holding the exhausted ion exchange material used in the analysis flow path is switched to the flow path position to which the regenerant supply means is connected, and the ion exchange material is regenerated on the spot. Therefore, the ion exchange material for the suppressor is regenerated during the analysis, and the flow path in the suppressor is appropriately changed, whereby the analysis work can be efficiently continued. Here, the regenerant supply means is mainly composed of, for example, a container containing a regenerant such as an acid or base useful for regenerating an ion exchange group, a pipe for guiding the regenerant therein to a chamber in the suppressor, and a liquid feed pump. Is composed of.

In addition to the means for equilibrating the ion exchange material with the eluent, instead of the regenerant supply means, means for filling the ion exchange material in at least two flow path positions that are not in communication with the analysis flow path, Means for discharging the ion exchange material may be connected. Here, the means for filling the ion-exchange material is mainly composed of, for example, a container containing a slurry-like ion-exchange resin, a pipe for guiding the ion-exchange resin therein to a chamber in the suppressor, and a liquid feed pump.

The means for discharging the ion exchange material is mainly configured by a discharge pipe for discarding the used ion exchange material or a discharge pipe leading to a waste container or the like. It is preferable to provide a pipe that connects the means for filling the ion-exchange material, that is, connects the outlet of the chamber filled with the ion-exchange material with the inlet of the chamber for connecting the means for discharging the ion-exchange material. .. As a result, the solvent extruded at the time of filling the ion exchange material can be guided to the chamber (flow path position) connected to the discharging means, and the ion exchange material can be charged to drive the discharge of the ion exchange material. The pump used for can be used.

The means for filling the ion exchange material may be the same or different in the connecting flow path position and the means for equilibrating the ion exchange material with the eluent. The position for connecting the means for discharging the ion-exchange material is naturally either the position for connecting with the means for equilibrating the ion-exchange material with the eluent or the position for connecting with the means for filling the ion-exchange material. different.

When the position of the equilibration chamber and the position of the ion exchange material filling chamber are the same, there is an advantage that the configuration of chamber switching can be simplified. With this configuration, after a new or separately regenerated ion exchange material for suppressor is filled in the chamber, the preservative solution or wash water of this ion exchange material can be immediately replaced by the eluent solution.

On the other hand, when the position of the equilibration chamber and the position of the chamber for filling the ion exchange material are different, after filling the chamber with an unused or separately regenerated ion exchange material for the suppressor through a dedicated supply channel, After switching this chamber to a dedicated flow path position to which means for equilibrating with the eluent is connected, the preservative solution of the ion exchange material or the washing water is replaced with the eluent. This configuration, in which the ion-exchange material is filled and the eluent is used for equilibration, is provided at a dedicated flow path position, which has an advantage that the flow paths are not contaminated with each other.

In the present invention, the solvent in contact with the ion exchange material can be replaced with the eluent in advance before switching the chamber of the suppressor means, so that the solvent fluctuation at the time of switching the chamber is minimized and the background signal is reduced. Can be effectively suppressed.

It is a figure for demonstrating an example of the ion chromatograph apparatus provided with the conventional switchable suppressor means of the type which exchanges an ion exchange material. It is a figure for demonstrating an example of the ion chromatograph apparatus provided with the switchable suppressor means characteristic of this invention of the type which exchanges an ion exchange material. It is a figure for demonstrating another example of the ion chromatograph apparatus provided with the switchable suppressor means characteristic to this invention of the system which exchanges an ion exchange material. It is a figure for demonstrating an example of the ion chromatograph apparatus provided with the switchable suppressor means characteristic to this invention of the system which regenerates an ion exchange material. FIG. 5 is a diagram comparing fluctuations in the detector signal due to switching of the conventional switchable suppressor means with suppressed fluctuations in the detector signal due to switching of the suppressor means characteristic of the present invention. A chromatogram accompanied by fluctuations in the detector signal due to switching of the conventional switchable suppressor means during measurement, and a chromatogram in which fluctuations in the detector signal due to switching of the switchable suppressor means characteristic of the present invention are suppressed. It is the figure which compared with the chromatogram without switching of suppressor means.

Hereinafter, a detailed description will be given of an ion chromatograph apparatus equipped with suppressor means characteristic of the present invention based on the mode shown in the drawings, but these are one embodiment of the present invention and limit the present invention. is not.

(Conventional example)
FIG. 1 is a diagram for explaining an example of an ion chromatograph apparatus equipped with a conventional switch-type suppressor means for exchanging an ion exchange material. This apparatus comprises an eluent tank (10), an eluent liquid feed pump (20) for feeding an eluent to a separation column, a sample introduction part (30) for injecting a measurement sample, and a target ion species. A separation column (40) for separation, a temperature control unit (column oven) (50) for stabilizing the temperature of the separation column, a suppressor means (60) having three chambers capable of being filled with an ion exchange material, It is mainly composed of a detector (electrical conductivity detector) (70) and an eluent waste liquid tank (80). In this example, the suppressor means (60) is in the form of using a rotary valve, and the three chamber positions can be switched by rotating the rotor holding the chamber with respect to the stator provided with the flow path connecting portion. .. The ion exchange material used for measurement at the use position (61a) in the analysis channel is discharged to the ion exchange material disposal tank (64) at the discharge position (61b), and ion exchanged at the filling position (61c). The unused ion exchange material in the material tank (62) is filled by the ion exchange material filling pump (63), and excess water is sent to the discharge position (61b) to wash the inside of the chamber. After the filling is completed, it is switched to the use position (61a) again and used for measurement.

(Example 1)
FIG. 2 is a diagram for explaining an example of the ion chromatograph device of the present invention. After the unused ion exchange material in the ion exchange material tank (62) is filled by the ion exchange material filling pump (63) at the filling position (61c), an eluent liquid sending pump (65) for sending liquid to the chamber. ), the solvent in contact with the ion exchange material in the chamber is replaced with the eluent, and then the use position (61a) in the analysis channel is switched to use for measurement. The suppressor chamber used in the analysis flow path and holding the consumed ion exchange material switches the flow path from the use position (61a) to the discharge position (61b) to discharge the ion exchange material to the ion exchange material disposal tank. If the amount of the eluent to be fed into the chamber is too large, the ion exchange capacity of the ion exchange material will be reduced or exhausted. Therefore, the chamber volume is about 0.1 to 5 times, more preferably 2 to It is preferably about 3 times.

(Example 2)
FIG. 3 is a diagram for explaining another example of the ion chromatograph device of the present invention. The suppressor means (60) has four chambers inside which can be filled with the ion exchange material. The suppressor means (60) is a rotary valve, and by rotating it, four chamber positions can be switched. After the unused ion exchange material in the ion exchange material tank (62) was filled by the ion exchange material filling pump (63) at the filling position (61c), it was rotated to move the chamber to the liquid replacement position (61d). Then, the ion-exchange material in the chamber is replaced with the eluent by the eluent-feeding pump (65), and then the position is switched to the use position (61a) in the analysis flow path for measurement. In the second embodiment, unlike the first embodiment, the flow passages at the filling position (61c) and the liquid replacement position (61d) are separated, and therefore some unused ion exchange material remaining in the flow passage outside the chamber is used. Is not replaced with the eluent. Further, the sent eluent can be discharged to the eluent waste liquid tank (80) instead of the ion exchange material waste tank (64). As in Example 1, if the amount of the eluent to be fed into the chamber is too large, the ion exchange capacity of the ion exchange material will be reduced or exhausted. It is more preferable that the amount is about 2 to 3 times.

(Example 3)
FIG. 4 is a diagram for explaining an example of a case where the regenerant supply means for the ion exchange material is connected to the suppressor means in the ion chromatograph device of the present invention. The apparatus configuration uses a rotary valve (60) having three chambers similar to that shown in FIG. The used ion exchange material is switched from the use position (61a) to the flow path position (61b). Instead of providing the means for discharging the ion exchange material shown in FIG. 2, a regenerant supply means for regenerating the ion exchange material is connected to this flow path position (61b). The regenerant supply means comprises a regenerant tank (11) and a liquid feed pump (14). Since an acid such as hydrochloric acid or sulfuric acid or a base such as sodium hydroxide or tetramethylammonium hydroxide is usually used as the regenerant, it should be appropriately washed with a washing liquid such as purified water before introducing it into the analysis flow channel. Sometimes it is better to stay. In this example, the chamber placed at the flow path position (61b) to be treated with the regenerant is next switched to the flow path position (61c), at which position the purified water (12) is fed by the liquid feed pump (13). It flows through the layer of ion exchange material and into the eluent waste liquid tank (80). After that, as in FIG. 2, the eluent (10) is passed through the ion exchange material by the liquid feed pump (65) to replace the liquid. The ion exchange material that has undergone the liquid replacement is switched to the use position (61a) in the analysis flow channel manually or according to the control of the apparatus. In addition, when the mixture of the regenerant and the eluent does not affect the analysis result, the ion exchange material may be replaced with the eluent immediately after the regeneration with the regenerant.

(Example 4)
FIG. 5 is a diagram showing a comparison between the fluctuation of the detector signal due to the switching of the conventional switching suppressor means and the fluctuation of the detector signal due to the switching according to the first embodiment. In the device configuration of the present invention and the conventional device configuration, a mixed aqueous solution of 3.8 mM sodium hydrogen carbonate and 3.0 mM sodium carbonate was used as an eluent, and TSKgel Super IC-Anion HS (manufactured by Tosoh Corporation) was used as a separation column. Then, the measurement was performed at a flow rate of 1.5 mL/min. The broken line is the background signal of the detector having the conventional device configuration, and the solid line is the background signal of the detector when the device configuration of the first embodiment is used. The signals are shifted up and down for easy comparison. In each case, the suppressor chamber is switched at the timing shown by the arrow in the figure. In the signal waveform of the broken line, fluctuations in the detector signal due to fluctuations in the eluent have occurred several seconds after the switching time, but fluctuations in the detector signal occur in the signal waveform in the solid line using the device configuration of the first embodiment. It can be seen that it was hardly detected.

(Example 5)
FIG. 5 shows ion chromatograms with/without switching of suppressor means in the device configuration of the present invention (Example 1, FIG. 2) and the conventional device configuration. All measurement samples were standard anion samples (fluoride ion 1 mg/L, chloride ion 1 mg/L, nitrite ion 5 mg/L, bromide ion 5 mg/L, nitrate ion 5 mg/L, phosphate ion 10 mg/L, sulfate ion 5 mg/L) was used. The signals are shifted up and down for ease of comparison. The dotted line is a normal chromatogram in which the suppressor means is not switched during the measurement, and seven ion species (fluoride ion, chloride ion, nitrite ion, bromide ion, nitrate ion, phosphoric acid from the left side) are added to the positive side. Ion, sulfate ion) are detected normally. The broken line is the chromatogram when the suppressor means is switched at the timing of the measurement indicated by the arrow in the figure using the conventional device configuration, and the solid line is the device configuration of the present invention (Example 1), It is a chromatogram when the suppressor means is switched during the measurement at the same timing. In the broken line, the detector signal derived from the fluctuation of the eluent at the time of switching the suppressor means interferes with the sixth ion species (phosphate ion), and the sixth ion species is not normally detected, whereas the solid line Then, it can be seen that it is detected normally.

10 Eluent Tank 11 Regenerant Tank 12 Purified Water Tank 13 Purified Water Pump 14 Regenerant Pump 20 Eluent Feed Pump 30 Sample Introducing Section 40 Separation Column 50 Column Oven 60 Suppressor Means 61a Use Position 61b in Analysis Channel Discharge Position /Regeneration position 61c Filling position /Washing position 61d Liquid replacement (equilibrium) position 62 Ion exchange material tank 63 Ion exchange material filling pump 64 Ion exchange material waste tank 65 Eluent feed pump 70 Detector 80 Eluent waste fluid tank

Claims (4)

In the ion chromatograph apparatus for guiding the sample and the eluent in the eluent tank to at least the separation column, the analysis flow path communicating with the suppressor means and the detector to detect the ion species,
The suppressor means includes a plurality of chambers capable of holding an ion exchange material for reducing background electric conductivity, and the plurality of chambers communicate with the analysis channel and a channel position where the chamber communicates with the analysis channel. are configured to be able to switch to one or more channels position not,
The ion chromatograph device, wherein the eluent tank is connected to a flow path position that does not communicate with the analysis flow path. Regeneration liquid supply means for regenerating the ion exchange material at a flow path position that does not communicate with the analysis flow path and is the same as or different from the position that is connected to the eluent tank in the chamber. ion chromatograph apparatus according to claim 1, characterized in that connecting. 2. The ion chromatograph apparatus according to claim 1, wherein a means for filling the ion exchange material and a means for discharging the ion exchange material are connected to at least two flow path positions that are not in communication with the analysis flow path. The ion chromatograph according to claim 3, wherein a means for filling the ion exchange material is connected to a flow path position that is the same as or different from a flow path position that is connected to the eluent tank in the chamber. apparatus.

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