Method for measuring silicon element in water by using ICP-MS collision reaction tank technology

Abstract

The invention relates to a method for determining a silicon element in water by using an ICP-MS collision reaction tank technology, and belongs to the technical field of environmental analysis and detection.The method creatively adopts an H2 / He multi-gas mode synergistic reaction mechanism, and by optimizing different sample injection gas proportions and reaction tank parameters, polyatomic ion interference is remarkably reduced, and the detection accuracy is improved. The high-precision measurement of the silicon element in different concentration ranges is realized; lithium ion internal standard correction is introduced, so that the influence of instrument fluctuation and matrix effect is effectively overcome, and the relative standard deviation of silicon element determination is less than 3.5%; compared with a traditional method, the method has the technical advantages of being easy and convenient to operate, low in analysis cost, capable of achieving the detection limit of 10 micrograms / L and the like, and is particularly suitable for accurate quantitative analysis of the silicon element in complex matrixes such as environmental water bodies and industrial wastewater.

Description

Technical Field

[0001] The present invention belongs to the field of environmental analysis and detection technology, and specifically relates to a method for determining elemental silicon using ICP-MS collision reaction cell technology. The method of the present invention is particularly suitable for the rapid and accurate determination of trace to constant silicon elements in environmental water bodies (including surface water, rivers, etc.) and in sewage treatment processes. Background Art

[0002] Silicon (Si) is the second most abundant element in the Earth's crust (27.7% by mass) and has complex biogeochemical cycle characteristics in aquatic environments. Silicon in natural water bodies mainly comes from the weathering process of silicate minerals in the regional geological context. Its occurrence forms include dissolved silicic acid (H4SiO4), colloidal silicon, and suspended particles (such as quartz), with concentrations generally ranging from 0.1 to 100 mg / L. Recent studies have shown that the silicon cycle is not only controlled by geological factors, but is also closely related to biological processes (such as diatom absorption) and human activities (such as industrial emissions). This makes the monitoring of silicon in water bodies of great environmental significance:

[0003] 1. Ecological Value: As an essential nutrient for phytoplankton such as diatoms, dissolved silicon concentration directly affects primary productivity in water bodies. The EU Water Framework Directive (2000 / 60 / EC) lists silicon as an auxiliary indicator for river ecological assessment.

[0004] 2. Industrial Challenges: Silicon-containing wastewater discharged from thermal power plants, semiconductor manufacturing, and sewage treatment plants may cause pipe scaling (SiO2 deposition). The U.S. Electric Power Research Institute (EPRI) recommends that the silicon concentration in circulating cooling water should be less than 50 mg / L.

[0005] 3. Potential health effects: Although silicon in drinking water is not listed as a toxic substance by the WHO, long-term exposure to high-silicon water (>60 mg / L) may be positively correlated with chronic kidney disease.

[0006] Existing silicon detection technologies each have their own characteristics, but all have obvious limitations in practical applications:

[0007] 1. Silica-molybdenum blue spectrophotometry: The silica-molybdenum blue spectrophotometry method involves the reaction of soluble silicon with ammonium molybdate under acidic conditions to form silica-molybdenum yellow, which is then reduced to silica-molybdenum blue using 1,2,4-aminonaphtholsulfonic acid. The absorbance at 660 nm is then measured to quantify silica. This method is susceptible to interference from tannins, iron, sulfides, and phosphates. Oxalic acid must be added to eliminate phosphate interference and control the concentration of interfering substances (iron <20 mg / L, sulfides <10 mg / L, phosphates <0.8 mg / L, and tannins <30 mg / L). Furthermore, contamination of glassware with dissolved silicon must be avoided, and blank correction must be performed throughout the entire procedure. Its detection range is relatively narrow (0.04-2 mg / L), with a limit of detection of 0.040 mg / L, making it suitable for determination of low to medium concentrations.

[0008] 2. Atomic absorption spectrometry is a commonly used quantitative analysis technique suitable for determining the silicon content in solutions. This method is based on the light absorption phenomenon produced when the element being measured absorbs light of its specific wavelength. For the determination of silicon, a nitrous oxide (N2O)-acetylene (C2H2) flame is typically used to effectively detect medium and high levels of silicon. A dedicated narrow-slit nitrous oxide-acetylene burner is required for this measurement. During the experiment, the nitrous oxide-acetylene flame is high, so safety precautions should be strengthened. The use of nitrous oxide requires a strict operating sequence because the nitrous oxide-acetylene flame burns rapidly. If the acetylene supply is insufficient, the nitrous oxide may "chase flame" into the acetylene cylinder, causing an explosion. This method requires strict operator control, so strictly adhere to operating procedures and provide adequate personal protection to ensure experimental safety.

[0009] 3. X-ray fluorescence spectrometry (XRF): XRF is a non-destructive analytical method suitable for determining silicon content in solid and liquid samples. This method uses X-rays generated by irradiating the sample surface and measuring the intensity of characteristic peaks in the fluorescence spectrum to determine the elemental content. XRF offers the advantages of high speed, ease of operation, and the ability to simultaneously determine multiple elements. However, XRF can be susceptible to interference in the analysis of low silicon content, resulting in significant errors.

[0010] 4. ICP-MS is a highly sensitive analytical technique widely used for the quantitative determination of elements in liquid and solid samples. This method achieves precise element detection by converting the sample into charged particles (ions) and analyzing their mass-to-charge ratio using a mass spectrometer. ICP-MS offers advantages such as low detection limits, high resolution, and the ability to simultaneously determine multiple elements, demonstrating excellent sensitivity and accuracy in elemental detection.

[0011] However, in actual application, ICP-MS is often interfered by coexisting elements and their isotopes in the sample matrix, resulting in deviations in the mass number signal, which in turn affects the accuracy of silicon determination. Especially in complex matrix samples, the problem of mass number interference is particularly significant. Taking the main isotope mass number of silicon (28) as an example, it is easily affected by polyatomic interference (CO) generated by carbon and nitrogen molecules in the sample or air during the ionization process during the injection and plasma process. + , etc.), significantly reducing detection sensitivity and data reliability. While traditional physical shielding mechanisms and collision / reaction cell technologies can mitigate interference issues to a certain extent, their removal efficiency is limited. Particularly in complex matrices such as those with high salt content and high organic matter content, complete purification of silicon signals remains difficult. Therefore, further enhancing anti-interference capabilities and improving the accuracy and stability of silicon detection by ICP-MS have become key technical challenges that urgently need to be addressed in the practical application of this technology. Summary of the Invention

[0012] The present invention provides a method for determining elemental silicon in surface water that is simple to operate, rapid, and has strong anti-interference ability, solving the problems of complex pretreatment, slow determination, and insufficient sensitivity in the prior art. By optimizing the collision reaction cell operating mode (H2 / He mixed mode) and the internal standard correction system, the present invention effectively overcomes the polyatomic ion interference problem existing in traditional methods, significantly improving the accuracy and sensitivity of silicon detection.

[0013] The technical solutions of the present invention are as follows:

[0014] A method for determining silicon using ICP-MS collision reaction cell technology comprises the following steps:

[0015] (1) Sample pretreatment: After collecting water samples, filter them through a 0.22 μm filter membrane. Samples with a total organic carbon content within the range of 1-2 μg / L can be directly measured. If the organic carbon content is too high, digestion treatment is required.

[0016] (2) Preparation of standard silicon solution: Using ammonium hexafluorosilicate (H8F6N2Si) as the silicon standard substance, a series of silicon-containing standard solutions with a concentration range of 10 μg / L-2000 μg / L were prepared using ultrapure water (18.2 MΩ·cm);

[0017] (3) Instrument tuning and calibration: The silicon-containing standard solution prepared in step (2) is introduced into the ICP-MS sampling system as a tuning solution. After optimizing the instrument parameters, the signal intensity of the silicon element is measured;

[0018] (4) Preparation of internal standard solution: Using Li+ as the internal standard element, prepare an internal standard solution of a certain concentration (internal standard concentration: adjusted in the online mixing mode to ensure that its signal intensity is in the same order of magnitude (10,000 cps) as the signal intensity of silicon in the sample). Add equal amounts of internal standard to both the sample and the standard solution; establish an internal standard calibration curve using the signal response ratio of Si to Li+ to correct for instrument fluctuations, matrix effects, and injection errors;

[0019] (5) Sample measurement;

[0020] (a) Using a 20% H2 / 80% He mixture as the collision gas, the Si and Li content of the sample was determined by ICP-MS. + The net intensity is calculated by the signal intensity ratio;

[0021] (b) Use mathematical methods such as the least squares method to perform curve fitting, establish a standard curve, and calculate the accurate concentration of elemental silicon in the water sample based on the standard curve.

[0022] In step (4), the concentration of the internal standard element is determined by online debugging to ensure that its signal intensity is within the same order of magnitude (10,000 cps) as the measured signal of silicon in the sample, avoiding setting the concentration too high or too low, thereby ensuring that the internal standard has good signal compensation capability and correction effect.

[0023] In step (5a), a 20% H2 / 80% He mixed gas was used as the collision gas, and the collision cell parameters were optimized (plasma argon flow rate was 18.0 L / min; auxiliary gas flow rate was 1.4 L / min; nebulizer gas flow rate was 0.71 L / min; collision flow rate was 4.0 mL / min) to effectively weaken the N2 + 、CO + In order to reduce the interference of polyatomic ions such as ions and improve the accuracy and stability of the silicon signal with a mass number of 28, the instrument should be operated under conditions of low oxide ratio and low double charge ratio during the tuning process to obtain the best analytical performance.

[0024] In step (5b), the sample is introduced into the sample injection system and mixed with the internal standard solution online. The sample is atomized by a concentric nebulizer and enters the argon plasma for ionization. The ionized sample ions are introduced into the mass spectrometer for mass analysis. During the measurement process, the main isotope of silicon ( 28 Si) was used as the quantitative ion, and the internal standard correction method was used to correct signal drift and matrix effects, thereby improving the accuracy and stability of the measurement results. All samples and standard solutions should maintain a matrix composition consistent with that of the water sample to ensure the accuracy, repeatability and comparability of the method.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) Reduce equipment dependence and cost pressure: Existing technologies mostly use ICP-MS / MS instruments, and combine oxygen (O2) or hydrogen (H2) reaction cell technology to determine the silicon element under the condition of having a tandem triple quadrupole structure. This type of equipment is expensive, with high procurement and maintenance costs, and most laboratories have not yet been equipped with it, which limits its promotion and application in routine testing. The present invention provides a method for quantitative analysis of silicon elements without relying on high-end mass spectrometry instruments, significantly reducing dependence on equipment configuration, and having higher economy and popularization.

[0027] (2) Improved the accuracy and reliability of silicon determination: The present invention determines the silicon in water by comparing the reaction effects under different gas collision modes and adopting internal standard correction. The study found that under the H2 / He mixed gas collision mode, the accuracy of ICP-MS determination of silicon in the conventional mode is significantly improved. This method effectively reduces the influence of polyatomic interference on silicon signals, enhances the stability and repeatability of detection data, and provides a feasible technical path for conventional laboratories without the need for high-end mass spectrometry equipment.

[0028] (3) Compared with other determination methods, the present invention has a lower detection limit and higher sensitivity, and can more accurately determine the element silicon in water quality; the method of the present invention has technical advantages such as low detection limit (up to μg / L level), wide linear range (10μg / L-2000μg / L), and strong anti-interference ability, providing a reliable technical solution for the standardized detection of silicon in water quality.

[0029] (4) The present invention is simple to operate and has low cost. It can be implemented under existing experimental conditions by improving existing instruments and equipment, and has high application value. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] Example 1

[0032] Silicon (Si) in water was determined in He mode. This example uses conventional helium collision mode (KED mode) for ICP-MS determination, aiming to verify the conventional detection capability of silicon in the absence of hydrogen. The He mode mainly relies on the physical collision mechanism to weaken the interference of polyatomic ions. It is one of the interference elimination technologies widely used in current ICP-MS systems. However, while this mode effectively reduces background interference, it also suppresses the target element signal to a certain extent. Since the first ionization potential of silicon is high, its ionization efficiency in plasma is relatively low, which leads to a weakening of the detection signal. In addition, polyatomic ion interference in plasma, solvent and sample matrix (such as N2 + 、CO + The presence of ions (e.g., ions with a low silicon content) will significantly increase the background signal, making the accurate determination of low silicon content a major challenge.

[0033] The specific steps are as follows:

[0034] 1. Sample preparation: After collecting water samples, filter them through a 0.22μm filter membrane; samples with a total organic carbon content within the range of 1-2μg / L can be directly measured. If the organic carbon content is too high, digestion treatment is required.

[0035] 2. Prepare the marking chemicals: Aladdin CAS number: 16919-19-0, ammonium hexafluorosilicate, chemical formula: H8F6N2Si; start preparing a series of standard solutions with a concentration gradient ranging from 10μg / L to 2000μg / L, and dilute the standard solutions with ultrapure water (18.2MΩ·cm). The specific preparation method is as follows:

[0036] 10 mg / L silicon standard solution stock: Weigh 3.185 mg of ammonium hexafluorosilicate (H8F6N2Si) into a 50 mL centrifuge tube, dissolve the drug in ultrapure water, and determine the calibration concentration by weight by adding ultrapure water.

[0037] 2000 μg / L standard solution: Take 10.00 mL of 10 mg / L silica stock solution and dilute to 50.0 mL with ultrapure water. Mix thoroughly and determine the calibration concentration by weight by adding ultrapure water.

[0038] 1000 μg / L standard solution: Take 5.00 mL of 10 mg / L silica stock solution and dilute to 50.0 mL with ultrapure water. Mix well and determine the calibration concentration by weight by adding ultrapure water.

[0039] 500 μg / L standard solution: Take 2.50 mL of 10 mg / L silica single standard stock solution, dilute to 50.0 mL with ultrapure water, mix well, and determine the calibration concentration by weight by adding ultrapure water.

[0040] 250 μg / L standard solution: Take 6.25 mL of a 2000 μg / L silica standard solution and dilute to 50.0 mL with ultrapure water. Mix thoroughly and determine the calibration concentration by weight using the ultrapure water method.

[0041] 125 μg / L standard solution: Take 6.25 mL of a 1000 μg / L silica standard solution and dilute to 50.0 mL with ultrapure water. Mix thoroughly and determine the calibration concentration by weight using the ultrapure water method.

[0042] 10 μg / L standard solution: Take 4.00 mL of 125 μg / L silica standard solution and dilute to 50.0 mL with ultrapure water. Mix well and determine the calibration concentration by weight by adding ultrapure water.

[0043] 3. Prepare internal standard solution: Use the ICP-MS nine-element standard solution sold by Tanmo Company (10 mg / L, including: lithium, scandium, germanium, yttrium, rhodium, indium, terbium, rhenium, and bismuth);

[0044] 4. Instrument preparation:

[0045] Purchase a certified standard tuning solution (PerkinElmer, USA) with a concentration of 1 μg / L, containing elements such as Be, Ce, Fe, In, Li, Mg, Pb, and U. This solution is used for instrument performance tuning and calibration. Place the tuning solution in the ICP-MS injection system and observe the intensity values ​​of each element to ensure that all parameters meet the test requirements.

[0046] 5. ICP-MS determination

[0047] (1) Instrument debugging and measurement

[0048] Tune and calibrate the instrument performance using certified standard tuning solutions. Place the tuning solutions in the ICP-MS injection system and observe the intensity values ​​of each element to ensure that all parameters meet the test requirements.

[0049] The specific parameters are as follows:

[0050] RF power is 1300W;

[0051] The plasma argon gas flow rate was 18.0 L / min;

[0052] The auxiliary gas flow rate is 1.4 L / min;

[0053] The nebulizer gas flow rate was 0.71 L / min;

[0054] The collision flow rate was 4.0 mL / min;

[0055] The detector voltage is analog level -2200V, pulse level 1400V;

[0056] The peak-jump scanning method was used, with an acquisition time of 1.5 s, 30 acquisitions, and 3 repetitions of the measurement;

[0057] (2) Internal standard calibration

[0058] Lithium (Li) was selected as the internal standard element. The internal standard concentration was set by online mixing to ensure that its signal intensity was within the same order of magnitude (10,000 cps) as the signal intensity of silicon in the sample to enhance the accuracy and stability of signal calibration.

[0059] (3) Sample testing

[0060] The standard solution or sample solution and the internal standard solution are connected through a three-way pipe for simultaneous injection. After the sample is atomized and ionized in the ICP, it enters the collision cell. Helium gas collides with the interfering ions to selectively eliminate them, retaining the silicon signal 28Si+. The ions are then separated and detected by a mass analyzer, and quantitative analysis is achieved using an external standard curve.

[0061] (4) Measurement results

[0062] Table 1 Determination of elemental silicon intensity in He mode (Li as internal standard)

[0063]

[0064]

[0065] Table 2 Comparison of element Si concentration measured in He mode and actual concentration

[0066]

[0067] As shown in Table 1, in pure He mode, lithium was used as the internal standard to determine the intensity of the elemental silicon. The average value was obtained through three sets of parallel measurements. Table 2 shows the comparison of the elemental Si concentration measured in He mode with the actual concentration. Calculation shows that the relative deviation between the measured results and the actual concentration is controlled within ±5%, showing good accuracy. The standard curve of the measured intensity and concentration fitting is: y = 0.001x + 0.000, Cor. Coeff.: 0.9991; among them, the "equivalent concentration" (Background Equivalent Concentration, BEC) of the instrument background is 1.324008 μg / L; the detection limit (DL) is 15.576850 μg / L.

[0068] The above results show that the standard curve of silicon element has a good linear relationship. The measured values ​​of each concentration gradient standard solution are in good agreement with the theoretical value. In the concentration range of 12.66-1993.95μg / L, the relative deviation between the measured results and the actual concentration is controlled within ±5%, showing good accuracy. In addition, the measured values ​​of all standard points maintain good consistency with the theoretical value within the concentration range of three orders of magnitude (R 2 >0.999).

[0069] Example 2

[0070] Silicon (Si) in water was determined in H2 / He mixed gas collision mode. In this example, a 20% H2 / 80% He mixed gas was used for in-situ mass measurement of Si. This is because the main Si isotope at m / z 28 is interfered with by the H2 / He mixed gas. 14 N2 + and 12 C 16 O + It reacts easily with H2, but Si + But it does not react with H2, so N2 + and CO + Interference is removed by reaction, and 28 Si + Can measure in situ mass without interference.

[0071] Specific steps:

[0072] 1. Sample preparation: After collecting water samples, filter them through a 0.22μm filter membrane; samples with a total organic carbon content within the range of 1-2μg / L can be directly measured. If the organic carbon content is too high, digestion treatment is required.

[0073] 2. Prepare the marking chemicals: Aladdin CAS number: 16919-19-0, ammonium hexafluorosilicate, chemical formula: H8F6N2Si; start preparing a series of standard solutions with a concentration gradient ranging from 10μg / L to 2000μg / L, and dilute the standard solutions with ultrapure water (18.2MΩ·cm). The specific preparation method is as follows:

[0074] 10 mg / L silicon standard solution stock: Weigh 3.185 mg of ammonium hexafluorosilicate (H8F6N2Si) into a 50 mL centrifuge tube, dissolve the drug in ultrapure water, and determine the calibration concentration by weight by adding ultrapure water.

[0075] 2000 μg / L standard solution: Take 10.00 mL of 10 mg / L silica stock solution and dilute to 50.0 mL with ultrapure water. Mix thoroughly and determine the calibration concentration by weight by adding ultrapure water.

[0076] 1000 μg / L standard solution: Take 5.00 mL of 10 mg / L silica stock solution and dilute to 50.0 mL with ultrapure water. Mix well and determine the calibration concentration by weight by adding ultrapure water.

[0077] 500 μg / L standard solution: Take 2.50 mL of 10 mg / L silica single standard stock solution, dilute to 50.0 mL with ultrapure water, mix well, and determine the calibration concentration by weight by adding ultrapure water.

[0078] 250 μg / L standard solution: Take 6.25 mL of a 2000 μg / L silica standard solution and dilute to 50.0 mL with ultrapure water. Mix thoroughly and determine the calibration concentration by weight using the ultrapure water method.

[0079] 125 μg / L standard solution: Take 6.25 mL of a 1000 μg / L silica standard solution and dilute to 50.0 mL with ultrapure water. Mix thoroughly and determine the calibration concentration by weight using the ultrapure water method.

[0080] 10 μg / L standard solution: Take 4.00 mL of 125 μg / L silica standard solution and dilute to 50.0 mL with ultrapure water. Mix well and determine the calibration concentration by weight by adding ultrapure water.

[0081] 3. Prepare internal standard solution: Use the ICP-MS nine-element standard solution sold by Tanmo Company (10 mg / L, including: lithium, scandium, germanium, yttrium, rhodium, indium, terbium, rhenium, and bismuth);

[0082] 4. Instrument preparation:

[0083] Purchase a certified standard tuning solution (PerkinElmer, USA) with a concentration of 1 μg / L, containing elements such as Be, Ce, Fe, In, Li, Mg, Pb, and U. This solution is used for instrument performance tuning and calibration. Place the tuning solution in the ICP-MS injection system and observe the intensity values ​​of each element to ensure that all parameters meet the test requirements.

[0084] 5. ICP-MS determination

[0085] (1) Instrument debugging and measurement

[0086] Tune and calibrate the instrument performance using certified standard tuning solutions. Place the tuning solutions in the ICP-MS injection system and observe the intensity values ​​of each element to ensure that all parameters meet the test requirements.

[0087] The specific parameters are as follows:

[0088] RF power is 1300W;

[0089] The plasma argon gas flow rate was 18.0 L / min;

[0090] The auxiliary gas flow rate is 1.4 L / min;

[0091] The nebulizer gas flow rate was 0.71 L / min;

[0092] The collision flow rate was 4.0 mL / min;

[0093] The detector voltage is analog level -2200V, pulse level 1400V;

[0094] The peak-jump scanning method was used, with an acquisition time of 1.5 s, 30 acquisitions, and 3 repetitions of the measurement;

[0095] (2) Internal standard calibration

[0096] Lithium (Li + ) was used as an internal standard element. The internal standard concentration was set by online mixing to ensure that its signal intensity was within the same order of magnitude (10,000 cps) as that of silicon in the sample, thereby enhancing the accuracy and stability of signal calibration.

[0097] (3) Sample testing

[0098] The standard solution or sample solution and the internal standard solution are connected through a three-way pipe for simultaneous injection. After the sample is atomized and ionized in the ICP, it enters the collision reaction cell. The hydrogen and helium mixed gas collides with the interfering ions to selectively eliminate the interfering ions and retain the silicon signal 28Si+. The ions are then separated and detected by the mass analyzer, and quantitative analysis is achieved using the external standard curve.

[0099] (4) Measurement results

[0100] Table 3 Determination of elemental silicon intensity in H2 / He mode (Li as internal standard)

[0101]

[0102]

[0103]

[0104] Table 4 Comparison of element Si concentration measured in H2 / He mode and actual concentration

[0105]

[0106] As shown in Table 3, in the H2 / He mixed reaction mode, the calibration line intensity table of elemental silicon was determined using lithium as the internal standard, and the average value was obtained through three sets of parallel measurements; Table 4 shows the comparison of the elemental Si concentration determined in the H2 / He mixed reaction mode with the actual concentration. Through calculation, it can be seen that the relative deviation between the measurement results and the actual concentration is controlled within ±2%, showing better accuracy. The standard curve of intensity and concentration fitting is: y=0.001x+0.000, Cor.Coeff.: 0.9997, among which the "equivalent concentration" (BEC) of the instrument background is -1.663924μg / L, and the detection limit (DL) is 5.763782μg / L.

[0107] The above results show that the silicon element standard curve of Example 2 has a better linear relationship, and the measured values ​​of each concentration gradient standard solution are consistent with the theoretical value better than that of Example 1. In the concentration range of 12.66-1993.95 μg / L, the relative deviation between the measured results and the actual concentration is controlled within ±2%, showing better accuracy. In addition, in the concentration range spanning three orders of magnitude, the measured values ​​of all standard points maintain good consistency with the theoretical value (R 2 >0.999).

[0108] Comparison between Example 1 and Example 2:

[0109] The standard curve constructed under the optimized experimental conditions of Example 2 (H2 / He mixed mode) has a good linear relationship, and the correlation coefficient (R 2 ) reached 0.9997, indicating that the method has extremely high accuracy and reliability within a certain concentration range.

[0110] The data in Table 5 show the calibration results of Si (28) determined using Li (7) as the internal standard in the H2 / He mixed mode. The Li intensity of the blank sample is 11365.4 cps (set as 100%), and the Li intensity of each standard sample fluctuates between 10049.8 and 11429.9 cps. The internal standard acceptance rate gradually increases from 88.4% of Std 1 to 100.6% of Std 6, indicating that the calibration effect is more stable at high concentrations. The Si signal increases from 444.5 cps (blank) to 31886.2 cps (Std 6), showing a good concentration gradient. Overall, this shows that the internal standard method can effectively correct signal fluctuations, but the reaction conditions need to be optimized in the low concentration area.

[0111] Table 5 H2 / He mixed mode calibration curve and internal standard online acceptance rate

[0112]

[0113] In the actual surface water sample tests, the internal standard acceptance rates for all samples ranged from 101.9% to 106.2% (Table 6), which were all higher than the 80% acceptance standard set by the method, fully verifying the applicability and reliability of the H2 / He collision reaction and internal standard calibration in this method.

[0114] Table 6 H2 / He collision reaction method concentration determination

[0115]

[0116] A comparative analysis of the data in Table 7 shows that there are certain differences in the results of surface water sample determination using the H2 / He mixed gas mode and the conventional He mode. The H2 / He method determination results for the three samples were 2.169, 1.205, and 1.274 mg / L, respectively, with relative standard deviations (RSDs) ranging from 1.5% to 3.2%. The He method determination results were 2.010, 1.338, and 1.150 mg / L, respectively, with RSDs ranging from 3.8% to 5.5%. The H2 / He method showed better precision (RSDs were all below 3.5%), and the determination values ​​in samples 1 and 3 were 7.9% and 10.8% higher than those in the He method, respectively, while they were 9.9% lower in sample 2. This difference may be due to the improvement of plasma stability by the H2 / He mixed gas and the difference in the correction effect of different matrix interferences.

[0117] Table 7 Comparison of data measured with pure helium collision gas

[0118]

[0119] The specific implementation methods of the present invention have been described in detail above in conjunction with specific embodiments. However, the present invention is not limited to the above implementation methods. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for determining silicon in water using ICP-MS collision reaction cell technology, characterized in that: The following steps are involved: (1) Sample pretreatment: After collecting water samples, filter them through a 0.22 μm filter membrane; (2) Preparation of standard silicon solution: Using ammonium hexafluorosilicate as the silicon standard substance, a series of silicon-containing standard solutions with a concentration range of 10 μg / L-2000 μg / L were prepared using ultrapure water; (3) Instrument tuning and calibration: The silicon-containing standard solution prepared in step (2) is introduced into the ICP-MS sampling system as a tuning solution. After optimizing the instrument parameters, the signal intensity of the silicon element is measured; (4) Preparation of internal standard solution: Li + As an internal standard element, prepare an internal standard solution and add equal amounts of internal standard solution to the sample and standard solution. + The internal standard calibration curve was established based on the signal response ratio to correct for instrument fluctuations, matrix effects and injection errors. (5) Sample determination: Si and Li in the sample were determined by ICP-MS in H2 / He mixed reaction mode. + The net intensity is calculated from the signal intensity ratio, and the accurate concentration of silicon in water is calculated based on the net intensity.

2. The method for determining silicon in water using ICP-MS collision reaction cell technology according to claim 1, characterized in that: The H2 / He mixed reaction mode in step (5) is a mixed gas mode with a volume fraction of 20% H2 / 80% He.

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