Diatomic catalyst for detecting carbosulfan pesticide residue and preparation method

Abstract

The invention relates to a diatomic catalyst for detecting carbosulfan pesticide residue and a preparation method, and belongs to the technical field of food safety detection. According to the invention, a reducing sulfide generated by breaking a nitrogen-sulfur (N-S) bond of carbosulfan under an acidic condition is used as a specific substance. The reductive sulfide not only can prevent bimetal active sites in the diatomic catalyst, but also consumes hydroxyl radicals generated by catalyzing hydrogen peroxide (H2O2), and the sensing switch enzyme formed by a dual enzyme inhibition mechanism causes the enzyme substrate 3, 4-dihydroxyl-3, 4-dione to be converted into the diatomic catalyst, so that the catalytic activity of the diatomic catalyst is improved. The blue color of the 3, 3 ', 5, 5'-tetramethyl benzidine (TMB) gradually becomes light along with the increase of the concentration of carbosulfan, sensitive visual detection is implemented, and after a blue product is read by using an ultraviolet spectrophotometer, the absorbance value generated by an ultraviolet absorption spectrum at 654 nm is linearly dependent on carbosulfan. The prepared diatomic catalyst effectively improves the detection sensitivity of the carbosulfan pesticide residue, and has good popularization and application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of food safety detection, and particularly relates to a diatomic catalyst for detecting carbosulfan pesticide residues and a preparation method thereof. Background Art

[0002] Carbosulfan is a broad-spectrum insecticide and acaricide belonging to the carbamate class of insecticides. It is primarily used to control various insects and mites in crops such as cotton, rice, corn, and vegetables. Carbosulfan is a highly toxic carbamate insecticide, and excessive intake can cause acute or chronic poisoning. Routine food testing can help identify and address potential problems in advance, preventing poisoning. Furthermore, regular testing of carbosulfan in environmental media such as water and soil helps assess its impact on ecosystems and enable timely measures to mitigate potential environmental pollution. Traditional methods for detecting carbosulfan rely primarily on the national standard GB 22609-2008, which involves large-scale instrumentation such as high-performance liquid chromatography (HPLC), gas chromatography (GC), liquid chromatography-mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). While effective in detecting pesticide residues, these methods require large, expensive instrumentation and specialized personnel. Therefore, there is an urgent need to develop on-site detection technologies that meet the needs of social development.

[0003] Currently, new technological research on carbosulfan is focused on enzyme inhibition strategies. Acetylcholinesterase (AChE) promotes the hydrolysis of acetylcholine (ATCh) to generate electroactive or reduced choline. Carbosulfan can block this catalytic process, making AChE a suitable biomarker for detecting carbosulfan. Notably, cascade enzyme systems consisting of AChE and nanozymes have been intensively studied and strongly promoted. Single-atom nanozymes are a class of nanomaterials with enzymatic catalytic activity. They combine the unique properties of nanomaterials with the efficient catalytic properties of traditional enzymes and have recently demonstrated widespread application in the prevention and control of environmental hazards. However, despite the significance of these studies, these detection methods often lack broad selectivity, as the AChE inhibitors used (including anticholinesterase drugs, organophosphorus pesticides, and carbamate pesticides) inhibit AChE activity and trigger signal changes. This makes them incapable of identifying individual pesticides under specific conditions. Furthermore, numerous cutting-edge and prominent studies have shown that diatomic catalysts not only retain the advantages of single-atom nanozymes but also introduce diverse interactions beyond the theoretical limitations of single-atom catalysis, potentially enabling applications in numerous areas of catalysis. While diatomic catalysts are flourishing in energy-related fields, they are still in their infancy in the biological field, and there are no reports on their use for pesticide detection. Therefore, there is a market need for the development of a biosensor specifically designed for the rapid and specific detection of carbosulfan residues in the environment. Summary of the Invention

[0004] In order to achieve high sensitivity and special rapid detection of carbosulfan residues in food matrices, the present invention proposes a diatomic catalyst for detecting carbosulfan pesticide residues and also provides a preparation method of the diatomic catalyst.

[0005] A diatomic catalyst for detecting carbosulfan pesticide residues is in the form of a yellow powder, soluble in water, and has powder particles in the shape of regular hexagons of 350-550 nm. It contains 62.3% by mass of carbon, 19.89% by mass of nitrogen, 8.76% by mass of oxygen, 8.15% by mass of zinc, 0.48% by mass of platinum, and 0.42% by mass of copper.

[0006] The preparation steps of a diatomic catalyst for detecting carbosulfan pesticide residues are as follows: (1) Take 1.761 g of zinc nitrate hexahydrate, 0.539 g of copper nitrate and 0.616 g of sodium chloroplatinate hexahydrate, mix them evenly to obtain a mixed dry powder; (2) Add 40 mL of 0.024 g / mL methanol solution to the mixed dry powder and ultrasonicate until dissolved and dispersed to obtain a first reaction solution; (3) Take another 2.43 g of 2-methylimidazole and add it to 40 mL of 0.024 g / mL methanol solution, and sonicate until dissolved to obtain a second reaction solution; (4) In a magnetic stirrer, the first reaction solution was stirred at room temperature, and the second reaction solution was added during the stirring process. During the stirring process, 70 mL of a methanol solution with a concentration of 0.024 g / mL was slowly added, and the mixture was stirred for 8 h. The mixture was allowed to stand for 2 h, and centrifuged at 10,000 × g for 15 min. The supernatant was discarded, and the precipitate was resuspended with 150 mL of a methanol solution with a concentration of 0.024 g / mL. The resuspension was repeated three times to obtain a resuspension; the resuspension was a diatomic catalyst solution with a concentration of 150 μg / mL; (5) The resuspension was dried at 60 ° C in an oven for 2.5 h to obtain a diatomic catalyst of 2-methylimidazole zinc salt co-doped with copper and platinum, which was the diatomic catalyst used to detect the amount of butansulfuron pesticide residues.

[0007] Further preparation operation technical scheme is as follows: In step (2), the ultrasonic conditions are: ultrasonic power 100 W, ultrasonic time 15 min.

[0008] In step (3), the ultrasonic conditions are: ultrasonic power 100 W, ultrasonic time 15 min.

[0009] In step (4), the resuspension conditions are as follows: resuspend the precipitate with 150 mL of methanol having a concentration of 0.024 g / mL, and then ultrasonicate in an ultrasonic cleaning machine at a power of 100 W for 5 min until the precipitate is dissolved.

[0010] The beneficial technical effects of the present invention are embodied in the following aspects: (1) In order to verify the high catalytic activity of the diatomic catalyst, the peroxidase catalysis of platinum (Pt) single atom catalyst, copper (Cu) single atom catalyst and diatomic catalyst was tested respectively. Figure 1 .exist Figure 1 As can be seen in the figure, the dissociation energies of platinum (Pt) single-atom catalysts, copper (Cu) single-atom catalysts, and diatomic catalysts for the conversion of excited hydrogen peroxide (H2O2) to 2OH* are -0.48, -0.52, and -1.08, respectively. The diatomic catalyst has a significantly lower dissociation energy for hydrogen peroxide (H2O2), lowering the catalytic energy barrier for peroxidase and exhibiting superior catalytic activity.

[0011] (2) This invention utilizes the excellent properties of organic frameworks, such as large specific surface area, low density, high porosity, structural diversity, and adjustable pore size, as carriers to anchor dispersed and high-density copper-platinum diatoms for the first time, resulting in excellent peroxidase-like performance. Compared with highly catalytically active single-atom catalysts, the catalytic efficiency of copper-platinum diatoms is increased by approximately 300%. Compared with cutting-edge research on the detection of carbosulfan, the sensitivity of this invention is increased by approximately two orders of magnitude. In addition, the detection cost of this invention is only 0.01% of that of traditional detection technologies, which has excellent cost-effectiveness.

[0012] (3) The detection principle of the present invention can be found in Figure 2 The researchers utilized reduced sulfide ([SH]) produced by carbosulfan under acidic conditions as a specific triggering agent for the sensor switch. The reduced sulfide not only blocked the metal active sites of the diatomic catalyst, reducing catalytic efficiency, but also consumed the hydroxyl radicals produced by hydrogen peroxide catalyzed by the copper-platinum diatomic catalyst, hindering the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). The highly efficient diatomic catalyst doubled its enzyme activity in the presence of the target compound, effectively creating an ultrasensitive sensor switch and lowering the detection limit for carbosulfan.

[0013] (4) The present invention utilizes the unique property of carbosulfan to produce reduced sulfide in an acidic environment to develop a specific sensing mode for detecting carbosulfan in ethyl carbamate. This is different from the currently reported sensing strategies that use enzyme inhibition mechanisms to discriminate ethyl carbamate pesticides with low specificity and difficulty in detecting carbosulfan specifically. This is more conducive to distinguishing the types of pesticide residues, optimizing pesticide ratios, and enabling farmers to use pesticides more scientifically. The present invention can achieve sensitive and specific detection of carbosulfan without the need for complex and expensive modification of recognition elements, simplifying the operating procedures and detection costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram of the peroxidase catalytic pathway for detecting the present invention.

[0015] Figure 2 This is a schematic diagram showing the principle of using the diatomic catalyst prepared in the present invention to detect carbosulfan pesticide residues.

[0016] Figure 3 This is the element mapping diagram of the diatomic catalyst in Example 2 of the present invention.

[0017] Figure 4 This is the r-space spectrum of the copper edge X-ray absorption fine structure of the copper foil and the diatomic catalyst in Example 2 of the present invention.

[0018] Figure 5 This is the r-space spectrum diagram of the platinum edge X-ray absorption fine structure of the platinum foil and the diatomic catalyst in Example 2 of the present invention.

[0019] Figure 6 This is a wavelet analysis diagram of the X-ray absorption fine structure of the copper K-edge (Cu K-edge) of the copper foil in Example 2 of the present invention.

[0020] Figure 7 This is a wavelet analysis diagram of the X-ray absorption fine structure of the copper K-edge (Cu K-edge) of the diatomic catalyst in Example 2 of the present invention.

[0021] Figure 8 This is a wavelet analysis diagram of the X-ray absorption fine structure of the platinum K-edge (Pt K-edge) of the platinum foil in Example 2 of the present invention.

[0022] Figure 9 This is a wavelet analysis diagram of the X-ray absorption fine structure of the platinum K-edge (Pt K-edge) of the diatomic catalyst in Example 2 of the present invention.

[0023] Figure 10 This is a color diagram of the detection method of the present invention for detecting different concentrations of carbosulfan.

[0024] Figure 11 The figures are the ultraviolet absorption spectra of carbosulfan when the detection method of the present invention is used to detect different concentrations of carbosulfan.

[0025] Figure 12 This is a detection equation diagram for detecting different concentrations of carbosulfan using the detection method of the present invention.

[0026] Figure 13 Figure 3. Specificity diagram of the detection method developed for the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the embodiments, but the present invention is not limited thereto.

[0028] Unless otherwise defined, technical and scientific terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0029] Unless otherwise specified, the experimental reagents and consumables used in the following examples are all conventional biochemical reagents; the experimental methods described are all conventional methods unless otherwise specified; the quantitative tests in the following examples are all repeated three times, and the results are averaged; the "%" in the following examples, unless otherwise specified, are all weight percentages.

[0030] The instruments, equipment, raw materials, reagents or method steps used in the present invention are all ensured to be processed under sterile conditions.

[0031] Instruments, equipment, raw materials, reagents or method steps not mentioned in the present invention are conventional or well-known technical methods for those skilled in the art and are not described in detail in the present invention. Example 1

[0032] The preparation steps of the diatomic catalyst of the present invention are as follows: (1) Take 1.761 g of zinc nitrate hexahydrate, 0.539 g of copper nitrate and 0.616 g of sodium chloroplatinate hexahydrate, mix them evenly and obtain a mixed dry powder.

[0033] (2) Add 40 mL of 0.024 g / mL methanol solution to the mixed dry powder; sonicate until dissolved and dispersed, with an ultrasonic power of 100 W and an ultrasonic time of 15 min to obtain the first reaction solution.

[0034] (3) Take another 2.43 g of 2-methylimidazole and add it to 40 mL of a 0.024 g / mL methanol solution. Ultrasonicate until dissolved at an ultrasonic power of 100 W and an ultrasonic time of 15 min to obtain a second reaction solution.

[0035] (4) In a magnetic stirrer, stir the first reaction solution at room temperature. Add the second reaction solution during the stirring process. Slowly add 70 mL of a 0.024 g / mL methanol solution during the stirring process. Stir for 8 h, let it stand for 2 h, centrifuge at 10,000 × g for 15 min, add 150 mL of a 0.024 g / mL methanol solution and resuspend. Repeat the resuspension three times to obtain a resuspension.

[0036] The resuspension is a diatomic catalyst solution with a concentration of 150 μg / mL, wherein the concentration of hydrogen peroxide (H2O2) is 0.006 g / mL and the concentration of 3,3',5,5'-tetramethylbenzidine (TMB) is 0.48 μg / μL.

[0037] (5) Dry in an oven at 60 °C for 2.5 h to obtain a diatomic catalyst of 2-methylimidazole zinc salt co-doped with copper and platinum. The diatomic catalyst is in the form of yellow powder, see Figure 3 The powder particles are 350-550nm in size and are hexagonal and soluble in water. The diatomic catalyst contains 62.3% carbon, 19.89% nitrogen, 8.76% oxygen, 8.15% zinc, 0.48% platinum, and 0.42% copper.

[0038] Figure 3 The carbon, nitrogen, oxygen, zinc, copper and platinum shown in the sample correspond to the morphology of the nanomaterial, proving that copper and platinum atoms are successfully anchored in the metal organic framework using 2-methylimidazole zinc as the skeleton. Figure 4 In order to show that the synthesized bimetallic atoms are all single atoms, the diatomic catalyst has a prominent peak at 1.47 Å, corresponding to the backscattering of copper-nitrogen (Cu-N), which is significantly different from that of copper foil, proving that there is no copper-copper (Cu-Cu) bond in the diatomic catalyst. Figure 5 The maximum peak of the diatomic catalyst in r space is 1.50 Å, which is significantly different from that of platinum foil. Figure 6 Wavelet analysis of the X-ray absorption fine structure signal of the copper-K edge in the copper foil sample. The copper K edge peak is 7.11 Å. -1 See also Figure 7 Wavelet analysis of the X-ray absorption fine structure signal of the copper-K edge in the diatomic catalyst sample. The copper K edge peak is 4.21 Å. -1 . Similarly, see Figure 8 , the Pt-K edge peak is 9.10 Å -1 See also Figure 9 , the Pt-K edge peak is 4.32 Å -1 . Figure 6-9 It can be concluded that the copper K edge peak in the diatomic catalyst is 4.21 Å -1, compared to 7.11 Å of copper foil -1 Similarly, the peak of the platinum-K edge of the diatomic catalyst is 4.32 Å. -1 , compared to 9.10 Å for platinum foil -1 In summary, both copper and platinum exist in the form of single atoms and do not contain nanoparticles. Example 2

[0039] The establishment of the detection equation, the specific detection steps are as follows: (1) Add 50 μL of a 150 μg / mL diatomic catalyst solution to 50 μL of a 0.006 g / mL hydrogen peroxide (H2O2) solution to obtain a mixed solution; (2) Add 150 μL of 0.041 g / mL acetic acid-sodium acetate buffer with a pH of 3.5 to the mixed solution and react for 10 minutes to obtain an acidified solution; (3) The acidified solution was divided into 10 equal volumes, and 200 μL of 0.041 g / mL acetic acid-sodium acetate buffer as a blank control solution and 200 μL of 9 different concentrations of carbosulfan solution with concentrations of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 μM were added to each of the 10 equal volumes. The reaction was continued for 35 min to obtain 10 inhibitory solutions. (4) Add 50 μL of 0.48 μg / μL 3,3',5,5'-tetramethylbenzidine (TMB) solution to each of the 10 inhibitory solutions and react for 15 min to obtain 10 signal solutions; (5) See Figure 10 Observe the color changes of 10 signal solutions with the naked eye. As the concentration of carbosulfan increases, the blue color gradually becomes lighter, and 10 reaction solutions are obtained. (6) Take 200 μL of each of the 10 reaction solutions and add them to a cuvette. Read the UV absorption wavelength of the reaction solution at 654 nm. (7) Observing the color of the reaction solution, the nine reaction solutions containing carbosulfan at concentrations of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 μM were light blue, indicating a positive result. The reaction solution containing the blank control solution was dark blue, indicating a negative result. The UV absorption spectra of 0-0.9 μM were measured as follows: Figure 11 As shown in FIG, as the concentration of carbosulfan increases, the UV absorption spectrum gradually decreases until the spectrum stabilizes at 0.9 μM, so the linear response range is 0-0.8 μM; the fluorescence intensity value at 654 nm is the vertical axis Y and the carbosulfan concentration is the horizontal axis X to draw a standard curve, the results are shown in FIG. Figure 12, the detection equation is: Y=-1.1569X+1.13122, and the correlation coefficient is 0.98773. Example 3

[0040] The diatomic catalyst prepared by the present invention is used in detecting the content of carbosulfan in soil.

[0041] (1) Pretreatment of the sample to be tested Soil samples were collected from Hefei University of Technology. After sieving to remove stones, the sample was ground and air-dried for 30 minutes. Subsequently, 1.0 g of the sample was added to 5 mL of water. After 5 minutes of ultrasonic treatment, the supernatant was collected by centrifugation. A 0.45 μM solution of carbosulfan was added to the supernatant to prepare the test solution.

[0042] (2) Detection (2.1) Add 50 μL of a 150 μg / mL diatomic catalyst solution to 50 μL of a 0.006 g / mL hydrogen peroxide (H2O2) solution to obtain a mixed solution. (2.2) Add 150 μL of 0.041 g / mL acetic acid-sodium acetate buffer (pH 3.5) to the mixed solution and react for 10 min to obtain an acidified solution. (2.3) Add 200 μL of the test solution to the acidified solution and react for 35 minutes to obtain the enzyme inhibition solution. (2.4) Add 50 μL of 0.48 μg / μL 3,3',5,5'-tetramethylbenzidine (TMB) solution to the enzyme inhibitory solution and react for 15 minutes to obtain the signal solution. (2.5) Observe the color change of the signal solution to obtain the reaction solution. Add 200 μL of the reaction solution to a cuvette and read the UV absorption wavelength of the solution at 654 nm.

[0043] (3) Calculate the test results (3.1) Observe the color change of the signal solution. When the signal solution is light blue or colorless and transparent, the test result is positive; when the signal solution is dark blue, the test result is negative. Substitute the absorbance value A of the reaction solution of the positive sample at 654 nm into the detection equation: Y = -1.1569X + 1.13122, where X is the concentration of carbosulfan, Y is A, and A is the absorbance value at 654 nm when the test solution is detected by the present invention. Calculate the concentration of carbosulfan in the test solution, and the test is complete. The detection equation is obtained from Example 2. (3.2) After observing the color of the signal solution, the signal solution was light blue, and the test result was positive. A positive reaction solution was obtained. The absorbance value of the positive reaction solution at 654 nm, 0.658, was substituted into the detection equation: Y = -1.1569X + 1.13122. The concentration of carbofuran in the test solution was calculated to be 0.41 μM. Example 4

[0044] The diatomic catalyst prepared by the present invention is used in detecting the content of carbosulfan in lake water.

[0045] (1) Pretreatment of the sample to be tested The lake water was collected from the Emerald Lake of Hefei University of Technology. The collected lake water was not treated in any way and was directly added with 0.45 μM carbosulfan solution to prepare the test solution.

[0046] (2) Detection (2.1) Add 50 μL of a 150 μg / mL diatomic catalyst solution to 50 μL of a 0.006 g / mL (H2O2) solution to obtain a mixed solution. (2.2) Add 150 μL of 0.041 g / mL acetic acid-sodium acetate buffer (pH 3.5) to the mixed solution and react for 10 min to obtain an acidified solution. (2.3) Add 200 μL of the test solution to the acidified solution and react for 35 minutes to obtain the enzyme inhibition solution. (2.4) Add 50 μL of 0.48 μg / μL 3,3',5,5'-tetramethylbenzidine (TMB) solution to the enzyme inhibitory solution and react for 15 minutes to obtain the signal solution. (2.5) Observe the color change of the signal solution to obtain the reaction solution. Add 200 μL of the reaction solution to a cuvette and read the UV absorption wavelength of the solution at 654 nm.

[0047] (3) Calculate the test results (3.1) Observe the color of the signal solution. When the signal solution is light blue or colorless and transparent, the test result is positive; when the signal solution is dark blue, the test result is negative. Substitute the absorbance value A of the reaction solution of the positive sample at 654 nm into the detection equation: Y = -1.1569X + 1.13122, where X is the concentration of carbosulfan, Y is A, and A is the absorbance value at 654 nm when the test solution is detected according to the present invention. Calculate the concentration of carbosulfan in the test solution, and the test is complete. The detection equation is obtained from Example 2. (3.2) After observing the color of the signal solution, the signal solution was light blue, and the test result was positive. A positive reaction solution was obtained. The absorbance value of the positive reaction solution at 654 nm, 0.727, was substituted into the detection equation: Y = -1.1569X + 1.13122. The concentration of carbofuran in the test solution was calculated to be 0.35 μM. Example 5

[0048] Application of the diatomic catalyst prepared by the present invention in detecting the content of carbosulfan in tomatoes.

[0049] (1) Sample processing Rinse the tomatoes with clean water, air-dry, and evenly spray them with carbosulfan. After air-drying, obtain the spiked sample. Finally, repeatedly spray the sample surface with 5 mL of ultrapure water. The effluent is the test solution.

[0050] Detection (2.1) Add 50 μL of a 150 μg / mL diatomic catalyst solution to 50 μL of a 0.006 g / mL hydrogen peroxide (H2O2) solution to obtain a mixed solution. (2.2) Add 150 μL of 0.041 g / mL acetic acid-sodium acetate buffer (pH 3.5) to the mixed solution and react for 10 min to obtain an acidified solution. (2.3) Add 200 μL of the test solution to the acidified solution and react for 35 minutes to obtain the enzyme inhibition solution. (2.4) Add 50 μL of 0.48 μg / μL 3,3',5,5'-tetramethylbenzidine (TMB) solution to the enzyme inhibitory solution and react for 15 minutes to obtain the signal solution. (2.5) Observe the color change of the signal solution to obtain the reaction solution. Add 200 μL of the reaction solution to a cuvette and read the UV absorption wavelength of the solution at 654 nm.

[0051] (3) Calculate the test results (3.1) Observe the color of the signal solution. When the signal solution is light blue or colorless and transparent, the test result is positive; when the signal solution is dark blue, the test result is negative. Substitute the absorbance value A of the reaction solution of the positive sample at 654 nm into the detection equation: Y = -1.1569X + 1.13122, where X is the concentration of carbosulfan, Y is A, and A is the absorbance value at 654 nm when the test solution is detected according to the present invention. Calculate the concentration of carbosulfan in the test solution, and the test is complete. The detection equation is obtained from Example 2. (3.2) After observing the color of the signal solution, it turned dark blue, indicating a negative test result. A negative reaction solution was obtained. To further ensure the test result, 200 μL of the negative reaction solution was placed in a cuvette. The fluorescence value at 654 nm was measured to be 1.142, which was close to the blank control value after being substituted into the test equation. Example 6

[0052] Specific Detection Method for Carbosulfan Sample processing Take 8 sterile centrifuge tubes and add 200 μL of 0.60 μM concentration of carbosulfan, furadan, dichlorvos, isocarbophos, paraoxon, thiram, glyphosate and thiamethoxam respectively to obtain 8 test solutions.

[0053] Detection (2.1) Take 8 50 μL of 150 μg / mL diatomic catalyst solution and add 50 μL of 0.006 g / mL hydrogen peroxide (H2O2) solution to obtain 8 mixed solutions; (2.2) Add 150 μL of 0.041 g / mL acetic acid-sodium acetate buffer (pH 3.5) to each of the eight mixed solutions and react for 10 min to obtain eight acidified solutions. (2.3) Add 200 μL of the test solution to each of the eight acidified solutions and react for 35 minutes to obtain eight enzyme inhibition solutions. (2.4) Add 50 μL of 0.48 μg / μL 3,3',5,5'-tetramethylbenzidine (TMB) solution to each of the eight enzyme inhibitor solutions and react for 15 min to obtain eight signal solutions. (2.5) Observe the color changes of the eight signal solutions to obtain eight reaction solutions. Add 200 μL of each reaction solution to a cuvette and read the UV absorbance of the solution at 654 nm.

[0054] (3) Calculate the test results (3.1) Observe the color of the signal solution. When the signal solution is light blue or colorless and transparent, the test result is positive; when the signal solution is dark blue, the test result is negative. Substitute the absorbance value A of the reaction solution of the positive sample at 654 nm into the detection equation: Y = -1.1569X + 1.13122, where X is the concentration of carbosulfan, Y is A, and A is the absorbance value at 654 nm of the test solution when detecting the test solution according to the present invention. Calculate the carbosulfan concentration in the test solution, and the test is complete. The detection equation is obtained from Example 2.

[0055] It was observed that the signal solution of carbofuran, dichlorvos, isocarbophos, paraoxon, thiram, glyphosate, and thiamethoxam was dark blue, and the test result was negative; the signal solution of carbosulfan was light blue, and the test result was positive; Figure 13 As shown, the absorbance values ​​of the eight reaction solutions at 654 nm were 0.505 for carbosulfan, 0.983 for furadan, 0.976 for dichlorvos, 1.021 for isocarbophos, 0.989 for paraoxon, 0.992 for thiram, 1.003 for glyphosate, and 1.058 for thiamethoxam. This demonstrates that the diatomic catalyst developed by the present invention has good detection specificity for carbosulfan.

Claims

1. A diatomic catalyst for detecting carbosulfan pesticide residues, characterized in that: The diatomic catalyst is in the form of a yellow powder, soluble in water, and has a powder particle shape of a regular hexagon of 350-550 nm. It contains 62.3% by mass of carbon, 19.89% by mass of nitrogen, 8.76% by mass of oxygen, 8.15% by mass of zinc, 0.48% by mass of platinum, and 0.42% by mass of copper.

2. The method for preparing a diatomic catalyst for detecting carbosulfan pesticide residues according to claim 1, characterized in that: The steps are as follows: (1) Take 1.761 g of zinc nitrate hexahydrate, 0.539 g of copper nitrate and 0.616 g of sodium chloroplatinate hexahydrate, mix them evenly to obtain a mixed dry powder; (2) Add 40 mL of 0.024 g / mL methanol solution to the mixed dry powder and ultrasonicate until dissolved and dispersed to obtain a first reaction solution; (3) Take another 2.43 g of 2-methylimidazole and add it to 40 mL of 0.024 g / mL methanol solution, and sonicate until dissolved to obtain a second reaction solution; (4) In a magnetic stirrer, the first reaction solution was stirred at room temperature, and the second reaction solution was added during the stirring process. During the stirring process, 70 mL of a 0.024 g / mL methanol solution was slowly added, and the mixture was stirred for 8 h. The mixture was allowed to stand for 2 h, and the mixture was centrifuged at 10,000 × g for 15 min. The supernatant was discarded, and the precipitate was resuspended with 150 mL of a 0.024 g / mL methanol solution. The resuspension was repeated three times to obtain a resuspension; the resuspension was a diatomic catalyst solution with a concentration of 150 μg / mL. (5) The resuspension was dried in an oven at 60 °C for 2.5 h to obtain a copper- and platinum-co-doped 2-methylimidazole zinc salt diatomic catalyst, which was used to detect the residue of carbosulfan.

3. The preparation method according to claim 2, wherein: In step (2), the ultrasonic conditions are: ultrasonic power 100 W, ultrasonic time 15 min.

4. The preparation method according to claim 2, wherein: In step (3), the ultrasonic conditions are: ultrasonic power 100 W, ultrasonic time 15 min.

5. The preparation method according to claim 2, wherein: In step (4), the resuspension conditions are as follows: resuspend the precipitate with 150 mL of methanol having a concentration of 0.024 g / mL, and then ultrasonicate in an ultrasonic cleaning machine at a power of 100 W for 5 min until the precipitate is dissolved.

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