CN102183600A - Ion chromatography-valve changeover analysis system - Google Patents

Abstract

The invention relates to a system for chemical instrument analysis, in particular to an ion chromatography-valve switching analysis system for simultaneously and efficiently detecting strongly retained ions (hexafluorophosphate) and weakly retained ions (conventional anions). The present invention combines the retention time of ions in the ion-exchange column with the length of the ion-exchange column, through valve switching, hexafluorophosphate (strongly retained ions) only passes through the guard column, and conventional anions (weakly retained ions) pass through both The guard column passes through the separation column, which not only achieves simultaneous separation, but also shortens the analysis time of hexafluorophosphate (strong retention ion), and can efficiently and quickly analyze hexafluorophosphate (strong retention ion) and conventional anions (weak retention ions), without complex eluents and organic modifiers, which improves the analysis efficiency.

Description

Ion Chromatography-Valve Switching Analysis System

technical field

The invention relates to a system for chemical instrument analysis, in particular to an ion chromatography-valve switching analysis system for simultaneously and efficiently detecting strongly retained ions (hexafluorophosphate) and weakly retained ions (conventional anions).

Background technique

With the rise of green chemistry in recent years, ionic liquids, as a new type of green solvent, have been used in extraction, organic synthesis, The fields of electrochemistry, catalysis and analytical chemistry are widely used. Ionic liquids are generally salt compounds composed of nitrogen- and phosphorus-containing organic cations (such as imidazolium ions, pyridinium ions, etc.) and inorganic anions (such as F ^- , Cl ^- , BF ₄ ^- , PF ₆ ^- Root (PF ₆ ^- ) is a very important class of anions in ionic liquids. In addition, because LiPF ₆ has the highest conductivity among lithium salts, LiPF ₆ is the most commonly used electrolyte in lithium batteries. Therefore, simultaneous detection of PF ₆ ^- and other anions is important for the purity, type and industrial application of ionic liquids. Lithium batteries The purity of the electrolyte and the safe life of the battery are of great significance. The general analysis methods of PF ₆ ^- are polarography, high performance liquid mass spectrometry, ion chromatography, etc. As an efficient, simple, fast and highly sensitive technology for analyzing anions and cations, ion chromatography is the main method for analyzing PF ₆ ^- method. However, since PF ₆ ^- is an easily polarizable ion, it has strong retention in conventional anion exchange columns and is difficult to be eluted. Simultaneous analysis with conventional anions seriously affects the analysis efficiency and separation effect. Ion chromatography analysis of PF ₆ ^- is usually done by selecting a suitable eluent, but the situation is more complicated, and it is difficult to achieve simultaneous analysis with conventional ions, or an organic modifier such as acetonitrile is added to the eluent to reduce the retention time of PF ₆ ^- , However, it has great damage to the chromatographic column and has defects. So far, there is no report on the simultaneous determination of PF ₆ ^- and conventional anions by ion chromatography-valve switching method.

Contents of the invention

The invention provides an ion chromatography-valve switching analysis system, using a Dionex ICS-2100 ion chromatography instrument and a single flow path system to realize simultaneous analysis of PF ₆ ^- and conventional anions in a short time, greatly improving the analysis efficiency.

Concrete technical scheme of the present invention is as follows:

The invention is an ion chromatography-valve switching analysis system, which is characterized in that the retention time of ions in the ion exchange column is combined with the length of the ion exchange column, and the hexafluorophosphate (strongly retained ion) is only Through the guard column, the conventional anions (weakly retained ions) can pass through both the guard column and the separation column, so as to achieve simultaneous separation and shorten the analysis time of hexafluorophosphate (strongly retained ions), which can efficiently and quickly analyze the hexafluorophosphate Fluorophosphate (strong retention ions) and conventional anions (weak retention ions) do not require complicated eluents and organic modifiers, which improves the analysis efficiency.

The whole system of the present invention only needs one instrument without additional equipment, and can be realized through a single flow system, and the chromatographic column and eluent used are conventional chromatographic columns and conventional eluent, which can be applied to a series of strong Problems with simultaneous analysis of retentive ions and weak retentive ions.

The present invention has following advantage and effect:

1. The present invention uses ion chromatography valve switching method to simultaneously measure PF ₆ ^- and conventional anions. The whole system has one ion chromatography instrument and one single-line flow path, and there is no need to select complicated eluents for separation and addition of organic modifiers. The method is simple , so that PF ₆ ^- can be eluted quickly only through a short guard column, and at the same time obtain a good separation effect with conventional anions, shorten the analysis time and improve the analysis efficiency.

2. The present invention can be applied to the simultaneous analysis of a series of strongly retained and weakly retained ions, and has high practical value.

Description of drawings

Fig. 1 is the schematic diagram of valve switching method;

Figure 2 is a diagram of the device before switching the ten-way valve;

Figure 3 is a diagram of the device after switching the ten-way valve;

Figure 4 shows the signal peaks of standard samples (PF ₆ ^- , F ^- , Cl ^- , NO ₃ ^- , SO ₄ ^2- ) in the ion chromatography-valve switching analysis system;

Figure 5 is the actual sample (ionic liquid) signal peak of the ion chromatography-valve switching analysis system;

Marked in Figure 1 as:

11-guard column AG16; 12-guard column AG11-HC; 13-separation column AS11-HC; 1-hexafluorophosphate; 2-conventional anion;

Marked in Figure 2 as:

6-inlet; 7-six-port valve; 8-pump; 9-quantitative loop; 10-ten-port valve; 11-guard column AG16; 12-guard column AG11-HC; 13-separation column AS11-HC; 14 - suppressor; 15 - conductivity detector; 16 - waste liquid;

Marked in Figure 3 as:

6-inlet; 7-six-port valve; 8-pump; 9-quantitative loop; 10-ten-port valve; 11-guard column AG16; 12-guard column AG11-HC; 13-separation column AS11-HC; 14 - suppressor; 15 - conductivity detector; 16 - waste liquid;

Marked in Figure 4 as:

17-PF ₆ ^- ; 18- F ^- ; 19- Cl ^- ; 20-NO ₃ ^- ; 21-SO ₄ ^2- ;

Marked in Figure 5 as:

22-PF ₆ ^- ; 23-F ^- ; 24-Cl ^- ; 25-NO ₃ ^- ; 26-SO ₄ ^2- .

specific implementation plan

The present invention will be further specifically described below in conjunction with the accompanying drawings.

Fig. 1 is the schematic diagram of the valve switching method; the present invention utilizes the difference in the retention time of strong and weak retained ions in the ion-exchange chromatographic column to combine with the difference in the length of the ion-exchange chromatographic column (guard column and separation column), and the principle of the method (see Fig. 1) When hexafluorophosphate 1 stays in the front protection short column 11, and other conventional anions 2 enter the rear protection short column 12 and separation long column 13, the front protection short The column 11 is placed at the end, and the hexafluorophosphate 1 directly enters the conductivity detector 15 without passing through the back protection short column 12 and the separation long column 13, and other conventional anions 2 pass through the protection short columns 11, 12 and the separation long column 13 And reach separation, have avoided hexafluorophosphate 1 to enter separation long column 13 and cause separation time too long like this, can allow conventional anion 2 to reach separation in separation long column 13 again, have realized hexafluorophosphate 1 and conventional anion 2 High efficiency of simultaneous separation.

The present invention utilizes the six-way valve 7 and the ten-way valve 10 that come with the Dionex ICS-2100 ion chromatograph, wherein the six-way valve 7 is used for sample injection, and the protection short columns 11, 12 and the separation long column 13 are sequentially connected to the ten-way valve On 10, switch the ten-way valve 10 to realize the sequential exchange of the positions of the protection short column 11 and (the protection short column 12+separation long column 13) (see Figure 2 and Figure 3 for the device). The method uses a conventional anion exchange column and a simple KOH Online eluent, single pump and single flow system, suppressed conductivity detection.

Figure 2 is a diagram of the device before the ten-way valve is switched, and Figure 3 is a diagram of the device after the ten-way valve is switched, as shown in Figure 2, the sample is loaded into the quantitative loop 9 from the inlet 6, and the mobile phase is transported from the ion chromatography pump 8 , the sample from the quantitative loop 9 is sent to the guard column AG1611, the guard column AG11-HC12, and the separation column AS11-HC13 are sequentially separated. Switch to Figure 3 (to determine the switching time, the guard column AG11-HC12 and the separation column AS11-HC13 can be removed, directly separated by the guard column AG1611, and the switching time is determined by the conductance test), the sample is converted into sequentially by the guard column AG11-HC12, Separation column AS11-HC13, guard column AG1611 separation, conductance detection after suppressor 14.

Figure 4 is the chromatogram of the five mixed anion standard solutions analyzed by the above method, and the chromatographic peaks of No. 17-21 are PF ₆ ^- (50ppm), F ^- (5ppm), Cl ^- (2ppm), NO ₃ ^- (2ppm) , SO ₄ ^2- (2ppm); Figure 5 is the chromatogram of the ionic liquid sample, and the chromatographic peaks No. 22-26 are PF ₆ ^- , F ^- , Cl ^- , NO ₃ ^- , SO ₄ ^2- .

Ion chromatograph Dionex ICS-2100 from Dionex, Ionpac AG16 (50mm×4mm) guard column, Ionpac AG11-HC (50mm×4mm) guard column, Ionpac AS11-HC (50mm×4mm) separation column , with 10mmol.L ^-1 KOH on-line eluent as mobile phase, flow rate of mobile phase is 1.0mL/min, injection volume is 25μL, after inhibition by ASRS300-4mm electrochemical self-regenerating suppressor 14, DS6 conductivity detector 15 detects .

Claims (3)

1. An ion chromatography-valve switching analysis system, which is characterized in that the retention time of ions in the ion exchange column is combined with the length of the ion exchange column, and through valve switching, hexafluorophosphate (strongly retained ions) can only pass through The guard column allows conventional anions (weakly retained ions) to pass through both the guard column and the separation column, which not only achieves simultaneous separation, but also shortens the analysis time of hexafluorophosphate (strongly retained ions), allowing efficient and rapid simultaneous analysis of hexafluorophosphate Phosphate (strong retaining ion) and conventional anion (weak retaining ion) do not require complicated eluents and organic modifiers, which improves the analysis efficiency. 2. The ion chromatography-valve switching analysis system according to claim 1, characterized in that the whole system only needs one instrument without additional equipment, and can be realized by a single flow system, and the chromatographic column and eluent used Both are conventional columns and conventional eluents. 3. The ion chromatography-valve switching analysis system according to claim 1, characterized in that it is applicable to the simultaneous analysis of a series of strongly retained ions and weakly retained ions.

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