A method for detecting insecticides in food and medicine

Abstract

The invention discloses a method for detecting insecticide in food and medicine. Copper nanoclusters BSA-CuNCs are used as fluorescent probes, and nano copper porphyrin DTAB-CuTPyP is used as a fluorescence quencher. When BSA-CuNCs and DTAB-CuTPyP are combined, DTAB-CuTPyP can induce aggregation of BSA-CuNCs, resulting in quenching of the fluorescence of BSA-CuNCs. After insecticide is added, the insecticide can be combined with DTAB-CuTPyP through electrostatic interaction, resulting in fluorescence recovery of BSA-CuNCs. The method provides a sensitive fluorescence platform for the determination of insecticide.

Description

Technical Field

[0001] The invention relates to the technical field of chemical analysis and detection, in particular to a method for detecting insecticides in food and medicine. Background Art

[0002] The insecticide is an artificially synthesized analogue of nereis toxin. Once it enters the body of an insect, it is rapidly converted into nereis toxin or dihydronereis toxin. It has strong contact, stomach poison and systemic transmission effects, and has a good control effect on the larvae of lepidopteran pests.

[0003] The main analytical methods for insecticides include colorimetry, gas chromatography, and liquid chromatography. Visual colorimetry has the disadvantage of low accuracy. If there is a second colored substance in the test solution, it may even be impossible to measure. In addition, since many colored solutions are unstable in color, the standard series cannot be stored for a long time and often need to be prepared during measurement, which is troublesome. Even if some stable colored substances, such as potassium dichromate, copper sulfate, and cobalt sulfate, can be used to prepare permanent standard series, or colored plastics and colored glass can be used to make permanent color scales, their colors are often different from the color of the test solution, so they also need to be calibrated. Both gas chromatography and liquid chromatography analysis rely on large instruments, resulting in high detection costs and long detection times. The operations of both are cumbersome and require strong professional knowledge of the test personnel.

[0004] The prior art has disclosed the "Calcium-palladium fluorescence spectrophotometric method for the determination of trace insecticides". Although this method meets the above requirements, the heavy metal palladium used in the detection process is very likely to cause environmental pollution. Therefore, there is an urgent need for an analysis method for insecticides with low detection cost, short detection time, high sensitivity and simple operation. Summary of the invention

[0005] The purpose of the present invention is to provide a method for detecting insecticides in food and medicine to solve the problems existing in the above-mentioned prior art. The fluorescent probe and fluorescent quencher used in the method are non-toxic and harmless, detection does not require large equipment, the operation is simple, the detection time is short, and the sensitivity is high.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for detecting insecticide in food and medicine, using BSA-CuNCs (copper nanoclusters) as a fluorescent probe and DTAB-CuTPyP (nano-copper porphyrin) as a fluorescence quencher, comprising the following steps:

[0008] The fluorescence quencher DTAB-CuTPyP was added to the fluorescent probe BSA-CuNCs to quench it, and then the insecticide test solution was added to measure the change in fluorescence intensity at 320-600nm. The concentration of insecticide in the test solution was obtained based on the linear regression equation of the fluorescence intensity change and the insecticide concentration.

[0009] Preferably, the molar ratio of BSA-CuNCs to DTAB-CuTPyP is 1:2.5-4.

[0010] Preferably, the preparation method of BSA-CuNC is:

[0011] Add BSA (bovine serum albumin) to water and stir until dissolved. Add anhydrous copper sulfate solution, mix, and stir until the solution turns into a light blue gel. Then add alkaline solution (preferably 0.1 mol·L -1 Adjust the pH to alkaline by adding sodium hydroxide solution, then add N 2 H 4 ·H 2 O (hydrazine hydrate) solution, seal and stir until the solution turns brown-yellow to obtain BSA-CuNCs solution.

[0012] Preferably, the concentration of the anhydrous copper sulfate solution is 0.05 mol / L, the added mass ratio of BSA to the anhydrous copper sulfate solution is 1:8, and the pH is 11.5-12.5.

[0013] Preferably, the preparation method of DTAB-CuTPyP is:

[0014] (1) Propionic acid, glacial acetic acid and nitrobenzene are mixed, heated to reflux, and then 4-pyridinecarboxaldehyde and pyrrole are added. After reacting for 2-3 hours, water is added, and the mixture is evaporated, the solvent is removed, and then suction filtered. The obtained solid is dried to obtain TPyP (tetrakis-(4-pyridyl)porphyrin);

[0015] (2) Weigh TPyP and dissolve it in DMF (N, N-dimethylformamide), heat it, add CuCl2 when reflux occurs, continue heating and react for 2.5-3.5 hours, add water after the reaction is completed, let it stand and precipitate, filter it with suction, and dry it to obtain CuTPyP (copper porphyrin);

[0016] (3) DTAB (dodecyltrimethylammonium bromide) and CuTPyP are mixed, sonicated, heated, and cooled to obtain DTAB-CuTPyP.

[0017] Preferably, the volume ratio of propionic acid, glacial acetic acid and nitrobenzene in step (1) is 1:1:1; and the molar ratio of 4-pyridinecarboxaldehyde and pyrrole in step (1) is 3:2.

[0018] Preferably, in step (2), TpyP and CuCl2 The mass ratio of DTAB to CuTPyP is 600-700:800-900; the molar ratio of DTAB to CuTPyP in step (3) is 20-200:1.

[0019] The beneficial effects are:

[0020] 1. The present invention discloses a method for detecting insecticides in food and medicine. The fluorescent probe BSA-CuNCs used has high chemical stability, high photostability and low toxicity. The fluorescent quencher DTAB-CuTPyP used has stable chemical properties. After preparation, it can be stored in a -4°C refrigerator for 3-6 months. It does not need to be prepared immediately before use. When used, it can be taken out and directly mixed according to proportion. Therefore, the determination method of the present invention is simple to operate and low in cost.

[0021] 2. The present invention first adds fluorescence quenching DTAB-CuTPyP to the fluorescent agent BSA-CuNCs, then adds the test solution, and measures the insecticide in the test solution through a specific sample addition order. When BSA-CuNCs and DTAB-CuTPyP are combined, DTAB-CuTPyP can induce BSA-CuNCs to aggregate, resulting in quenching of the fluorescence of BSA-CuNCs. After adding a solution containing insecticide, the insecticide can combine with DTAB-CuTPyP through electrostatic interaction, resulting in fluorescence recovery of BSA-CuNCs. Under optimal conditions, the molar ratio of BSA-CuNCs to DTAB-CuTPyP is 1:4, and the reaction time of DTAB-CuTPyP and insecticide is 1 min. This method provides a sensitive fluorescence platform for the determination of insecticide. The detection method is simple to operate, does not require large-scale equipment, takes a short time to measure, does not require excessive professional requirements for operators, and has high accuracy, high sensitivity, and a good linear range. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A is the TEM characterization image of BSA-CuNCs in Example 1; Figure 1 B is the XPS result of Cu in BSA-CuNCs;

[0024] Figure 2 A is the TEM characterization image of DTAB-CuTPyP in Example 1; Figure 2B is the UV-visible absorption spectra of CuTPyP and DTAB-CuTPyP;

[0025] Figure 3 This is a schematic diagram of the detection principle of Example 1;

[0026] Figure 4 The fluorescence spectra of BSA-CuNCs, BSA-CuNCs+DTAB-CuTPyP and BSA-Cu NCs+DTAB-CuTPyP+monosultap in Example 1;

[0027] Figure 5 This is a linear relationship diagram between the insecticide concentration and the change in fluorescence intensity in Example 1. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] The room temperature in the present invention refers to 25±2°C.

[0034] The embodiment of the present invention provides a method for detecting insecticide in food and medicine, using BSA-CuNCs as a fluorescent probe and DTAB-CuTPyP as a fluorescence quencher, comprising the following steps:

[0035] The fluorescence quencher DTAB-CuTPyP was added to the fluorescent probe BSA-CuNCs to quench it, and then the insecticide test solution was added to measure the change in fluorescence intensity at 320-600nm. The concentration of insecticide in the test solution was obtained based on the linear regression equation of the fluorescence intensity change and the insecticide concentration.

[0036] Among them, the molar ratio of BSA-CuNCs and DTAB-CuTPyP is 1:2.5-4.

[0037] By controlling the dosage ratio of copper nanoclusters BSA-CuNCs and nanocopper porphyrin DTAB-CuTPyP to 1:2.5-4, all copper nanoclusters BSA-CuNCs are effectively quenched. DTAB-CuTPyP plays a role in quenching the fluorescence intensity of BSA-CuNCs in this detection system. If the dosage of DTAB-CuTPyP is too small, the quenching intensity is low, resulting in a narrow detection range of the insecticide; if the dosage of DTAB-CuTPyP is too large, the fluorescence intensity of BSA-CuNCs will be severely quenched, and a high concentration of insecticide must be added to achieve fluorescence recovery, resulting in a detection limit that is too high.

[0038] Through stirring, copper ions cooperate with functional groups such as -NH, -OH, and -SH in BSA to form a hydrogel; the pH is controlled at 11.5-12.5.

[0039] BSA-CuNCs have good electrical and optical properties, not only have ultra-small size, but also have high chemical stability, high photostability and low toxicity; porphyrin is composed of four pyrrole rings, which are connected together by neutral carbon bridges to form a ring structure; metal porphyrin is a type of coordination compound, which is composed of porphyrin and metal ions and contains conjugated macrocycles; nanosized metal porphyrin is used as a fluorescence quencher to detect various metal ions and pesticide residues; the present invention proposes a method of combining BSA-CuNCs and DTAB-CuTPyP, utilizing the specific reaction between double coppers, first adding DTAB-CuTPyP to the BSA-CuNCs solution, after fluorescence quenching, adding a test solution, the insecticide in the test solution is combined with DTAB-CuTPyP through electrostatic interaction, resulting in the fluorescence recovery of BSA-CuNCs, and the specific sample addition sequence is used to detect insecticide in food and medicine.

[0040] Wherein, the preparation method of BSA-CuNC is:

[0041] Add BSA to water and stir until dissolved. Add anhydrous copper sulfate solution, mix, and stir until the solution becomes a light blue gel. Add alkaline solution to adjust the pH to alkaline, and then add 85% (mass concentration) N 2 H 4 ·H 2 O solution, sealed and stirred until the solution turned brown-yellow to obtain copper nanocluster BSA-CuNCs solution.

[0042] In some preferred embodiments of the present invention, the mass ratio of BSA to anhydrous copper sulfate solution is 1:8, and the pH value is 11.5-12.5.

[0043] The preparation method of DTAB-CuTPyP is as follows:

[0044] (1) Propionic acid, glacial acetic acid and nitrobenzene are mixed, heated to reflux, and then 4-pyridinecarboxaldehyde and pyrrole are added. After reacting for 2-3 hours, water is added, and the mixture is evaporated, the solvent is removed, and then suction filtered. The obtained solid is dried to obtain TPyP (tetrakis-(4-pyridyl)porphyrin);

[0045] (2) Weigh TPyP and dissolve it in DMF (N, N-dimethylformamide), heat it, add CuCl2 when reflux occurs, continue heating and react for 2.5-3.5 hours, add water after the reaction is completed, let it stand and precipitate, filter it with suction, and dry it to obtain CuTPyP (copper porphyrin);

[0046] (3) DTAB (dodecyltrimethylammonium bromide) and CuTPyP are mixed, sonicated, heated, and cooled to obtain DTAB-CuTPyP.

[0047] In some preferred embodiments of the present invention, the volume ratio of propionic acid, acetic acid and nitrobenzene in step (1) is 1:1:1; the rotary evaporation temperature is 65-75°C; the molar ratio of 4-pyridinecarboxaldehyde to pyrrole in step (1) is 3:2, the drying temperature is 60-80°C, and the drying time is 12-24h; in step (2), TpyP and CuCl 2 The mass ratio of DTAB and CuTPyP is 600-700:800-900; in step (3), the molar ratio of DTAB and CuTPyP is 20-200:1, the ultrasonic time is 10-15min, the heating time is 15-20min, and the heating temperature is 65-70°C.

[0048] By adding DTAB to nanosize CuTPyP, the specific surface area of ​​CuTPyP is increased, thereby improving the optical properties of porphyrin and its affinity with other substances, which helps it to better combine with the fluorescent agent and cause fluorescence quenching at the nanometer level; after adding insecticide, it helps it to electrostatically combine with insecticide, thereby improving the detection sensitivity.

[0049] The room temperature in the embodiments of the present invention refers to 25±2°C.

[0050] The chemical reagents and solvents used in the examples were all analytically pure, the stirring was carried out using a magnetic stirrer, and the fluorescence spectrum measurement conditions were an emission wavelength of 330-600 nm, an excitation wavelength of 320 nm, and a slit width of 10 nm.

[0051] Example 1

[0052] A method for detecting insecticides in food and medicine:

[0053] The preparation method of BSA-CuNCs is:

[0054] Add 200 g of BSA powder to 10 mL of ultrapure water and stir until BSA is dissolved. Then add 10 mL of 0.1 mol L -1 The anhydrous copper sulfate solution was stirred at room temperature for 10 min. During the stirring process, the copper ions combined with the -NH, -OH, -SH and other functional groups in the bovine serum albumin to form a hydrogel. The solution turned into a light blue gel. When 0.1 mol·L -1 The pH of the solvent was adjusted to 12 with sodium hydroxide solution. During the addition of sodium hydroxide solution, the mixed solution gradually became clear and the color of the solution eventually turned to light purple. Then, 1 mL of 85% (mass concentration) N 2 H 4 ·H 2 O was injected into the mixed solution and stirred at room temperature for 4 h. The color of the solution gradually changed to brown-yellow to obtain a BSA-CuNCs solution with a concentration of 0.05 mol·L -1 . Figure 1 A in the figure is the TEM characterization image of BSA-CuNCs. Figure 1 Figure B is the XPS result of Cu in BSA-CuNCs.

[0055] The preparation method of DTAB-CuTPyP is:

[0056] (1) 30 mL of propionic acid, 30 mL of glacial acetic acid and 30 mL of nitrobenzene were added to a round-bottom flask respectively. The mixed solution was refluxed in an oil bath at 150 °C. Then 3.0 mL of 10 mmol·L -1 4-pyridinecarboxaldehyde solution and 2mL of 10mmol·L -1 After 2 h of reaction, ultrapure water was added to the round-bottom flask while it was hot, and then rotary evaporated at 70 °C to remove the solvent and filter. The obtained solid was dried at 70 °C for 24 h to obtain purple powder TPyP.

[0057] (2) Accurately weigh 0.0687 g of TPyP powder and dissolve it in 30 mL of DMF. Heat it in an oil bath at 150 °C. When reflux occurs, add 0.0887 g of CuCl 2 The heating reaction was continued for 3 h. After the reaction was completed, 60 mL of ultrapure water was added to the round-bottom flask, and the mixture was allowed to stand for 180 min for precipitation. The precipitate was then filtered and dried to obtain powdered CuTPyP.

[0058] (3) Add 28.5 mL of 0.02 mol·L -1 DTAB and 1.5 mL of 5 × 10 -4 mol·L -1 After CuTPyP was ultrasonically mixed for 10 min, the mixed solution was heated in a water bath at 70 °C for 15 min, and the solution color was observed to change to light purple. After cooling to room temperature, DTAB-CuTPyP was obtained. Figure 2 A in the figure is the TEM characterization image of DTAB-CuTPyP. Figure 2 B is the UV-visible absorption spectrum of CuTPyP and DTAB-CuTPyP, the abscissa is the wavelength, and the ordinate is the absorbance.

[0059] 120 μL of BSA-CuNCs solution and 80 μL of DTAB-CuTPyP were added to a 1.5 mL cuvette, so that the molar ratio of BSA-CuNCs to DTAB-CuTPyP was 1:4, and then 730 μL of ultrapure water was added. After mixing for 1 min, the fluorescence spectrum was measured at 350-600 nm, and the fluorescence was quenched at 400 nm. 120 μL of BSA-CuNCs solution and 80 μL of DTAB-CuTPyP were added to a 1.5 mL cuvette, and then 100 μL of insecticide (concentration of 10 -4 mol·L -1 ) and 700 μL ultrapure water, fluorescence recovery at 400 nm, schematic diagram of detection principle see Figure 3 , fluorescence scanning diagram see Figure 4 .

[0060] Depend on Figure 4It can be seen that the pure BSA-CuNCs solution exhibits strong fluorescence absorption at 400nm. DTAB-CuTPyP is a good fluorescence quencher. After adding DTAB-CuTPyP, the fluorescence intensity of the BSA-CuNCs mixed solution at 400nm is quenched, resulting in the fluorescence "turn-off" phenomenon of BSA-CuNCs. However, after adding the systemic pesticide cypermethrin, the fluorescence intensity of BSA-CuNCs recovered. This may be because cypermethrin can interact with DTAB-CuTPyP, resulting in a decrease in the fluorescence quenching effect of DTAB-CuTPyP on BSA-Cu NCs, resulting in the fluorescence "turn-on" phenomenon of BSA-CuNCs.

[0061] Determination of the linear range of the method for detecting insecticide in food and medicine: 6 points were selected, and the concentration of insecticide added to each point was 0.33*10 -2 mg / kg, 15*10 -2 mg / kg, 20*10 -2 mg / kg, 25*10 -2 mg / kg, 30*10 -2 mg / kg, 33.3*10 -2 mg / kg, the reaction time of DTAB-CuTPyP and the above insecticides was 1 min. Under the above conditions, a linear relationship was established. The results are shown in Figure 5 shown.

[0062] pass Figure 5 The detection limit of the insecticide can be determined as follows: According to the linear equation y = 14.33x + 439.729, according to the 3σ / s principle (σ is the standard deviation of the blank sample, s is the slope of the linear regression curve), the detection limit (LOD) of the sensing method for detecting cartap is calculated to be 0.098 (*10 -2 )mg / kg.

[0063] The steps of applying a method for detecting insecticides in food and medicine to detect insecticides in fruits, vegetables, Chinese medicinal materials and soil matrices are as follows:

[0064] 100 μL of insecticide with concentrations of 10 mg / kg, 15 mg / kg, and 30 mg / kg were mixed with different substrates (apple, chrysanthemum, and soil) and 100 μL of copper nanoclusters BSA-CuNCs, 80 μL of nanocopper porphyrin DTAB-CuTPyP, and 140 μL of ultrapure water for 1 min. The fluorescence absorption of the mixed solution was measured under 320 nm excitation. Figure 5The recovery rate of chlorpyrifos in actual samples was calculated using the linear regression equation of the standard curve of chlorpyrifos, and the results are shown in Table 1. As can be seen from Table 1, the accuracy of the method for detecting chlorpyrifos in food and medicine provided by the present invention is good, and its content can be accurately determined even in a complex matrix.

[0065] Table 1

[0066]

[0067] Comparative Examples 1-5

[0068] Same as Example 1, except that the concentration and volume of BSA-CuNCs were fixed, and the volume of DTAB-CuTPy added was changed, see Table 2.

[0069] Table 2

[0070]

[0071] As can be seen from Table 2, the amount of BSA-CuNCs and DTAB-CuTPy added has a great influence on the fluorescence intensity. By examining the relationship between the concentration of insecticide and the change in fluorescence intensity, it is found that as the amount of DTAB-CuTPyP added gradually increases, its fluorescence recovery value also gradually increases. When the volume of DTAB-CuTPyP added exceeds 80ul, its fluorescence recovery value gradually decreases, indicating that the low concentration of insecticide can no longer restore the fluorescence intensity of BSA-CuNCs. Therefore, the optimal amount of DTAB-CuTPyP is 80ul.

[0072] Comparative Example 6

[0073] A method for detecting insecticides in food and medicine:

[0074] The preparation method of BSA-CuNCs solution and DTAB-CuTPy was the same as that in Example 1. BSA-CuNCs and DTAB-CuTPy were mixed in a molar ratio of 4:1 and then the insecticide was measured. The linear relationship between the concentration of insecticide and the change in fluorescence intensity was investigated. It was found that with the increase of the concentration of insecticide, the fluorescence intensity of BSA-CuNCs / DTAB-CuTPyP sensing gradually increased. The concentration of insecticide was 0.33-33.3 (*10 -2 )mg / kg range, and the fluorescence intensity of the BSA-CuNCs / DTAB-CuTPyP system showed a good linear relationship. The linear relationship between the two is y=14.33x+439.729(R 2 =0.9948), indicating that the sensor can be used for quantitative detection of insecticide, but the detection sensitivity decreased due to the change in the mixing molar ratio of BSA-CuNCs and DTAB-CuTPyP.

[0075] In the detection system provided by the present invention, DTAB-CuTPyP is used as a fluorescence quencher to quench the fluorescence intensity of BSA-CuNCs, so the ratio between the two needs to be limited. The amount of BSA-CuNCs is fixed, and the amount of DTAB-CuTPyP added is changed. It can be found that as the amount of DTAB-CuTPyP increases, the fluorescence intensity of the system first increases and then decreases (as shown in Table 2). This is because the amount of DTAB-CuTPyP added is small at the beginning, and after adding the insecticide, the fluorescence intensity of BSA-CuNCs can be effectively restored. However, when the mixing molar ratio of BSA-CuNCs and DTAB-CuTPyP exceeds 1:4, the amount of DTAB-CuTPyP is too much. Even if the insecticide can inhibit the effect of part of DTAB-CuTPyP after adding the insecticide, the excessive DTAB-CuTPyP will still produce fluorescence quenching on BSA-CuNCs, resulting in a decrease in detection sensitivity.

[0076] Comparative Examples 7-10

[0077] A method for detecting insecticides in food and medicine:

[0078] Same as Example 1, the concentration of insecticide was fixed at 33.3*10 -2 The difference is that the reaction time of DTAB-CuTPyP and insecticide is adjusted, and the change between the reaction time and fluorescence intensity of DTAB-CuTPyP and insecticide is investigated. The results are shown in Table 3.

[0079] Table 3

[0080]

[0081] By examining the changes in the reaction time and fluorescence intensity between DTAB-CuTPyP and insecticide, it was found that as the reaction time between DTAB-CuTPyP and insecticide increased, the fluorescence recovery effect gradually weakened. Therefore, it can be determined that the optimal reaction time between DTAB-CuTPyP and insecticide is 1 minute.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting insecticides in food and medicine, characterized in that: Using BSA-CuNCs as a fluorescent probe and DTAB-CuTPyP as a fluorescence quencher, the method includes the following steps: Adding a fluorescence quencher DTAB-CuTPyP to the fluorescent probe BSA-CuNCs to quench it, then adding the insecticide test solution, measuring the change in fluorescence intensity at 320-600 nm, and obtaining the concentration of insecticide in the test solution according to a linear correlation standard curve between the change in fluorescence intensity and the concentration of insecticide; The molar ratio of the BSA-CuNCs to the DTAB-CuTPyP is 1:2.5-4; The preparation method of the DTAB-CuTPyP is: (1) Propionic acid, glacial acetic acid and nitrobenzene are mixed, heated to reflux, and then 4-pyridinecarboxaldehyde and pyrrole are added. After reacting for 2-3 hours, water is added, and the mixture is evaporated and the solvent is removed by suction filtration. The resulting solid is dried to obtain TPyP; (2) Weigh TPyP and dissolve it in DMF, heat it, add CuCl2 when reflux occurs, continue heating and react for 2.5-3.5 hours, add water after the reaction is completed, let it stand and precipitate, filter it and dry it to obtain CuTPyP; (3) mixing DTAB and CuTPyP, ultrasonicating, heating, and cooling to obtain DTAB-CuTPyP; In step (1), the volume ratio of propionic acid, glacial acetic acid and nitrobenzene is 1:1:1, and the molar ratio of 4-pyridinecarboxaldehyde and pyrrole is 3:2; In step (2), the mass ratio of TpyP to CuCl2 is 600-700: 800-900; In step (3), the molar ratio of DTAB to CuTPyP is 20-200:1, the ultrasonic time is 10-15 min, the heating time is 15-20 min, and the heating temperature is 65-70°C.

2. A method for detecting insecticides in food and medicine according to claim 1, characterized in that: The preparation method of the BSA-CuNCs is: BSA was added to water and stirred until dissolved, anhydrous copper sulfate solution was added, mixed, and stirred until the solution became a light blue gel, and then an alkaline solution was added to adjust the pH to alkaline, and then N2H4·H2O solution was added, and the mixture was sealed and stirred until the solution turned brown-yellow to obtain a BSA-CuNCs solution.

3. A method for detecting insecticides in food and medicine according to claim 2, characterized in that: The concentration of the anhydrous copper sulfate solution is 0.05 mol / L; The added mass ratio of the BSA to the anhydrous copper sulfate solution is 1:8, and the pH is 11.5-12.5.

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