JPH0196556A - ion chromatography equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion chromatography device for separating and analyzing anions or cations, and particularly in a gradient elution method of an eluent, the electric conductivity and absorbance of the eluent are measured. This invention relates to an ion chromatography device that simultaneously separates and analyzes various types of anions and cations while keeping the temperature constant.

(Prior Art) Conventional ion chromatography that simultaneously analyzes anions and cations is classified into the following types.

(1) A suitable chelating agent is used as an eluent to guide cations into an anion complex, and the cations and anions are simultaneously analyzed using an anion exchange column.

This method can be used, for example, in analytical chemistry (An
al, Chem,), May 1984, pp-8
32-833. However, this method has the drawback that the type of eluent for the chelating agent is limited, and the types of ions to be analyzed are restricted.

(2) This is an ion chromatography device in which an anion exchange column and a cation exchange column are connected in series, and is a device that simultaneously analyzes anions and cations using an appropriate eluent. In this regard, for example, Analytical Mistry (Anal.

Chem, ), 54. (1982) pp, 462-4
Discussed in 69.

(3) This is an ion chromatography device in which an anion exchange column and a cation exchange column are connected in parallel, and the sample and eluent are dispensed into each column and separated for separate analysis. This is disclosed in, for example, Japanese Unexamined Patent Publication No. 56-77757.

(4) In column switching type ion chromatography, an anion exchange column and a cation exchange column are provided, and the columns are connected in series only for a predetermined period of time, and the eluent of one ion is fed. The ion is eluted, and then the eluent flow path system is switched, and the eluent for the other ion is sent to the other column to elute the ion. This is a device that separates and analyzes each ion species using two columns.

Furthermore, with respect to ion chromatography apparatuses, the application of a gradient elution method using an eluent has been proposed and discussed in the Ion Chromatography Forum (1986).

This method is performed with a single suppressor. One suppressor type uses a column with a small exchange capacity to flow a dilute eluent, and a column with a strong cation exchange type (for example, hydrogen cations) to flow the eluent, sodium carbonate, to convert the eluate into carbonic acid, a weak electrolyte. This method significantly reduces the electrical conductivity of the eluent. This is a method in which a gradient elution method is performed using a single type of suppressor to lower the electrical conductivity of the eluent and to reduce changes in electrical conductivity due to gradient elution.

[Problem that the invention seeks to solve]

The above conventional technology (1) chelating agent eluent, (2) negative,
The series type of cation exchange column and (3) parallel type of anion and cation exchange columns are both methods of simultaneously analyzing anions and cations by flowing one type of eluent at a constant flow rate. . However, no consideration has been taken to flow different eluents into anion exchange columns and cation exchange columns, and at different flow rates, making it difficult to completely separate various types of anions and cations. be.

In addition, (4) in the column switching type method, it is possible to flow different types of eluents at different flow rates to the respective anion exchange columns and cation exchange columns. However, since there are more ions in the eluent than ions in the sample, during column switching, for example, part of the eluent for cation separation may be removed at the same time as the anion sample.
Introduced into an anion exchange column, the baseline of the eluent fluctuates on the detected chromatogram, and large peaks due to anions appear in the eluent for cation separation.

Furthermore, in the ion chromatography using the gradient elution method described above, the purpose is not to simultaneously analyze anions and cations, which is impossible in principle with a method using a Sublesser force ram.

Therefore, an object of the present invention is to solve the problems of the above-mentioned ion chromatography device, to simultaneously separate various types of anions and cations, to prevent overlapping of chromatogram peaks, and to accurately and quickly separate each ion type. The purpose of the present invention is to provide an ion chromatography device that performs separation and analysis.

[Means for solving problems]

The ion chromatography apparatus of the present invention includes: a first pump section that transports a first mixed eluent that is a mixture of a plurality of eluents; and a sample introduction device that injects a sample liquid into the first mixed eluent. , an anion exchange column that separates anions in the sample or a cation exchange column that separates cations in the first mixed eluent, and a detector that detects the anions or cations that are separated and eluted. The chromatography apparatus is equipped with a flow path system downstream of the anion exchange column or the cation exchange column for transporting a second mixed eluent to a confluence section by a second pump section. .

Further, the anion exchange column and the cation exchange column, or the cation exchange column and the anion exchange column are sequentially connected in series, and the first mixed eluent is sent to the first column. , the apparatus is provided with a flow path system for transporting the second mixed eluent to the confluence section between the 10th column and the 20th column by the second pump section.

Further, after the first mixed eluent and the second mixed eluent are combined, the first mixed eluent, the second mixed eluent, etc. A device in which a controller is provided to control the feeding of each of the mixed eluents, and the controller is provided with a function of controlling the mixing ratio and flow rate of the first mixed eluent and the second mixed eluent over time. is preferred.

In short, this chromatography apparatus mixes a plurality of eluents to be delivered by two pumps, flows the first mixed eluent into an anion exchange column or a cation exchange column, and flows the second mixed eluent into an anion exchange column or a cation exchange column. This is a device in which the eluent is caused to flow downstream of this column using a second pump and join together. In addition, in the case of an anion exchange column and a cation exchange column, or a cation exchange column and an anion exchange column in series, the second mixed eluent is pumped between these two columns using a second pump. This is a device that flows between the two and merges. Furthermore, it is an apparatus in which the mixing ratio and liquid volume of the first mixed eluent and the second mixed eluent are controlled over time using a controller, thereby allowing various types of anions and cations to be simultaneously analyzed with high precision.

[Effect]

The method using this chromatography device is a gradient elution method in which the composition of the eluent flowing through an anion exchange column and a cation exchange column is changed over time, that is, an eluent with a high elution power is used for ions that are difficult to elute. is applied. In conventional chromatography apparatuses, when detecting an eluent, the accuracy of ion analysis is low due to fluctuations in the background (baseline) of the electrical conductivity or optical absorbance of the eluent. However, in the present invention, by controlling the composition and flow rate of the eluent sent from the second pump with a controller, it is possible to minimize background fluctuations and accurately quantify the detected ions from their peaks. do. Furthermore, by connecting an anion exchange column and a cation exchange column, various types of anions and cations can be simultaneously and rapidly quantified.

(Example) The configuration of a preferred specific example of the ion chromatography apparatus of the present invention is shown in FIG.
Eluents 1a to 1C are used as second eluents, and eluents 1d to 1f are used as first eluents. Eluent 1d to 1f
is taken at any mixing ratio by opening and closing the solenoid valves 2d to 2f,
Mix with mixer 3b. Pump the mixed eluent (P
r) 4b to the sample introducer 6; A predetermined amount of sample is injected into the eluent using the sample introducer 6, and the eluate is passed through the anion exchange column 7a. Thereafter, anions in the sample are separated by an anion exchange column 7a. On the other hand, the eluents 1a to IC are adjusted to an arbitrary mixing ratio by opening and closing the solenoid valves 28 to 2c, and mixed by the mixer 3a. The mixed eluent is sent by a pump (Pz) 4a to a mixer 3C disposed downstream of the anion exchange column 7a.

There, the mixed eluent from the anion exchange column 7a and the mixed eluate from the pump 4a are combined and sent to the cation exchange column 7b. Cations in the sample are separated by the cation exchange column 7b, and then sent to a detector 8 to detect anions and cations, and a response signal of the detected ion species is recorded in a recorder 9. In this case, the anion exchange column 7a and the cation exchange column 7b are sequentially arranged in series, but the arrangement of the columns may be reversed. In addition, a gradient controller (C) 5 is provided to control the opening and closing of the solenoid valves 2a to 2f and the flow rates of the pumps 4a and 4b to keep the background of the electrical conductivity of the eluent sent to the detector 8 at a constant level. so that it becomes

FIG. 2 shows the background of the electrical conductivity of the eluent.

Eluents 1a and 10 are equal, 2mM benzoic acid + 2mM
A mixture of tris(hydroxymethyl)aminomethane (
Background conductivity.

BG=183 μs/an) is used. The eluent 1d is 2mM benzoic acid (background conductivity).

BG=156μs/C! l) is used. Curve 10.11 shows the temporal change in background electrical conductivity when these eluents were subjected to gradient elution. Curve 10 shows eluent 1 when the flow rate of pump 4a is 0.5 mR/min and the flow rate of pump 4b is 1.0 mQ/min.
The composition ratio of d and 1e is 50: '50 to 30 near 0
shows the change in background electrical conductivity when it is changed linearly over a period of 15 minutes.

On the other hand, the curve 11 shows the flow rate of the pump 4b and the eluent 1d.
The temporal change in the composition ratio of
It shows the change in background electrical conductivity when simultaneously changing Omfl/min linearly. This is an attempt to reduce the background increase over time due to changes in the composition ratio of eluents 1d and 18, and to subtract the increase in background by reducing the amount of eluent 1a, thereby making the background extremely constant. be. In this way, curve 10
In the case of curve 11, the baseline change was about 40 μs/■, but in the case of curve 11, it could be reduced to about 5 μs/an.

In addition, in the flow path system of FIG. 1, the flow rates of the pumps 4a and 4b are constant, the eluents 1a and 1d, and 1b and 18 are set equally, and the mixing ratio of the eluents 1d and 1e is as follows:
It is also possible to flow the eluents 1a and 1b with the mixing ratio reversed, and finally keep the background conductivity constant.

Next, we will show the results of separating and analyzing various types of anions and cations using this ion chromatography device.

FIG. 3(a) shows a chromatogram when a gradient elution method similar to that of curve 11 in FIG. 2 is applied. In order to accelerate the elution of the anion S 042-(21), the eluent gradient (ld:le) was changed over time, and the flow rate of eluent 1a was changed accordingly to minimize baseline fluctuations. I kept it and analyzed it. The detected ion species peaks in the chromatogram are separated individually and L i+(12
'), N a+ (13).

NHa÷(12), K+(15), C
D″″(16).

NO! ''' (17), Br'''' (18), N0a-(1
9).

8042″″ (21) etc. were detected. Furthermore, peak 20
is the pecanto peak. In this way, various types of anions,
It has become clear that cations can be separated simultaneously and quantified with high precision in a short time.

For comparison, the flow rate of pump 4a is set to 0 m12/m.
in, and the flow rate of the pump 4b is 1.0 mQ/min,
FIG. 3(b) shows a chromatogram obtained when the composition ratio of eluents 1d and 1e was 50:50. In this conventional eluent flow path system, the peaks of anions and cations overlap, making it impossible to quantify most of each ion species. In addition, in FIG. 3(c), the composition ratio of the eluents 1d and 1e is the same as in FIG. 3(b), the flow rate of the pump 4a is 0.7 mQ/min, and the flow rate of the pump 4b is 0.7 mQ/min. A chromatogram at 3 mA is shown. In this case, it was possible to separate and elute the anions and cations, but since the composition ratio of the eluents 1d and 1e was not changed over time, the anions were eluted as shown in Figure 3 (a). ) compared to the case of
It's twice as slow.

〔Effect of the invention〕

The ion chromatography device of the present invention applies the gradient elution method of the eluent and detects eluted ions while keeping the background electrical conductivity of the eluent constant with minimal changes in absorbance. It is possible to simultaneously and quickly separate ions and cations and perform quantitative analysis with high precision.

[Brief explanation of the drawing]

Figure 1 shows the configuration flow sheet 1- of the ion chromatography apparatus of the present invention, Figure 2 shows the temporal change in background electrical conductivity, and Figure 3 shows the analysis results of anions and cations. Figure a) shows the results obtained using the ion chromatography apparatus of the present invention, and Figures (b) and (c) show the results obtained using the conventional apparatus. 1a to 1f...Eluent, 2a to 2f...Solenoid valve, 3
8~3f...Mixer, 4a, 4b...Pump, 5
... Gradient controller 1 to roller, 6 ... Sample introducer, 7a ... Anion (positive) ion exchange column, 7b
... Anion (positive) ion exchange column, 8 ... Detector, 9
...Recorder, 10...Curve showing changes in background conductivity. 11...Curve showing the change in background corrected according to the present invention, 12-...t, i+, 13-Na+, 1
4...N H4+, 15...K+, 16...CQ
-'', 17-N O2-118-Br-, 19-N
O3-520-...pecant peak, 21...5o
tz″″.

Claims (1)

[Scope of Claims] 1. A first pump unit that transports a first mixed eluent obtained by mixing a plurality of eluents, and a sample introduction device that injects a sample liquid into the first mixed eluent. , an anion exchange column that separates anions in the sample with a first mixed eluent, or a cation exchange column that separates cations;
In a chromatography apparatus equipped with a detector for detecting anions or cations to be separated and eluted, a second mixed eluent is applied to the downstream side of the anion exchange column or the cation exchange column by a second pump section. An ion chromatography apparatus characterized in that a flow path system for transporting liquid is provided at a confluence section. 2. Connecting the anion exchange column and the cation exchange column, or the cation exchange column and the anion exchange column in series, and sending the first mixed eluent to the first column. , a flow path system is provided for transporting the second mixed eluent by the second pump section to the confluence section between the first column and the second column. The ion chromatography device according to item 1. 3. After the first mixed eluent and the second mixed eluent are combined, the first mixed eluent and the second mixed eluent are combined so that the background of the electrical conductivity or absorbance of the eluent becomes constant. 3. The ion chromatography apparatus according to claim 1, further comprising a controller for controlling the feeding of each of the mixed eluents. 4. The ion according to claim 3, wherein the controller is equipped with a function of controlling the mixing ratio and flow rate of the first mixed eluent and the second mixed eluent over time. Chromatography equipment.