JPH0225146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for analyzing anions contained in a sample liquid by ion chromatography.

What is ion chromatography?
Published by Small et al. It is primarily a name for high-performance liquid chromatography of inorganic ions.
(Anal. Chem. 47, 1801 (1975).

Ion chromatography has already been put into practical use and is being widely used for various trace analyzes such as analysis of environmental samples and biological samples, control analysis of various processes, and elemental analysis.

FIG. 1 is an explanatory diagram of the configuration of a flow path system of a conventional ion chromatograph for anion analysis.

In FIG. 1, the ion chromatograph consists of an eluent tank 1 that stores NaOH as an eluent, and a pump 2 that pumps the eluent in tank 1 to a sample injection valve 3.
, a sample injection valve 3 for collecting a predetermined amount of sample liquid and transporting the collected sample liquid to a separation column 4 using an eluent; and an anion exchange resin electrostatically bonded to a cation exchange resin. It consists of a separation column 4 filled with a resin adjusted to be anionic as a whole and separates and elutes each ion species contained in the injected fluid, and a strong acidic cation exchange resin filled with a column 4 that separates and elutes each ion species contained in the injected fluid. It has a background removal column 5 (hereinafter referred to as BSC) that captures ions in the liquid, and a conductivity meter 6 that introduces the fluid flowing out from the BSC into the cell and measures the conductivity.

The problem with the ion chromatograph having the above configuration lies in the BSC.

One of them is that the BSC needs to be regenerated every 8 to 10 hours under normal analysis conditions.
The BSC was established to capture ions in the eluent, lower the background of the conductivity meter due to the ions in the eluent, and improve the detection sensitivity of the measured ions. decrease. This is because a reaction based on formula (1) takes place within the column, and the ion exchange resin shifts from H type to Na type.

NaOH (eluent) + strong Resin-H ⁺ (BSC) → Resin-Na + H ₂ O (1) When all the ion exchange resin becomes Na type, the reaction based on equation (1) no longer progresses, and the As the baseline increases, the amplification function for each anion will be lost. For this reason, conventional ion chromato glasses are operated by flowing 1N to 3N HCl through the BSC at predetermined time intervals to regenerate its function. Of course, under analysis conditions that require high-concentration eluent to flow at a high flow rate, the above regeneration operation interval is short, 1 to 2
Sometimes it's hourly.

Another problem is that when the fluid eluted from the separation column is passed through the BSC, the peak shape collapses. This means that the BSC has an inner diameter of 3~6mm and a length of 25~
This is due to the fact that the 50cm pipe is filled with ion exchange resin.

The present invention was developed in view of the above, and its purpose is to accurately maintain peak shapes without interrupting analysis and performing regeneration operations.
To lower the baseline (background),
The object of the present invention is to provide a method and apparatus for analyzing anions contained in a sample liquid, which is equipped with a diffusion type cation removal means having a flow path made of a cation exchange composition after a separation column.

In the present invention, in order to remove cations of an eluent contained in a fluid eluted from a separation column, the liquid eluted from the separation column is introduced into a flow path composed of a cation exchange composition, and the cation exchange composition is removed. After the composition is brought into contact with the scavenge liquid, a chromatogram signal is detected using a conductivity meter.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is an explanatory diagram of the configuration of an analyzer according to an embodiment of the present invention.

The analyzer shown in FIG. 2 consists of an elution tank 1 that stores an alkaline eluent, for example, 0.004 MNa ₂ CO ₃ /0.004 MNaHCO ₃ , a pump 2 that pumps the eluent in the tank 1 to a sample introduction device 3, and a micro A predetermined amount of sample liquid is injected into the channel using a syringe, etc.
A sample introduction device 3 transports the sample to the separation column 4 using the eluent from the pump 2, and the synthetic resin fine particles having anion exchange groups are transferred to the surface of the synthetic resin particles having no ion exchange groups. A separation column 4 filled with an ion exchanger formed by holding and immobilizing a resin having the same composition or a similar composition to the synthetic resin particles, and a perfluorocarbon sulfonic acid type cation exchange composition, for example,
A diffusion type cation removal device 7 consisting of an eluent chamber and a scavenging liquid chamber that share a wall made of Nafion (trade name of Du Pont), and a scavenging liquid such as dodecylbenzenesulfonic acid (hereinafter referred to as DBS). A scavenging liquid tank 8 which stores the liquid, a pump 9 which pumps the scavenging liquid in the tank 8 to the scavenging liquid chamber of the cation removal device 7, and a fluid flowing out from the eluent chamber of the cation removal device 7 into the cell. A conductivity meter 6 that outputs a signal to a recorder etc. in accordance with the conductivity, a constant temperature bath 12 that houses the separation column 4, a cation removal device, a conductivity meter 6, etc., and a conductivity meter 6. It has a tank 10 for storing the measured fluid flowing out from the cation removal device 7, and a tank 11 for storing the scavenge liquid flowing out from the cation removal device 7.

Next, the configuration of the cation removal device 7 will be explained in detail with reference to FIGS. 3 to 6.

Figure 3 is a diagram explaining the basic configuration of the cation removal device, Figure A is a cross-sectional view of the device in the axial direction, Figure B is
FIG.

In FIG. 3, the device 7 uses a tube 71 made of a cation exchange composition and a tube 72 containing the tube 71, and configures a double tube with an appropriate distance between each tube. Both ends of the tube are closed with lids 73 and 74 to constitute an independent eluent chamber 75 and a scavenge chamber 76, and holes 75a and 75 are provided to communicate each chamber with the outside.
b, 76a and 76b. In the eluent chamber 75, the fluid eluted from the separation column 4 flows in the direction of the hole 75a→chamber→75b, and in the scavenge liquid chamber 76, the fluid eluted from the separation column 4 flows in the direction of the hole 75a→chamber→75b.
The scavenging fluid pumped through the hole 75b→chamber→
76a, ie, in the opposite direction to the eluent.

Specifically, such a cation removal device:
As shown in Figures 4 to 6 (BB sectional view in Figure 5), two cheese unions (T-shaped joints)
21 and 22, inner diameter approximately 0.4mm, outer diameter approximately 0.55mm,
A perfluorocarbon sulfonic acid type cation exchange membrane tube 23 with a length of 5 mm, for example, a Nafion tube (trade name of DuPont) that can be heated and stretched and is easy to make into a desired diameter, and a flexible tube 24 with an inner diameter of about 1.0 mm. For example, a Teflon tube (trade name of Du Pont) is placed in a case 39 made of a material with good thermal conductivity, such as aluminum (75 mm in length and width, 27 mm in height), and tubes 31Y, 35, 46, and 47, which will be described later. is housed in a protruding manner and is fixed with a dosing mold 50 made of epoxy resin or the like.

The connection ports 25, 26, 32, and 33 in the cheese unions 21 and 22 are connected to a stainless steel tube 30 by a SWETSUJIROCK (trade name of SWETSUJIROKU Co., Ltd.) consisting of a front ferrule 27, a back ferrule 8, a cap nut 29, etc. , 31, 34 and 35, and tube 30
and 34 are connected to each other by the tube 24, and the tube 2
3 is inserted through the pipe, and the connection ports 42 and 43 are sealed with adhesives 48 and 49 to form a double pipe structure. Also, both ends 4 of the tube 23
0 and 41 have stainless steel tubes 46 and 47 secured with adhesives 44 and 45.

As mentioned above, the analytical effects of the double-tube structure of the cation removal device including the Nafion tube will be described later, but there are also advantages in terms of structure. In other words, the Nafion tube is highly flexible like the Teflon tube, so a long double tube structure can be used in a small case 39.
The cation removal device 7 itself can be made small and compact. Therefore, the constant temperature bath 12 that houses the cation removal device 7 can also be made smaller. In addition, the double pipe structure part is one
Since it consists of a Nafion tube, one Teflon tube, etc., these terminals can be processed easily and with almost no wasted volume.

Next, the operation of the analyzer having the above configuration will be explained.

By pump 2, 0.004MNa ₂ CO ₃ /
The 0.004M NaOHCO ₃ eluent was introduced at a flow rate of approximately 2.0 ml/min into the sample introduction device 3 → separation column 4 → eluent chamber 75 of the cation removal device 7 → cell of the conductivity meter 6 →
It is flowing in tank 10. Also, by the pump 9,
DBS's scavenger liquid is applied to the scavenger liquid chamber 76 of the cation removal device 7 at a flow rate of approximately 2 ml/min.
→Flows to tank 11.

Now, in the sample introduction device 3, Cl ^- 100mg/
(ppm), NO ₃ ^- 10mg/(ppm) and SO ² ₄ ^- 100
100 μ of a sample solution containing mg/(ppm) of each ion species is injected into the eluent stream and conveyed to the separation column 4. Each ion species is separated in the separation column 4. The chromatogram of the liquid at the outlet of the separation membrane 4 is the seventh one.
It looks like the picture. That is, 0.004MNa ₂ CO ₃ /
The conductivity of 0.004M NaHCO ₃ is approximately 1550 μS/cm as the baseline, and cations (Na ⁺ if the counter ion of the measured anion is Na, K ⁺ if K, etc.),
They appear in the order of Cl ^- , NNO ₃ ^- and SO ² ₄ ^- . in fact,
Each anionic species associates with Na ^- in the eluent and Cl ^-
is NaCl, NO ₃ ^- is NaNO ₃ and SO ^2- ₄ is Na ₂ SO ₄ , and these are 0.004MNaO ₃ /
Since it is eluted in the form contained in 0.004M NaHCO ₃ C, for example, the change in conductivity at the Cl ^- peak is about 25 μS/cm.

The third section describes the actions performed by each ion species separated and eluted as described above in the cation removal device 7.
This will be explained with reference to the figures.

While the scavenge liquid DBS changes into H ⁺ and DBS ^- and passes through the scavenge liquid chamber 76, an operation of replacing the cation exchange group with H ⁺ is continuously performed on the wall of the tube 71, which is a cation exchange composition. , tube 71 is a so-called H type cation exchange composition. On the wall of this tube 71,
The eluent containing each ion species separated and eluted in the separation column 4 is connected, and the reaction of equation (2) is carried out, Na ⁺ in the eluent is replaced with H ⁺ in the tube 71, and the eluent is H ₂ It becomes _CO3 .

NaHCO ₃ +Resin−H ⁺ →H ₂ CO ₃ +Resin−Na ⁺ (2) Na ₂ O _3By this reaction, the conductivity of the ionizing solution of the eluent is
It becomes from about 1550 μS/cm to 20 to 30 μS/cm, and the background of the chromatogram becomes extremely small.

On the other hand, the Na ⁺ that entered the wall of the tube 71 is because the Na ⁺ concentration in the scavenge liquid is almost zero.
It moves by diffusion through the wall towards the scavenging liquid and reaches the contact surface with the scavenging liquid. Since the scavenge liquid is a DBS solution with a relatively high concentration, the reaction of formula (3) takes place, and the Na ⁺ in the wall of the tube 71 is replaced with H ⁺ in the scavenge liquid (this reaction is caused by the ion exchange resin (This reaction is the same as that observed when regenerating ion exchange resin in a water purification system using

Resin−Na ⁺ +DBS→Resin −H ⁺ +DBS−Na (3) Similarly, cations other than H ⁺ in the above eluent also
It moves through the wall of the tube 71 by diffusion and reaches the surface in contact with the scavenge liquid. The transferred cations are carried away by the continuous flow of scavenge fluid and discharged outside, so they do not accumulate inside the room. For this reason,
The diffusion rate on the walls of tube 71 is not reduced. That is, the tube 71 of cation exchange composition will always be regenerated by the scavenge fluid. (It has become H-shaped).

In addition, the anion species separated and eluted in the separation column 4 are NaCl, NaNO ₃ , Na ₂ SO ₄ as described above.
enters the eluent chamber 75 and undergoes the reactions of equations (4), (5), and (6).

NaCl+Resin→H ⁺ →HCl+Resin−Na ⁺ (4) NaNO ₃ +Resin−H ⁺ →HNO ₃ +Resin−Na ⁺ (5) Na ₂ SO ₄ +Resin−2H ⁺ →H ₂ SO ₄ +Resin−2Na ⁺ (6) Like this In this case, the eluent is reacted by the reaction of equation (2).
At the same time as it changes to H ₂ CO ₃ , each ionic species also undergoes the reactions of formulas (4) to (6) and changes from the Na salt form to the acid form.
As shown in Figure 8, the chromatogram of the fluid that has passed through the cation removal device 7 shows that the baseline is very low and stable, the peak shape of cations disappears, and the peak shape of anion species is large. (Generally, the conductivity of the solution is higher in the acid type than in the salt type). That is, in the cation removal device, the conductivity of the anion species is increased.

Therefore, the analyzer according to the present invention can obtain a stable chromatogram with a low baseline as long as the scavenging liquid continues to flow into the scavenging liquid chamber 76 of the cation removal device 7.

Next, the characteristics of the actual analyzer according to the present invention will be explained based on experimental results.

FIGS. 9A to 9D are diagrams showing the analysis time of the apparatus according to the present invention, and are data obtained by changing the eluent flow rate. In addition, the experiment was conducted at a constant temperature bath temperature of 40℃, eluent concentration of 0.004MNa ₂ CO ₃ /0.004MNaHCO ₃ , scavenge liquid concentration and flow rate of 0.05MDBS2ml/min,
Sample injection amount was 100μ.

Figure A shows the relationship between the eluent flow rate and the retention time of various anions, and Figures B to D are the chromatograms obtained at this time. 1.9ml/min, 4ml/min.

As is clear from Figure 9 A to D, even if the eluent flow rate is set to 4 ml/min, the state of separation of various anions is not impaired, and analysis can be performed within 4 minutes. . Therefore, according to the analyzer according to the present invention, analysis time can be shortened.

10 to 13 are characteristic diagrams of the BSC 5 and the cation removal device 7. Each figure shows the BSC 5 and the cation removal device 7 installed after the same separation column 4 under different analysis conditions. were obtained under exactly the same conditions.

Figures 10 and 12 are chromatograms and peak height characteristics over time obtained by an apparatus having BSC5 (hereinafter referred to as the conventional apparatus);
1 and 13 are chromatograms and peak height characteristics over time of an apparatus having the cation removal apparatus 7 (hereinafter referred to as the apparatus of the present invention).

Comparing Figures 10 and 11, the shape of each ion peak for the same component and the same concentration is different in each device, and the device of the present invention has a higher peak shape for each ion than the conventional device. It can be seen that there is a peak, that is, high sensitivity. In particular, there is a difference in the size of the NO ₂ ^- ion peak.

Furthermore, as is clear from FIGS. 12 and 13, the peak height characteristics over time in the device of the present invention are stable, but the peak height in the conventional device changes with time, especially when NO ₂ ^- has poor characteristics. For this reason, it can be said that the conventional apparatus has a problem in quantitative performance. (Anal.Chem51, 1571 (1979)
) As mentioned above, the cation removal device 7
5, the cation removal device 7 has one perfluorocarbon sulfonic acid type cation exchange membrane tube (hereinafter referred to as
It is clear that this is due to the fact that the main part is a double pipe with an inner pipe of Nafioon) and the DBS scavenge liquid is used.

Since the double-tube structure has a single thin Nafion tube as its inner tube, there is almost no peak broadening at the end or within the tube, and it is thought that the chromatogram shown in Figure 11 is obtained (when multiple tubes are used) When the fluid eluted from the separation column is passed,
Since it is difficult to flow fluid at the same speed through multiple tubes,
peak spreads within the tube).

In addition, since the outer tube of the double tube structure is made thinner and the flow rate of the scavenge liquid is increased, the diffusion layer is made thinner, increasing the efficiency of ion exchange, and it is thought that the chromatogram shown in Figure 11 will be obtained. It will be done.

Furthermore, according to the experiments of the present inventors, Nafion
Since it has CO ₂ permeability, it is thought that the chromatogram shown in FIG. 11 is obtained (the effect will be described later).

The experiment was conducted in the configuration shown in Figure 14 (each symbol is
(used in the same meaning as in Figure 2), switch the solenoid valve 13 and
(0.004MNaCO ₃ /0.004MNaOH ₂ storage) → Pump 2 → BSC 5 → Conductivity meter 6 → Channel consisting of tank 10 (bottom, referred to as A channel), or Tank 1 → Pump 2 →
A flow path (hereinafter referred to as B flow path) consisting of BSC 5 → eluent chamber of cation removal device 7 → conductivity meter 6 → tank 10 is constructed, and tank 14 (pure water storage) → pump 9 → cation removal A flow path (hereinafter referred to as
C flow path), each conductivity meter 6
From the indicated values of 6 and 6', it was confirmed that Nafuon has CO ₂ permeability.

The experimental values are 24.5 μS/cm and 5 μS/cm for conductivity meters 6 and 6' when channel A is configured, and conductivity meters 6 and 6 when channel B is configured. ′
The respective indicated values were 20.0 μS/cm and 221.5 μS/cm.

The following can be said from the above experimental values.

In BSC5, Na ₂ CO ₃ /NaHCO ₃ is H ₂ CO ₃
and in the A flow path and B flow path, (7)
The reaction of formula is taking place.

CO ₂ +H ₂ O〓H ₂ CO ₃ 〓H ⁺ +HCO ₃ ^- (7) Then, when the generated CO ₂ forms the B flow path, it passes through Nafion and enters the C flow path, so the conductivity meter The indicated values of 6 and 6' are almost equal.

As mentioned above, the CO ₂ permeability of Nafion is advantageous in various ways. For example, if CO ₂ is removed from the eluent chamber in the cation removal device 7, the reaction in equation (7) proceeds (progresses to the left in the equation), and the H ₂ CO ₃ concentration in the eluent chamber decreases. ,
H ⁺ and HCO ₃ ^- also decrease, and the background becomes even lower. When the background becomes lower, the negative peak of water (water dip) becomes smaller, making it easier to perform high-sensitivity measurements. Furthermore, by removing CO ₂ from the eluent chamber, even if a highly concentrated eluent is used, the generation of bubbles in the eluent chamber can be prevented, allowing stable measurements.

Next, experimental results regarding the length of the double tube structure portion of the cation removal device 7 will be explained.

Figure 15 is a diagram showing the background removal effect in the cation removal device.
It was determined using the eluent flow rate as a parameter at a 0.05MDBS scavenge liquid flow rate of 2 ml/min, and the flow rates in graphs a, b, and c are as follows:
They are 1 ml/min, 2 ml/min and 3 ml/min.
As is clear from FIG. 15, when the channel length is 4 m to 6 m, the background is sufficiently removed and the baseline is stable regardless of the eluent flow rate.

16 and 17 show that from the sample injection valve 3,
FIG. 2 is a peak surface density-channel length characteristic diagram and a peak height-channel length characteristic diagram in a chromatogram when 100 μm of 10 ppm Cl ⁻ ions are injected. FIG. Each figure shows a constant temperature bath at 40℃, eluent (0.004MNa ₂ CO ₃ /
0.004MNaHCO ₃ ) and the scavenging liquid at a flow rate of 2 ml/min, using the concentration of the scavenging liquid as a parameter. graph d
The scavenge fluid in and e is 0.05MDBS
and 0.2MDBS. As is clear from each graph, both the peak area-channel length characteristic and the peak height-channel length characteristic are the same for the channel length of 4 m to 6 m.
It has become saturated.

From the above results, when using the cation removal device at a temperature of 40°C, an eluent flow rate of 1 to 3 ml/min, and a scavenge liquid flow rate of approximately 2 ml/min, the flow path length should be 4 m to 6 m. , it can be seen that the most stable characteristics are obtained.

Further, the constant temperature bath temperature of 40° C. in the above embodiment is the most desirable temperature in the analyzer having the above configuration, and was determined by taking into consideration the lifespan and characteristics of the separation column and the cation removal device.

Generally, when the temperature of a separation column is high, the reaction rate increases and the separation time becomes short, which is advantageous in terms of separation characteristics, but disadvantageous in terms of service life. In particular, a separation column packed with an ion exchanger with fine particles of anion exchange resin electrostatically attached to the surface of the cation exchange resin particles is better than a separation column packed with an ion exchanger as in the above example. However, the influence of temperature on the lifespan is greater.

Furthermore, in the cation removal device 7, when the temperature rises, the amount of acid leaking from the scavenge liquid chamber 76 to the eluent chamber 75 through the tube 71 increases, the background becomes high, and the S/N of the detection signal increases. The ratio worsens. For example, the background at 50°C is approximately 1.5 times that at 40°C. Also, as the temperature rises, Na ₂ CO ₃ and NaHCO ₃
CO ₂ is easily generated, and the generated CO ₂ (bubbles) makes measurement by the conductivity meter 6 unstable.

Conversely, when the temperature of the cation removal device 7 decreases, the reaction efficiency (ion transmission efficiency) of the tube 71 decreases.
decreases, a sufficient peak height in the chromatogram cannot be obtained, and the S/N ratio deteriorates. For example, when the temperature is below 20°C, the reaction efficiency becomes extremely poor.

Further, since the ambient temperature of an ion chromatograph (temperature in a laboratory, laboratory, etc.) is usually within a range of 5 to 35°C, it is easy to control the constant temperature bath to 40°C.

In view of the above, the temperature setting of the constant temperature bath 12 is set to 40°C.

Next, the separation column in the above embodiment and the conventional separation column will be considered.

As is well known, conventional separation columns for anion and anion analysis are filled with strongly basic anion exchange resins and weakly basic anion exchange resins. There is one in which fine particles of ion exchange resin are filled with an ion exchanger to which they are electrostatically attached.

The separation column in the above example uses a novel ion exchanger, that is, synthetic resin fine particles having anion exchange groups, on the surface of synthetic resin particles having no ion exchange groups, and does not have the ionic exchanger. It is filled with synthetic resin particles that are held and fixed using the same composition or similar composition.

Such an ion exchanger can completely separate each ion in a sample in a short time, is mechanically and chemically stable, and does not deteriorate due to coexisting components in the sample.
There is little contamination, and even if contamination occurs, it is easy to regenerate by cleaning.

By the way, in the cation removal device, only H ⁺ ions in the scavenge liquid are removed from tube 71.
HCl, HCO ₃ , etc. may be used as the scavenger liquid, as long as a reaction occurs in which the scavenging liquid passes through the DBS and exchanges with Na ⁺ ions in the eluent. It was confirmed that more stable characteristics were obtained.

Figures 18 and 19 are diagrams showing the experimental results. Figure 18 is a peak height characteristic diagram, and Figure 19 is a diagram showing the experimental results.
The figure is a baseline characteristic diagram. In each figure, graph a represents DBS, and graph b represents
Using HNO ₃ as the scavenger liquid, a 20μ sample of 50ppmCl ^- ions was mixed with 0.004MNa ₂ CO ₃ /
Eluent flow of _0.004MNaHCO3 (2ml/min)
It was obtained by injecting it into Incidentally, the set temperature of the constant temperature bath 12 is 40°C.

As is clear from FIGS. 18 and 19, there is almost no difference in peak height due to the difference in scavenge liquid, but the baseline is
DBS skiavenge is more stable.

Therefore, the relationship between peak height and noise, that is, the S/N ratio, is better when using DBS than when using HNO ₃ , and ppb levels for Cl ^- ion measurement can be easily achieved.

In addition, the Na salt of DBS is a type of sodium alkylbenzelsulfonate, an anionic surfactant, and a synthetic detergent, and DBS itself has a strong surfactant effect. Therefore, the "wetting" of the scavenge liquid side of the tube 71 is very improved. Therefore, the CO ₂ gas generated by the reaction of equation (7) in the cation removal device 7 and passing through the tube 71 can be easily discharged without being attached to the surface of the tube 71. Therefore, the above-mentioned CO ₂ gas is not introduced into the measurement cell of the conductivity meter 6,
Signal detection becomes stable. The scavenge liquid should be a liquid that has the same properties as the above-mentioned DBS, that is, a strong acid with a high degree of dissociation (can act as an acid as an H ⁺ ion donor), and a large counter anion to the H ⁺ ion ( Liquids that are difficult to pass through the tube 23 even if there is a concentration gradient, such as alkylbenzenesulfonic acid (dodecyl group as an alkyl group) or N-methyltauric acid, which is an acid before saponification of an anionic surfactant having a sulfonic group. can be used.

As explained in detail above, according to the ion chromatography of the present invention, cations are passed through the cation exchange composition, Na ⁺ in the eluent and H ⁺ in the scavenge liquid are replaced, Since it supplies H ⁺ and removes Na ⁺ , there is no need to interrupt the analysis and perform a regeneration operation, unlike in ion chromatography using BSC, as long as the scavenge liquid is flowing. .

In addition, the eluent and DBS scavenging solution are brought into contact through a 4m to 6m perfluorocarbon sulfonic acid type ion exchange resin tube, resulting in a low baseline, no peak collapse, and a high chromatogram. can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a flow path system of a conventional ion chromatograph for anion analysis, FIG. 2 is an explanatory diagram of the configuration of an analyzer according to an embodiment of the present invention, and FIG.
The figure is a basic configuration diagram of a cation removal device using a cation exchange composition, and FIGS. 4 to 6 are specific configuration diagrams of a cation removal device according to an embodiment of the present invention. FIG. 7 is a chromatogram at the outlet of the separation column, FIG. 8 is a chromatogram at the outlet of the cation removal device, and FIG. 9 A to D are diagrams showing analysis time of the analyzer according to an embodiment of the present invention. , Figures 10 and 12 are characteristic diagrams of the BSC, Figures 11 and 13 are characteristic diagrams of the cation removal device, and Figure 14 is an explanatory diagram of the configuration of Nafion's CO ₂ permeability experimental device. , Figures 15 to 17
The figure is a flow path length characteristic diagram of the cation removal device, No. 18.
19 and 19 are characteristic diagrams of the scavenge liquid in the cation removal device. 1... Eluent tank, 2 and 9... Pump, 3...
Sample introduction device, 4... Separation column, 6... Conductivity meter, 7... Diffusion type cation removal device, 71...
...tube consisting of a cation exchange composition, 72...
...Tube made of stainless steel, 75...Eluent chamber, 76...Scavenger liquid chamber, 8...Scavenge liquid storage tank, 10 and 11...tanks.

Claims (1)

[Scope of Claims] 1. After transporting a predetermined amount of sample liquid using an eluent and injecting it into a separation column filled with an anion exchange resin to separate anions in the sample liquid, the eluate from the separation column is is introduced into a diffusion type removal device to remove cations contained in the eluate from the separation column, and then introduced into a conductivity meter to measure the conductivity of the eluate. In a method for chromatographically analyzing ions, a first tube made of a perfluorocarbon sulfonic acid type cation exchange composition and a liquid not containing an ion exchange composition contained therein are sealed so that their central axes coincide with each other. A double tube is formed by providing a certain interval between the tube and the second tube made of the structural material, and the double tube forms an independent inner chamber and an outer chamber, and each of these chambers is provided with an external wall. The diffusion type removal device is configured by providing an inlet port and an outlet port that communicate with each other, and the eluate from the separation column is introduced into the inner chamber through the inner chamber inlet port to flow through the inner chamber outlet port. At the same time, a scavenge liquid made of alkylbenzenesulfonic acid or N-methyltauric acid is introduced into the outer chamber through the outer chamber inlet in a direction opposite to the flow direction of the fluid in the inner chamber, and is allowed to flow outside. By sending the anions to the outside from the chamber outlet, the first
An anion analysis method characterized in that the cations are moved from the fluid in the inner chamber to the scavenge liquid in the outer chamber via a tube, and the cations are moved and removed from the fluid in the inner chamber. 2. The anion analysis method according to claim 1, wherein the alkylbenzenesulfonic acid is dodecylbenzenesulfonic acid. 3. An eluent storage section that stores an eluent, a means for pumping the eluent to a sample introduction device, a sample introduction device that collects a predetermined amount of the sample solution, and an anion exchange resin filled with the sample solution. A separation column that chromatographically separates anions in the sample liquid when carried in by an eluent, a scavenge liquid storage section that stores a scavenge liquid, and a scavenger liquid storage section that pumps the scavenge liquid to a diffusion type removal device. means for removing the cations contained in the eluate from which the eluate from the separation column is carried by the eluent; and a diffusion type removal device for removing the cations contained in the eluate; An anion analyzer for analyzing anions contained in the sample liquid, comprising a conductivity meter carried in by the eluent and measuring the conductivity of the eluate,
between a first tube made of a perfluorocarbon sulfonic acid type cation exchange composition and a second tube made of a material with a liquid-tight structure that is not an ion exchange composition, and the tubes are contained so that their central axes coincide with each other; The above-mentioned diffusion type removal is performed by forming double pipes with appropriate intervals, forming independent inner and outer chambers by the double pipes, and providing respective inlet/outlet ports communicating these chambers with the outside. Along with configuring the device,
a scavenge liquid storage section configured to store a scavenge liquid made of alkylbenzenesulfonic acid or N-methyltauric acid; means for pressure-feeding the scavenge liquid to the outer chamber through the outer chamber inlet at a constant flow rate; means for controlling the temperature of the heavy pipe, and introducing the eluate from the separation column into the inner chamber through the inner chamber inlet and sending it to the conductivity meter from the inner chamber outlet; Anion analysis comprising: guiding the scavenge liquid into the outer chamber through the outer chamber inlet in a direction opposite to the flow direction of the fluid in the inner chamber, and sending it out from the outer chamber outlet. Device. 4. The anion analyzer according to claim 3, wherein the double tube has a length of 4 m to 6 m. 5. The anion analyzer according to claim 3, wherein the set temperature of the temperature control means is about 40°C.