A method for detecting the content of basic copper nitrate using a chemical sensor

Abstract

The application provides a method for detecting the content of basic copper nitrate by using a chemical sensor; in the process of detecting copper ions, a test solution is provided with a rhodamine compound containing a Schiff base group, which can be combined with copper ions as a chemical sensor, so that the ring-opening reaction of the spiro ring structure of the test solution is caused, and the color of the solution changes from colorless to red after the test solution is mixed with a sample solution to be detected. When the chemical sensor of the application is used for detecting copper ions in an aqueous solution, the chemical sensor shows obvious changes in ultraviolet-visible absorption spectrum, has high detection sensitivity, and has a low detection limit of 170 nM; the chemical sensor has ultrahigh selectivity to copper ions, and is hardly interfered by other common metal ions, and in particular, the chemical sensor can accurately quantitatively analyze the purity of basic copper nitrate raw materials and the content and distribution of basic copper nitrate in a gas generating agent.

Description

Technical Field

[0001] This invention relates to the field of environmental testing technology, and in particular to a method for detecting the content of basic copper nitrate using a chemical sensor. Background Technology

[0002] In the actual production of gas generators for automotive airbags, the purity of raw materials and the uniformity of mixing of each component have a crucial impact on the performance of the agent. Firstly, chemical raw materials are highly susceptible to quality problems during transportation, storage, and use. Moreover, even different batches of chemical raw materials from the same manufacturer rarely exhibit absolute consistency in purity and content, and these subtle differences can sometimes have a significant impact on the final performance of the gas generator. Accurate testing of the purity and content of raw materials in the initial stages of gas generator production helps companies assess raw material quality standards and improve production efficiency. Therefore, developing a testing method that is convenient and quick to operate, has low dependence on equipment, is stable under environmental conditions, and requires minimal technical expertise from testing personnel is urgently needed.

[0003] Airbag gas generators are composite energetic materials containing multiple functional components. Each component has different flow characteristics, density, and surface properties. Therefore, a mixing process is necessary to ensure sufficient contact between the different components, resulting in a faster and more complete combustion reaction. The uniformity of the mixture directly affects the performance of the gas generator. Improving the uniformity of the mixture maximizes gas generation efficiency. In actual production, a suitable mixing method must be selected based on the gas generator's solubility, density, sensitivity, and other physicochemical properties, as well as production costs.

[0004] Basic copper nitrate (BCN) is a crucial component of automotive airbag gas generators, often used in combination with guanidine nitrate to form the core formulation of the gas generator. Basic copper nitrate (BCN) is an effective oxidant with an effective oxygen content of 30%, providing sufficient oxygen for the combustion of combustibles. Its good thermal stability results in stable performance of the prepared gas generator, exhibiting advantages such as high gas production rate, low enthalpy of formation, low hygroscopicity, and easy filtration of combustion residues. The purity of the basic copper nitrate raw material and the uniformity of mixing with other components have a crucial impact on the combustion performance of the agent, thereby affecting the performance of the gas generator and the airbag. Traditional methods typically characterize the distribution and composite effect of the components in the gas generator using elemental analysis, scanning electron microscopy, and inductively coupled plasma atomic absorption spectrometry. However, these methods suffer from drawbacks such as cumbersome sample preparation, complex instrument operation, low accuracy, and inability to eliminate interference from coexisting ions. In addition, in order to evaluate different mixing processes and mixing parameters, pressure performance tests, flame tests and residue tests are generally conducted after the gas generating agent and gas generator are matched. However, this method has disadvantages such as being cumbersome to operate, costly and time-consuming.

[0005] Therefore, establishing a simple, efficient, and accurate method for detecting basic copper nitrate, and using this method to measure the mixing uniformity of the components of the gas generator, is of great significance for raw material quality control and evaluation of different mixing processes. Summary of the Invention

[0006] In view of this, this application provides a method for detecting the content of basic copper nitrate using a chemical sensor, in order to solve the technical problems of existing methods for detecting the content of basic copper nitrate in gas generators, such as cumbersome operation, high cost and long time consumption.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] To achieve the above technical objectives, this application adopts the following technical solution:

[0009] This invention provides a method for detecting the content of basic copper nitrate using a chemical sensor, comprising:

[0010] S10, gradually add different volumes of copper ion standard solution to the test solution and test the absorbance of the mixed solution after each addition; the test solution includes rhodamine compounds containing Schiff base groups;

[0011] S20, a standard curve was plotted based on the relationship between copper ion concentration and absorbance;

[0012] S30, the test sample solution is quantitatively added to the test solution to obtain the reaction solution, and the absorbance of the reaction solution is tested; the test sample solution is prepared by dissolving, diluting and making up to volume commercially available basic copper nitrate raw material or a gas generator containing basic copper nitrate.

[0013] S40, determine the concentration of copper ions in the sample solution according to the standard curve and the absorbance of the reaction solution.

[0014] Preferably, the preparation method of the test solution in step S10 includes the following steps:

[0015] The hydrazine adduct of rhodamine, 2-methylmercaptobenzaldehyde, and absolute ethanol were mixed and subjected to an anaerobic reflux reaction.

[0016] After the anaerobic reflux reaction is completed, the mixture is naturally cooled to room temperature, and the crude product is obtained by removing absolute ethanol by vacuum distillation.

[0017] The crude product was filtered and recrystallized in anhydrous ethanol to obtain rhodamine compounds containing Schiff base groups.

[0018] A test solution is prepared by mixing a rhodamine-like compound containing a Schiff base group, an organic solvent, and a buffer solution.

[0019] Preferably, the molar ratio of the hydrazine adduct of rhodamine to 2-methylmercaptobenzaldehyde is 1:(1.2~7.5); the molar ratio of the hydrazine adduct of rhodamine to absolute ethanol is 1g:(30~100)mL.

[0020] Preferably, in the anaerobic heating reflux reaction, the reaction atmosphere is an inert atmosphere, the reflux reaction temperature is 80~90℃, and the reflux reaction time is 6~10h.

[0021] Preferably, the organic solvent includes any one of dimethyl sulfoxide, acetonitrile, tetrahydrofuran, N,N-dimethylformamide and acetone, and the buffer solution includes 4-hydroxyethylpiperazine ethanesulfonic acid.

[0022] Preferably, the concentration of rhodamine compounds containing Schiff base groups in the test solution is 5 × 10⁻⁶. -7 ~2×10 - 6 mol / L; the volume ratio of buffer solution to organic solvent is (1~50):5, and the pH value of the buffer solution is 5.5~10.

[0023] Preferably, the rhodamine compounds containing Schiff base groups include structures as shown in structural formula (I):

[0024] (I).

[0025] Preferably, in step S20, a standard curve is obtained by linearly fitting the absorbance corresponding to different copper ion concentrations at 558 nm as the ordinate and the copper ion concentration as the abscissa.

[0026] Preferably, the preparation method of the sample solution to be tested in step S30 includes the following steps:

[0027] Select commercially available basic copper nitrate raw material or randomly sample from the same batch of gas generator columns, and grind thoroughly to obtain a solid sample of the reagent;

[0028] The solid sample of the reagent is dissolved in nitric acid, filtered through a microfilter to remove insoluble impurities, and then diluted and brought to volume with deionized water to obtain the test sample solution. Preferably, when the test sample solution is prepared from commercially available basic copper nitrate raw material, step S40 further includes: accurately determining the copper content in the test sample solution using a standard curve and comparing it with the content indicated on the product label;

[0029] When the sample solution to be tested is prepared from a gas generator containing basic copper nitrate, step S40 includes: sequentially testing the ultraviolet-visible absorption spectrum of the reaction solution, characterizing the distribution of copper elements by the trend of the absorption spectrum, and finally evaluating the uniformity of the mixing of each component material in the gas generator.

[0030] Beneficial Effects: This invention provides a method for detecting the content of basic copper nitrate using a chemical sensor. During the detection of copper ions, the test solution contains rhodamine-like compounds with Schiff base groups. These compounds, acting as a chemical sensor, can complex with copper ions, causing a ring-opening reaction in the spirocyclic structure of the test solution. After mixing the test solution with the sample solution, the solution color changes from colorless to red. When used for detecting copper ions in aqueous solutions, the chemical sensor of this invention exhibits a significant change in the ultraviolet-visible absorption spectrum, high detection sensitivity, and a detection limit as low as 170 nM. It demonstrates extremely high selectivity for copper ions with almost no interference from other common metal ions. In particular, it can accurately quantify the purity of basic copper nitrate raw materials and the content and distribution of basic copper nitrate in gas generators. Attached Figure Description

[0031] Figure 1 This is a schematic flowchart of a method for detecting the content of basic copper nitrate using a chemical sensor, provided in an embodiment of the present invention.

[0032] Figure 2 This is a UV-Vis absorption titration diagram of the test solution provided in Example 1 of the present invention for different concentrations of copper ions;

[0033] Figure 3 The graph shows the linear relationship between the absorbance of the test solution at 558 nm and the concentration of copper ions provided in Example 1 of this invention.

[0034] Figure 4 The image shows the recognition response of the test solution provided in Example 1 of this invention to copper ions when common interfering ions coexist.

[0035] Figure 5 The ultraviolet-visible absorption spectrum of the test sample solution A prepared by adding commercially available basic copper nitrate raw material to the test solution provided in Example 1 of the present invention;

[0036] Figure 6 The graph shows the trend of UV-Vis absorption spectra of sample solution B prepared by adding gas generators produced by different mixing processes to the test solution provided in Example 1 of this invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] Chemical sensors are a class of molecular devices with "reporting" capabilities. They can change their properties based on the presence of a target analyte, thereby achieving specific recognition and detection of guest molecules. Among them, fluorescence technology, as an emerging detection method, has become the mainstream in chemical sensor design due to its high sensitivity, fast response speed, and low detection limit.

[0039] In view of this, this invention proposes a high-performance colorimetric sensor that utilizes ingenious molecular design and organic synthesis to achieve rapid, accurate, and highly sensitive detection of the content of basic copper nitrate in gas generators. By testing the concentration and content of copper, the purity and quality of the basic copper nitrate raw material are evaluated. By preparing test samples from different parts of the reagent, the distribution of copper ions is characterized by changes in the ultraviolet-visible absorption spectrum, thus determining the impact of different mixing processes on the uniformity of material mixing. This provides a convenient, rapid, and reliable evaluation method for raw material assessment and quality control, mixing process selection, and mixing process parameter setting in actual industrial production.

[0040] Specifically, unless otherwise specified in this invention, conditions shall be performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0041] Please see Figure 1 , Figure 1 A schematic flowchart of a method for detecting the content of basic copper nitrate using a chemical sensor, provided in an embodiment of this application; wherein the method includes the following steps:

[0042] S10, gradually add different volumes of copper ion standard solution to the test solution and test the absorbance of the mixed solution after each addition; the test solution includes rhodamine-like compounds containing Schiff base groups.

[0043] Specifically, step S10 also includes:

[0044] First, the test solution is prepared, and the preparation method includes the following steps:

[0045] The hydrazine adduct of rhodamine, 2-methylmercaptobenzaldehyde, and absolute ethanol were mixed and subjected to an anaerobic heating reflux reaction under magnetic stirring.

[0046] After the anaerobic heating and reflux reaction is completed, the mixture is naturally cooled to room temperature, and absolute ethanol is removed by vacuum distillation. After standing overnight at room temperature, the crude product is precipitated.

[0047] The crude product was sequentially filtered and recrystallized from anhydrous ethanol to obtain rhodamine compounds containing Schiff base groups.

[0048] A test solution is prepared by mixing a rhodamine-like compound containing a Schiff base group, an organic solvent, and a buffer solution.

[0049] Specifically, the molar ratio of the hydrazine adduct of rhodamine to 2-methylmercaptobenzaldehyde is 1:(1.2~7.5); the molar ratio of the hydrazine adduct of rhodamine to absolute ethanol is 1g:(30~100)mL; wherein, making the amount of 2-methylmercaptobenzaldehyde in excess relative to the hydrazine adduct of rhodamine is beneficial for the reaction to proceed in the direction of generating the target product, a rhodamine-like compound containing a Schiff base group.

[0050] Specifically, rhodamine compounds containing Schiff base groups include structures as shown in structural formula (I):

[0051] (I).

[0052] Specifically, the chemical reaction equation for the anaerobic heating reflux reaction is as follows:

[0053] ;

[0054] The reaction atmosphere is inert, the reflux reaction temperature is 80~90℃, and the reflux reaction time is 6~10h.

[0055] Furthermore, the hydrazine group in the hydrazine adduct of rhodamine may react with oxygen, leading to a decrease in product yield or the formation of impurities. In an inert atmosphere, such as by using nitrogen or argon to purge oxygen from the reaction system, oxidation reactions can be avoided, ensuring the reaction proceeds along the intended path and improving product purity and yield.

[0056] Furthermore, a reflux reaction temperature of 80-90°C can provide sufficient energy for the reaction of rhodamine hydrazine adduct with 2-methylmercaptobenzaldehyde, accelerating the reaction rate and enabling the reaction to achieve a high conversion rate within a reasonable time.

[0057] Furthermore, a reaction time of 6–10 hours ensures sufficient time for the hydrazine adduct of rhodamine to react with 2-methylmercaptobenzaldehyde, resulting in a high conversion rate. If the reaction time is too short, the reactants may not react completely, leading to a lower product yield.

[0058] Specifically, the organic solvent includes any one of dimethyl sulfoxide, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, and acetone, and the buffer includes 4-hydroxyethylpiperazine ethanesulfonic acid (HEPES).

[0059] Specifically, the volume ratio of buffer solution to organic solvent is (1~50):5, and the pH value of buffer solution is 5.5~10. By adjusting the volume ratio of buffer solution to organic solvent, a detection application can be created that can make the reactants and products have good solubility and can adapt to different conditions.

[0060] Specifically, the concentration of rhodamine-like compounds containing Schiff base groups in the test solution was 5 × 10⁻⁶. -7 ~2×10 - 6 The concentration range is mol / L; this range falls within the optimal sensitivity range for absorbance of the UV-Vis spectrophotometer. It can accurately detect the absorption signal produced by rhodamine-like compounds containing Schiff base groups, thus accurately determining their concentration. If the compound concentration is too high, it may cause instrument signal saturation, making accurate measurement impossible; if the concentration is too low, the signal may be masked by instrument noise, making accurate resolution difficult.

[0061] In one embodiment, a test solution comprising a rhodamine-like compound containing a Schiff base group is obtained through the following steps:

[0062] The concentration range of 1×10⁻⁶ is prepared using organic solvents. -4 ~1×10 -1 A stock solution of rhodamine-like compounds containing Schiff base groups was prepared at mol / L, and then diluted to 5 × 10⁻⁶ mol / L using buffer and organic solvent. -7 ~2×10 -6 The test solution was obtained by applying a concentration of mol / L.

[0063] Specifically, the organic solvent can be dimethyl sulfoxide, acetonitrile, tetrahydrofuran (THF), N,N-dimethylformamide, acetone, etc., and the present invention does not limit it; the buffer can be 4-hydroxyethylpiperazine ethanesulfonic acid (HEPES) buffer, and the pH value of the buffer is 5.5~10.

[0064] Furthermore, in the test solution, the volume ratio of buffer solution to organic solvent ranges from (1 to 50): 5.

[0065] Next, different volumes of copper ion standard solution were gradually added to the test solution, mixed thoroughly, and the absorption spectrum was measured using a UV-Vis spectrophotometer. The absorbance of the mixed solution after each addition was also measured.

[0066] Specifically, the preparation process of the copper ion standard solution is as follows: weigh a certain mass of analytical grade copper salt, add deionized water to dissolve it completely, and obtain the copper ion standard solution; the analytical grade copper salt can be CuCl2 and Cu(NO3)2, etc., and this invention does not limit it.

[0067] The detection process in step S10 is as follows: The carbonyl oxygen, nitrogen, and sulfur atoms in the rhodamine-like compound (I) with the Schiff base group can chelate with copper ions, causing the spirocyclic structure to hydrolyze and form an open-ring structure. The color of the solution after mixing the test solution and the sample solution changes from almost colorless to red. The specific process is as follows:

[0068] .

[0069] S20, a standard curve was plotted based on the relationship between copper ion concentration and absorbance.

[0070] Specifically, step S20 also includes:

[0071] Among them, by testing the absorption spectrum response of the test solution of rhodamine-like compounds containing Schiff base groups to the standard copper ion solution, a standard curve of the relationship between copper ion concentration and absorbance was obtained: the change in absorbance at 558 nm of mixed solutions containing different copper ion concentrations was used as the ordinate and the copper ion concentration as the abscissa to perform linear fitting, and the standard curve of the relationship between copper ion concentration and absorbance was obtained.

[0072] S30, after quantitatively adding the sample solution to the test solution, a reaction solution is obtained, and the absorbance of the reaction solution is tested; the sample solution is prepared by dissolving, diluting and making up to volume commercially available basic copper nitrate raw material or a gas generator containing basic copper nitrate.

[0073] Specifically, step S30 also includes:

[0074] Select commercially available basic copper nitrate raw material or randomly sample from the same batch of gas generator columns, and grind thoroughly to obtain a solid sample of the reagent;

[0075] The solid sample of the reagent was dissolved in nitric acid, filtered through a microfilter to remove insoluble impurities, and then diluted and brought to volume with deionized water to obtain the sample solution to be tested.

[0076] The test sample solution is quantitatively added to the test solution to obtain the reaction solution, and the absorbance of the reaction solution is measured.

[0077] In one embodiment, step S30 specifically includes:

[0078] Basic copper nitrate from the same manufacturer was provided, and 10 samples were randomly selected. The solid samples were thoroughly ground, dissolved in nitric acid, filtered through a microfilter to remove insoluble impurities, and then diluted and brought to volume with deionized water to obtain the test sample solution.

[0079] Add the above-mentioned sample solution to the test solution, mix well, and use a UV-Vis spectrophotometer to measure its absorption spectrum to determine the absorption spectral intensity of the sample solution at 558 nm for different amounts of the sample solution added.

[0080] In another embodiment, step S30 specifically includes:

[0081] Four gas generator reagents from the same production batch were provided, and five samples were randomly taken from different parts of each reagent, resulting in a total of 20 solid samples. The solid samples were thoroughly ground, dissolved in nitric acid, filtered through a microfilter to remove insoluble impurities, and then diluted and brought to volume with deionized water to obtain the test sample solution.

[0082] Next, the test sample solution was quantitatively added to the test solution to obtain the reaction solution. After mixing evenly, the absorption spectrum of the reaction solution was measured using a UV-Vis spectrophotometer to determine the absorption spectral intensity of the test sample solution at 558 nm for different added amounts.

[0083] S40, determine the concentration of copper ions in the sample solution according to the standard curve and the absorbance of the reaction solution.

[0084] Specifically, step S40 also includes:

[0085] When the test sample solution is prepared from commercially available basic copper nitrate raw material, the test sample solution is quantitatively added dropwise to the above test solution, and then its absorbance is measured. Based on the obtained standard curve, the copper ion concentration in the test sample solution is calculated. The copper ion concentration is then converted into the mass of copper element to assess the purity and quality of the commercially available basic copper nitrate raw material.

[0086] When the test sample solution is prepared by a gas generator containing basic copper nitrate, the test sample solution is quantitatively added to the above test solution, and then its absorption spectrum is measured sequentially. The distribution of copper element is characterized by the trend of the absorption spectrum, and finally the uniformity of the mixing of each component material in the gas generator is evaluated.

[0087] Furthermore, the concentration of copper ions in the sample solution to be tested is determined according to the standard curve of copper ions; if the concentration of copper ions in the sample solution to be tested is too high, it needs to be diluted with deionized water to the range of copper ion concentration applicable to the standard curve.

[0088] The present invention will now be further described with reference to specific embodiments.

[0089] Example 1:

[0090] This embodiment 1 provides a method for detecting the content of basic copper nitrate using a chemical sensor, the specific steps of which include the following:

[0091] Step (1) Preparation of Rhodamine-like compounds (I) containing Schiff base groups: Under a nitrogen atmosphere, the hydrazine adduct of rhodamine (0.46 g, 1 mmol) and 2-methylmercaptobenzaldehyde (0.61 g, 4 mmol) were dissolved in 10 mL of absolute ethanol and stirred magnetically at 90 °C. o The reaction mixture was heated under reflux at C for 7 hours. After the reaction was complete, it was allowed to cool naturally to room temperature. Part of the solvent was removed by vacuum distillation, and the reaction solution was concentrated to 5 mL. After standing overnight at room temperature, the crude product precipitated. The crude product was filtered and recrystallized from anhydrous ethanol to obtain the target compound (I).

[0092] The structural characterization results of the target compound (I) by 1H NMR are as follows:

[0093] 1 HNMR (500MHz, CDCl3): 9.02 (1H, s, -CH=N), 8.70 (2H, d, J = 5.0 Hz), 8.17 (2H, d, J = 5.0 Hz, ArH), 7.90 (4H, m, ArH), 7.46 (4H, m, ArH), 6.80 (2H,d, J = 10.0 Hz, ArH), 2.96 (8H, q, J = 5.0 Hz, -CH2-), 1.63 (3H, s, -SCH3), 1.36 (12H, t, J = 5.0 Hz, -CH3);

[0094] 13CNMR (125MHz, DCl3): 75.8, 175.4, 172.9, 171.6, 164.5, 163.8, 158.3, 153.8, 149.1, 1 37.8, 127.5, 122.9, 122.2, 120.0, 109.3, 108.7, 105.7, 58.8, 50.3, 45.0, 27.2, 21.2;

[0095] MS(ESI), m / z (rel. / Cal.): [M+H] + 591.0 / 591.3.

[0096] Step (2) Preparation of test solutions: Prepare a 10 mM HEPES buffer solution with a pH of 7.1; prepare a CH3CN solution of compound (I) to obtain a concentration of 1 × 10⁻⁶. -4 The first solution was prepared at a concentration of 1 mol / L. 1 mL of this first solution was placed in a 10 mL colorimetric tube and diluted to volume with 9 mL of HEPES buffer solution to obtain a concentration of 1 × 10⁻⁶ mol / L. -5 A mol / L test solution (CH3CN to HEPES buffer solution volume ratio 1:9).

[0097] Step (3) Preparation of copper ion standard solution: Prepare a 3.0×10⁻⁶ copper ion standard solution using deionized water. -3 A mol / L aqueous solution of Cu(NO3)2.

[0098] Step (4) Plot the standard curve of copper ion concentration and absorbance: Take 3 mL of the test solution prepared in step (2) and place it in a quartz cuvette. Under room temperature conditions, the excitation wavelength is 410 nm, and the absorption spectrum is measured using a UV-Vis spectrophotometer. Then, add the Cu(NO3)2 aqueous solution prepared in step (2) in the following order (unit: μL): 0, 2.0, 2.0, 2.0, 2.0, 2.0, 3.0, 3.0, 3.0, 3.0, 4.0, 4.0, 5.0, 5.0 and 10.0 (the effect on the total volume is negligible) to the test solution, and continuously test the absorption spectrum under the same conditions.

[0099] Please see Figure 2 , Figure 2 This is a UV-Vis absorption titration diagram of the test solution provided in Example 1 of the present invention for different concentrations of copper ions; Figure 2 The titration curves at 558 nm, from bottom to top, represent the copper ion concentrations in the system (unit: 10). -5The absorption spectra of the system when the concentrations (mol / L) are 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.3, 1.6, 1.9, 2.2, 2.6, 3.0, 3.5, 4.0 and 5.0 respectively.

[0100] from Figure 2 As can be seen, the UV-Vis absorption spectrum intensity gradually increases with increasing copper ion concentration, with the maximum absorption peak located at 558 nm. Furthermore, when the copper ion concentration in the system is only 2 × 10⁻⁶, the absorption intensity decreases. -6 At mol / L, the absorption intensity showed a very significant change compared to the blank solution; when the copper ion concentration increased to 5.0 × 10⁻⁶, the absorption intensity was significantly different. -5 At mol / L, the absorption spectrum intensity reaches its peak, with the absorption intensity at 558 nm increasing by nearly 500 times.

[0101] Please see Figure 3 , Figure 3 This is a linear relationship graph showing the change in absorbance at 558 nm and the concentration of copper ions for the test solution provided in Example 1 of this invention; Figure 3 It can be seen that, within the concentration range of 0–50 μM, the change in the absorption spectrum exhibits a good linear relationship with that of copper ions (R0). 2 =0.9977). The linear equation obtained from the simulation is y = -0.00738 + 0.20488*x (y represents the absorbance at 558 nm, x represents the concentration of copper ions, in units of 10). -5 (mol / L), indicating that the detection method provided by this invention can achieve accurate quantitative analysis of copper ions. According to the formula: Detection limit = The detection limit of this complex was calculated to be as low as 170 nM. The standard deviation of the absorbance of the blank solution represents ten measurements, and k represents... Figure 3 The slope of the fitted curve. It can be seen that the target compound (I) of Example 1 of this invention can achieve highly sensitive detection of copper ions.

[0102] Step (5) Repeat the preparation of test solutions: Prepare a 10 mM HEPES buffer solution with a pH of 7.1; prepare a THF solution of compound (I) to obtain a concentration of 1 × 10⁻⁶. -4 The first solution was prepared at a concentration of 1 mol / L. 1 mL of this first solution was placed in a 10 mL colorimetric tube and diluted to volume with 9 mL of HEPES buffer solution to obtain a concentration of 1 × 10⁻⁶ mol / L. -5 A mol / L test solution (THF to HEPES buffer solution volume ratio 1:9).

[0103] Step (6) Prepare aqueous solutions of different cations: Prepare deionized water solutions of NaNO3, KNO3, LiCl, AgNO3, MgSO4, MnSO4·2H2O, Zn(NO3)2·6H2O, Ni(NO3)2·6H2O, Pb(NO3)2, Ba(NO3)2, Ca(NO3)2·4H2O, CoCl2·6H2O, CdSO4·8H2O, Fe(NO3)3·9H2O, Al(NO3)3·9H2O, and Cr(NO3)3·9H2O. The cation concentration of each of the above deionized water solutions is 1×10⁻⁶. -2 mol / L.

[0104] Step (7) Selectivity experiment for copper ions: Take 3 mL of the test solution prepared in step (5) and place it in a quartz cuvette; then, add 30 μL of aqueous solutions of each different cation prepared in step (6) to the test solution; under room temperature conditions, excite at a wavelength of 410 nm and measure its absorption spectrum using a UV-Vis spectrophotometer. Then continue to add copper ion solution with a concentration of 5.0 × 10⁻⁶. -5 The concentration was mol / L, and its absorption spectrum was measured using a UV-Vis spectrophotometer.

[0105] Please see Figure 4 , Figure 4 This is a graph showing the recognition response of the test solution provided in Example 1 of the present invention to copper ions in the presence of common interfering ions; where the vertical axis represents the change in absorption intensity at 558 nm, and the horizontal axis represents the concentration at 10 × 10⁻⁶. - 5 Aqueous solutions of various cations at mol / L (interfering ions), and aqueous solutions of various cations with added copper ions (interfering ions plus copper ions). Comparison. Figure 4 As can be seen from the height of the bar chart, the absorption spectrum response of compound (I) in Example 1 of this invention to other common metal ions is much smaller than that to copper ions. Moreover, even under conditions of coexisting interfering ions, compound (I) still exhibits a good response to copper ions. The error bars represent the standard deviation of three measurements, indicating that Example 1 of this invention can achieve highly selective detection of copper ions.

[0106] Step (8) Repeat the preparation of test solutions: Prepare a 10 mM HEPES buffer solution with a pH of 7.1; prepare a THF solution of compound (I) to obtain a concentration of 1 × 10⁻⁶. -4 The first solution was prepared at a concentration of 1 mol / L. 1 mL of this first solution was placed in a 10 mL colorimetric tube and diluted to volume with 9 mL of HEPES buffer solution to obtain a concentration of 1 × 10⁻⁶ mol / L. -5 A mol / L test solution (THF to HEPES buffer solution volume ratio 1:9).

[0107] Step (9) Prepare sample solution A: Select 10 basic copper nitrate samples from the same manufacturer, each weighing 2.0g. After thoroughly grinding the solid samples, dissolve them in 10mL of nitric acid, filter with a microfilter to remove insoluble impurities, and dilute with deionized water 100 times to obtain sample solution A.

[0108] Step (10) Test the copper ion concentration in the sample solution A to be tested: Take 10 μL of each of the above sample solutions A from multiple batches, add them to 10 mL of the test solution, shake well, and measure the copper ion concentration.

[0109] Please see Figure 5 , Figure 5 The UV-Vis absorption spectrum of the test sample solution A prepared by adding commercially available basic copper nitrate to the test solution provided in Example 1 of this invention; wherein, as Figure 5 As shown, the absorption intensity of 10 test sample solutions A was measured, and the average value of the absorption intensity change (A-A0) was 0.33, corresponding to a copper ion concentration of 1.63 × 10⁻⁶ in the standard curve. -5 The relative atomic mass of copper is 63.5 g / mol, which calculates to a mass of 1.04 g of copper, consistent with the 53% copper content stated on the product packaging.

[0110] Step (11) Repeat the preparation of test solutions: Prepare a 10 mM HEPES buffer solution with a pH of 7.1; prepare a THF solution of compound (I) to obtain a concentration of 1 × 10⁻⁶. -4 The first solution was prepared at a concentration of 1 mol / L. 1 mL of this first solution was placed in a 10 mL colorimetric tube and diluted to volume with 9 mL of HEPES buffer solution to obtain a concentration of 1 × 10⁻⁶ mol / L. -5 A mol / L test solution (THF to HEPES buffer solution volume ratio 1:9).

[0111] Step (12) Preparation of test sample solution B: Five batches of materials in the same state were continuously produced using both traditional mechanical mixing and pneumatic mixing processes, with the same gas generator formulation. Four parallel samples were taken from each batch. A total of 40 solid samples were obtained, each weighing 1.5g. After thoroughly grinding the solid samples, they were dissolved in 10mL of nitric acid, filtered through a microfilter to remove insoluble impurities, and diluted 10 times with deionized water to obtain test sample solution B.

[0112] Step (13) Test the copper ion concentration in the sample solution B: Take 200 μL of each of the above sample solutions B from multiple batches, add them to 10 mL of the test solution, shake well, and measure the copper ion concentration.

[0113] Please see Figure 6 , Figure 6 This is a graph showing the trend of UV-Vis absorption spectra of sample solution B prepared by adding gas generators produced by different mixing processes to the test solution provided in Example 1 of the present invention; wherein, as shown in the graph... Figure 6 As shown, among the 20 samples of gas generators produced using a pneumatic mixing process, the copper element distribution showed relatively small fluctuations, indicating good mixing uniformity and composite effect of the components. In contrast, the gas generator columns produced using a mechanical mixing process showed larger fluctuations in copper element distribution, indicating poor mixing uniformity and product consistency of this process.

[0114] Furthermore, such as Figure 6 As shown, the average absorbance change of the 20 test sample solutions produced by the pneumatic mixing process was 0.467, corresponding to a copper ion concentration of 2.21 × 10⁻⁶ in the standard curve. -5 The calculated mass of basic copper nitrate was 702 mg, which is basically consistent with the 48% content of basic copper nitrate added in the formula. This indicates that the method can accurately determine the content of basic copper nitrate in the gas generator sample.

[0115] This invention discloses a method for detecting basic copper nitrate in a gas generator using a chemical sensor, comprising the following steps: First, a rhodamine derivative containing a Schiff base group undergoes a ring-opening reaction under the catalysis of copper ions, causing the solution to change from almost colorless to red, enabling naked-eye identification and detection of copper ions. The rhodamine derivative containing a Schiff base group provided by this invention, when used as a colorimetric sensor for detecting copper ions in aqueous solutions, exhibits a significant enhanced absorption spectrum response, high detection sensitivity, and a detection limit as low as 170 nM. Using a standard curve, the purity of the basic copper nitrate raw material can be accurately determined, and the precise content and distribution of basic copper nitrate in the gas generator can be determined, thereby evaluating the quality of the mixing process. It exhibits extremely high selectivity for copper ions, with almost no interference from other common metal ions.

[0116] Therefore, the detection method provided by this invention can conveniently and quickly detect the purity of basic copper nitrate raw materials, and by testing the content of basic copper nitrate in different parts of the reagent, it can determine the influence of different process parameters on the uniformity of material mixing, providing a convenient, fast and reliable evaluation method for the selection of mixing processes and the setting of mixing process parameters in actual industrial production.

[0117] In summary, the method for detecting basic copper nitrate in a gas generator using a chemical sensor provided by this invention can achieve highly sensitive and selective detection of copper ions. In particular, it can determine the purity and quality of commercially available basic copper nitrate raw materials. Furthermore, by testing the content and distribution of basic copper nitrate in the gas generator, the uniformity of the reagent mixing process and the composite effect of each component of the reagent can be evaluated. This provides a convenient, fast, and reliable evaluation method for raw material evaluation and quality control, selection of mixing processes, and parameter setting of mixing processes in actual industrial production.

[0118] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the content of basic copper nitrate using a chemical sensor, characterized by, The application relates to a method for determining the concentration of copper ions in a sample solution. The method comprises the following steps: S10, gradually adding copper ion standard solutions with different volumes into a test solution, and testing the absorbance of the mixed solution after each time of adding is completed; The test solution comprises a rhodamine compound containing a Schiff base group; S20, drawing a standard curve according to the relationship between the copper ion concentration and the absorbance; S30, adding a sample solution to be tested into the test solution to obtain a reaction solution, and testing the absorbance of the reaction solution; the sample solution to be tested is prepared by dissolving, diluting and constant-volume processing of commercially available basic copper nitrate raw materials or a gas generating agent containing basic copper nitrate; S40, determining the copper ion concentration in the sample solution to be tested according to the standard curve and the absorbance of the reaction solution; The preparation method of the test solution in the S10 step comprises the following steps: adding hydrazine addition product of rhodamine, 2-methyl mercaptobenzaldehyde and absolute ethanol, and then performing an anaerobic heating reflux reaction; After the anaerobic heating reflux reaction is completed, the crude product is obtained by naturally cooling to room temperature and removing the absolute ethanol through reduced pressure distillation; The crude product is sequentially subjected to filtration and anhydrous ethanol recrystallization to obtain the rhodamine compound containing a Schiff base group; 2. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 1, characterized in that, The rhodamine compound containing a Schiff base group, an organic solvent and a buffer solution are mixed to obtain the test solution.

3. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 1, characterized in that, The molar ratio of the hydrazine addition product of rhodamine to 2-methyl mercaptobenzaldehyde is 1: (1.2-7.5), and the dosage ratio of the hydrazine addition product of rhodamine to absolute ethanol is 1g: (30-100) mL.

4. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 1, characterized in that, In the anaerobic heating reflux reaction, the reaction atmosphere is an inert atmosphere, the reflux reaction temperature is 80-90 DEG C, and the reflux reaction time is 6-10h.

5. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 4, characterized in that, The concentration of the rhodamine compound containing Schiff base group in the test solution is 5×10 -7 -2×10 -6 mol / L; the volume ratio of the buffer to the organic solvent is (1-50):5, and the pH value of the buffer is 5.5-10.

6. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 1, characterized in that, The organic solvent comprises any one of dimethyl sulfoxide, acetonitrile, tetrahydrofuran, N, N-dimethylformamide and acetone, and the buffer solution comprises 4-hydroxyethyl piperazine ethanesulfonic acid. (I)。 7. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 1, characterized in that, The rhodamine compound containing a Schiff base group comprises a structure as shown in the structural formula (I):

8. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 1, characterized in that, In the S20 step, the change value of the absorbance at 558nm with different copper ion concentrations is taken as the ordinate, and the copper ion concentration is taken as the abscissa to perform linear fitting, so that the standard curve is obtained. The preparation method of the sample solution to be tested in the S30 step comprises the following steps: The commercially available basic copper nitrate raw materials or the solid sample of the gas generating agent is selected from the same batch of gas generating agent, and the solid sample is obtained by being fully ground; 9. The method for detecting the content of basic copper nitrate using a chemical sensor according to claim 8, characterized in that, The solid sample of the gas generating agent is dissolved in nitric acid, the insoluble impurities are removed through a micro filter, and then the sample solution to be tested is obtained by being sequentially diluted and constant-volume processed with deionized water. When the sample solution to be tested is prepared from commercially available basic copper nitrate raw materials, the S40 step further comprises the following steps: accurately determining the content of copper elements in the sample solution to be tested by using the standard curve, and comparing the content with the content marked on the product label. When the sample solution is prepared by the gas generating agent containing the basic copper nitrate, the step S40 is followed by: testing the ultraviolet-visible absorption spectrum of the reaction solution in sequence, characterizing the distribution of the copper element through the change trend of the ultraviolet-visible absorption spectrum, and finally evaluating the uniformity of the mixed components in the gas generating agent.

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