Method for detecting chlorine ions in electronic grade organic solvents

Abstract

The application provides a detection method for chlorine ions in electronic-grade organic solvents, and belongs to the technical field of ion detection. The detection method adopts a matrix elimination eluent, performs online matrix elimination on a matrix through ion chromatography, and detects chlorine ions. The detection method provided by the application has high detection sensitivity, stable operation, small loss of organic solvents to instruments, and is simple, low in detection cost, and the like.

Description

Technical Field

[0001] This invention belongs to the field of ion detection technology, and particularly relates to a method for detecting chloride ions in electronic-grade organic solvents. Background Technology

[0002] With the development of the electronics industry, including semiconductors and flat panel displays, electronic-grade organic solvents are crucial in photolithography processes. Chloride ions in these solvents can affect the stability of the photolithography process and product quality, requiring detection at the μg / L (ppb) level. Conventional methods for detecting anions include titration and ion chromatography. However, titration has a high detection limit, which cannot meet the ppb-level detection requirements for electronic-grade products, and it is also severely affected by the organic solvent matrix, resulting in poor stability.

[0003] Currently, ion chromatography is the mainstream technique for detecting trace anions, typically employing an aqueous eluent system. However, directly injecting insoluble organic solvent samples into the ion chromatography system presents four major problems: severe matrix interference, leading to peak distortion, retention time drift, and increased background noise; instrument wear and tear risk, as long-term injection of high-concentration organic solvents accelerates the swelling and degradation of the inhibitor membrane and damages the column packing material; difficulty in achieving the required sensitivity, as offline dilution, liquid-liquid extraction, and other pretreatment processes simultaneously dilute the target ions, and the mixing of insoluble organic solvents with water easily leads to emulsification and stratification, further reducing detection sensitivity; and cumbersome operation and susceptibility to contamination, as offline pretreatment steps are numerous and manual operation can easily introduce external contamination.

[0004] To address these issues, researchers have been exploring new detection methods. Several invention patents have been developed to address the problems of low sensitivity, complex operation, and significant matrix interference in anion detection in electronic-grade organic solvents. For example, CN117368341A discloses a method for anion detection in electronic-grade PGMEA. This method involves injecting the test solution into a two-dimensional ion chromatograph for separation and detection, performing first-dimensional and second-dimensional separation sequentially, and using an external standard method to determine the anion content in the test solution. The recovery rate of this method ranges from 90% to 110%, and the linear range is 0.5-50 μg / kg. However, this method still suffers from matrix interference during detection, and the detection sensitivity needs improvement.

[0005] CN117571854A proposes a method for detecting chloride and / or sulfate ions in electronic-grade carbon dioxide. This method uses ultrapure water to absorb anions from electronic-grade carbon dioxide to obtain the test solution. Chloride and sulfate ions are pretreated to eliminate interference, and then concentrated and enriched before quantification by ion chromatography. This method has high accuracy and precision, is simple and rapid, and has good reproducibility; however, the selection of the pretreatment column and the mobile phase conditions still need optimization. Summary of the Invention

[0006] In view of this, the present invention provides a method for detecting chloride ions in electronic-grade organic solvents. The method provided by the present invention has high detection sensitivity, stable operation, low wear and tear on the instrument caused by organic solvents, and is simple and low in detection cost.

[0007] To address the aforementioned technical problem, this invention provides a method for detecting chloride ions in electronic-grade organic solvents. The method employs a matrix elimination eluent, performs online matrix elimination via ion chromatography, and then detects chloride ions. The matrix elimination eluent is an electronic-grade aqueous ethanol solution and / or an electronic-grade aqueous isopropanol solution; The alcohol content in the matrix elimination eluent is 50%-90% by volume percentage; The electronic-grade organic solvents include propylene glycol methyl ether and / or propylene glycol methyl ether acetate.

[0008] Preferably, the method for detecting chloride ions in the electronic-grade organic solvent includes the following steps: 1) The sample solution enters the concentration column of the ion chromatograph through the injection path. The concentration column is washed with matrix elimination eluent to remove organic components in the sample solution, while anions are enriched on the concentration column. 2) The concentration column is washed with eluent in reverse phase. The enriched ions in the concentration column are washed with eluent and enter the chromatographic column for separation, and then enter the suppressor. 3) In the suppressor, the cations are replaced, and then the generated spectrum is detected in the conductivity detector; 4) Calculate the chloride ion concentration.

[0009] Preferably, in step 1), the flow rate of the matrix elimination eluent used to rinse the concentration column is 0.5-1.2 mL / min, and the rinsing time is 4 minutes.

[0010] Preferably, the rinsing solution in step 2) is a 2-5 mmol / L sodium carbonate aqueous solution with a flow rate of 0.2-1.0 mL / min.

[0011] Preferably, the inhibitor regeneration solution in the inhibitor in step 3) is a 100-400 mmol / L aqueous solution of phosphoric acid.

[0012] Preferably, the conductivity detector in step 3) is an IC Conductivity Detector MB with a measurement range of 0-15000 μS / cm.

[0013] Preferably, step 1) further includes venting the ion chromatograph, baseline balancing, and preheating the instrument before injection.

[0014] Preferably, the eluent flow rate during instrument baseline equilibration is 0.5-1.2 mL / min, the column equilibration temperature is 30-40℃, the suppressor regenerator flow rate is 0.2-1.0 mL / min, and the matrix elimination eluent flow rate is 0.6-1.5 mL / min.

[0015] Preferably, the external standard method is used for quantitative detection of chloride ions.

[0016] Preferably, the quantitative detection of chloride ions using the external standard method includes the following steps: (1) Prepare electronic-grade ethanol standard solutions with different chloride ion concentrations; (2) Collect chromatograms of the above electronic grade ethanol standard solutions with different chloride ion concentrations respectively; (3) Plot the curve of peak area versus concentration, which is the standard curve; (4) Calculate the chloride ion content in the sample to be tested based on the standard curve.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for detecting chloride ions in electronic-grade organic solvents. It employs a matrix elimination eluent, using ion chromatography for online matrix elimination and chloride ion detection. This invention utilizes an alcohol-based matrix elimination eluent with both water solubility and PGME / PGMEA solubility to eliminate high concentrations of organic matrix (PGME / PGMEA), thereby eliminating interference from high-concentration organic matrix and improving chloride ion detection. - Peak shape and baseline stability are improved, thereby enhancing detection accuracy. This invention employs a matrix elimination eluent for online matrix elimination, eliminating the need for offline dilution and liquid-liquid extraction. This avoids target ion loss and emulsion stratification issues, achieving Cl... - High-sensitivity detection at the ppb level.

[0018] The matrix elimination eluent provided by this invention is compatible with aqueous ion chromatography systems, has low cost, reduces detection costs, and is suitable for large-scale detection.

[0019] Furthermore, this method integrates valve position switching, matrix removal, enrichment, elution, and detection through process design, reducing manual operation and lowering the risk of external contamination.

[0020] Furthermore, optimizing the eluent ratio and suppressor operating conditions reduces the wear and tear on the instrument caused by organic solvents and improves the system's operational stability. Attached Figure Description

[0021] Figure 1 This is a state diagram when the baseline is balanced; Figure 2 The chromatogram of the prepared 10 ppb electronic grade ethanol standard solution is shown. Figure 3 The standard curve obtained; Figure 4 The ion chromatogram for detection in Example 1; Figure 5 This is the ion chromatogram after spiked addition in Example 1; Figure 6 The ion chromatogram for comparison example 1 is shown. Figure 7 This is the ion chromatogram after spiked Comparative Example 1. Detailed Implementation

[0022] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0023] This invention provides a method for detecting chloride ions in electronic-grade organic solvents, which uses a matrix elimination eluent to perform online matrix elimination and chloride ion detection via ion chromatography; The matrix elimination eluent is an electronic-grade aqueous ethanol solution and / or an electronic-grade aqueous isopropanol solution; The alcohol content in the matrix elimination eluent is 50%-90% by volume percentage; The electronic-grade organic solvents include propylene glycol methyl ether and / or propylene glycol methyl ether acetate.

[0024] This invention employs an alcohol-based matrix elimination eluent that combines water solubility with PGME / PGMEA dissolving ability to eliminate high concentrations of organic matrix (PGME / PGMEA), thereby eliminating interference from high concentrations of organic matrix and improving Cl - Peak shape and baseline stability are improved, thereby enhancing detection accuracy. This invention employs a matrix elimination eluent for online matrix elimination, eliminating the need for offline dilution and liquid-liquid extraction. This avoids target ion loss and emulsion stratification issues, achieving Cl... - High-sensitivity detection at the ppb level.

[0025] In this invention, the method for detecting chloride ions in the electronic-grade organic solvent preferably includes the following steps: 1) The sample solution enters the concentration column of the ion chromatograph through the injection path. The concentration column is washed with matrix elimination eluent to remove organic components in the sample solution, while anions are enriched on the concentration column. 2) The concentration column is washed with eluent in reverse phase. The enriched ions in the concentration column are washed with eluent and enter the chromatographic column for separation, and then enter the suppressor. 3) In the suppressor, the cations are replaced, and then the generated spectrum is detected in the conductivity detector; 4) Calculate the chloride ion concentration.

[0026] In this invention, the process preferably includes venting the ion chromatograph, baseline balancing, and preheating before sample injection. This ensures a smooth instrument baseline and improves detection accuracy (instrument balancing takes approximately 30 minutes, and UV detector balancing takes approximately 1 hour). In this invention, the venting is preferably performed in the following manner: Open the vent valve and turn on the ion chromatograph. With the pump off, change the flow rate to 2 mL / min and the minimum pressure to 0 MPa. Connect the syringe to the vent line of the ion chromatograph and slowly pull the syringe outward (vent valve open, pump off) until you see droplets entering the syringe. Remove the syringe and place a beaker on one end of the vent line. Click the "Start" button. When you see liquid continuously flowing from the vent line and no air bubbles in the entire eluent line, click the "Stop" button and close the vent valve. The venting process is now complete.

[0027] In this invention, the eluent flow rate during instrument baseline equilibration is preferably 0.5-1.2 mL / min, the column equilibration temperature is preferably 30-40℃, the suppressor regenerator flow rate is preferably 0.2-1.0 mL / min, and the matrix elimination eluent flow rate is preferably 0.6-1.5 mL / min.

[0028] During instrument equilibration, the eluent background should be between 0.8-3 μS / cm (depending on the composition and concentration of the eluent). Scale the y-axis to 0.2 μS / cm; at this point, the baseline should be a smooth straight line. The chemical suppressor will switch every ten minutes, causing the baseline background to change. Sample injection can begin when the backgrounds of all three suppressor channels are consistent. Figure 1 As shown, this is the state when the baseline is balanced.

[0029] Before injection, this invention sets the condition switching valve to the matrix elimination position. The sample solution is introduced into the concentration column of the ion chromatograph through the injection path. The concentration column is then flushed with matrix elimination eluent to remove organic components from the sample solution, while anions are enriched on the column. In this invention, the preferred flow rate of the matrix elimination eluent during column flushing is 0.5-1.2 mL / min, and the preferred flushing time is 4 minutes. Detection can be performed at room temperature.

[0030] The smaller the steric hindrance of the matrix elimination eluent provided by this invention, the easier it is for solvent molecules to approach and surround chloride ions, forming a tight and effective solvation layer. The matrix elimination eluent is used to flush the concentration column, acting as a driving force to separate the organic components from the anionic components in the sample. Anions in the sample are enriched on the concentration column, while the organic components are discharged.

[0031] After online matrix elimination is completed, switch the valve position to the analysis position and use the eluent to flush the concentration column in reverse phase. The enriched ions in the concentration column are then washed into the chromatographic column for separation, and then enter the suppressor.

[0032] In this invention, the suppressor is used to replace cations in the system. To ensure that the baseline is not too high during detection and to guarantee detection accuracy, the suppressor is rinsed with suppressor regeneration solution (because the strongest signal during detection is only around 20; without cation replacement, the baseline could be in the hundreds, which is too large relative to 20, and even a small error would significantly affect signal detection).

[0033] In this invention, the rinsing solution is preferably a 2-5 mmol / L sodium carbonate aqueous solution, and the flow rate is preferably 0.2-1.0 mL / min. In this invention, the suppressor regeneration solution in the suppressor is preferably a 100-400 mmol / L phosphoric acid aqueous solution. The conductivity detector is preferably an IC Conductivity Detector MB (2.850.9020), and the measurement range is preferably 0-15000 μS / cm.

[0034] In this invention, the external standard method is preferably used for the quantitative detection of chloride ions. The quantitative detection of chloride ions using the external standard method preferably includes the following steps: (1) Prepare electronic-grade ethanol standard solutions with different chloride ion concentrations; (2) Collect chromatograms of the above electronic grade ethanol standard solutions with different chloride ion concentrations respectively; (3) Plot the curve of peak area versus concentration, which is the standard curve; (4) Calculate the chloride ion content in the sample to be tested based on the standard curve.

[0035] In this invention, to further improve the accuracy of detection, an ion chromatograph is used for automatic dilution and to plot a standard curve. The specific operation is as follows: To prepare an electronic-grade ethanol standard solution with a chloride ion concentration of 10 ppb: Transfer 1 mL of a standard aqueous solution with a chloride ion concentration of 1 ppm to a 100 mL volumetric flask, then dilute to 100 mL with anhydrous electronic-grade ethanol. Mix thoroughly to obtain a 10 ppb electronic-grade ethanol standard solution for later use. The chromatogram of this electronic-grade ethanol standard solution is shown below. Figure 2 As shown.

[0036] The above-mentioned electronic-grade ethanol standard solution with a chloride ion concentration of 10 ppb was placed into the ion chromatography automated injection system for injection, and the standard curve injection program was set. Injection categories (standard 1, standard 2, standard 3, standard 4, and standard 5) were set, and electronic-grade ethanol standard solutions with a chloride ion concentration of 10 ppb were injected under each category. The corresponding dilution concentrations were standard 1 (10 ppb), standard 2 (5 ppb), standard 3 (2 ppb), standard 4 (1 ppb), and standard 5 (0.5 ppb), respectively.

[0037] To process standard curve injection data: Left-click to select all standards, then right-click and select the "Reprocess" button from the pop-up list to reprocess the standard samples. In the reprocessing window, select Standard 1 and perform all necessary updates on Standard 1. These updates will be copied to all standards.

[0038] Calibration: Update standard time — Left-click the component button — Double-click the component to be changed — In the pop-up dialog box, enter the correct retention time and window value (default 5%, peaks within 5% of the entered retention time will be automatically recognized by the system as that ion). After all changes are completed, click the OK button.

[0039] Calibration: Update standard concentration — When the concentration of each ion in the standard is the same (for example, the concentration of standard 1 is 10 ppm), simply enter the concentration of the first ion and click the copy button, and all ion concentrations will be the same as the first ion concentration.

[0040] After Standard 1 is updated, click the "Reprocess" button to open the batch processing dialog box. In the dialog box, select "Use the standards in the reprocess list" and click the "OK" button. In the chromatogram window, select "Calibration Curve" to view all the standard curves. The prepared standard curves are shown below. Figure 3 As shown.

[0041] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] In the embodiments and comparative examples of the present invention, the determination was performed using a Metropole 940 ion chromatograph with a Metrosep A Supp 7-250 / 4.0 column.

[0043] Example 1 In this embodiment, the matrix elimination eluent is a 70% (v / v) electronic grade ethanol aqueous solution (filtered through a 0.22 μm filter membrane after preparation). The rinsing solution was a 3.2 mmol / L sodium carbonate aqueous solution; The inhibitor regeneration solution is a 300 mmol / L aqueous solution of phosphoric acid; The sample to be tested was OK73 (mass ratio of propylene glycol monomethyl ether to propylene glycol methyl ether acetate = 7:3).

[0044] System preparation: After turning on the ion chromatograph and purging the air, perform instrument baseline equilibration (eluent flow rate 1.2 mL / min, column equilibration temperature 30℃, inhibitor regenerator flow rate 1.0 mL / min, matrix elimination eluent flow rate 1.2 mL / min), and run until the baseline is stable; Injection and matrix elimination: Set the injection volume to 20 μL, switch the valve to the elimination position, and flush the concentration column with matrix elimination eluent at a flow rate of 1.2 mL / min for 4 minutes; Analysis and Detection: Switch the valve to the analysis position, elute the column with 3.2 mmol / L sodium carbonate eluent at a flow rate of 0.5 mL / min using reverse phase, then transfer to the suppressor. Elute with 300 mmol / L phosphoric acid aqueous solution at a flow rate of 1.0 mL / min. Detect conductivity. The ion chromatogram is shown below. Figure 4 As shown, the external standard method was finally used for quantification, Cl - The concentration was 0.03 μg / L. 1.Cl - Precision verification is shown in Table 1: Table 1 Cl - Precision verification (intra-day precision, n=6)

[0045] 2.Cl - Spike recovery validation (sample spiked with 50 μg / L), with the ion chromatogram as shown below. Figure 5 As shown in Table 2: Table 2 Cl - Spike recovery validation (n=3)

[0046] As can be seen from Table 2, Cl - The spiked recovery rate met the requirements of 80%-120%, the chromatographic baseline was stable, and there was no interference from organic matrix.

[0047] Example 2 In this embodiment, the matrix elimination eluent is a 90% (v / v) electronic grade isopropanol aqueous solution (filtered through a 0.22 μm filter membrane after preparation). The rinsing solution was a 5 mmol / L sodium carbonate aqueous solution; The inhibitor regeneration solution is a 400 mmol / L aqueous solution of phosphoric acid; The sample to be tested is propylene glycol methyl ether.

[0048] System preparation: After turning on the ion chromatograph and purging the air, perform instrument baseline equilibration (eluent flow rate 0.5 mL / min, column equilibration temperature 40℃, inhibitor regenerator flow rate 0.5 mL / min, matrix elimination eluent flow rate 0.6 mL / min), and run until the baseline is stable; Injection and matrix elimination: Set the injection volume to 20 μL, switch the valve to the elimination position, and flush the concentration column with matrix elimination eluent at a flow rate of 0.5 mL / min for 4 minutes; Analysis and detection: Switch the valve to the analytical position, elute the column with 5 mmol / L sodium carbonate eluent at a flow rate of 0.2 mL / min using reverse phase, then transfer to the suppressor. Elute with 400 mmol / L phosphoric acid aqueous solution at a flow rate of 0.2 mL / min. Detect conductivity, and finally quantify using the external standard method. Cl - With a concentration of 0.08 μg / L and a recovery rate of 72%, it can be seen that using 90% (v / v) electronic-grade isopropanol aqueous solution as the matrix elimination eluent is relatively less effective than using 70% (v / v) electronic-grade ethanol aqueous solution in Example 1. However, the recovery rate can still reach 72%. Although it is not as good as using electronic-grade ethanol aqueous solution as the matrix elimination eluent, the accuracy is still relatively high.

[0049] Example 3 In this embodiment, the matrix elimination eluent is a 50% (v / v) electronic grade ethanol aqueous solution (filtered through a 0.22 μm filter membrane after preparation). The rinsing solution was a 2 mmol / L sodium carbonate aqueous solution; The inhibitor regeneration solution is a 100 mmol / L aqueous solution of phosphoric acid; The sample to be tested is propylene glycol methyl ether acetate.

[0050] System preparation: After turning on the ion chromatograph and purging the air, perform instrument baseline equilibration (eluent flow rate 1.2 mL / min, column equilibration temperature preferably 30℃, inhibitor regenerator flow rate 1.0 mL / min, matrix elimination eluent flow rate preferably 1.5 mL / min), and run until the baseline stabilizes; Injection and matrix elimination: Set the injection volume to 20 μL, switch the valve to the elimination position, and flush the concentration column with matrix elimination eluent at a flow rate of 1.2 mL / min for 4 minutes; Analysis and detection: Switch the valve to the analytical position, rinse the column with 2 mmol / L sodium carbonate eluent at a flow rate of 1.0 mL / min using reverse phase, then transfer to the suppressor. Rinse with 100 mmol / L phosphoric acid aqueous solution at a flow rate of 1.0 mL / min. Detect conductivity, and finally quantify using the external standard method. Cl - The concentration was 0.10 μg / L, and the recovery rate was 118%.

[0051] Comparative Example 1 In this comparative example, the matrix elimination eluent was a 90% (v / v) electronic-grade tert-butanol aqueous solution (filtered through a 0.22 μm filter membrane after preparation). The rinsing solution was a 3.2 mmol / L sodium carbonate aqueous solution; The inhibitor regeneration solution is a 300 mmol / L aqueous solution of phosphoric acid; The sample to be tested is propylene glycol methyl ether acetate.

[0052] System preparation: After turning on the ion chromatograph and purging the air, perform instrument baseline equilibration (eluent flow rate 1.2 mL / min, column equilibration temperature preferably 30℃, inhibitor regenerator flow rate 1.0 mL / min, matrix elimination eluent flow rate preferably 1.5 mL / min), and run until the baseline stabilizes; Injection and matrix elimination: Set the injection volume to 20 μL, switch the valve to the elimination position, and flush the concentration column with matrix elimination eluent at a flow rate of 1.2 mL / min for 4 minutes; Analysis and Detection: Switch the valve to the analysis position, elute the column with 2 mmol / L sodium carbonate eluent at a flow rate of 1.0 mL / min using reverse phase, then transfer to the suppressor. Elute with 100 mmol / L phosphoric acid aqueous solution at a flow rate of 1.0 mL / min. Detect conductivity. The ion chromatogram is shown below. Figure 6 As shown, the external standard method was finally used for quantification (ion chromatogram as shown). Figure 7 (as shown), Cl - The concentration was 0.01 μg / L, and the recovery rate was 2.5%. It can be seen that using 90% (v / v) electronic-grade tert-butanol aqueous solution as the matrix elimination eluent resulted in a recovery rate of only 2.5%, indicating low detection accuracy.

[0053] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting chloride ions in electronic-grade organic solvents, characterized in that, A matrix elimination eluent was used to perform online matrix elimination and chloride ion detection by ion chromatography; The matrix elimination eluent is an electronic-grade aqueous ethanol solution and / or an electronic-grade aqueous isopropanol solution; The alcohol content in the matrix elimination eluent is 50%-90% by volume percentage; The electronic-grade organic solvents include propylene glycol methyl ether and / or propylene glycol methyl ether acetate.

2. The detection method according to claim 1, characterized in that, Includes the following steps: 1) The sample solution enters the concentration column of the ion chromatograph through the injection path. The concentration column is washed with matrix elimination eluent to remove organic components in the sample solution, while anions are enriched on the concentration column. 2) The concentration column is washed with eluent in reverse phase. The enriched ions in the concentration column are washed with eluent and enter the chromatographic column for separation, and then enter the suppressor. 3) In the suppressor, the cations are replaced, and then the generated spectrum is detected in the conductivity detector; 4) Calculate the chloride ion concentration.

3. The detection method according to claim 2, characterized in that, In step 1), the flow rate of the matrix elimination eluent used to rinse the concentration column is 0.5-1.2 mL / min, and the rinsing time is 4 minutes.

4. The detection method according to claim 2, characterized in that, The rinsing solution mentioned in step 2) is a sodium carbonate aqueous solution of 2-5 mmol / L, with a flow rate of 0.2-1.0 mL / min.

5. The detection method according to claim 2, characterized in that, The inhibitor regeneration solution in the inhibitor mentioned in step 3) is a 100-400 mmol / L aqueous solution of phosphoric acid.

6. The detection method according to claim 2, characterized in that, The conductivity detector mentioned in step 3) is an ICConductivity Detector MB, with a measurement range of 0-15000 μS / cm.

7. The detection method according to claim 2, characterized in that, Step 1) also includes venting the ion chromatograph, baseline balancing, and preheating before sample injection.

8. The detection method according to claim 7, characterized in that, During instrument baseline equilibration, the eluent flow rate is 0.5-1.2 mL / min, the column equilibration temperature is 30-40℃, the suppressor regenerator flow rate is 0.2-1.0 mL / min, and the matrix elimination eluent flow rate is 0.6-1.5 mL / min.

9. The detection method according to claim 2, characterized in that, In step 4), the external standard method is used to quantitatively detect chloride ions.

10. The detection method according to claim 9, characterized in that, The quantitative detection of chloride ions using the external standard method includes the following steps: (1) Prepare electronic-grade ethanol standard solutions with different chloride ion concentrations; (2) Collect chromatograms of the above electronic grade ethanol standard solutions with different chloride ion concentrations respectively; (3) Plot the curve of peak area versus concentration, which is the standard curve; (4) Calculate the chloride ion content in the sample to be tested based on the standard curve.

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