Test strip and method for detecting cyfluthrin

Abstract

The present invention discloses a test strip and method for detecting flucythrinate. The test strip comprises a sample absorption pad, a conjugate release pad, a reaction membrane, a water absorbent pad and a bottom plate, the reaction membrane has a detection line coated with a flucythrinate hapten-carrier protein conjugate and a quality control line coated with a sheep anti-mouse anti-antibody, and the conjugate release pad is sprayed with a flucythrinate monoclonal antibody-colloidal gold marker. The present invention also provides a method for detecting flucythrinate in fruit and vegetable samples using the above-mentioned test strip. The test strip provided by the present invention has the advantages of simple operation, high sensitivity, fast detection speed, low cost, and suitability for large-scale sample screening, and can meet the needs of my country's food regulatory authorities for on-site monitoring and detection.

Description

Technical Field

[0001] The invention relates to a test strip and a method for detecting cyfluthrin, and in particular to a colloidal gold test strip for detecting cyfluthrin, which is particularly suitable for detecting cyfluthrin residues in fruits and vegetables. Background Art

[0002] Cyfluthrin is a pyrethroid insecticide with high insecticidal activity. Its main mode of action on pests is contact killing and stomach poisoning. It has good control effects on a variety of lepidopteran pests and some underground pests. It is widely used in fruits, vegetables, tea and tobacco. However, due to long-term excessive use, the environmental problems caused by its pollution and residues have attracted widespread attention. my country's national standard GB 2763 stipulates the maximum residue limit of cyfluthrin in vegetables and some fruits. Therefore, it is imperative to establish a detection method for cyfluthrin in corresponding agricultural products.

[0003] The methods reported so far for detecting cyfluthrin are mainly instrumental methods such as gas chromatography, gas chromatography-mass spectrometry, high performance liquid chromatography, and liquid chromatography-mass spectrometry. These methods must be operated under laboratory conditions, and the sample pretreatment is cumbersome and time-consuming. Expensive instruments and equipment are also required. The detection cost is high, the time is long, and the operation is complicated. There are great limitations in the actual application process, and it is difficult to meet the needs of rapid detection of a large number of samples and on-site samples. Therefore, a simple and fast colloidal gold test strip suitable for cyfluthrin residues in fruits and vegetables is developed, which can meet the on-site screening and monitoring of a large number of samples, and can better meet the detection work of my country's food regulatory authorities. Summary of the invention

[0004] The purpose of the present invention is to provide a colloidal gold test strip capable of detecting cyfluthrin residues in fruits and vegetables, and to provide a detection method which is efficient, accurate, simple and suitable for on-site monitoring and screening of a large number of samples.

[0005] The test strip for detecting cyfluthrin provided by the present invention comprises a sample absorption pad, a conjugate release pad, a reaction membrane, a water absorption pad and a bottom plate; the reaction membrane is provided with a detection line coated with a cyfluthrin hapten-carrier protein conjugate and a quality control line coated with a goat anti-mouse anti-antibody; the conjugate release pad is sprayed with a cyfluthrin monoclonal antibody-colloidal gold marker.

[0006] The cyfluthrin monoclonal antibody is prepared by using the cyfluthrin hapten-carrier protein conjugate as an immunogen.

[0007] The cyfluthrin hapten-carrier protein conjugate is obtained by coupling the cyfluthrin hapten with a carrier protein, wherein the carrier protein is bovine serum albumin, ovalbumin, hemocyanin, thyroid protein or human serum albumin. The cyfluthrin hapten is obtained by reacting hydroxydichloropermethrin acid with thionyl chloride in pyridine to form an acyl chloride, then condensing with (alpha S)-4-fluoro-alpha-hydroxy-3-phenoxy-phenylacetonitrile to form an ester, and then reacting with succinic anhydride to form an ester. The molecular structure is:

[0008]

[0009] The sample absorption pad, the conjugate release pad, the reaction membrane and the water absorption pad are sequentially pasted on the bottom plate, and 1 / 3 to 1 / 2 of the conjugate release pad is covered under the sample absorption pad.

[0010] The bottom plate can be a PVC bottom plate or other hard non-absorbent material; the sample absorption pad can be filter paper or oil filter paper; the conjugate release pad can be glass wool or polyester material; the water absorbent pad is absorbent paper; the reaction membrane can be a nitrocellulose membrane or a cellulose acetate membrane.

[0011] Another object of the present invention is to provide a method for preparing the above-mentioned test strip, which comprises the steps of:

[0012] 1) preparing a release pad sprayed with a conjugate of cyfluthrin monoclonal antibody-colloidal gold marker;

[0013] 2) preparing a reaction membrane having a detection line coated with a cyfluthrin hapten-carrier protein conjugate and a quality control line coated with a goat anti-mouse anti-antibody;

[0014] 3) Assemble the conjugate release pad, reaction membrane, sample absorption pad, water absorption pad and bottom plate prepared in 1) and 2) into a test strip.

[0015] Specifically, the steps include:

[0016] 1) preparing a cyfluthrin hapten by reacting hydroxydichloropermethrin acid with thionyl chloride in pyridine, condensing the acyl chloride with (alpha S)-4-fluoro-alpha-hydroxy-3-phenoxy-phenylacetonitrile to form an ester, and then esterifying the cyfluthrin with succinic anhydride;

[0017] 2) coupling the cyfluthrin hapten to a carrier protein to prepare a cyfluthrin hapten-carrier protein conjugate;

[0018] 3) Immunizing mice with a cyfluthrin hapten-carrier protein conjugate, fusing mouse spleen cells and mouse myeloma cells, and screening to obtain a hybridoma cell line that secretes a cyfluthrin monoclonal antibody;

[0019] 4) extracting mouse IgG and immunizing healthy goats to obtain goat anti-mouse antibodies;

[0020] 5) coating the cyfluthrin hapten-carrier protein conjugate and goat anti-mouse anti-antibody on the detection line (T) and quality control line (C) of the reaction membrane respectively;

[0021] 6) preparing colloidal gold by reacting trisodium citrate with chloroauric acid;

[0022] 7) adding the prepared flucythrinate monoclonal antibody to the prepared colloidal gold to obtain a flucythrinate monoclonal antibody-colloidal gold marker;

[0023] 8) Spraying the cyfluthrin monoclonal antibody-colloidal gold marker onto the conjugate release pad, drying at 37° C. for 1 hour, taking out, and storing in a dry environment for later use;

[0024] 9) Soak the sample absorption pad in phosphate buffer containing 0.5% bovine serum albumin, pH 7.2, 0.1 mol / L for 2 h, and dry at 37°C for 2 h;

[0025] 10) Paste the sample absorption pad, conjugate release pad, reaction membrane, and water absorption pad on the bottom plate in order, and cover 1 / 3 of the conjugate release pad from the starting end with the sample absorption pad. Finally, cut into 3mm wide strips, put in plastic boxes, vacuum pack, and store at 4-30℃ for 12 months.

[0026] Another object of the present invention is to provide a method for detecting cyfluthrin residues in fruits and vegetables using the above test strip, which comprises the steps of:

[0027] (1) Sample pretreatment;

[0028] (2) Testing with test strips;

[0029] (3) Analyze the test results.

[0030] The cypermethrin rapid detection test strip of the present invention adopts highly specific antibody-antigen reaction and immunochromatographic analysis technology, fixes the cypermethrin monoclonal antibody-colloidal gold marker on the conjugate release pad, and the cypermethrin in the sample is combined with the cypermethrin monoclonal antibody-colloidal gold marker on the conjugate release pad during the flow process to form a drug-antibody-colloidal gold marker. The drug in the sample competes with the cypermethrin hapten-carrier protein conjugate on the reaction membrane detection line to bind to the cypermethrin monoclonal antibody-colloidal gold marker, and whether the sample liquid to be tested contains cypermethrin residue is determined according to the depth of the red band of the detection line.

[0031] During the test, the sample is treated and then dripped into the hole of the test strip. When the concentration of flucythrinate in the sample is lower than the detection limit or zero, the monoclonal antibody-colloidal gold marker will bind to the flucythrinate hapten-carrier protein conjugate fixed on the reaction membrane during the chromatography process, and a red strip will appear on the test line (T) and the quality control line (C), and the color of the T line is darker than that of the C line or consistent with the color of the C line; if the concentration of flucythrinate in the sample is equal to or higher than the detection limit, the monoclonal antibody-colloidal gold marker will completely bind to flucythrinate, so that no red strip will appear at the T line because of the competitive reaction, and the flucythrinate hapten-carrier protein conjugate will not bind to the T line, or the color will be lighter than that of the C line. Figure 3 shown.

[0032] Negative: When the control line (C) shows a red strip, the test line (T) also shows a red strip, and the color of the (T) line is close to or darker than the (C) line, it is judged as negative.

[0033] Positive: When the control line (C) shows a red strip, and the test line (T) does not show color or the color of the (T) line is lighter than that of the (C) line, it is judged as positive.

[0034] Invalid: When the control line (C) does not show a red strip, the test strip is considered invalid regardless of whether the test line (T) shows a red strip or not.

[0035] The test strip of the present invention has the advantages of high sensitivity, strong specificity, low cost, simple operation, short detection time, suitable for use by various units, simple storage and long shelf life. The method of using the test strip of the present invention to detect cyfluthrin residues is simple, rapid, intuitive, accurate, has a wide range of applications, low cost and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the synthesis diagram of cypermethrin hapten.

[0037] Figure 2 Schematic diagram of the cross-sectional structure of the test strip.

[0038] Figure 3 This is a diagram for determining the test strip test results. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0040] Example 1 Preparation of a test strip for detecting cyfluthrin

[0041] The preparation method of the test strip mainly comprises the following steps:

[0042] 1) preparing a release pad sprayed with a conjugate of cyfluthrin monoclonal antibody-colloidal gold marker;

[0043] 2) preparing a reaction membrane having a detection line coated with a cyfluthrin hapten-carrier protein conjugate and a quality control line coated with a goat anti-mouse anti-antibody;

[0044] 3) Assemble the conjugate release pad, reaction membrane, sample absorption pad, water absorption pad and bottom plate prepared in 1) and 2) into a test strip.

[0045] The following is a detailed step-by-step description:

[0046] 1. Synthesis of cyfluthrin hapten (synthesis route see attached Figure 1 )

[0047] Take 2.5 g of hydroxydichloropermethrin acid, add 50 mL of pyridine to dissolve, add 1.53 g of dichlorothionyl, stir at room temperature for 2 h, and evaporate directly to obtain a red oil; add 100 mL of dichloromethane to dissolve, add 2.4 g of (alpha S)-4-fluoro-alpha-hydroxy-3-phenoxy-benzeneacetonitrile, add 2 mL of triethylamine, stir at room temperature for 3 h, stop the reaction, add 80 mL of water to shake, let stand, separate the water phase, dry the organic phase over anhydrous sodium sulfate, evaporate to dryness, apply to a silica gel column, and elute and separate with a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 3:1 to obtain 1.25 g of the intermediate compound.

[0048] Take 1.25 g of the intermediate compound, add 100 mL of acetonitrile to dissolve, add 3 mL of triethylamine to stir well, add 0.55 g of succinic anhydride, heat and reflux to react for 4 h, stop the reaction, and remove acetonitrile and triethylamine by rotary evaporation to obtain a crude product. Add 100 mL of water, adjust the pH value to 6 with 1 mol / L HCl, add 70 mL of ethyl acetate × 3, extract three times, combine the organic phases, evaporate to dryness, and apply to a silica gel column. Elute and separate with a dichloromethane-methanol mixed solution with a volume ratio of 10:1 to obtain 0.64 g of succinic flucythrin, which is the flucythrin hapten.

[0049] 2. Preparation of immunogen

[0050] Take 21 mg of flucythrin hapten, add 1 mL of N,N-dimethylformamide (DMF) to dissolve, add 20 μL of triethylamine, add 133 μL of isobutyl chloroformate, cool to 0-5°C, react for 3 hours, and obtain hapten solution A; take 50 mg of bovine serum albumin (BSA), add 0.05 mol / L CB buffer to dissolve, and obtain solution B; add solution A dropwise to solution B, react at 4°C for 8 hours, dialyze and purify with 0.02 mol / L PBS buffer for 3 days, change the solution 3 times a day, and obtain flucythrin hapten-BSA conjugate, which is the immunogen, and store at -20°C.

[0051] 3. Preparation of coating

[0052] Take 12 mg of flucythrin hapten, add 1 mL of dimethyl sulfoxide (DMSO) to dissolve, add 10 mg of N-hydroxysuccinimide (NHS) and 12 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), react at room temperature for 3 hours to obtain hapten solution A; take 50 mg of ovalbumin (OVA), add 0.05 mol / L PB buffer to dissolve, and obtain solution B; add solution A dropwise to solution B, react at 4°C for 8 hours, dialyze and purify with 0.02 mol / L PBS buffer for 3 days, change the solution 3 times a day, and obtain flucythrin hapten-OVA conjugate, which is the coating source, and store at -20°C.

[0053] 4. Preparation of monoclonal antibodies against cyfluthrin

[0054] (1) Animal immunization

[0055] The immunogen obtained in step 2 was injected into Balb / c mice at an immunization dose of 150 μg / mouse to produce antiserum.

[0056] (2) Cell fusion and cloning

[0057] Spleen cells of immune Balb / c mice were taken and fused with SP2 / 0 myeloma cells at a ratio of 8:1 (quantity ratio), and the cell supernatant was measured by indirect competitive ELISA to screen positive wells. The positive wells were cloned by limiting dilution method until a hybridoma cell line that stably secreted monoclonal antibodies was obtained.

[0058] (3) Cell cryopreservation and recovery

[0059] Hybridoma cells were cryopreserved in 1×10 6 Cell suspensions of 100 cells / mL were stored in liquid nitrogen for a long time. When thawing, the cryopreserved tubes were taken out and immediately placed in a 37°C water bath for rapid thawing. After centrifugation to remove the cryopreservation solution, the cells were transferred to culture bottles for culture.

[0060] (4) Preparation and purification of monoclonal antibodies

[0061] Incremental culture method: hybridoma cells are placed in cell culture medium and cultured at 37°C. The obtained culture fluid is purified using the caprylic acid-saturated ammonium sulfate method to obtain monoclonal antibodies, which are then stored at -20°C.

[0062] The cell culture medium is prepared by adding calf serum and sodium bicarbonate to RPMI1640 culture medium, so that the final concentration of calf serum in the cell culture medium is 20% (mass fraction), and the final concentration of sodium bicarbonate in the cell culture medium is 0.2% (mass fraction); the pH value of the cell culture medium is 7.4.

[0063] 5. Preparation of goat anti-mouse antibodies

[0064] Sheep are used as immune animals, and mouse antibodies are used as immunogens to immunize pathogen-free sheep to obtain sheep anti-mouse antibodies.

[0065] 6. Preparation of cyfluthrin monoclonal antibody-colloidal gold label

[0066] (1) Preparation of colloidal gold

[0067] Dilute 1% chloroauric acid to 0.01% (mass fraction) with double distilled deionized water, take 100 mL and place it in a conical flask, heat it to boiling with a constant temperature electromagnetic stirrer, add 2.5 mL 1% trisodium citrate under continuous high temperature and continuous stirring, continue to stir and heat at a uniform speed until the solution turns translucent red, stop, cool to room temperature, restore to the original volume with deionized water, and store at 4°C. The prepared colloidal gold has a pure, translucent appearance, no precipitation and floating matter, and the color is wine red when observed under sunlight.

[0068] (2) Preparation of cyfluthrin monoclonal antibody-colloidal gold label

[0069] Under magnetic stirring, adjust the pH value of colloidal gold to 7.2 with 0.2 mol / L potassium carbonate solution, add the above-mentioned flucythrinate monoclonal antibody to the colloidal gold solution according to the standard of adding 20-50 μg antibody per ml of colloidal gold solution, continue stirring and mixing for 30 minutes; after standing for 10 minutes, add 10% BSA to make the final concentration in the colloidal gold solution 1%, and stand for 10 minutes. Centrifuge at 12000r / min and 4℃ for 40 minutes, discard the supernatant, wash the precipitate twice with resolubilization buffer, resuspend the precipitate with resolubilization buffer with a volume of 1 / 10 of the initial colloidal gold volume, and set at 4℃ for use.

[0070] Reconstitution buffer: 0.02 mol / L phosphate buffer containing 0.1% to 0.3% BSA by mass, 0.05% to 0.2% Tween-80 by mass, and pH 7.2.

[0071] 7. Preparation of conjugate release pad

[0072] The conjugate release pad was soaked in a phosphate buffer containing 0.5% BSA, pH 7.2, 0.5 mol / L, and evenly soaked for 1 hour, and then dried at 37°C for 3 hours for use. The prepared flucythrinate monoclonal antibody-colloidal gold marker was evenly sprayed on the conjugate release pad using an Isoflow film sprayer. After spraying 0.01 mL of flucythrinate monoclonal antibody-colloidal gold marker per 1 cm of the conjugate release pad, it was placed in a 37°C environment (humidity <20%) for 60 minutes, taken out, and placed in a dry environment (humidity <20%) for storage.

[0073] 8. Preparation of sample absorption pad

[0074] The sample absorption pad was immersed in a phosphate buffer solution containing 0.5% bovine serum albumin, pH 7.2, and 0.1 mol / L for 2 h, and then dried at 37°C for 2 h for later use.

[0075] 9. Preparation of reaction membrane

[0076] The cyfluthrin hapten-ovalbumin conjugate was coated on the reaction membrane to form a detection line, and the goat anti-mouse antibody was coated on the reaction membrane to form a quality control line.

[0077] Coating process: Dilute the cypermethrin hapten-ovalbumin conjugate to 1 mg / mL with phosphate buffer, and coat it on the test line (T line) on the nitrocellulose membrane with an Isoflow film dispenser, with a coating amount of 1.0 μL / cm; dilute the goat anti-mouse anti-antibody to 200 μg / mL with 0.01 mol / L, pH 7.4 phosphate buffer, and coat it on the quality control line (C line) on the nitrocellulose membrane with an Isoflow film dispenser, with a coating amount of 1.0 μL / cm. Dry the coated reaction membrane at 37°C for 2 hours for use.

[0078] 10. Assembly of test strips

[0079] According to the attached Figure 2 The cross-sectional structure of the test strip is shown, wherein a sample absorption pad (1), a conjugate release pad (2), a reaction membrane (3), and a water absorption pad (4) are sequentially pasted on a PVC bottom plate (7); 1 / 3 of the conjugate release pad is covered by the sample absorption pad from the starting end, the end of the conjugate release pad is connected to the starting end of the reaction membrane, the end of the reaction membrane is connected to the starting end of the water absorption pad, the starting end of the sample absorption pad is aligned with the starting end of the PVC bottom plate, and the end of the water absorption pad is aligned with the end of the PVC bottom plate; a detection line (5) and a quality control line (6) are provided on the reaction membrane, and both the detection line (T line) and the quality control line (C line) are strips perpendicular to the length of the test strip; the detection line is located on a side close to the end of the conjugate release pad; and the quality control line is located on a side away from the end of the conjugate release pad; the test strip is cut into small strips of 3 mm width by a machine, placed in a special plastic card, and stored in an environment of 4 to 30° C., with a validity period of 12 months.

[0080] Example 2 Detection of cyfluthrin in fruits and vegetables

[0081] 1. Sample pretreatment

[0082] Take a fresh sample, wipe off the dirt, and cut it into pieces less than 1 cm square; weigh (1.00±0.05) g of sample into a 15 mL centrifuge tube, add 5 mL of phosphate buffer, cover the tube, shake manually for 30 seconds, let it stand for 1 minute, and take the supernatant as the sample solution to be tested.

[0083] 2. Test with test strips

[0084] Use a micropipette to draw 70 μL of the sample liquid to be tested and drop it vertically into the sample well; start timing when the liquid flows, react for 10 minutes, and determine the result.

[0085] 3. Analyze the test results

[0086] Negative (-): The color of T line is darker than that of C line or the same as that of C line, indicating that the concentration of cyfluthrin in the sample is lower than the detection limit. Figure 3 a, 3b.

[0087] Positive (+): The color of the T line is lighter than that of the C line or the T line is not colored, indicating that the concentration of cyfluthrin in the sample is equal to or higher than the detection limit. Figure 3 c. 3d.

[0088] Invalid: No C line appears, indicating incorrect operation process or the test strip has deteriorated and become invalid, such as Figure 3 e, 3f.

[0089] Example 3 Sample detection example

[0090] 1. Detection limit test

[0091] Take blank leek, cabbage, cauliflower, Chinese cabbage, spinach, eggplant, apple, pear, and orange samples, add cypermethrin to the final concentrations of 0.05 mg / kg, 0.1 mg / kg, and 0.2 mg / kg, respectively, take test strips for testing, and repeat the measurement three times for each sample.

[0092] When the test strips were used to detect samples of leek, cabbage, cauliflower, Chinese cabbage, spinach, eggplant, apple, pear, and orange, when there was no flucythrinate and the added concentration was 0.05 mg / kg, the T line shown on the test strip was darker than the C line or consistent with the C line, indicating a negative result; when the added concentration of flucythrinate was 0.1 mg / kg or 0.2 mg / kg, the T line shown on the test strip was lighter than the C line or the T line did not show any color, indicating a positive result, indicating that the detection limit of this test strip for flucythrinate in fruits and vegetables is 0.1 mg / kg.

[0093] 2. False positive rate and false negative rate test

[0094] Twenty portions each of blank leek, cabbage, cauliflower, Chinese cabbage, spinach, eggplant, apple, pear, and orange samples and 20 portions each of positive leek, cabbage, cauliflower, Chinese cabbage, spinach, eggplant, apple, pear, and orange samples with cypermethrin added to a final concentration of 0.1 mg / kg were tested using test strips produced in three batches, and their positive and negative rates were calculated.

[0095] The results show that when the test strips produced in three batches are used to detect positive samples, the results are all positive, which means that the positive coincidence rate is 100% and the false negative rate is 0; when the negative samples are detected, the results are all negative, which means that the negative coincidence rate is 100% and the false positive rate is 0. This indicates that the test strip for detecting cyfluthrin of the present invention can quickly detect cyfluthrin residues in fruit and vegetable samples.

[0096] 3. Specificity test

[0097] When this test strip is used to detect 10 mg / kg of cypermethrin, chlorflucythrinate, cypermethrin, flucythrinate, bifenthrin, permethrin, cypermethrin, deltamethrin, ethomethrin and other pyrethroid insecticides, the T line on the test strip is darker than or consistent with the C line, and the result is negative, indicating that this test strip has no cross reaction to these drugs.

Claims

1. A test strip for detecting flucythrinate, comprising a sample absorption pad, a conjugate release pad, a reaction membrane, a water absorption pad and a bottom plate, wherein the reaction membrane has a detection line coated with a flucythrinate hapten-carrier protein conjugate and a quality control line coated with a goat anti-mouse anti-antibody, and the conjugate release pad is sprayed with a flucythrinate monoclonal antibody-colloidal gold marker; the flucythrinate monoclonal antibody is prepared using the flucythrinate hapten-carrier protein conjugate as an immunogen; the flucythrinate hapten-carrier protein conjugate is obtained by coupling the flucythrinate hapten with a carrier protein, and the carrier protein is bovine serum albumin, ovalbumin, hemocyanin, thyroid protein or human serum albumin, characterized in that The cyfluthrin hapten is obtained by reacting hydroxydichloropermethrin acid with thionyl chloride in pyridine to form an acyl chloride, then condensing with (alphaS)-4-fluoro-alpha-hydroxy-3-phenoxy-phenylacetonitrile to form an ester, and then esterifying with succinic anhydride. The molecular structure is as follows:

2. The test strip as claimed in claim 1, characterized in that The sample absorption pad, the conjugate release pad, the reaction membrane and the water absorption pad are sequentially pasted on the bottom plate.

3. A test strip as described in any one of claims 1-2, characterized in that 1 / 3 to 1 / 2 of the conjugate release pad is covered under the sample absorption pad.

4. A method for preparing the test strip according to any one of claims 1 to 3, comprising the steps of: 1) preparing a release pad sprayed with a conjugate of cyfluthrin monoclonal antibody-colloidal gold marker; 2) preparing a reaction membrane having a detection line coated with a cyfluthrin hapten-carrier protein conjugate and a quality control line coated with a goat anti-mouse anti-antibody; 3) Assemble the conjugate release pad, reaction membrane, sample absorption pad, water absorption pad and bottom plate prepared in 1) and 2) into a test strip.

5. A method for detecting cyfluthrin residues in fruit and vegetable samples, comprising the steps of: 1) Sample pretreatment; 2) Testing with the test strip according to any one of claims 1 to 3; 3) Analyze the test results.

Images