Device system for detecting trace fluosilicic acid in hydrofluoric acid and detection method

Abstract

The invention belongs to the technical field of analysis and detection, and relates to a device system and a detection method for detecting trace fluosilicic acid in hydrofluoric acid, the device system comprises a sample introduction unit, a first-dimensional separation unit, an enrichment conversion unit, a second-dimensional separation unit, a post-column derivatization unit and a detection unit which are connected in sequence; wherein the first-dimensional separation unit is used for separating hydrofluoric acid and fluosilicic acid; the enrichment conversion unit is used for enriching fluosilicic acid and converting the fluosilicic acid into fluorine ions and silicate radicals in an alkaline environment; the second-dimensional separation unit is used for separating fluorine ions and silicate radicals; the post-column derivation unit is used for gradually converting silicate into silicon molybdenum blue; the detection unit is used for detecting the absorbance of silicon molybdenum blue, and qualitative and quantitative analysis of fluosilicic acid is realized through signal response of specific wavelength. According to the method, accurate detection of ppb-grade trace fluosilicic acid in high-purity hydrofluoric acid is realized, and the actual detection requirements of high-end manufacturing industry on high-purity hydrofluoric acid quality control are effectively met.

Description

Technical Field

[0001] This invention belongs to the field of analytical detection technology, and relates to a method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid, and more particularly to an apparatus system and detection method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid. Background Technology

[0002] High-purity hydrofluoric acid plays a vital role in high-end manufacturing fields such as semiconductors and new energy, and is widely used in key processes such as wafer etching and photovoltaic silicon wafer cleaning. Its impurity content directly determines the product grade and performance. Fluorosilicic acid, as a typical harmful impurity in high-purity hydrofluoric acid, is prone to complexation reactions with other ions in the system and can also corrode the substrates of semiconductor devices and photovoltaic cells. Therefore, accurate quantitative detection of fluorosilicic acid is an important part of the quality control of high-purity hydrofluoric acid.

[0003] Currently, the industry's detection technology for fluorosilicic acid is based on ion chromatography, with the most representative method being ion chromatography-tandem post-column derivatization detection. This method is also the mainstream technique for fluorosilicic acid detection at present, mainly used for the detection of fluorosilicic acid in industrial waste liquids such as wafer etching waste hydrofluoric acid. The concentration of fluorosilicic acid in this type of waste liquid matrix is ​​at a high ppm level, the impurity composition is relatively simple, and the interference from the hydrofluoric acid matrix is ​​low. Existing ion chromatography, through single-column separation combined with conventional detector detection, can achieve quantitative analysis of fluorosilicic acid in such samples.

[0004] However, existing technologies for detecting trace amounts of fluorosilicic acid in high-purity hydrofluoric acid exhibit significant technical bottlenecks. Firstly, matrix interference is difficult to eliminate: high-purity hydrofluoric acid contains a large amount of hydrofluoric acid matrix, and since hydrofluoric acid and fluorosilicic acid have similar physicochemical properties, their retention characteristics highly overlap in a single-column separation system, making effective separation impossible. Furthermore, the large amount of hydrofluoric acid masks and interferes with the detection signal of fluorosilicic acid, leading to large qualitative identification deviations and distorted quantitative results. In addition, the detection limits of existing ion chromatography methods only reach the ppm level, while the semiconductor and new energy industries have extremely high purity requirements for high-purity hydrofluoric acid, requiring fluorosilicic acid content control at the ppb level. The detection limits of existing methods are far higher than the actual industry needs, making accurate detection of trace fluorosilicic acid in high-purity hydrofluoric acid impossible.

[0005] It is evident that existing fluorosilicic acid detection technologies generally suffer from weak resistance to interference from the hydrofluoric acid matrix and low detection sensitivity. They cannot effectively separate fluorosilicic acid from hydrofluoric acid, nor can they meet the detection requirements for trace fluorosilicic acid at the ppb level in high-purity hydrofluoric acid, thus failing to meet the actual detection needs of high-end manufacturing industries for quality control of high-purity hydrofluoric acid. Therefore, developing a precise detection method for trace fluorosilicic acid compatible with the high-purity hydrofluoric acid matrix has become an urgent technical problem to be solved in the industry. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a device system and detection method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid, achieving accurate detection of ppb-level trace fluorosilicic acid in high-purity hydrofluoric acid, and effectively meeting the actual detection needs of high-end manufacturing industries for quality control of high-purity hydrofluoric acid.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an apparatus system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid, comprising a sample injection unit, a first-dimensional separation unit, an enrichment and conversion unit, a second-dimensional separation unit, a post-column derivatization unit, and a detection unit connected in sequence.

[0009] The first-dimensional separation unit includes an ion-rejection chromatographic column for separating hydrofluoric acid and fluorosilicic acid; the enrichment and conversion unit includes a capture column, an alkaline eluent generator, and a guard column for enriching fluorosilicic acid and converting it into fluoride ions and silicate ions in an alkaline environment; the second-dimensional separation unit includes an anion exchange chromatographic column for separating fluoride ions and silicate ions; the post-column derivatization unit includes at least two mixing reactors for stepwise conversion of silicate ions into silicomolybdenum blue; and the detection unit includes an ultra-long wavelength detector for detecting the absorbance of silicomolybdenum blue, achieving qualitative and quantitative analysis of fluorosilicic acid through signal response at a specific wavelength.

[0010] This invention combines anion-rejection chromatographic columns with anion-exchange chromatographic columns to construct a two-dimensional ion chromatography separation system. This effectively eliminates a large amount of interference from the hydrofluoric acid matrix. Combined with the conversion reaction of silicate ions by the post-column derivatization unit, it achieves precise separation of fluorosilicic acid from hydrofluoric acid, silicic acid, and other impurity ions. Ultimately, it enables the accurate detection of ppb-level trace fluorosilicic acid in high-purity hydrofluoric acid, effectively meeting the actual detection needs of high-end manufacturing industries for quality control of high-purity hydrofluoric acid.

[0011] Preferably, the sample injection unit includes a first six-way valve and a quantitative ring disposed inside the first six-way valve, and the first six-way valve is provided with a sample inlet, an ultrapure water inlet, a waste liquid outlet and a sample outlet, for quantitatively introducing the sample to be tested and mixing ultrapure water with the sample to be tested.

[0012] Preferably, the ion-rejection functional column comprises an ion-rejection functional column containing sulfonic acid functional groups.

[0013] Preferably, the enrichment and conversion unit further includes a second six-way valve, and the capture column is disposed inside the second six-way valve.

[0014] Preferably, the second six-way valve is provided with a sample inlet, an alkaline rinsing solution inlet, a waste liquid outlet, and a sample outlet.

[0015] Preferably, the anion exchange column comprises a polymer matrix column containing alkyl quaternary ammonium functional groups or alkanol quaternary ammonium functional groups.

[0016] Preferably, the post-column derivation unit includes a first mixing reactor and a second mixing reactor connected in sequence.

[0017] Preferably, the first mixing reactor is used to mix silicate and sodium molybdate to produce heteropolyacid; the second mixing reactor is used to mix heteropolyacid and reducing agent to produce silicomolybdenum blue.

[0018] Secondly, the present invention provides a method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid using the apparatus system described in the first aspect, comprising the following steps:

[0019] (1) Pass the sample to be tested into an ion-repulsion chromatographic column for first-dimensional separation;

[0020] (2) Enrichment step (1) Separate the obtained fluorosilicic acid and convert it into fluoride ions and silicate ions in an alkaline environment;

[0021] (3) The fluoride ions and silicate ions obtained in step (2) are passed into an anion exchange chromatography column for second-dimensional separation;

[0022] (4) The silicate ions obtained in step (3) are gradually converted into molybdenum blue;

[0023] (5) Detect the absorbance of the silicomolybdenum blue obtained in step (4) and realize the qualitative and quantitative analysis of fluorosilicic acid through the signal response of a specific wavelength.

[0024] Preferably, the injection volume of the sample to be tested in step (1) is 5~1000μL.

[0025] Preferably, in step (1), the first dimension separation uses ultrapure water as the separation medium.

[0026] Preferably, the resistivity of the ultrapure water is 15.0~18.2 MΩ·cm.

[0027] Preferably, the alkaline environment in step (2) is constructed by rinsing with an alkaline solution.

[0028] Preferably, the solute in the alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, or potassium carbonate.

[0029] Preferably, when the solute in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, or lithium hydroxide, the concentration of the alkaline solution is 5-50 mM.

[0030] Preferably, when the solute in the alkaline solution is sodium carbonate and / or potassium carbonate, the concentration of the alkaline solution is 1~15mM.

[0031] Preferably, the rinsing flow rate of the alkaline solution is 0.2~2.0 mL / min.

[0032] Preferably, the method of gradually converting silicate into silicomolybdenum blue in step (4) includes: first mixing silicate and sodium molybdate to produce heteropolyacid, and then mixing heteropolyacid and reducing agent to produce silicomolybdenum blue.

[0033] Preferably, the method further includes: preparing a series of fluorosilicic acid standard solutions and establishing a standard curve before detection.

[0034] Preferably, the standard curve is established by: establishing a standard curve for fluorosilicic acid based on the correspondence between the detection signals and concentrations of a series of fluorosilicic acid standard solutions.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention constructs a two-dimensional ion chromatography separation system by using an ion exclusion functional chromatographic column and an anion exchange chromatographic column. By utilizing the dual differences in ion ionization ability and ion type, it achieves precise stepwise separation of hydrofluoric acid and fluorosilicic acid, and fluoride ions and silicate ions. This completely eliminates the masking and interference of a large amount of hydrofluoric acid matrix on the detection of fluorosilicic acid, and ensures the accuracy of the detection signal.

[0037] (2) This invention combines the conversion of fluorosilicic acid under alkaline conditions, the characteristic color development of post-column derivatized silicomolybdenum blue, and the precise detection of ultra-long wavelength detectors to raise the detection limit of fluorosilicic acid from the ppm level of existing technologies to the ppb level, thereby realizing the precise qualitative and quantitative determination of trace fluorosilicic acid in high-purity hydrofluoric acid and filling the technical gap in the detection of trace fluorosilicic acid in high-purity hydrofluoric acid in the industry. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the device system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid provided by the present invention.

[0039] Wherein: 10-Injection unit; 11-First six-way valve; 12-Quantitative loop; 13-Water purifier; 20-First-dimensional separation unit; 21-Ion repulsion column; 30-Enrichment and conversion unit; 31-Second six-way valve; 32-Capture column; 33-Alkaline eluent generator; 34-Guard column; 40-Second-dimensional separation unit; 41-Anion exchange column; 50-Post-column derivatization unit; 51-First mixing reactor; 52-Second mixing reactor; 60-Detection unit; 61-Ultra-long wavelength detector.

[0040] Figure 2 It is the standard curve obtained by the method provided in Example 1.

[0041] Figure 3 It is a superimposed graph of the standard curve obtained by the method provided in Example 1.

[0042] Figure 4 It is the minimum point graph of the standard curve obtained by the method provided in Example 1.

[0043] Figure 5 It is an overlay of the sample test spectrum obtained by the method provided in Example 1. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0045] One embodiment of the present invention provides an apparatus system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid, such as... Figure 1 As shown, the device system includes a sample injection unit 10, a first-dimensional separation unit 20, an enrichment and conversion unit 30, a second-dimensional separation unit 40, a post-column derivatization unit 50, and a detection unit 60 connected in sequence.

[0046] The first-dimensional separation unit 20 includes an ion-rejection chromatographic column 21 for separating hydrofluoric acid and fluorosilicic acid; the enrichment and conversion unit 30 includes a capture column 32, an alkaline eluent generator 33, and a guard column 34 for enriching fluorosilicic acid and converting it into fluoride ions and silicate ions in an alkaline environment; the second-dimensional separation unit 40 includes an anion exchange chromatographic column 41 for separating fluoride ions and silicate ions; the post-column derivatization unit 50 includes at least two mixing reactors for stepwise conversion of silicate ions into silicomolybdenum blue; and the detection unit 60 includes an ultra-long wavelength detector 61 for detecting the absorbance of silicomolybdenum blue, achieving qualitative and quantitative analysis of fluorosilicic acid through signal response at a specific wavelength.

[0047] This invention utilizes an ion-rejection chromatographic column 21 in synergy with an anion-exchange chromatographic column 41 to construct a two-dimensional ion chromatography separation system. This effectively eliminates significant interference from the hydrofluoric acid matrix. Combined with the conversion reaction of silicate ions by the post-column derivatization unit 50, it achieves precise separation of fluorosilicic acid from hydrofluoric acid, silicic acid, and other impurity ions. Ultimately, it enables the accurate detection of ppb-level trace fluorosilicic acid in high-purity hydrofluoric acid, effectively meeting the actual detection needs of high-end manufacturing industries for quality control of high-purity hydrofluoric acid.

[0048] In some embodiments, the sample introduction unit 10 includes a first six-way valve 11 and a quantitative ring 12 disposed inside the first six-way valve 11. The first six-way valve 11 is provided with a sample inlet, an ultrapure water inlet, a waste liquid outlet and a sample outlet, for quantitatively introducing the sample to be tested and mixing the ultrapure water with the sample to be tested.

[0049] The present invention uses a six-way valve with a quantitative ring 12 in the sample injection unit 10 to realize the quantitative introduction of the sample to be tested, while also having the functions of ultrapure water mixing and waste liquid discharge, providing standardized samples for subsequent separation.

[0050] In some embodiments, ultrapure water is introduced into the ultrapure water inlet via water purifier 13.

[0051] In some embodiments, the ion-rejection functional column 21 includes an ion-rejection functional column containing sulfonic acid functional groups.

[0052] In the aforementioned ion-rejection chromatographic column 21, the weaker the ionization, the stronger the retention. Since fluorosilicic acid has a stronger ionization ability than hydrofluoric acid and silicic acid, it can achieve the preliminary separation of fluorosilicic acid, hydrofluoric acid, and silicic acid.

[0053] In some embodiments, the enrichment conversion unit 30 further includes a second six-way valve 31, and the capture column 32 is disposed inside the second six-way valve 31.

[0054] In some embodiments, the second six-way valve 31 is provided with a sample inlet, an alkaline rinsing solution inlet, a waste liquid outlet, and a sample outlet.

[0055] In some embodiments, the anion exchange column 41 comprises a polymer matrix column containing alkyl quaternary ammonium functional groups or alkanol quaternary ammonium functional groups, such as a PAS-19 anion exchange column.

[0056] In some embodiments, the post-column derivation unit 50 includes a first mixing reactor 51 and a second mixing reactor 52 connected in sequence.

[0057] In some embodiments, the first mixing reactor 51 is used to mix silicate and sodium molybdate to produce heteropolyacid; the second mixing reactor 52 is used to mix heteropolyacid and reducing agent to produce silicomolybdenum blue.

[0058] For example, the reducing agent may be selected from at least one of ascorbic acid, 1,2,4-aminonaphthol sulfonic acid, N-methyl-p-aminophenol, sodium sulfite, sodium bisulfite, stannous chloride, or ferrous ammonium sulfate.

[0059] One embodiment of the present invention also provides a method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid using the apparatus system described in any of the above embodiments, comprising the following steps:

[0060] (1) The sample to be tested is passed into the ion-repulsion chromatographic column 21 for first-dimensional separation;

[0061] (2) Enrichment step (1) Separate the obtained fluorosilicic acid and convert it into fluoride ions and silicate ions in an alkaline environment;

[0062] (3) The fluoride ions and silicate ions obtained in step (2) are passed into anion exchange chromatography column 41 for second-dimensional separation;

[0063] (4) The silicate ions obtained in step (3) are gradually converted into molybdenum blue;

[0064] (5) Detect the absorbance of the silicomolybdenum blue obtained in step (4) and realize the qualitative and quantitative analysis of fluorosilicic acid through the signal response of a specific wavelength.

[0065] In some embodiments, the injection volume of the sample to be tested in step (1) is 5~1000μL, for example, it can be 5μL, 10μL, 100μL, 200μL, 300μL, 400μL, 500μL, 600μL, 700μL, 800μL, 900μL or 1000μL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0066] In some embodiments, the first dimension separation in step (1) uses ultrapure water as the separation medium.

[0067] In some embodiments, the resistivity of the ultrapure water is 15.0~18.2 MΩ·cm, for example, it can be 15.0 MΩ·cm, 15.5 MΩ·cm, 16.0 MΩ·cm, 16.5 MΩ·cm, 17.0 MΩ·cm, 17.5 MΩ·cm, 18.0 MΩ·cm or 18.2 MΩ·cm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0068] In some embodiments, the alkaline environment described in step (2) is constructed by rinsing with an alkaline solution.

[0069] In some embodiments, the solute in the alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, or potassium carbonate.

[0070] In some embodiments, when the solute of the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide or lithium hydroxide, the concentration of the alkaline solution is 5 to 50 mM, for example, it can be 5 mM, 10 mM, 15 mM, 20 mM, 25 mM, 30 mM, 35 mM, 40 mM, 45 mM or 50 mM, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0071] In some embodiments, when the solute of the alkaline solution is sodium carbonate and / or potassium carbonate, the concentration of the alkaline solution is 1 to 15 mM, for example, it can be 1 mM, 2 mM, 3 mM, 4 mM, 5 mM, 6 mM, 7 mM, 8 mM, 9 mM, 10 mM, 11 mM, 12 mM, 13 mM, 14 mM or 15 mM, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0072] In this invention, the concentration unit mM specifically refers to mmol / L.

[0073] In some embodiments, the rinsing flow rate of the alkaline solution is 0.2 to 2.0 mL / min, for example, it can be 0.2 mL / min, 0.3 mL / min, 0.4 mL / min, 0.5 mL / min, 0.6 mL / min, 0.7 mL / min, 0.8 mL / min, 0.9 mL / min, 1.0 mL / min, 1.5 mL / min or 2.0 mL / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0074] It should be noted that when using chromatographic columns with different inner diameters or different packing types, the concentration and flow rate of the eluent should be adjusted accordingly. As long as the conversion of fluorosilicic acid and the separation of fluoride ions and silicate ions can be achieved, they are all within the scope of protection of this invention.

[0075] In some embodiments, the method of gradually converting silicate into silicomolybdenum blue in step (4) includes: first mixing silicate and sodium molybdate to produce heteropolyacid, and then mixing heteropolyacid and reducing agent to produce silicomolybdenum blue.

[0076] In some embodiments, the method further includes: preparing a series of fluorosilicic acid standard solutions and establishing a standard curve prior to detection.

[0077] In some embodiments, the standard curve is established by: establishing a standard curve for fluorosilicic acid based on the correspondence between the detection signals and concentrations of a series of fluorosilicic acid standard solutions.

[0078] As a preferred technical solution of the present invention, the detection method provided in some embodiments includes the following steps:

[0079] (1) First-dimensional separation: 5~1000μL of the sample to be tested is passed into the ion exclusion function column 21, and ultrapure water with a resistivity of 15.0~18.2MΩ·cm is used as the separation medium to separate hydrofluoric acid and fluorosilicic acid;

[0080] (2) Enrichment and conversion: The fluorosilicic acid obtained by enrichment and separation is used to create an alkaline environment by rinsing with an alkaline solution at a rate of 0.2~2.0 mL / min, so as to convert the fluorosilicic acid into fluoride ions and silicate ions; wherein, when the solute of the alkaline solution is at least one of sodium hydroxide, potassium hydroxide or lithium hydroxide, the concentration of the alkaline solution is 5~50 mM; when the solute of the alkaline solution is sodium carbonate and / or potassium carbonate, the concentration of the alkaline solution is 1~15 mM;

[0081] (3) Second-dimensional separation: Fluoride ions and silicate ions are passed into anion exchange chromatography column 41 to achieve precise separation of the two and extract silicate ions;

[0082] (4) Post-column derivatization: Silicate ions are sequentially introduced into two mixed reactors, first reacting with sodium molybdate to generate heteropolyacids, and then reacting with a reducing agent to reduce the heteropolyacids to silicomolybdenum blue, thus completing the chemical transformation of silicate ions;

[0083] (5) Detection and analysis: The absorbance of silicomolybdenum blue is detected by ultra-long wavelength detector 61. Combined with the standard curve established by the standard series of fluorosilicic acid solutions, the qualitative and quantitative analysis of fluorosilicic acid is achieved by the signal response of a specific wavelength.

[0084] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0085] Example 1

[0086] This embodiment provides a method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid using the above-described apparatus system, as follows:

[0087] (1) Instruments and reagents

[0088] IC-20 ion chromatograph, MSS-II multifunctional pretreatment device, TLD detector, sodium fluorosilicate solid reagent, derivatizing reagent, sodium hydroxide solution, ultrapure water (18.2 MΩ·cm).

[0089] (2) Experimental procedures

[0090] (2.1) Detection method

[0091] To eliminate the interference of a large amount of hydrofluoric acid in the sample matrix, this embodiment uses two-dimensional chromatography for separation.

[0092] First-dimensional separation: Hydrofluoric acid and fluorosilicic acid in the sample are separated by an ion-rejection chromatographic column, and fluorosilicic acid is enriched in the capture column.

[0093] Second-dimensional separation: Fluorosilicic acid is separated from other impurity ions by anion exchange chromatography column, and qualitative and quantitative analysis of fluorosilicic acid is performed by post-column derivatization at absorbance at a specific wavelength.

[0094] (2.2) Preparation of standard series solutions

[0095] A series of standard solutions were prepared using sodium fluorosilicate solid reagent. The solution concentrations are shown in Table 1 below:

[0096] Table 1

[0097]

[0098] (2.3) Analytical conditions

[0099] One-dimensional analytical chromatographic column: an ion-repulsion functional chromatographic column containing sulfonic acid functional groups.

[0100] Two-dimensional analytical chromatographic column: PAS-19 anion exchange chromatographic column.

[0101] Rinsing solution: 10mM sodium hydroxide solution.

[0102] Derivatization reagents: prepared manually.

[0103] Flow rate: 1.0 mL / min.

[0104] Injection volume: 200 μL.

[0105] (2.4) Analysis process

[0106] Using the standard series solutions prepared in step (2.2), a SiF6 system was established. 2- The standard curve is used to determine the linearity of the method.

[0107] (2.5) Experimental Results

[0108] ① See the standard curve. Figure 2 It can be seen that SiF6 2- The linearity is better than 0.999; the overlay plot of the standard curve is shown below. Figure 3 .

[0109] ② The minimum point graph of the standard curve is shown in [reference needed]. Figure 4 Based on the noise and signal-to-noise ratio at the lowest point, the detection limit is calculated using three times the signal-to-noise ratio, as shown in Table 2 below:

[0110] Table 2

[0111]

[0112] ③ The sample test results are shown in Table 3 below:

[0113] Table 3

[0114]

[0115] ④ The overlay of the sample test spectrum is shown in the figure. Figure 5 .

[0116] In summary, for the detection method of fluorosilicic acid in hydrofluoric acid, a curve was established with an injection volume of 200 μL, and SiF6 was used. 2- The linearity is better than 0.999; it can detect trace amounts of fluorosilicic acid down to 0.01 ppm in hydrofluoric acid samples, with a sample spike recovery rate between 80% and 115%, a detection limit of 0.0006 ppm, and a total sample analysis time of 20 min.

[0117] As can be seen, this invention synergistically combines anion-rejection chromatographic columns with anion-exchange chromatographic columns to construct a two-dimensional ion chromatography separation system, effectively eliminating a large amount of interference from the hydrofluoric acid matrix. Combined with the conversion reaction of silicate ions by the post-column derivatization unit, it achieves precise separation of fluorosilicic acid from hydrofluoric acid, silicic acid, and other impurity ions, ultimately realizing the accurate detection of ppb-level trace fluorosilicic acid in high-purity hydrofluoric acid, effectively meeting the actual detection needs of high-end manufacturing industries for quality control of high-purity hydrofluoric acid.

[0118] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A device system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid, characterized in that, The device system includes a sample injection unit, a first-dimensional separation unit, an enrichment and conversion unit, a second-dimensional separation unit, a post-column derivatization unit, and a detection unit connected in sequence. The first-dimensional separation unit includes an ion-rejection chromatographic column for separating hydrofluoric acid and fluorosilicic acid; the enrichment and conversion unit includes a capture column, an alkaline eluent generator, and a guard column for enriching fluorosilicic acid and converting it into fluoride ions and silicate ions in an alkaline environment; the second-dimensional separation unit includes an anion exchange chromatographic column for separating fluoride ions and silicate ions; the post-column derivatization unit includes at least two mixing reactors for stepwise conversion of silicate ions into silicomolybdenum blue; and the detection unit includes an ultra-long wavelength detector for detecting the absorbance of silicomolybdenum blue, achieving qualitative and quantitative analysis of fluorosilicic acid through signal response at a specific wavelength.

2. The apparatus system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 1, characterized in that, The sample introduction unit includes a first six-way valve and a quantitative ring disposed inside the first six-way valve. The first six-way valve is provided with a sample inlet, an ultrapure water inlet, a waste liquid outlet and a sample outlet, for quantitatively introducing the sample to be tested and mixing ultrapure water with the sample to be tested. And / or, the ion-rejection functional column includes an ion-rejection functional column containing sulfonic acid functional groups.

3. The apparatus system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 1 or 2, characterized in that, The enrichment and conversion unit further includes a second six-way valve, and the capture column is disposed inside the second six-way valve; The second six-way valve is equipped with a sample inlet, an alkaline rinsing solution inlet, a waste liquid outlet, and a sample outlet. And / or, the anion exchange column comprises a polymer matrix column containing alkyl quaternary ammonium functional groups or alkanol quaternary ammonium functional groups.

4. The apparatus system for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 1 or 2, characterized in that, The post-column derivation unit includes a first mixing reactor and a second mixing reactor connected in sequence; The first mixing reactor is used to mix silicate and sodium molybdate to produce heteropolyacids; the second mixing reactor is used to mix heteropolyacids and reducing agents to produce silicomolybdenum blue.

5. A method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid using the apparatus system described in any one of claims 1 to 4, characterized in that, The method includes the following steps: (1) Pass the sample to be tested into an ion-repulsion chromatographic column for first-dimensional separation; (2) Enrichment step (1) Separate the obtained fluorosilicic acid and convert it into fluoride ions and silicate ions in an alkaline environment; (3) The fluoride ions and silicate ions obtained in step (2) are passed into an anion exchange chromatography column for second-dimensional separation; (4) The silicate ions obtained in step (3) are gradually converted into molybdenum blue; (5) Detect the absorbance of the silicomolybdenum blue obtained in step (4) and realize the qualitative and quantitative analysis of fluorosilicic acid through the signal response of a specific wavelength.

6. The method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 5, characterized in that, The injection volume of the sample to be tested in step (1) is 5~1000μL; And / or, in step (1), the first dimension separation uses ultrapure water as the separation medium; The resistivity of the ultrapure water is 15.0~18.2 MΩ·cm.

7. The method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 5, characterized in that, The construction of the alkaline environment in step (2) includes rinsing with an alkaline solution; The solute in the alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, or potassium carbonate. When the solute in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, or lithium hydroxide, the concentration of the alkaline solution is 5~50mM. When the solute in the alkaline solution is sodium carbonate and / or potassium carbonate, the concentration of the alkaline solution is 1~15mM. And / or, the rinsing flow rate of the alkaline solution is 0.2~2.0 mL / min.

8. The method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 5, characterized in that, The method of gradually converting silicate into silicomolybdenum blue in step (4) includes: first mixing silicate and sodium molybdate to produce heteropolyacid, then mixing heteropolyacid and reducing agent to produce silicomolybdenum blue.

9. The method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to any one of claims 5 to 8, characterized in that, The method further includes: preparing a series of fluorosilicic acid standard solutions and establishing a standard curve before detection.

10. The method for detecting trace amounts of fluorosilicic acid in hydrofluoric acid according to claim 9, characterized in that, The standard curve is established by means of: establishing a standard curve for fluorosilicic acid based on the correspondence between the detection signals and concentrations of a series of fluorosilicic acid standard solutions.

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