A simple method for detecting carbofuran in vegetables and fruits

Abstract

The application discloses a simple detection method for carbofuran in vegetables and fruits, which comprises the following steps: step one, quantum dot preparation; step two, polymer synthesis; step three, characterization test; step four, fluorescence test; step five, adsorption test; step six, pretreatment adjustment; and step seven, detection comparison. Compared with the existing detection method for carbofuran in vegetables and fruits, the application uses quantum dots as a fluorescent sensor recognition element, introduces hydroxylated graphene, uses a carbofuran standard as a template molecule, and uses a molecular imprinting technique to synthesize a fluorescent molecular imprinting polymer, so that the detection of carbofuran has certain specificity, the accuracy of detection is improved, and false negative or false positive results are avoided. The application has a short detection time, can achieve on-site detection and result output, greatly improves the detection efficiency, is simple to operate, has small required detection instrument volume and low cost, is convenient to carry, and is favorable for popularization of the detection method.

Description

Technical Field

[0001] This invention relates to the field of food safety technology, specifically to a simple method for detecting carbofuran in vegetables and fruits. Background Technology

[0002] The government has always attached great importance to pesticide residues in fruits and vegetables, investing significant manpower and resources annually to ensure food safety. However, some unscrupulous vendors still illegally use pesticides for profit, resulting in excessive pesticide residues in agricultural products. This seriously affects people's daily lives. Carbofuran, a broad-spectrum and highly effective insecticide, is widely used. It has a long residual effect, typically a half-life of 30-60 days in soil, and is not easily degraded, easily causing environmental pollution. Excessive carbofuran residues in food can cause reactions such as runny nose, tearing, and narrowed pores in consumers; in severe cases, it can lead to serious health problems. The rapid detection of carbofuran residues in food is crucial due to potential adverse effects such as decreased blood pressure and altered mental status. Existing methods for detecting carbofuran in fruits and vegetables mostly employ high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS), which are prone to false negatives or false positives. These methods are also time-consuming, inefficient, and cannot provide on-site results. Furthermore, they are complex to operate, require large, expensive, and inconvenient instruments, hindering their widespread adoption. Summary of the Invention

[0003] The purpose of this invention is to provide a simple method for detecting carbofuran in vegetables and fruits, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a simple method for detecting carbofuran in vegetables and fruits, comprising the following steps: Step 1, preparing quantum dots; Step 2, synthesizing polymers; Step 3, characterization testing; Step 4, fluorescence testing; Step 5, adsorption testing; Step 6, pretreatment adjustment; Step 7, detection comparison.

[0005] In step one above, colloidal semiconductor nanocrystals are prepared using an electrochemical method. These colloidal semiconductor nanocrystals are used as the recognition element of a sensor, and hydroxylated graphene is introduced during the process to obtain a polymer.

[0006] In step two above, a carbofuran standard is taken as a template molecule and mixed with the polymer obtained in step one. Carbofuran fluorescent molecularly imprinted polymer is synthesized using a bulk polymerization method.

[0007] In step three above, scanning electron microscopy is used to characterize the synthesized fluorescent molecularly imprinted polymer using various characterization methods, and the optimal synthesis method is determined based on the characterization results.

[0008] In step four above, the carbofuran fluorescent molecular imprinted polymer from step two is taken, the imprinted molecules are dissociated, and then the imprinted molecules are used to perform a series of fluorescence performance tests on the target carbofuran.

[0009] In step five above, the imprinted molecule used in step four is taken to perform an adsorption experiment on the target carbofuran. The adsorption results are compared, and the one with the highest adsorption result is determined to be the ideal fluorescent molecular imprinted polymer.

[0010] In step six above, the vegetables to be tested are first dried, crushed, and sieved. Then, acetone is added for ultrasonic extraction. The extract is centrifuged to obtain the supernatant, which is then evaporated. Then, methanol, anhydrous sodium sulfate, and Florisil are added. Finally, elution buffer is used to elute and evaporate the sample to obtain the analyte containing carbofuran.

[0011] In step seven above, the detection of carbofuran in vegetables is achieved based on the linear response of the constructed fluorescent molecular imprinted sensor to carbofuran at a certain concentration.

[0012] Preferably, in step two, the template molecules and polymer are placed in a pore-forming agent, and then a crosslinking agent is added to form a rigid polymer by heating.

[0013] Preferably, in step three, the characterization methods include infrared spectroscopy and fluorescence spectroscopy.

[0014] Preferably, in step four, the fluorescence performance test includes tests for detection limit, sensitivity, linear range, etc.

[0015] Preferably, in step six, multiple sample pretreatments are performed by changing the extraction time, extraction temperature, and acetone addition amount to maximize the extraction of carbofuran from the vegetables.

[0016] Preferably, in step seven, in order to verify the effectiveness and accuracy of the fluorescence sensing method, after the carbofuran detection is completed, the detection results need to be compared and verified with the detection results of the traditional high performance liquid chromatography method.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: Compared with existing methods for detecting carbofuran in fruits and vegetables, this invention uses quantum dots as the fluorescent sensor recognition element, introduces hydroxylated graphene, uses carbofuran standards as template molecules, and uses molecular imprinting technology to synthesize fluorescent molecularly imprinted polymers, which have a certain specificity for the detection of carbofuran, improves the accuracy of detection, and avoids false negative or false positive results; the detection time required by this invention is shorter, and on-site detection and results can be obtained, which greatly improves the detection efficiency; the operation of this invention is simple, and the required detection instruments are small in size, low in price, and easy to carry, which is conducive to the promotion of this detection method. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 The present invention provides an embodiment of a simple method for detecting carbofuran in fruits and vegetables, comprising the following steps:

[0021] Step 1: Quantum dot fabrication; Step 2: Polymer synthesis; Step 3: Characterization and testing; Step 4: Fluorescence testing; Step 5: Adsorption testing; Step 6: Pretreatment adjustment; Step 7: Detection and comparison.

[0022] In step one above, colloidal semiconductor nanocrystals are prepared using an electrochemical method. These colloidal semiconductor nanocrystals are used as the recognition element of a sensor, and hydroxylated graphene is introduced during the process to obtain a polymer.

[0023] In step two above, a sample of carbofuran standard is taken as a template molecule and mixed with the polymer obtained in step one. Carbofuran fluorescent molecularly imprinted polymer is synthesized by bulk polymerization, that is, the template molecule and the polymer are placed in a pore-forming agent, and then a crosslinking agent is added. A rigid polymer is formed by heating.

[0024] In step three above, the synthesized fluorescent molecularly imprinted polymer is characterized using scanning electron microscopy and characterization methods such as infrared spectroscopy and fluorescence spectroscopy, and the optimal synthesis method is determined based on the characterization results.

[0025] In step four above, the carbofuran fluorescent molecular imprinted polymer from step two is taken, the imprinted molecules are dissociated, and then the imprinted molecules are used to perform a series of fluorescence performance tests on the target carbofuran, including tests for detection limit, sensitivity, linear range, etc.

[0026] In step five above, the imprinted molecule used in step four is taken to perform an adsorption experiment on the target carbofuran. The adsorption results are compared, and the one with the highest adsorption result is determined to be the ideal fluorescent molecular imprinted polymer.

[0027] In step six above, the vegetables to be tested are first dried, crushed, and sieved. Then, acetone is added for ultrasonic extraction. The extract is centrifuged, the supernatant is collected and evaporated, and then methanol, anhydrous sodium sulfate, and Florisil are added. Finally, elution buffer is used to elute and evaporate the sample to obtain the analyte containing carbofuran. By changing the extraction time, extraction temperature, and amount of acetone added, multiple sample pretreatments are established to maximize the extraction of carbofuran from the vegetables.

[0028] In step seven above, the linear response of the constructed fluorescent molecularly imprinted sensor to carbofuran at a certain concentration is used to detect carbofuran in vegetables. To verify the effectiveness and accuracy of the fluorescence sensing method, after the carbofuran detection is completed, the detection results need to be compared and verified with the detection results of the traditional high performance liquid chromatography method.

[0029] Based on the above, the advantages of this invention are that, due to its low detection limit and specificity, the detection method provided by this invention avoids false negatives or false positives that occur in previous rapid detection methods, thus ensuring the precision and accuracy of the detection. Traditional detection methods require about one month from sampling to issuing a test report, while this invention greatly reduces the detection time and improves detection efficiency. This invention is simple to operate, and the required detection instruments are small in size, inexpensive, and portable, which is conducive to its promotion in rapid pesticide detection methods.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A simple method for detection of carbofuran in vegetables and fruits comprising the steps of: Step 1: Fabrication of quantum dots; Step 2: Polymer synthesis; Step 3: Characterization and testing; Step 4: Fluorescence testing; Step 5: Adsorption testing; Step 6: Pretreatment adjustment; Step 7: Detection and comparison; Its characteristic is: In step one above, colloidal semiconductor nanocrystals are prepared using an electrochemical method. These colloidal semiconductor nanocrystals are used as the recognition element of a sensor, and hydroxylated graphene is introduced during the process to obtain a polymer. In step two above, a carbofuran standard is taken as a template molecule and mixed with the polymer obtained in step one. Carbofuran fluorescent molecularly imprinted polymer is synthesized using a bulk polymerization method. In step three above, scanning electron microscopy is used to characterize the synthesized fluorescent molecularly imprinted polymer using various characterization methods, and the optimal synthesis method is determined based on the characterization results. In step four above, the carbofuran fluorescent molecular imprinted polymer from step two is taken, the imprinted molecules are dissociated, and then the imprinted molecules are used to perform a series of fluorescence performance tests on the target carbofuran. In step five above, the imprinted molecule used in step four is taken to perform an adsorption experiment on the target carbofuran. The adsorption results are compared, and the one with the highest adsorption result is determined to be the ideal fluorescent molecular imprinted polymer. In step six above, the vegetables to be tested are first dried, crushed, and sieved. Then, acetone is added for ultrasonic extraction. The extract is centrifuged to obtain the supernatant, which is then evaporated. Then, methanol, anhydrous sodium sulfate, and Florisil are added. Finally, elution buffer is used to elute and evaporate the sample to obtain the analyte containing carbofuran. In step seven above, the detection of carbofuran in vegetables is achieved based on the linear response of the constructed fluorescent molecular imprinted sensor to carbofuran at a certain concentration.

2. The simple method for detecting carbofuran in vegetables and fruits according to claim 1, characterized in that: In step two, the template molecules and polymer are placed in a pore-forming agent, and then a crosslinking agent is added to form a rigid polymer by heating.

3. The method as claimed in claim 1, wherein the method is simple and rapid for detection of carbofuran in vegetables and fruits. In step three, the characterization methods include infrared spectroscopy and fluorescence spectroscopy.

4. The method as claimed in claim 1, wherein the method is simple and rapid for detection of carbofuran in vegetables and fruits. In step four, the fluorescence performance test includes tests for detection limit, sensitivity, and linear range.

5. The method as claimed in claim 1, wherein the method is simple and rapid for detection of carbofuran in vegetables and fruits. In step six, multiple sample pretreatments are performed by changing the extraction time, extraction temperature, and acetone addition to maximize the extraction of carbofuran from the vegetables.

6. The method as claimed in claim 1, wherein the method is simple and rapid for detection of carbofuran in vegetables and fruits. In step seven, in order to verify the effectiveness and accuracy of the fluorescence sensing method, after the carbofuran detection is completed, the detection results need to be compared and verified with the detection results of the traditional high performance liquid chromatography method.

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