Pesticide detection device and method and preparation method of detection material of pesticide detection device

Abstract

The invention discloses a pesticide detection device and method and a preparation method of a detection material of the pesticide detection device, the pesticide detection device comprises a detection main body and a detachable detection cover, the detection cover is provided with a screen-printed electrode, and the screen-printed electrode is connected with a screen-printed electrode communicating vessel; a liquid outlet is further formed in the electrochemical detection cavity; a detection tube is arranged at the bottom of the detection main body; a micro peristaltic pump is arranged in the detection main body; the outlet side of the micro peristaltic pump is communicated with the electrochemical detection cavity through a one-way valve, and the inlet side of the micro peristaltic pump is connected with the detection pipe. The method further comprises detection method steps of S1-S4 and detection material preparation steps of A1-A2. The detection material prepared by the invention is a carbon nano composite material based on a metal organic framework (MOF), and the composite material can perform specific recognition and selective enrichment on organophosphorus pesticides. The portable pesticide detection device is matched with a detection material and a detection method, is convenient to carry and apply, and can detect pesticide residues on site in real time.

Description

Technical Field

[0001] The present invention relates to the field of pesticide detection, and in particular, to a pesticide detection device, method and preparation method of its detection material. Background Art

[0002] As is well known, organophosphorus pesticides are widely used in agriculture, animal husbandry and gardening. However, the improper use of pesticides has led to serious over-standard of organophosphorus pesticides in foods such as wheat, fruits and vegetables, seriously threatening people's life and health. At present, the detection of pesticide residues is generally based on large-scale instruments, such as gas chromatography, high-performance liquid chromatography, etc., which are not only expensive, have a long analysis and detection cycle, but also have high requirements for experimental personnel. In contrast, electrochemical sensor technology has gradually become one of the most dynamic means in on-site detection of pesticide residues due to its advantages such as simple operation, high sensitivity, rapid detection, low equipment requirements, easy miniaturization and integration. The traditional electrochemical detection device is a three-electrode system, which requires multiple samplings for detection during the detection process, and the process is cumbersome. Moreover, limited by the complex preparation process of the sensor, most electrochemical sensors have poor stability, poor anti-interference ability and are difficult to achieve batch production. In addition, the traditional electrochemical detection instruments are huge and difficult to be portable, and cannot be used for on-site detection, which limits the further development and industrial application of electrochemical detection technology.

[0003] Molecular imprinting technology is similar to the relationship between a key and a lock, which can achieve specific recognition and enrichment of target molecules, and at the same time has high selectivity. Metal-organic frameworks (MOFs) have advantages such as large pore size and large specific surface area, and have good catalytic effects on analytes. Combining the advantages of molecular imprinting technology and MOF materials can simply, rapidly, efficiently, highly specifically and low-cost realize the enrichment and separation of ultra-trace target molecules in complex samples. Therefore, it is necessary to combine the specific recognition and enrichment of the prepared molecular imprinted materials for on-site detection of pesticide residues, and provide a pesticide detection device, method and preparation method of its detection material. Summary of the Invention

[0004] Aiming at the above-mentioned deficiencies of the prior art, in order to solve the problems such as long process, poor stability, time-consuming and laborious in electrochemical detection, the present invention provides a pesticide detection device, method and preparation method of its detection material, which integrates sampling, enrichment, separation and detection, is convenient to carry and is suitable for on-site detection.

[0005] In order to achieve the above invention purpose, the technical solutions adopted by the present invention are as follows:

[0006] Provided is a portable pesticide detection device, which includes a detection main body and a detachable detection cover. A screen-printed electrode is provided on the detection cover. The detection main body and the detection cover form a sealed detection chamber. The screen-printed electrode is connected to a screen-printed electrode connector. An outlet is further provided on the electrochemical detection chamber, and a detection tube is provided at the bottom of the detection main body. The interior of the detection main body is partitioned into an electrochemical detection chamber and a working chamber. The screen-printed electrode is located in the electrochemical detection chamber, and a micro peristaltic pump is provided in the working chamber. The outlet side of the micro peristaltic pump is communicated with the electrochemical detection chamber through a one-way valve, and the inlet side of the micro peristaltic pump is connected to the detection tube.

[0007] Further, an outlet is also provided at the bottom of the electrochemical detection chamber, and a ball valve is provided on the outlet. An air hole is further provided on the detection cover.

[0008] Further, the screen-printed electrode is a carbon electrode. The screen-printed electrode includes a working electrode, a reference electrode, and a counter electrode. A filtering device is provided on the detection tube, and the filtering device is a polyethersulfone microporous membrane.

[0009] A detection method for a pesticide detection device includes the following steps:

[0010] S1: Extract a redox probe;

[0011] Start the peristaltic pump to extract the electroactive substance. Coat 5 μL of the detection material on the surface of the screen-printed electrode, dry it by irradiating with an infrared lamp, insert it into the electroactive substance, and connect the screen-printed electrode connector to a micro electrochemical workstation for electrochemical DPV to obtain an initial response current signal I0.

[0012] S2: Adsorb the dimethoate solution;

[0013] The electroactive substance after the test in step S1 is discharged through the ball valve. Then, start the micro peristaltic pump again to extract the dimethoate solution to be detected, so that the dimethoate solution completely submerges the screen-printed electrode, and the dimethoate solution is fully adsorbed by the screen-printed electrode.

[0014] S3: Test the operation process;

[0015] The adsorbed dimethoate solution is discharged through the ball valve. Then, extract the electroactive substance again through the micro peristaltic pump for DPV test to obtain an inhibited response current signal I1.

[0016] S4: Calculate the response current difference ΔI = I0 - I1. According to the linear fitting, obtain the linear regression equation of the dimethoate concentration log(C) and the response current difference ΔI, and calculate the dimethoate concentration in the solution to be detected. Specifically: According to the regression line y = bx + a for fitting, the linear regression equation of the relationship between the dimethoate concentration log(C) and the response current difference ΔI is obtained as follows:

[0017] ΔI = 0.9064 log(C) + 9.656(R 2 = 0.9961).

[0018] Further, the electroactive substance is dopamine solution.

[0019] Further, the detection material is molecularly imprinted metal-organic framework carbon material MIP / MOF-808 / A.

[0020] A preparation method of a detection material, characterized by comprising the following steps:

[0021] A1: Prepare metal-organic framework carbon material MOF-808 / AB;

[0022] A11: Weigh 0.97 g ZrOCl2·8H2O and 3.252 mg AB and add them to 50 ml of DMF and FA (1:1 V1 / V2) to obtain solution A. Ultrasonically disperse solution A for 30 mins to obtain clear solution B. Then weigh 0.21 g of H3BTC and add it to clear solution B, and then ultrasonically disperse clear solution B to obtain homogeneous solution C;

[0023] A12: Transfer the homogeneous solution C obtained in step A11 to a Teflon autoclave, react at 120 °C for 21 h to obtain solution D. Centrifuge and precipitate solution D, and then wash the obtained precipitate with DMF and methanol 5 times respectively. Then dry the precipitate at 60 °C for one day to obtain MOF-808 / AB powder;

[0024] A2: Use metal-organic framework carbon material MOF-808 / AB to prepare molecularly imprinted metal-organic framework carbon material MIP / MOF-808 / AB;

[0025] A21: Weigh 0.25 g of the MOF-808 / AB powder prepared in step A1, 10 μL of APTES and 2 ml of NH3·H2O (25%) and mix them to obtain solution E. Then add 0.01 g of DIM and stir for 10 minss to obtain solution F; Mix the obtained solution F with 5 ml of TEOS and stir at room temperature for 12 h for chemical polymerization;

[0026] A22: Centrifuge and precipitate the solution F obtained in step A21. Wash the obtained precipitate with ethanol 5 times, and then dry the precipitate at 60 °C for one day to obtain MIP / MOF-808 / AB powder.

[0027] The beneficial effects of the present invention are:

[0028] The detection material prepared by the present invention is a carbon nanocomposite based on metal-organic framework (MOF), and this composite material can specifically recognize and selectively enrich organophosphorus pesticides.

[0029] The portable pesticide detection device of the present invention, combined with the detection material and detection method, is convenient to carry and apply, and can detect pesticide residues in real time and on-site.

[0030] The present invention synthesizes a metal-organic framework molecularly imprinted composite material based on chemical polymerization. The synthesis method is simple and easy to implement, and has specificity and high selectivity for the enrichment of analytes.

[0031] The present invention is combined with a disposable screen-printed electrode for the disposable detection of pesticides in fruits and vegetables, effectively solving the disadvantages of cumbersome procedures and inability to detect in real time and on-site in the traditional electrochemical detection process;

[0032] The present invention integrates sampling, enrichment, separation, and detection, with low cost and accurate results, and can meet the commercial requirements and daily detection requirements.

[0033] The metal-organic framework (MOFs) of the present invention has advantages such as large pore size and large specific surface area, has a good catalytic effect on the analyte, and has important practical significance; acetylene black (AB) as a commonly used conductive agent can improve the conductivity of the material; the molecularly imprinted polymer (MIP) uses dimethoate as a template and can achieve specific adsorption of dimethoate.

[0034] The present invention integrates sampling, enrichment, separation, and detection, effectively solving the problems of long process, poor stability, time-consuming and laborious in electrochemical detection.

[0035] The present invention disperses the prepared material in the test solution containing the target molecule for specific enrichment of the target molecule; and coats the detection material enriched with the target to be detected on the screen-printed electrode and immerses it in the solution containing the electroactive substance to construct an inhibitory electrochemical sensor to achieve portable electrochemical detection of the target molecule. Description of the Drawings

[0036] Figure 1 It is the front view of the constructed portable detection device;

[0037] Figure 2 It is the sectional view of the constructed portable detection device;

[0038] Figure 3 It is the synthesis flow chart and detection principle diagram of the metal-organic framework molecularly imprinted carbon material MIP / MOF-808 / AB prepared in the example;

[0039] Figure 4 It is the scanning electron micrograph of the prepared material;

[0040] Figure 5 It is the transmission electron microscope image of the prepared material;

[0041] Figure 6 It is the square wave voltammetry waveform diagram for the detection of the organophosphorus pesticide dimethoate in the examples;

[0042] Figure 7 It is the linear fitting diagram of the concentration of the organophosphorus pesticide dimethoate in the examples.

[0043] The descriptions of the main component symbols in the figure are as follows:

[0044] 1. Filter device; 2. Micro peristaltic pump; 3. Check valve; 4. Electrochemical detection chamber; 5. Screen-printed electrode; 6. Ball valve; 7. Air hole; 8. Screen-printed electrode connector. Specific embodiments

[0045] The following describes the specific embodiments of the present invention to facilitate the understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

[0046] As Figure 1 and 2 shown, a pesticide detection device includes a detection main body and a detachable detection cover. A screen-printed electrode 5 is provided on the detection cover. The detection main body and the detection cover form a sealed detection chamber. The screen-printed electrode 5 is connected to a screen-printed electrode connector 8. An outlet is also provided on the electrochemical detection chamber 4, and a detection tube is provided at the bottom of the detection main body. The interior of the detection main body is partitioned into an electrochemical detection chamber 4 and a working chamber. The screen-printed electrode 5 is located in the electrochemical detection chamber 4, and a micro peristaltic pump 2 is provided in the working chamber. The outlet side of the micro peristaltic pump 2 is connected to the electrochemical detection chamber 4 through a check valve 3, and the inlet side of the micro peristaltic pump 2 is connected to the detection tube. An outlet is also provided at the bottom of the electrochemical detection chamber 4, and a ball valve 6 is provided on the outlet. An air hole 7 is also provided on the detection cover.

[0047] The screen-printed electrode 5 is a carbon electrode. The screen-printed electrode 5 includes a working electrode, a reference electrode, and a counter electrode. A filter device 1 is provided on the detection tube. The filter device 1 is composed of an external support material and an internal filter membrane. The filter device 1 filters the inhaled liquid, removes particulate impurities, and performs sterilization filtration on the liquid and gas. The filter device 1 is preferably a polyethersulfone microporous membrane, and the pore diameter of the polyethersulfone microporous membrane is preferably 0.45 μm.

[0048] As Figure 3 、 4A preparation method of a detection material, comprising the following steps:

[0049] A1: Prepare the metal-organic framework carbon material MOF-808 / AB; specifically including:

[0050] A11: Weigh 0.97 g of ZrOCl2·8H2O and 3.252 mg of AB, add them to 50 ml of DMF and FA (1:1 V1 / V2) to obtain solution A. Ultrasonically disperse solution A for 30 mins to obtain a clear solution B. Then weigh 0.21 g of H3BTC and add it to the clear solution B, and then ultrasonically disperse the clear solution B to obtain a homogeneous solution C;

[0051] A12: Transfer the homogeneous solution C obtained in step A11 to a Teflon autoclave, react at 120 °C for 21 h to obtain solution D. Centrifuge and precipitate the obtained solution D, and then wash the obtained precipitate with DMF and methanol 5 times respectively. Then dry the precipitate at 60 °C for one day to obtain MOF-808 / AB powder;

[0052] A2: Use the metal-organic framework carbon material MOF-808 / AB to prepare the molecularly imprinted metal-organic framework carbon material MIP / MOF-808 / AB; dissolve or disperse the target molecule in a solution containing the metal-organic framework carbon material and the functional monomer, and make it adsorb on the surface of the MOF material; then, under the action of an initiator (NH3·H2O (25%)), initiate the polymerization of the monomer, and bond the target molecule to the surface of the MOF material; finally, wash and remove the target molecule to prepare the metal-organic framework molecularly imprinted nanomaterial. The target molecule is the organophosphorus pesticide dimethoate, the functional monomer is 3-aminopropyltriethoxysilane (APTES), the initiator is NH3·H2O (25%), the MOF material is MOF-808, and the carbon material is acetylene black (AB); the specific preparation steps are as follows:

[0053] A21: Weigh 0.25 g of the MOF-808 / AB powder prepared in step A1, 10 μL of APTES and 2 ml of NH3·H2O (25%), mix them to obtain solution E, and then add 0.01 g of DIM and stir for 10 mins to obtain solution F; mix the obtained solution F with 5 ml of TEOS and stir at room temperature for 12 h for chemical polymerization;

[0054] A22: The solution F obtained in step A21 is centrifuged and precipitated, and the obtained precipitate is washed with ethanol 5 times, and then the precipitate is dried at 60 °C for one day to obtain MIP / MOF-808 / AB powder.

[0055] Among them, DMF is dimethylformamide; ZrOCl2·8H2O is zirconium oxychloride octahydrate; H3BTC is trimesic acid; DIM is the analyte dimethoate; TEOS is tetraethyl orthosilicate.

[0056] A method for detecting pesticides using the aforementioned detection materials and detection devices, comprising the following steps:

[0057] S1: Extract the redox probe;

[0058] Since dimethoate does not have electroactivity, dopamine solution is selected as the electroactive substance, that is, the redox probe, to indirectly measure the concentration of dimethoate. As Figure 2 shown, assembled into one, first start the peristaltic pump to extract dopamine solution, apply 5 μL of the molecularly imprinted metal-organic framework carbon material MIP / MOF-808 / AB detection material on the surface of the screen-printed electrode, irradiate and dry with an infrared lamp, insert it into the dopamine solution, connect the screen-printed electrode connector to a micro electrochemical workstation for electrochemical DPV testing, and obtain the initial response current signal I0;

[0059] S2: Adsorb the dimethoate solution;

[0060] The probe solution after the test in step S1 is discharged by the ball valve 6. Then, start the micro peristaltic pump 4 again to extract the dimethoate solution to be measured, so that the dimethoate solution completely submerges the screen-printed electrode, and the dimethoate solution is fully adsorbed by the screen-printed electrode;

[0061] S3: Test the operation process;

[0062] The adsorbed dimethoate solution is discharged by the ball valve 6, extract dopamine solution again, perform DPV testing, and obtain the inhibited response current signal I1. The detection process is as Figure 1 shown;

[0063] S4: Calculate the response current difference ΔI = I0 - I1; according to the linear fitting equation, calculate the linear regression equation between ΔI and the dimethoate concentration, and calculate the dimethoate concentration in the solution to be measured;

[0064] As Figure 6 shown, when detecting dimethoate solutions of 10000, 1000, 100, 10, 1, 0.1 nM, the square wave voltammograms measured show that it can be clearly seen from the curve that as the concentration of the dimethoate solution gradually increases, the response current difference ΔI gradually increases, which conforms to the response law of the inhibition-type sensor.

[0065] From Figure 7 it can be seen that the linear regression equation for the relationship between the dimethoate concentration and the change in the response current difference is:

[0066] ΔI = 0.9064log(C) + 9.656 (R 2= 0.9961), with a detection range of 0.1 - 10000 nM and a detection limit of 0.85 nM (S / N = 3). Among them, R 2 is the correlation coefficient after fitting, which is together with the linear equation. R 2 The closer it is to 1, the better the fitting effect and the more accurate the result.

[0067] Now, the standard addition method is adopted to use the present invention for detecting the target substance in actual samples (the detection process is carried out in the aforementioned manner), and a recovery experiment is conducted. The recovery rate refers to the relative recovery rate, and the calculation formula is:

[0068] [Measured value of the spiked sample - True value] / Spiked amount × 100%, and its purpose is to examine the accuracy, that is, to measure the closeness between the measured value using the present invention and the true value.

[0069] The specific implementation steps are as follows: Add a known concentration of dimethoate solution to the ABS buffer solution with a pH of 5.5, and its added concentration refers to Table 1. The detection results of the organophosphorus pesticide dimethoate are shown in Table 1.

[0070] Table 1 MIP / MOF - 808 / AB portable electrochemical sensor in actual samples

[0071] It can be seen from Table 1 that the recovery rate of this patent is between 86.4 - 104.7%, and the RSD is less than 5%. The measurement results are relatively ideal. Compared with the traditional detection method, this detection is relatively simple and fast.

[0072] In the agricultural field, pesticides are an inevitable component, and they play various roles, such as fungicides, herbicides, etc. However, as the main pesticides, organophosphorus pose a serious threat to the ecological environment due to their extensive use, endangering human health and life safety. Continuous exposure to organophosphorus pesticides can cause disorders of the human nervous system, such as respiratory paralysis, organ damage, carcinogenesis, and even death. Dimethoate is one of the most common organophosphorus insecticides, with the chemical name of O,O - dimethyl - S - (N - methylcarbamoylmethyl) dithiophosphate, which is used to kill insects harmful to plants. The abuse of dimethoate will lead to accumulation in water bodies, food, and soil. Therefore, it is necessary to remove the dimethoate residues in water bodies, food, and soil. Using the pesticide detection device, detection materials, and detection methods of the present invention, the residual dimethoate pesticides can be detected, which is convenient

[0073]

[0074] to quickly detect the concentration of dimethoate pesticides contained in actual samples.

Claims

1. A portable pesticide detection device, characterized in that, It includes a detection body and a detachable detection cover. A screen-printed electrode (5) is provided on the detection cover. The detection body and the detection cover form a sealed detection chamber. The screen-printed electrode (5) is connected to a screen-printed electrode connector (8); an outlet is also provided on the electrochemical detection chamber (4), and a detection tube is provided at the bottom of the detection body. The interior of the detection body is partitioned into an electrochemical detection chamber (4) and a working chamber. The screen-printed electrode (5) is located in the electrochemical detection chamber (4), and a micro peristaltic pump (2) is provided in the working chamber; the outlet side of the micro peristaltic pump (2) is communicated with the electrochemical detection chamber (4) through a one-way valve (3), and the inlet side of the micro peristaltic pump (2) is connected to the detection tube.

2. The pesticide detection device according to claim 1, wherein, An outlet is further provided at the bottom of the electrochemical detection chamber (4), and a ball valve (6) is provided on the outlet; an air hole (7) is also provided on the detection cover.

3. The pesticide detection device according to claim 1, characterized in that, The screen-printed electrode (5) is a carbon electrode. The screen-printed electrode (5) includes a working electrode, a reference electrode, and a counter electrode; a filtering device (1) is provided on the detection tube, and the filtering device (1) is a polyethersulfone microporous membrane.

4. A detection method using the pesticide detection device according to any one of claims 1-3, characterized in that, It includes the following steps: S1: Extract the redox probe; Start the peristaltic pump to extract the electroactive substance. Apply 5 μL of the detection material on the surface of the screen-printed electrode, dry it by irradiating with an infrared lamp, insert it into the electroactive substance, connect the screen-printed electrode connector to a micro electrochemical workstation for electrochemical DPV test, and obtain the initial response current signal I0. S2: Adsorb the dimethoate solution; The electroactive substance tested in step S1 is discharged through the ball valve. Then, start the micro peristaltic pump again to extract the dimethoate solution to be detected, so that the dimethoate solution completely submerges the screen-printed electrode, and the dimethoate solution is fully adsorbed by the screen-printed electrode. S3: Test operation process; The adsorbed dimethoate solution is discharged through the ball valve. Then, extract the electroactive substance again through the micro peristaltic pump for DPV test to obtain the inhibited response current signal I1. S4: Calculate the response current difference ΔI = I0 - I1, obtain the linear regression equation of the dimethoate concentration log(C) and the response current difference ΔI according to linear fitting, and calculate the dimethoate concentration in the solution to be detected.

5. The detection method of the pesticide detection device according to claim 4, characterized in that The linear regression equation of the change relationship between the dimethoate concentration log(C) and the response current difference ΔI is: ΔI = 0.9064 log(C) + 9.656(R 2 = 0.9961).

6. The detection method of the pesticide detection device according to claim 4, characterized in that, The electroactive substance is dopamine solution.

7. The detection method of the pesticide detection device according to claim 4, characterized in that, The detection material is a molecularly imprinted metal-organic framework carbon material MIP / MOF-808 / A.

8. A method for preparing the detection material according to any one of claims 4-7, characterized in that, It includes the following steps: A1: Prepare the metal-organic framework carbon material MOF-808 / AB; specifically including: A11: Weigh 0.97 g of ZrOCl2·8H2O and 3.252 mg of AB and add them to 50 ml of DMF and FA (1:1 V1 / V2) to obtain solution A. Ultrasonically disperse solution A for 30 minutes to obtain a clear solution B. Then weigh 0.21 g of H3BTC and add it to the clear solution B, and then ultrasonically disperse the clear solution B to obtain a homogeneous solution C. A12: Transfer the homogeneous solution C obtained in step A11 into a Teflon autoclave, react at 120 °C for 21 h to obtain solution D, centrifuge and precipitate the obtained solution D, then wash the obtained precipitate with DMF and methanol 5 times respectively, and then dry the precipitate at 60 °C for one day to obtain MOF-808 / AB powder; A2: Prepare a molecularly imprinted metal-organic framework carbon material MIP / MOF-808 / AB using the metal-organic framework carbon material MOF-808 / AB; specifically including: A21: Weigh 0.25 g of the MOF-808 / AB powder prepared in step A1, 10 μL of APTES and 2 mL of NH3·H2O (25%) and mix them to obtain solution E, then add 0.01 g of DIM and stir for 10 mins to obtain solution F; mix the obtained solution F with 5 mL of TEOS and stir at room temperature for 12 h for chemical polymerization; A22: The solution F obtained in step A21 is centrifuged and precipitated, and the obtained precipitate is washed with ethanol 5 times, and then the precipitate is dried at 60 °C for one day to obtain MIP / MOF-808 / AB powder.

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