A method for detecting dinotefuran

Abstract

The present invention belongs to the technical field of pesticide detection, and specifically relates to a method for detecting dinotefuran, which is detected by GC-MS, weighing fruit and vegetable samples, adding methanol and grinding for 1.5 minutes, and then centrifuging for 5 minutes at a speed of 12500r / min, taking the supernatant, passing through a molecularly imprinted nanocomposite membrane, and then eluting the molecularly imprinted nanocomposite membrane with 10mL of eluent to obtain a sample solution to be tested; the sample solution to be tested is detected by GC-MS, and the test result is substituted into a standard curve to obtain the content of dinotefuran in the sample solution to be tested. The present invention detects dinotefuran by a gas chromatography-mass spectrometry method, and the detection equipment cost is low and the detector used is simple.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticide detection, and particularly relates to a method for detecting dinotefuran. Background Art

[0002] Dinotefuran is the latest generation of super nicotine insecticide. Its chemical structure is quite different from that of existing nicotine insecticides. Its tetrahydrofuran group replaces the previous chloropyridyl and chlorothiazolyl groups, and it does not contain halogen elements. At the same time, its performance is also different from that of nicotine, and its insecticidal spectrum is wider.

[0003] However, excessive intake of dinotefuran can cause symptoms such as breathing difficulties or respiratory arrest, coma, tachycardia, hypotension, nausea or vomiting, sweating, mydriasis, bradycardia, fever, dizziness, oral ulcers, difficulty swallowing, epilepsy and abdominal pain, which are harmful to human health and may cause the occurrence of diseases.

[0004] The existing detection methods of dinotefuran generally use LC-MS (liquid chromatography mass spectrometry) detection, for example, a method for determining 101 pesticide residues in wolfberry with application number CN201811346153.6, which detects the dinotefuran residue in wolfberry through LC-MS / MS analysis. Although the above LC-MS / MS analysis method for detecting dinotefuran residue can accurately detect the content of dinotefuran in wolfberry, the LC-MS detection pre-treatment is complicated and the machine is expensive, and the detection cost is high. Summary of the invention

[0005] The object of the present invention is to provide a method for detecting dinotefuran to solve the problems raised in the above background technology.

[0006] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0007] A method for detecting dinotefuran, comprising the following steps:

[0008] S1, preparation of molecularly imprinted nanocomposite membranes;

[0009] The mesoporous silica nanoparticles were placed in a mixed solution of 3-aminopropyltriethoxysilane and toluene, and ultrasonically treated for 10 minutes, and then refluxed in an oil bath at 110° C. for 12 hours, and the obtained mixture was washed to obtain amino-functionalized silica nanoparticles;

[0010] Adding amino-functionalized silica nanoparticles to an acrylic acid aqueous solution, ultrasonically treating for 1 hour, washing and drying the obtained mixture to obtain functionalized mesoporous silica nanoparticles C-MSN;

[0011] C-MSN was added to tetrahydrofuran and ultrasonically treated for 30 min. The supernatant was evenly dropped on two glass plates. The PVDF membrane was placed between the two glass plates. The glass plates were placed in a 90°C oven for 4 h. After cooling at room temperature, a C-MSN double-sided PVDF membrane was obtained.

[0012] The template molecule dinotefuran and C-MSN double-sided PVDF membrane were dissolved in ethanol and stirred for 15 minutes, and then functional monomers and cross-linking agents were added thereto, stirred for 15 minutes, and then ammonia water was dropped thereinto, stirred at room temperature for 4 hours, and then rinsed with deionized water to obtain a molecularly imprinted nanocomposite membrane;

[0013] S2, preparation of sample solution to be tested;

[0014] Weigh the fruit and vegetable samples, add methanol and grind for 1.5 min, then centrifuge at 12500 r / min for 5 min, take the supernatant, pass it through the molecularly imprinted nanocomposite membrane, and then elute the molecularly imprinted nanocomposite membrane with 10 mL of eluent to obtain the sample solution to be tested;

[0015] S3, preparation of spiked sample solution;

[0016] Take the sample solution to be tested, add dinotefuran to dissolve it, and form a spiked sample solution, wherein 100 ng of dinotefuran is added to every 1 mL of the sample solution to be tested;

[0017] S4, GC-MS detection;

[0018] The test sample solution and the spiked sample solution were respectively subjected to GC-MS detection, the injection volume of the test sample solution and the spiked sample solution was 1 μL, and then the test results were substituted into the standard curve to obtain the content of dinotefuran in the test sample solution.

[0019] As an improvement, the conditions for GC-MS detection are as follows:

[0020] Gas chromatography detection conditions;

[0021] Chromatographic column: Chromatographic column DB-5MS, length 30m, inner diameter 0.25mm, film thickness 0.25μm, carrier gas He, column flow rate 1.69mL / min;

[0022] Heating program: initial temperature 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 260℃ at a heating rate of 10℃ / min, hold for 3min;

[0023] The splitless mode was used, and the injection port temperature was 250 °C;

[0024] Mass spectrometry detection conditions;

[0025] The mass spectrometer detector used an EI ion source, the ionization voltage was 70 eV, the ion source temperature was 230 °C, the scanning mode was selected ion scanning, and the solvent delay time was 1.5 min;

[0026] The qualitative ion fragments of dinotefuran are 55 and 95

[0027] As a further improvement, in step S4, the method for drawing the standard curve is as follows:

[0028] S21, adding methanol to the dinotefuran standard to prepare a 1 mg / mL dinotefuran-methanol solution, and then diluting the dinotefuran-methanol solution stepwise with methanol to prepare six standard sample solutions of 5 ng / mL, 50 ng / mL, 200 ng / mL, 800 ng / mL, 1600 ng / mL and 3200 ng / mL;

[0029] S22. Perform GC-MS detection on the six standard sample solutions respectively, and draw a standard curve with the peak area of ​​dinotefuran as the ordinate y and the mass concentration of dinotefuran as the abscissa x.

[0030] As a further improvement, in step S1, the PVDF membrane is prepared using polyvinylidene fluoride and polyvinyl pyrrolidone as raw materials.

[0031] As a further improvement, in step S1, the molar ratio of the template molecule dinotefuran, the functional monomer and the cross-linking agent is 1:4:20;

[0032] The functional monomer is a mixed solution of acrylamide and methacrylic acid, the molar ratio of acrylamide to methacrylic acid is 1:1, and the cross-linking agent is ethylene glycol dimethacrylate.

[0033] As a further improvement, the GC-MS detection conditions were screened based on the characteristic ion fragments of dinotefuran to change the temperature conditions of GC-MS detection. The specific method is as follows:

[0034] Based on the characteristic ion fragment 57 of dinotefuran, the temperature conditions were adjusted, and the 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS and the TIC diagram was drawn;

[0035] Based on the characteristic ion fragments 55, 69, and 95 of dinotefuran, the temperature conditions were adjusted, and the 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS and the TIC diagram was drawn;

[0036] Based on the characteristic ion fragments 55, 69, 95, 115, 130, and 88 of dinotefuran, 1 mg / mL dinotefuran-methanol standard solution and methanol solution were detected by GC-MS and TIC diagrams were drawn;

[0037] According to the TIC graph obtained under the above detection conditions, the temperature conditions used for the best peak shape were selected, and the peak time of dinotefuran and the characteristic ion fragments of dinotefuran were determined.

[0038] As a further improvement, based on the characteristic ion fragment 57 of dinotefuran, GC-MS detection was performed on a 1 mg / mL dinotefuran-methanol standard solution using conditions 1 and 2 respectively;

[0039] Condition one:

[0040] Gas chromatography conditions:

[0041] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0042] Heating program: initial temperature 40℃, hold for 2min, increase the temperature to 320℃ at a heating rate of 25℃ / min, hold for 20min;

[0043] The splitless mode was used, and the injection port temperature was 250 °C;

[0044] The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 250 °C, ion scanning selected as scanning mode, and solvent delay time of 1.5 min;

[0045] Condition two:

[0046] Gas chromatography conditions:

[0047] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0048] Heating program: initial temperature 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 300℃ at a heating rate of 10℃ / min, hold for 15min;

[0049] The splitless mode was used, and the injection port temperature was 250 °C;

[0050] The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 200°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

[0051] As a further improvement, based on the characteristic ion fragments 55, 69, and 95 of dinotefuran, GC-MS detection was performed on a 1 mg / mL dinotefuran-methanol standard solution using conditions three and four, respectively;

[0052] Condition three:

[0053] Gas chromatography conditions:

[0054] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0055] Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 250℃ at a heating rate of 5℃ / min, hold for 0min;

[0056] The splitless mode was used, and the injection port temperature was 250 °C;

[0057] The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 200°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

[0058] Condition four:

[0059] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0060] Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 220℃ at a heating rate of 2℃ / min, hold for 3min;

[0061] The splitless mode was used, and the injection port temperature was 250 °C;

[0062] The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 230°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

[0063] As a further improvement, based on the characteristic ion fragments 55, 69, 95, 115, 130, and 88 of dinotefuran, GC-MS detection was performed on the 1 mg / mL dinotefuran-methanol standard solution and the methanol solution without dinotefuran using condition five;

[0064] Condition five:

[0065] Gas chromatography conditions:

[0066] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0067] Heating program: initial temperature is 50℃, hold for 1min, increase the temperature to 125℃ at a heating rate of 25℃ / min, hold for 0min, increase the temperature to 260℃ at a heating rate of 10℃ / min, hold for 3min;

[0068] The splitless mode was used, and the injection port temperature was 250 °C;

[0069] The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 230°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

[0070] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0071] The invention provides a method for detecting dinotefuran, which detects dinotefuran by gas chromatography-mass spectrometry, selects an optimal solvent, changes programmed temperature conditions, screens out the optimal GC-MS method for detecting dinotefuran, and determines the dinotefuran elution time.

[0072] The heating conditions will affect the separation degree between the target and the impurities, the peak shape, the analysis efficiency, etc. Therefore, based on the characteristic ion fragments of dinotefuran, the present invention changes the heating conditions, determines the peak time of dinotefuran and the characteristic ion fragments for the quantitative detection of dinotefuran, and screens out the most suitable detection temperature to improve the detection accuracy of dinotefuran. In addition, the present invention verifies that the result of the detection of dinotefuran by GC-MS in the present invention is accurate and reliable by performing spiked detection on the dinotefuran sample solution.

[0073] The method of gas chromatography-mass spectrometry is used to detect dinotefuran. The detection equipment cost is low, the detection equipment used is simple, and the GC-MS detection and analysis process is simple and fast, making the detection of dinotefuran fast and convenient.

[0074] The molecular imprinting nanocomposite membrane is used to selectively identify dinotefuran in the sample, and then the dinotefuran bound to the molecular imprinting nanocomposite membrane is eluted with an eluent. The obtained sample solution does not contain other impurities, and the GC-MS test result is more accurate.

[0075] The molecularly imprinted nanocomposite membrane selected in the present invention mixes polyvinyl pyrrolidone with amphiphilic functions into the membrane substrate as a pore-forming agent, provides an anchoring effect for functionalized mesoporous silica nanoparticles C-MSN, and anchors them on the PVDF membrane. The uniform and dense C-MSN on the membrane surface can synergistically promote the membrane flux, improve the filtration efficiency, and improve the binding ability with dinotefuran, thereby preventing dinotefuran from passing through the molecularly imprinted nanocomposite membrane and improving the accuracy of the detection result.

[0076] The present invention selects methanol as the solvent according to the solubility of dinotefuran in different solvents and the toxicity of various solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 This is the TIC graph of dinotefuran measured under condition 1 as the detection condition in Example 1;

[0078] Figure 2 This is the TIC graph of dinotefuran measured under condition 2 as the detection condition in Example 1;

[0079] Figure 3 It is a TIC graph of dinotefuran measured under condition three as the detection condition in Example 1;

[0080] Figure 4 It is the TIC graph of dinotefuran measured under condition 4 as the detection condition in Example 1;

[0081] Figure 5 This is the TIC graph of dinotefuran measured under condition five as the detection condition in Example 1;

[0082] Figure 6 is the TIC graph of methanol measured under condition five as the detection condition in Example 1;

[0083] Figure 7 1 is the TIC graph of the 6 concentrations of the dinotefuran standard samples in Example 2;

[0084] Figure 8 is the standard curve of dinotefuran in Example 2;

[0085] Fig. 9 is the TIC graph of dinotefuran for 6 samples in Example 4;

[0086] Fig.10 This is the TIC graph of dinotefuran detected by spiked testing of 6 samples in Example 4. DETAILED DESCRIPTION

[0087] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0088] Example 1 This example provides the optimization steps of the temperature program in the GC-MS (gas chromatography-mass spectrometry) detection method of dinotefuran, which are as follows:

[0089] Take the dinotefuran standard and use methanol to prepare a 1 mg / mL dinotefuran-methanol standard solution.

[0090] (1) Based on the characteristic ion fragment 57 of dinotefuran, two different detection conditions, condition 1 and condition 2, were used to perform GC-MS detection on a 1 mg / mL dinotefuran-methanol standard solution and draw a TIC diagram;

[0091] Condition one:

[0092] Gas chromatography conditions:

[0093] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0094] Heating program: initial temperature is 40℃, hold for 2min, increase the temperature to 320℃ at a heating rate of 25℃ / min, and hold for 20min;

[0095] The splitless mode was used, and the injection port temperature was 250 °C;

[0096] The mass spectrometry conditions were as follows: an EI ion source was used, an ionization voltage of 70 eV, an ion source temperature of 250° C., an ion scan was selected as the scanning mode, and a solvent delay time of 1.5 min.

[0097] Condition two:

[0098] Gas chromatography conditions:

[0099] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0100] Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 300℃ at a heating rate of 10℃ / min, hold for 15min;

[0101] The splitless mode was used, and the injection port temperature was 250 °C;

[0102] The mass spectrometry conditions were as follows: an EI ion source was used, an ionization voltage of 70 eV, an ion source temperature of 200° C., an ion scan was selected as the scanning mode, and a solvent delay time of 1.5 min.

[0103] The GC-MS detection of the dinotefuran-methanol standard solution was performed under conditions 1 and 2, and the obtained TIC graphs were as follows: Figure 1 and Figure 2As shown, the injection volume of the dinotefuran-methanol standard solution was 1 μL, and both sets of GC-MS detections showed a peak at 7.75 min. This peak is likely to be the characteristic peak of dinotefuran, but further verification is needed.

[0104] (2) Based on the characteristic ion fragments 55, 69, and 95 of dinotefuran, 1 mg / mL dinotefuran-methanol standard solution was detected by GC-MS using two different detection conditions, condition 3 and condition 4, respectively.

[0105] Condition three:

[0106] Gas chromatography conditions:

[0107] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0108] Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 250℃ at a heating rate of 5℃ / min, hold for 0min;

[0109] The splitless mode was used, and the injection port temperature was 250 °C;

[0110] The mass spectrometry conditions were as follows: an EI ion source was used, an ionization voltage of 70 eV, an ion source temperature of 200° C., an ion scan was selected as the scanning mode, and a solvent delay time of 1.5 min.

[0111] Condition four:

[0112] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0113] Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 220℃ at a heating rate of 2℃ / min, hold for 3min;

[0114] The splitless mode was used, and the injection port temperature was 250 °C;

[0115] The mass spectrometry conditions were as follows: an EI ion source was used, an ionization voltage of 70 eV, an ion source temperature of 230° C., an ion scan was selected as the scanning mode, and a solvent delay time of 1.5 min.

[0116] The 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS using conditions 3 and 4, and the TIC graphs obtained were as follows: Figure 3 and Figure 4 As shown, the injection volume of the dinotefuran-methanol standard solution was 1 μL. Based on the characteristic ion fragments 55, 69, and 95, the detection results under different temperature conditions all peaked at 6-7 min, further verifying that this peak was the characteristic peak of dinotefuran.

[0117] (3) Based on the characteristic ion fragments of dinotefuran 55, 69, 95, 115, 130, and 88, condition five was used as the detection condition, and GC-MS was performed on 1 mg / mL dinotefuran-methanol standard solution and methanol solution, respectively.

[0118] Condition five:

[0119] Gas chromatography conditions:

[0120] The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min;

[0121] Heating program: initial temperature is 50℃, hold for 1min, increase the temperature to 125℃ at a heating rate of 25℃ / min, hold for 0min, increase the temperature to 260℃ at a heating rate of 10℃ / min, hold for 3min;

[0122] The splitless mode was used, and the injection port temperature was 250 °C;

[0123] The mass spectrometry conditions were as follows: an EI ion source was used, an ionization voltage of 70 eV, an ion source temperature of 230° C., an ion scan was selected as the scanning mode, and a solvent delay time of 1.5 min.

[0124] The GC-MS detection of the dinotefuran-methanol standard solution and the methanol solution was performed using condition 5. The TIC graphs obtained are shown in Figure 5 and Figure 6 As shown, the injection volumes of the dinotefuran-methanol standard solution and the methanol solution were both 1 μL. By performing GC-MS detection on the methanol solution and eliminating the interference of the solvent, it was determined that the peak time of dinotefuran was 6-7 min.

[0125] In this example, it is finally determined that the peak time of dinotefuran is about 6.139 min, and the characteristic ion fragments of dinotefuran are mainly 55 and 95. The detection condition five is the best detection condition.

[0126] The solubility of dinotefuran in different solvents at 20°C is shown in Table 1.

[0127]

[0128] According to Table 1, this embodiment uses methanol as a solvent to prepare a dinotefuran-methanol standard solution.

[0129] Example 2 The drawing of the dinotefuran standard curve is as follows:

[0130] S1. Take the dinotefuran standard and add methanol to prepare a 1 mg / mL solution, and then dilute it step by step into 6 standard sample solutions of different concentrations: 5 ng / mL, 50 ng / mL, 200 ng / mL, 800 ng / mL, 1600 ng / mL, and 3200 ng / mL;

[0131] S2. The above six standard sample solutions are subjected to GC-MS detection respectively to obtain TIC graphs of the six standard sample solutions, such as Figure 7 As shown, the injection volume of the 6 standard sample solutions is 1 μL, and the specific detection conditions are:

[0132] Chromatographic column: Chromatographic column DB-5MS, length 30m, inner diameter 0.25mm, film thickness 0.25μm, carrier gas He, column flow rate 1.69mL / min;

[0133] Heating program: initial temperature is 50℃, hold for 1min, increase the temperature to 125℃ at a heating rate of 25℃ / min, hold for 0min, increase the temperature to 260℃ at a heating rate of 10℃ / min, hold for 3min;

[0134] The splitless mode was used, and the injection port temperature was 250 °C;

[0135] The mass spectrometer detector used an EI ion source, the ionization voltage was 70 eV, the ion source temperature was 230 °C, the scanning mode was selected as ion scanning (Scan), and the solvent delay time was 1.5 min;

[0136] S3. Draw a standard curve with the peak area of ​​dinotefuran as the ordinate y and the mass concentration of dinotefuran as the abscissa x, such as Figure 8 shown.

[0137] Example 3 Preparation of molecularly imprinted nanocomposite membrane, the specific method is as follows:

[0138] S1. 0.5 g of mesoporous silica nanoparticles were placed in a mixture containing 5 mL of 3-aminopropyltriethoxysilane and 50 mL of toluene, and ultrasonically treated for 10 min. The mixture was then refluxed in an oil bath at 110 °C for 12 h. The resulting mixture was washed with ethanol and deionized water, respectively, to obtain amino-functionalized silica nanoparticles.

[0139] The preparation method of mesoporous silica nanoparticles is as follows: 1.5 mL of ethanol, 3.2 mL of tetraethyl orthosilicate and 30 mL of cyclohexane are stirred and mixed to obtain a mixed solution, and then 2.4 g of hexadecyltrimethylammonium bromide, 0.6 g of urea and 30 mL of deionized water are quickly added to the mixed solution, and the mixture is continuously stirred, and then kept in an oven at 120° C. for 4 hours, and after cooling, the obtained mixture is washed three times with acetone and deionized water respectively, and then vacuum dried at 60° C. for 12 hours to obtain mesoporous silica nanoparticles;

[0140] S2, adding 0.2 g of amino-functionalized silica nanoparticles to a mixture containing 6 mL of acrylic acid and 200 mL of deionized water, treating with ultrasound for 1 h, washing the obtained mixture three times with deionized water, and then drying in a vacuum oven at 60° C. for 6 h to obtain functionalized mesoporous silica nanoparticles C-MSN;

[0141] S3, 14 mg C-MSN was added to 20 mL tetrahydrofuran and ultrasonically treated for 30 min, the supernatant was evenly dropped on two glass plates, the PVDF membrane was placed between the two glass plates, the glass plates were placed in a 90 ° C oven for 4 h, and the C-MSN double-sided PVDF membrane was obtained after cooling at room temperature;

[0142] The preparation method of the PVDF membrane is as follows: 4 g of polyvinylidene fluoride powder and 0.2 g of polyvinyl pyrrolidone are dissolved in 30 mL of NN-dimethylacetamide, and the mixture is continuously stirred at 60° C. for 24 h. After the mixed solution is allowed to stand at room temperature for 12 h, a film is quickly scraped on a glass plate with a scraper, and then the glass plate is immediately placed in a coagulation bath and immersed for 20 h. The membrane is then transferred to deionized water and immersed for 48 h, and dried at room temperature to obtain a PVDF membrane.

[0143] S4. Dissolve 0.04 mmol of the template molecule dimethoate and 3 C-MSN double-sided PVDF membranes in 30 mL of ethanol and stir for 15 min. Then add 0.16 mmol of a mixture of acrylamide and methacrylic acid and 0.8 mmol of a cross-linking agent ethylene glycol dimethacrylate and stir for 15 min. Then, drop 0.5 mL of ammonia water into the mixture, stir at room temperature for 4 h, and then rinse with deionized water to obtain a molecularly imprinted nanocomposite membrane, wherein the molar ratio of acrylamide to methacrylic acid is 1:1.

[0144] Example 4 Detection of dinotefuran in fruit and vegetable samples, the specific method is as follows:

[0145] Fruits and vegetables of the season were randomly selected for dinotefuran detection. In this embodiment, grapes, nectarines, watermelons, cucumbers, spinach, and celery were selected as samples for dinotefuran detection.

[0146] S1. Pre-treatment

[0147] 200 mg of the above six samples were weighed respectively, and each sample was added with 1 mL of methanol and ground for 1.5 min, and then centrifuged at a speed of 12500 r / min for 5 min, and the supernatant was taken and passed through the molecularly imprinted nanocomposite membrane respectively, and then the molecularly imprinted nanocomposite membrane was eluted with 10 mL of eluent to obtain the sample solution to be tested, and the eluent was a mixture of methanol and acetic acid, wherein the volume ratio of methanol to acetic acid was 95:5;

[0148] S2. GC-MS detection

[0149] The above 6 test sample solutions were detected by GC-MS, and condition five was used as the detection condition to obtain TIC graphs of the 6 test sample solutions, respectively. Among them, the injection volume of the test sample solutions was 1 μL. The test results were substituted into the standard curve to obtain the content of dinotefuran in the test sample solutions. Each test sample solution was measured three times, and the average of the three results was taken.

[0150] The specific steps for spike detection are as follows:

[0151] Take 6 sample solutions to be tested in S1 respectively, add dinotefuran thereto to dissolve respectively, and obtain 6 spiked sample solutions. Perform GC-MS detection on the 6 spiked sample solutions respectively to obtain TIC graphs of the 6 spiked sample solutions, wherein the injection volume of the 6 spiked sample solutions is 1 μL. Substitute the detection results into the standard curve to obtain the content of dinotefuran in the spiked sample solutions. Repeat the measurement three times for each spiked sample solution, and take the average of the three results.

[0152] Wherein, 100 ng of dinotefuran was added to every 1 mL of the sample solution to be tested.

[0153] As shown in Table 2, the test results of dinotefuran in the 6 sample solutions and the spiked test results are shown. Fig. 9 This is the TIC diagram of dinotefuran detection of 6 sample solutions to be tested in this embodiment, Fig.10 : TIC diagram of 6 spiked sample solutions in this example.

[0154]

[0155] It can be seen from Table 2 that the relative standard deviation of the detection of fruit and vegetable samples and the relative standard deviation of the spiked detection were both <10%.

[0156] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for detecting dinotefuran, characterized in that: The following steps are involved: S1, preparation of molecularly imprinted nanocomposite membranes; The mesoporous silica nanoparticles were placed in a mixed solution of 3-aminopropyltriethoxysilane and toluene, and ultrasonically treated for 10 minutes, and then refluxed in an oil bath at 110° C. for 12 hours, and the obtained mixture was washed to obtain amino-functionalized silica nanoparticles; Adding amino-functionalized silica nanoparticles to an acrylic acid aqueous solution, ultrasonically treating for 1 hour, washing and drying the obtained mixture to obtain functionalized mesoporous silica nanoparticles C-MSN; C-MSN was added to tetrahydrofuran and ultrasonically treated for 30 min. The supernatant was evenly dropped on two glass plates. The PVDF membrane was placed between the two glass plates. The glass plates were placed in a 90°C oven for 4 h. After cooling at room temperature, a C-MSN double-sided PVDF membrane was obtained. The template molecule dinotefuran and C-MSN double-sided PVDF membrane were dissolved in ethanol and stirred for 15 minutes, and then functional monomers and cross-linking agents were added thereto, stirred for 15 minutes, and then ammonia water was dropped thereinto, stirred at room temperature for 4 hours, and then rinsed with deionized water to obtain a molecularly imprinted nanocomposite membrane; S2, preparation of sample solution to be tested; Weigh the fruit and vegetable samples, add methanol and grind for 1.5 min, then centrifuge at 12500 r / min for 5 min, take the supernatant, pass it through the molecularly imprinted nanocomposite membrane, and then elute the molecularly imprinted nanocomposite membrane with 10 mL of eluent to obtain the sample solution to be tested; S3, preparation of spiked sample solution; Take the sample solution to be tested, add dinotefuran to dissolve it, and form a spiked sample solution, wherein 100 ng of dinotefuran is added to every 1 mL of the sample solution to be tested; S4, GC-MS detection; The test sample solution and the spiked sample solution were respectively subjected to GC-MS detection, the injection volume of the test sample solution and the spiked sample solution was 1 μL, and then the test results were substituted into the standard curve to obtain the content of dinotefuran in the test sample solution.

2. The method for detecting dinotefuran according to claim 1, characterized in that: The conditions for GC-MS detection are as follows: Gas chromatography detection conditions; Chromatographic column: Chromatographic column DB-5MS, length 30m, inner diameter 0.25mm, film thickness 0.25μm, carrier gas He, column flow rate 1.69mL / min; Heating program: initial temperature 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 260℃ at a heating rate of 10℃ / min, hold for 3min; The splitless mode was used, and the injection port temperature was 250 °C; Mass spectrometry detection conditions; The mass spectrometer detector used an EI ion source, the ionization voltage was 70 eV, the ion source temperature was 230 °C, the scanning mode was selected ion scanning, and the solvent delay time was 1.5 min; The qualitative ion fragments of dinotefuran are 55 and 95.

3. The method for detecting dinotefuran according to claim 1, characterized in that: In step S4, the method for drawing the standard curve is as follows: S21, adding methanol to the dinotefuran standard to prepare a 1 mg / mL dinotefuran-methanol solution, and then diluting the dinotefuran-methanol solution stepwise with methanol to prepare six standard sample solutions of 5 ng / mL, 50 ng / mL, 200 ng / mL, 800 ng / mL, 1600 ng / mL and 3200 ng / mL; S22. Perform GC-MS detection on the six standard sample solutions respectively, and draw a standard curve with the peak area of ​​dinotefuran as the ordinate y and the mass concentration of dinotefuran as the abscissa x.

4. The method for detecting dinotefuran according to claim 1, characterized in that: In step S1, the PVDF membrane is prepared using polyvinylidene fluoride and polyvinyl pyrrolidone as raw materials.

5. The method for detecting dinotefuran according to claim 1, characterized in that: In step S1, the molar ratio of the template molecule dinotefuran, the functional monomer and the cross-linking agent is 1:4:20; The functional monomer is a mixed solution of acrylamide and methacrylic acid, the molar ratio of acrylamide to methacrylic acid is 1:1, and the cross-linking agent is ethylene glycol dimethacrylate.

6. The method for detecting dinotefuran according to claim 2, characterized in that: The conditions for GC-MS detection are screened based on the characteristic ion fragments of dinotefuran to change the temperature conditions for GC-MS detection. The specific method is as follows: Based on the characteristic ion fragment 57 of dinotefuran, the temperature conditions were adjusted, and the 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS and the TIC diagram was drawn; Based on the characteristic ion fragments 55, 69, and 95 of dinotefuran, the temperature conditions were adjusted, and the 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS and the TIC diagram was drawn; Based on the characteristic ion fragments 55, 69, 95, 115, 130, and 88 of dinotefuran, 1 mg / mL dinotefuran-methanol standard solution and methanol solution were detected by GC-MS and TIC diagrams were drawn; According to the TIC graph obtained under the above detection conditions, the temperature conditions used for the best peak shape were selected, and the peak time of dinotefuran and the characteristic ion fragments of dinotefuran were determined.

7. The method for detecting dinotefuran according to claim 6, characterized in that: Based on the characteristic ion fragment 57 of dinotefuran, 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS using conditions 1 and 2 respectively; Condition one: Gas chromatography conditions: The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min; Heating program: initial temperature 40℃, hold for 2min, increase the temperature to 320℃ at a heating rate of 25℃ / min, hold for 20min; The splitless mode was used, and the injection port temperature was 250 °C; The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 250 °C, ion scanning selected as scanning mode, and solvent delay time of 1.5 min; Condition two: Gas chromatography conditions: The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min; Heating program: initial temperature 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 300℃ at a heating rate of 10℃ / min, hold for 15min; The splitless mode was used, and the injection port temperature was 250 °C; The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 200°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

8. The method for detecting dinotefuran according to claim 6, characterized in that: Based on the characteristic ion fragments 55, 69, and 95 of dinotefuran, 1 mg / mL dinotefuran-methanol standard solution was tested by GC-MS using conditions 3 and 4, respectively; Condition three: Gas chromatography conditions: The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min; Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 250℃ at a heating rate of 5℃ / min, hold for 0min; The splitless mode was used, and the injection port temperature was 250 °C; The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 200 °C, selected ion scanning, and solvent delay time of 1.5 min; Condition four: The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min; Heating program: initial temperature is 50℃, hold for 1min, heat to 125℃ at a heating rate of 25℃ / min, hold for 0min, heat to 220℃ at a heating rate of 2℃ / min, hold for 3min; The splitless mode was used, and the injection port temperature was 250 °C; The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 230°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

9. The method for detecting dinotefuran according to claim 6, characterized in that: Based on the characteristic ion fragments 55, 69, 95, 115, 130, and 88 of dinotefuran, GC-MS was performed using condition five for the 1 mg / mL dinotefuran-methanol standard solution and the methanol solution without dinotefuran; Condition five: Gas chromatography conditions: The chromatographic column used was DB-5MS, with a length of 30 m, an inner diameter of 0.25 mm, a film thickness of 0.25 μm, a carrier gas of He, and a column flow rate of 1.69 mL / min; Heating program: initial temperature is 50℃, hold for 1min, increase the temperature to 125℃ at a heating rate of 25℃ / min, hold for 0min, increase the temperature to 260℃ at a heating rate of 10℃ / min, hold for 3min; The splitless mode was used, and the injection port temperature was 250 °C; The mass spectrometry conditions were as follows: EI ion source, ionization voltage of 70 eV, ion source temperature of 230°C, ion scanning as the scanning mode, and solvent delay time of 1.5 min.

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