Pesticide residue detection method based on conductive material
By combining conductive materials with agglomerated powder materials, the detection method solves the problem of the stringent requirements on the morphology of the tested substances in traditional pesticide residue detection methods. It achieves rapid, accurate, and broad-spectrum pesticide residue detection, improving detection efficiency and sensitivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-03-24
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Traditional pesticide residue detection methods have stringent requirements on the morphology of the analytes, are cumbersome to operate, are prone to pesticide molecule loss or the introduction of impurities, have long detection cycles, and are prone to false negative or false positive results, making it difficult to meet the needs of rapid, accurate, and broad-spectrum detection.
The detection method combines conductive materials with agglomerated powder materials. The pretreatment method is selected according to the moisture content of the sample through probe or crushing. The pesticide residue is analyzed by utilizing the interaction between conductive materials and pesticide molecules and combining the Lambert-Beer law.
It enables rapid and accurate detection of analytes in different forms, avoids pesticide molecule loss and impurity interference, broadens the scope of detection applications, improves detection efficiency and sensitivity, and reduces operational complexity.
Smart Images
Figure CN121721091A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pesticide residue detection technology, specifically relating to a pesticide residue detection method based on conductive materials. Background Technology
[0002] In the fields of agricultural production, food safety supervision, and environmental monitoring, pesticide residue detection is a crucial link in protecting human health and controlling the quality of agricultural products. With the continuous enrichment of pesticide types (such as organophosphates, carbamates, and pyrethroids) and the diversification of application scenarios (plant cultivation, fruit and vegetable cultivation, etc.), traditional pesticide residue detection methods are no longer sufficient to meet the practical needs of rapid, accurate, and broad-spectrum detection.
[0003] Traditional pesticide residue detection methods (such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) have stringent requirements on the morphology of the analytes, necessitating the uniform processing of samples into liquid extracts. For analytes with high water content (such as strawberries, cucumbers, and lettuce), while pesticides are easily extracted, direct crushing can lead to juice loss and pesticide molecule loss. For analytes with low water content (such as apples, carrots, and dried wheat leaves), a large amount of organic solvent needs to be added for extraction, which is not only cumbersome but may also introduce impurities that interfere with the detection results. Furthermore, for some special morphological samples, such as seeds and waxy fruit and vegetable peels, the dense structure makes it difficult for pesticide molecules to be fully released. Traditional methods often require multiple extractions and purifications, significantly extending the detection cycle and increasing the likelihood of false negatives or false positives. Summary of the Invention
[0004] The purpose of this invention is to provide a pesticide residue detection method based on conductive materials. This method utilizes a combination of agglomerated powder materials and conductive materials, achieving breakthroughs in multiple dimensions such as detection adaptability, efficiency, sensitivity, and cost, and is highly practical.
[0005] The specific technical solution adopted by this invention is as follows:
[0006] A pesticide residue detection method based on conductive materials, the method comprising the following steps:
[0007] S1: Select the test substance containing pesticide residues and differentiate them according to the moisture content of the test substance;
[0008] In step S1, the substance being tested includes any one of plants or fruits and vegetables, and the pretreatment method is selected according to the water content.
[0009] S2: Pre-treatment is carried out according to the different moisture content of the tested substance. Pre-treatment includes direct treatment and crushing treatment.
[0010] In step S2, the specific steps for the direct processing of the detected object are as follows:
[0011] S21: Select an object with a high water content, then directly insert the probe into the object and pull it out, leaving three detection holes of varying depths on the object.
[0012] S22: Use a probe to pick up agglomerated powder material, insert it into the detection hole again, send the agglomerated powder material into the detection hole, and mix it with the moisture in the sample being tested;
[0013] S23: Remove the probe and let the sample stand for 5-15 minutes in preparation for testing.
[0014] For substances with high moisture content, the following testing procedures are required:
[0015] The conductive material is inserted into the pre-drilled hole and left to stand for 3-5 minutes. Then, an electric current is applied to the conductive material. The pesticide molecules agglomerate due to the action of the agglomerating powder material. The pesticide molecules interact with the surface of the conductive material, which changes the resistance and current of the conductive material. The pesticide residue can be obtained by using the calibration curve through the background control system in accordance with the Lambert-Beer law.
[0016] In step S2, the specific steps for the crushing process of the tested object are as follows:
[0017] S211: Select the test substance with low water content, cut it into pieces, and then place it in a blender for crushing. Use the juice mode of the blender and crush for 1-2 minutes to obtain a thicker test substance.
[0018] S212: Pour the crushed test material into a glass container, and add the agglomerated powder material into the glass container at a ratio of 10:0.2-0.5, and stir evenly;
[0019] S213: Let stand at room temperature for 5-15 minutes before testing.
[0020] For test subjects with low moisture content, the following testing procedures are performed:
[0021] The conductive material is inserted into a glass container, immersing it in a relatively thick sample. After standing for 3-5 minutes, an electric current is applied to the conductive material. The pesticide molecules agglomerate due to the action of the agglomerating powder material. The pesticide molecules interact with the surface of the conductive material, changing the resistance and current of the conductive material. The analysis is then conducted through a background control system in accordance with the Lambert-Beer law, and the pesticide residue level can be obtained using a calibration curve.
[0022] S3: The pretreated sample is tested for pesticide residues using conductive materials;
[0023] S4: Connect the conductive material to the background control system for reading and recording test data.
[0024] The conductive material is graphene.
[0025] The agglomerated powder material is any one of montmorillonite, chitosan, or modified starch.
[0026] The technical effects achieved by this invention are as follows:
[0027] The present invention provides a pesticide residue detection method based on conductive materials, which adopts a direct detection processing method without breaking the sample. It uses the moisture of the sample itself to disperse the agglomerated powder, which avoids pesticide loss due to juice loss. Furthermore, the shallow-medium-deep gradient design of the detection orifice covers the pesticide residue detection from the sample surface to the interior, solving the problem that traditional methods can only detect surface residues.
[0028] This invention provides a pesticide residue detection method based on conductive materials, employing a fragmentation detection process to prepare the sample into a uniform, viscous substance. This ensures thorough mixing of the agglomerated powder with pesticide molecules. Furthermore, a powder addition ratio of 10:0.2-0.5 is specified to avoid the problems of excessive or insufficient solvent addition in traditional methods. In addition, a water replenishment step can be flexibly added for samples with extremely low moisture content, such as seeds, further broadening the applicability of the detection method and achieving coverage of all morphological samples, including plants and fruits and vegetables. Attached Figure Description
[0029] Figure 1 These are embodiments of the present invention;
[0030] Figure 2 This is a flowchart of the present invention;
[0031] Wherein, a is the probe piercing the detection hole; b is the probe dipping into the agglomerated powder material; c is the agglomerated powder material being fed into the detection hole; and d is the conductive material being prepared to be inserted into the detection hole for detection.
[0032] The attached diagram lists the components represented by each number as follows:
[0033] 1. Item to be tested; 2. Detection hole; 3. Probe; 4. Agglomerated powder material; 5. Conductive material. Detailed Implementation
[0034] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.
[0035] like Figure 1As shown, a pesticide residue detection method based on conductive materials includes the following steps:
[0036] S1: Select the test substance containing pesticide residues and differentiate them according to the moisture content of the test substance;
[0037] The moisture content of the tested items is measured using a handheld moisture meter. Items with a moisture content ≥80% are classified as having high moisture content (such as strawberries, cucumbers, lettuce, etc.), while those with a moisture content <80% are classified as having low moisture content (such as apples, carrots, potatoes, etc.). During testing, samples should be taken from different parts of the tested items three times, and the average value is taken as the final moisture content to avoid misjudgment of the pretreatment method due to local moisture differences.
[0038] In S1, the tested substance includes any one of the following: plants or fruits and vegetables, and the pretreatment method is selected according to the moisture content.
[0039] For plant-based products, leafy plants (such as lettuce and wheat leaves) have a water content of ≥80% and are suitable for direct treatment; seed-based plants (such as dried soybeans and corn) have a water content of <15% and require an additional small amount of water replenishment step, adding deionized water to the crushed sample to make the sample consistency reach a state that can adhere to the surface of conductive materials.
[0040] After the water replenishment ratio is 10:1 (sample:water), the mixture is then subjected to appropriate crushing treatment.
[0041] S2: Pre-treatment is carried out according to the different moisture content of the tested substance. Pre-treatment includes direct treatment and crushing treatment.
[0042] In S2, the specific steps for the direct processing of the detected substance are as follows:
[0043] S21: Select the test object with a high water content, then directly insert the probe into the test object and pull it out, leaving three test holes of varying depths on the test object; the probe is a medical-grade 304 stainless steel probe, and the three test holes are arranged linearly from peel to pulp to core. In direct detection, the probe treatment method can accurately reflect the pesticide residue content at different locations.
[0044] S22: Use a probe to pick up agglomerated powder material and insert it into the detection well to deliver the agglomerated powder material into the detection well and mix it with the moisture in the analyte. Taking montmorillonite as an example, the amount picked up at one time is 0.8-1mg, the particle size is 100-200 mesh, and the water content is ≤5%. Slowly insert the probe with the powder into the bottom of the detection well and gently rotate the probe 2 times to ensure that the powder falls evenly into the detection well. Then slowly pull out the probe. The moisture in the analyte will automatically mix with the powder to form a paste mixture (no additional water is needed, the moisture in the sample itself is sufficient to meet the powder dispersion requirements). The paste mixture can encapsulate pesticide molecules in the well and provide a carrier for subsequent agglomeration.
[0045] S23: Remove the probe and allow the sample to stand for 5-15 minutes before testing. Allow the sample to stand at room temperature (20-25℃) in the dark (avoid light exposure to prevent pesticide molecule decomposition and ensure accurate detection). Adjust the standing time according to the type of sample: for softer samples such as strawberries and lettuce, stand for 5-8 minutes (avoid prolonged standing to prevent sample rotting); for harder samples such as cucumbers, stand for 10-15 minutes (to ensure sufficient interaction between the powder and pesticide molecules). Avoid touching the sample during the standing period to prevent leakage of the mixture from the detection well.
[0046] For substances with high moisture content, the following testing procedures are required:
[0047] The conductive material is inserted into the pre-drilled hole and left to stand for 3-5 minutes. Then, an electric current is applied to the conductive material. The pesticide molecules agglomerate due to the action of the agglomerating powder material. The pesticide molecules interact with the surface of the conductive material, which changes the resistance and current of the conductive material. The pesticide residue can be obtained by using the calibration curve through the background control system in accordance with the Lambert-Beer law.
[0048] In S2, the specific steps for handling the crushing of the tested object are as follows:
[0049] S211: Select the test substance with low water content, cut it into pieces, and then place it in a blender for crushing. Use the juice mode of the blender and crush for 1-2 minutes to obtain a thicker test substance.
[0050] S212: Pour the crushed test material into a glass container, and add the agglomerated powder material into the glass container at a ratio of 10:0.2-0.5, and stir evenly;
[0051] When applying the powder, it is necessary to use an electronic balance (accuracy 0.001g) to accurately weigh the powder to avoid improper proportions that may lead to deviations in the effect (too low a proportion will result in insufficient agglomeration ability; too high a proportion will cause the powder to agglomerate itself, interfering with pesticide detection).
[0052] S213: Let stand at room temperature for 5-15 minutes, ready for detection. Allow the agglomerated powder to fully diffuse in the viscous sample, adsorb pesticide molecules and form clusters (20-60nm in diameter), while ensuring that the clusters are in close contact with the surface of the conductive material (the viscosity of the viscous sample can fix the position of the clusters and prevent the clusters from detaching from the conductive material with the flow of the liquid).
[0053] For test subjects with low moisture content, the following testing procedures are performed:
[0054] The conductive material is inserted into a glass container, immersing it in a relatively thick sample. After standing for 3-5 minutes, an electric current is applied to the conductive material. The pesticide molecules agglomerate due to the action of the agglomerating powder material. The pesticide molecules interact with the surface of the conductive material, changing the resistance and current of the conductive material. The analysis is then conducted through a background control system in accordance with the Lambert-Beer law, and the pesticide residue level can be obtained using a calibration curve.
[0055] Specifically, a constant voltage of 0.6V is applied (the resistance of viscous samples is slightly higher; appropriately increasing the voltage ensures that the current signal can be acquired), and the sampling frequency is 1Hz. When applying Lambert-Beer's law, the calibration curve needs to use a standard solution that matches the sample matrix (e.g., when testing apple samples, a standard solution is prepared using apple pulp and standard pesticides to eliminate matrix effect interference). The goodness of fit R... 2 ≥0.99, the final pesticide residue unit is ng / g (fresh weight of the tested substance).
[0056] S3: The pretreated sample is tested for pesticide residues using conductive materials;
[0057] The detection methods are divided into direct detection and breakage detection. In practice, the detection method needs to be selected according to the characteristics of the plant or fruit and vegetable being tested.
[0058] S4: Connect the conductive material to the background control system for reading and recording test data.
[0059] The conductive material is connected to the electrochemical workstation of the back-end control system via shielded wires (to avoid external electromagnetic interference); the system displays the "resistance change value (ΔR)" and "current change value (ΔI)" in real time, and automatically calculates the pesticide residue; the recorded content includes: sample name, moisture content, pretreatment method, detection time, three parallel detection data, average value, and relative standard deviation (RSD); the data must be automatically stored (cannot be manually modified) and can be exported to Excel format (including the original signal curve and calculation process);
[0060] Result determination: The system has a built-in national standard threshold library (such as GB2763 "National Food Safety Standard Maximum Residue Limits for Pesticides in Food"). After the test is completed, it automatically compares the thresholds and outputs the judgment result of "qualified" (residue ≤ threshold) or "exceeding the standard" (residue > threshold), and marks the corresponding national standard number (such as the maximum residue limit of dichlorvos in apples is 0.1 mg / kg).
[0061] The conductive material is graphene.
[0062] Graphene has a single-atom-layer two-dimensional structure and ultra-high electrical conductivity (10⁻⁶). 6 S / m), ultra-large specific surface area (approximately 2630m²) 2 Its properties of being easily functionalized and modified have made it a core conductive material in the field of pesticide residue detection.
[0063] Among them, graphene can be used in conjunction with sensor structures to make up for the shortcomings of traditional detection methods (such as high performance liquid chromatography and gas chromatography) that are large in size, complex in operation, and long in detection cycle.
[0064] Graphene has an inert surface but contains a large number of π-electron conjugated systems, which can form π-π stacking, hydrogen bonds, or van der Waals forces with the polar groups of pesticide molecules (such as P=O, COC). After adsorption, pesticide molecules occupy the electron transport channels on the graphene surface or transfer charge to the graphene (such as the dipole moment of polar molecules changing the local electron cloud density of graphene), resulting in a decrease in the conductivity and an increase in the resistance of graphene. The change in electrical signal is linearly related to the concentration of pesticide molecules (following the Lambert-Beer law), and the amount of pesticide residue can be inferred by using the calibration curve.
[0065] For example, when a graphene-modified electrode detects dichlorvos, the phosphate ester groups of the dichlorvos molecule form hydrogen bonds with the hydroxyl groups on the graphene surface, which reduces the carrier mobility of the graphene. The resistance increases linearly with the dichlorvos concentration (0.1–100 ng / mL), and the detection limit can reach 0.05 ng / mL.
[0066] The agglomerated powder material can be any one of montmorillonite, chitosan, or modified starch.
[0067] Specifically, the core principle of adsorbing pesticide residues and promoting pesticide molecule agglomeration is to adsorb pesticide molecules (mostly small organic molecules, such as organophosphates and pyrethroids) on the surface or shallow layer of fruits and vegetables into the structure of the pesticide itself through physical adsorption (such as pore trapping and surface charge action) or chemical / physical aggregation (such as colloidal flocculation and hydrophobic action), and promote the aggregation of pesticide molecules into clusters through intermolecular forces.
[0068] In this solution, when the moisture in the sample comes into contact with the conductive material, the pesticide molecules are adsorbed by the agglomerated powder material. Therefore, whether the process is direct or crushed, the contact surface with the conductive material can be maximized, thereby increasing the contact area between the pesticide molecules and the conductive material and improving the accuracy of pesticide residue detection.
[0069] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.
Claims
1. A method for detecting pesticide residues based on conductive materials, characterized in that: The detection method includes the following steps: S1: Select the test substance containing pesticide residues and differentiate them according to the moisture content of the test substance; S2: Pre-treatment is carried out according to the different moisture content of the tested substance. Pre-treatment includes direct treatment and crushing treatment. S3: The pretreated sample is tested for pesticide residues using conductive materials; S4: Connect the conductive material to the background control system for reading and recording test data.
2. The pesticide residue detection method based on conductive materials according to claim 1, characterized in that: In step S1, the substance being tested includes any one of plants or fruits and vegetables, and the pretreatment method is selected according to the water content.
3. The pesticide residue detection method based on conductive materials according to claim 1, characterized in that: In step S2, the specific steps for the direct processing of the detected object are as follows: S21: Select an object with a high water content, then directly insert the probe into the object and pull it out, leaving three detection holes of varying depths on the object. S22: Use a probe to pick up agglomerated powder material, insert it into the detection hole again, send the agglomerated powder material into the detection hole, and mix it with the moisture in the sample being tested; S23: Remove the probe and let the sample stand for 5-15 minutes in preparation for testing.
4. The pesticide residue detection method based on conductive materials according to claim 3, characterized in that: For substances with high moisture content, the following testing procedures are required: The conductive material is inserted into the pre-drilled hole and left to stand for 3-5 minutes. Then, an electric current is applied to the conductive material. The pesticide molecules agglomerate due to the action of the agglomerating powder material. The pesticide molecules interact with the surface of the conductive material, which changes the resistance and current of the conductive material. The pesticide residue can be obtained by using the calibration curve through the background control system in accordance with the Lambert-Beer law.
5. The pesticide residue detection method based on conductive materials according to claim 1, characterized in that: In step S2, the specific steps for the crushing process of the tested object are as follows: S211: Select the test substance with low water content, cut it into pieces, and then place it in a blender for crushing. Use the juice mode of the blender and crush for 1-2 minutes to obtain a thicker test substance. S212: Pour the crushed test material into a glass container, and add the agglomerated powder material into the glass container at a ratio of 10:0.2-0.5, and stir evenly; S213: Let stand at room temperature for 5-15 minutes before testing.
6. The pesticide residue detection method based on conductive materials according to claim 5, characterized in that: For test subjects with low moisture content, the following testing procedures are performed: The conductive material is inserted into a glass container, immersing it in a relatively thick sample. After standing for 3-5 minutes, an electric current is applied to the conductive material. The pesticide molecules agglomerate due to the action of the agglomerating powder material. The pesticide molecules interact with the surface of the conductive material, changing the resistance and current of the conductive material. The analysis is then conducted through a background control system in accordance with the Lambert-Beer law, and the pesticide residue level can be obtained using a calibration curve.
7. The pesticide residue detection method based on conductive materials according to claim 1, characterized in that: The conductive material is graphene.
8. The pesticide residue detection method based on conductive materials according to claim 1, characterized in that: The agglomerated powder material is any one of montmorillonite, chitosan, or modified starch.