Method for detecting dinotefuran and timicosin in wetland system

Abstract

The invention discloses a method for detecting dinotefuran and timicosin in a wetland system, and belongs to the technical field of environmental pollutant monitoring and analysis. Aiming at common veterinary drugs and pesticides, an acetonitrile mixed solvent with a certain pH value is adopted, so that trace drugs can be fully extracted; the method provided by the invention has the advantages of high sensitivity, simplicity in operation, rapidness, accuracy and wide application range, and can be used for high-throughput analysis of large-batch samples. The method provided by the invention can be used for rapidly extracting environmental sediments and veterinary drug tilmicosin and pesticide dinotefuran in plants, and is simple to operate, short in time consumption and less in required solvent.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental pollutant monitoring and analysis, and particularly relates to a method for detecting dinotefuran and tilmicosin in a wetland system. Background Art

[0002] Neonicotinoid insecticides act as modulators in the nicotinic acetylcholine receptor (nAChR) of the insect central nervous system and are widely used in different fields such as crop protection and pest control. Neonicotinoid compounds are widely present in the human environment, and neonicotinoid pesticides are also widely distributed in wetlands, rivers and sediments.

[0003] Tilmicosin is a macrolide antibiotic for animals, mainly used for treating infections caused by Actinobacillus pleuropneumoniae, Pasteurella and Mycoplasma. Tilmicosin has the characteristics of medium water solubility, strong environmental persistence and easy binding with soil organic matter. Its degradation rate in sewage treatment is less than 40%, resulting in more than 60% of tilmicosin remaining in wastewater sludge or directly entering the natural ecosystem with irrigation water.

[0004] Wetlands are a unique ecosystem on the earth, located in the transitional zone between terrestrial and aquatic systems. As an ecological sewage treatment technology, constructed wetlands have received extensive attention and research in recent years for removing emerging pollutants. The construction, maintenance and operation costs of constructed wetlands are relatively low. In addition to the action of wetland matrix and microorganisms, wetland plants, due to their high growth rate and extensive root systems, also provide nutrients and habitats for microorganisms. Many of these microorganisms promote plant growth and in-situ degrade pollutants between plants and the environment. Tilmicosin and dinotefuran enter constructed wetlands with the treated sewage effluent and will be present in wetland matrix and plants due to their activity and environmental persistence.

[0005] Therefore, it is of great significance to establish a detection method for tilmicosin and dinotefuran in wetland sediments and plants to evaluate the migration and transformation of tilmicosin and dinotefuran and the removal efficiency of the wetland system. At present, most methods for quantifying emerging pollutants use a detection system based on liquid chromatography and triple quadrupole tandem mass spectrometry because this analytical instrument has high precision, high sensitivity, and high stability. However, the detection of tilmicosin and dinotefuran in wetland sediments and plants is restricted by various factors. Dinotefuran contains polar groups such as nitro and ether bonds, which may form hydrogen bonds or coordination bonds with -Si-OH in clay minerals in sediments or -COOH / -OH in plant cell walls, reducing the extraction efficiency. In addition, the concentration of demethylated or ring-opened metabolites may be as low as the ng / g level, requiring an ultra-high sensitivity detector (such as the MRM mode of UPLC-MS / MS), but the matrix background noise (such as humic acid fragment ions) will reduce the signal-to-noise ratio. During the detection process, chlorophyll, alkaloids in plants, or dissolved organic matter (DOM) in sediments may be co-extracted, generating co-elution peaks (such as overlapping retention times in HPLC) or mass spectrometry ion suppression (such as matrix effects in the ESI source) in chromatographic analysis. In addition, due to the different chemical properties of the two drug active substances, existing studies have designed different detection systems, including pretreatment methods and detection instrument conditions, which also result in waste of costs for sampling, transportation, manpower, consumables, and experimental waste treatment. Summary of the Invention

[0006] In view of the above-mentioned prior art, the present invention provides a method for detecting dinotefuran and tilmicosin in a wetland system to solve the technical problems of complex process, low precision, and high cost of existing detection methods.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is to provide a method for detecting dinotefuran and tilmicosin in a wetland system, including the following steps: S1: Pretreat the detection object in the wetland system to obtain a pretreated sample; the detection object is wetland sediment or wetland plant; S2: Extract the pretreated sample to obtain an extract; S3: Dissolve dinotefuran and tilmicosin reference substances in methanol to prepare a standard stock solution; extract a blank detection object using the same extraction method as in S2 to obtain a matrix solution; then add different amounts of the standard stock solution to the matrix solution to configure an external standard standard working curve with concentrations of 1.0 μg / L, 5.0 μg / L, 10.0 μg / L, 50 μg / L, 100 μg / L, and 500 μg / L; S4: Detect dinotefuran and tilmicosin in the extract using chromatography-mass spectrometry; S5: Using the peak area of the target drug's quantitative ion pair and the corresponding drug integrated peak area value Y as the ordinate, and the relative concentration X of the external standard standard working curve working solution as the abscissa, establish a matrix-matched working curve; obtain the concentration of the target drug in the extract, and thus obtain the content of the target drug in the test object.

[0008] Based on the above technical solutions, the present invention can also be improved as follows.

[0009] Further, the test object is wetland sediment, and its pretreatment method is: freeze the wetland sediment at -20°C for 24h, and then freeze-dry it at a pressure of 0.1 Pa for 48h.

[0010] Further, the extraction method of the pretreated sample includes the following steps: S21: Disperse the pretreated sample in an ammonia-acetonitrile extract, and vortex for 1 min; then centrifuge at 4200 rpm for 10 min to separate the supernatant and the lower solid; extract the lower solid again using the same extraction method, and combine the supernatants extracted twice; S22: Add C18 filler to the obtained supernatant, vortex for 1 min, then centrifuge at 4200 rpm for 10 min, and collect the supernatant; then filter with a 0.22 μm PTFE filter membrane, and then evaporate to dryness under a nitrogen gas stream. Dissolve the residue in methanol and filter with a 0.22 μm PTFE filter membrane to obtain the extract.

[0011] Further, the ammonia-acetonitrile extract is composed of ammonia and acetonitrile, and ammonia in the mixed solution accounts for 10% of the volume of acetonitrile.

[0012] Further, the ratio of the pretreated sample to the ammonia-acetonitrile extract is 1 g:2 mL.

[0013] Further, the test object is wetland plants, and its pretreatment method is: dry the wetland plants and then grind them into powder.

[0014] Further, the extraction method of the pretreated sample includes the following steps: S21: Disperse the pretreated sample in a formic acid-acetonitrile extract, and vortex for 1 min; then add magnesium sulfate and sodium chloride, and vortex for 1 min again. Subsequently, centrifuge at 8000 rpm for 10 min to separate the supernatant and the lower solid; extract the lower solid again using the same extraction method, and combine the supernatants extracted twice; S22: Add C18 filler and PSA / GCB to the obtained supernatant, vortex for 1 min, then centrifuge at 8000 rpm for 10 min, and collect the supernatant; and evaporate to dryness under a nitrogen gas stream. Dissolve the residue in methanol and filter with a 0.22 μm PTFE filter membrane to obtain the extract.

[0015] Further, the formic acid - acetonitrile extraction solution is composed of formic acid and acetonitrile, and formic acid accounts for 5% of the volume of acetonitrile in the mixed solution.

[0016] Further, the material - liquid ratio of the pretreated sample to the ammonia - acetonitrile extraction solution is 0.2 g:5 mL; the mass ratio of the added magnesium sulfate and sodium chloride to the pretreated sample is 1:1:1.

[0017] Further, the chromatographic conditions for the chromatography - mass spectrometry detection in S4 are as follows: The chromatographic column is a Shim - pack Velox PFPP column, the column temperature is 30 °C, the flow rate is 0.3 mL / min, the injection volume is 5 μL; the mobile phase uses 0.1% formic acid aqueous solution as phase A and methanol as phase B, the total running time is 15 minutes, gradient elution is adopted, and the elution program is set as follows: 0 - 6 min, the volume ratio of methanol linearly increases from 5% to 95%; 6 - 14 min, the volume ratio of methanol remains at 95%; 14 - 15 min, the volume ratio of methanol linearly decreases to 5%; The mass spectrometry conditions are as follows: The ion source is an electrospray ionization source, the scanning mode is full scan, and the parent ion, daughter ion, collision energy, and RFlens of dinotefuran and tilmicosin are as follows: .

[0019] The beneficial effects of the present invention are: 1. The commonly used ultrasonic extraction / solid - phase extraction purification method has a complex process, long time consumption, large solvent consumption, and requires the use of special instrument equipment for operation, which consumes a large amount of manpower and material resources for the screening and analysis of a large number of samples; the method in the present invention can quickly extract the veterinary drug tilmicosin and the pesticide dinotefuran in environmental sediments and plants, with simple operation, short time consumption, and less solvent required.

[0020] 2. The qualitative and quantitative analysis of the present invention is scientific and accurate. In the range of 5 - 500 μg / L, the linear correlation coefficient R of the regression equations of the two target drugs 2 is greater than 0.99. The recovery rate range of the target drugs in environmental sediment and plant samples at the added concentration levels of 100 ng / g and 500 ng / g is 86% - 110%, and the recovery rate range in environmental plants at the added concentration level has a relative standard deviation of 1% - 10% in the laboratory, which can accurately quantify the trace veterinary drug tilmicosin and the pesticide dinotefuran in environmental sediments and plants.

[0021] 3. The physicochemical properties of veterinary drugs and pesticide compounds in the environment vary greatly, making it difficult to analyze different types of drugs simultaneously using a single method. For common veterinary drugs and pesticides, the present invention uses an acetonitrile mixed solvent with a certain pH value to enable sufficient extraction of trace drugs. The method proposed by the present invention has high sensitivity, is simple to operate, fast and accurate, has a wide range of applications, and can be used for high-throughput analysis of a large number of samples. Description of the Drawings

[0022] Figure 1 It is the extracted ion chromatogram of the veterinary drug tilmicosin (TIM); Figure 2 It is the extracted ion chromatogram of the pesticide dinotefuran (DIN). Detailed Description of the Invention

[0023] The following further describes in detail the specific embodiments of the present invention with reference to the embodiments.

[0024] Embodiment 1 A method for detecting dinotefuran and tilmicosin in a wetland system, comprising the following steps: (1) Pretreatment of sediment samples: Take 2 g of artificial wetland sediment (Caiyunhu Wetland Park, Chongqing) into a 15 mL centrifuge tube, place it in a -20 °C refrigerator and freeze for 24 h, then freeze-dry it for 48 h under a pressure of 0.1 Pa using a vacuum freeze dryer. When freeze-drying, cover the centrifuge tube mouth with a layer of plastic wrap and puncture the plastic wrap with a needle to facilitate water evaporation.

[0025] (2) Extraction of the pesticide dinotefuran (DIN) and the veterinary drug tilmicosin (TIM) from the sediment: Transfer the freeze-dried artificial wetland sediment sample to a 15 mL centrifuge tube, add 4.0 mL of 10% ammonia-acetonitrile (ammonia accounts for 10% of the volume of acetonitrile) to resuspend the freeze-dried sediment, and vortex the mixture for 1 min; then centrifuge the mixture at 4200 rpm for 10 min and collect the supernatant; repeat the extraction twice, combine the supernatants, add 50 mg of C18 to purify the supernatant, vortex the mixture for 1 min, and then centrifuge the mixture at 4200 rpm for 10 min and collect the supernatant; the supernatant is filtered through a 0.22 μm PTFE filter membrane and evaporated to dryness under a nitrogen stream, and the residue is dissolved in 1 mL of methanol and filtered through a 0.22 μm PTFE filter membrane for subsequent analysis.

[0026] (3) Preparation of a matrix-matched standard working curve: Accurately weigh the standard substances of dinotefuran and tilmicosin respectively, and prepare standard stock solutions with a concentration of 1000 mg / L in methanol respectively; use blank sediment as a sample, extract it according to the method described in step (2), and the obtained solution is used as the matrix solution; then use the matrix solution as the solvent, add different amounts of the standard stock solution, and configure external standard standard working curves with concentrations of 1.0 μg / L, 5.0 μg / L, 10.0 μg / L, 50 μg / L, 100 μg / L, and 500 μg / L.

[0027] (4) Quantitative determination of pesticide DIN and veterinary drug TIM: Determine the above-mentioned extract by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry. The ultra-high performance liquid chromatography conditions are as follows: the chromatographic column is a Shim-pack Velox PFPP column (100 mm × 2.1 mm, 1.8 μm), the column temperature is 30 °C, the flow rate is 0.3 mL / min, and the injection volume is 5 μL; the mobile phase is 0.1% formic acid aqueous solution (phase A) and methanol (phase B), the total running time is 15 minutes, and gradient elution is adopted. The elution program is set as follows: 0 - 6 min, the volume ratio of methanol linearly increases from 5% to 95%; 6 - 14 min, the volume ratio of methanol remains 95%; 14 - 15 min, the volume ratio of methanol linearly decreases to 5%. The mass spectrometry conditions are as follows: the ion source is an electrospray ionization source (ESI+); the scanning mode is full scan, and specific parent ions and daughter ions are selected as quantitative ions. The retention times, parent ions, daughter ions, collision energies, and RF lens of the two drugs are shown in Table 1.

[0028] Table 1 Mass spectrometry conditions for two drugs

[0029] Using the peak area of the quantitative ion pair of the target drug and the integrated peak area value Y of the corresponding drug as the ordinate, and the relative concentration X of the standard curve working solution as the abscissa, establish a matrix-matched working curve; obtain the concentration of the target drug in the sample solution, so as to obtain the content of the target drug in the sediment sample. The results show that the peak emergence times of TIM and DIN are 8.36 min and 4.62 min respectively; the standard curves of TIM and DIN are respectively fitted as Y = -12237.7 + 131032*X and Y = -279916 + 51891.5*X, and the correlation coefficients are 0.9949 and 0.9981 respectively. The extracted ion chromatograms of TIM and DIN are shown in Figure 1 and Figure 2 .

[0030] (5) Spike recovery rate and repeatability: The recovery rate was determined by three parallel spiking experiments to examine the spiking concentration. The spiking method was as follows: an appropriate amount of the mixed standard intermediate solution of the two target drugs was added to the sediment sample without the target drugs, so that the spiking concentrations of the two target drugs in the sediment sample were 100 ng / g. The extraction and detection were carried out according to the above steps, and the measured concentration was compared with the theoretical added concentration. The repeatability of the method was examined by calculating the relative standard deviation of three parallel spiked samples. The spiking recovery rates of the two target drugs in the sediment by the method of the present invention are shown in Table 2. It can be seen that the recovery rates of the two target drugs DIN and TIM in the sediment are 105.90% and 86.47% respectively; the relative standard deviation RSD of the parallel samples is less than 10%, indicating that the method of the present invention has high recovery rate and good repeatability and can be used for the detection of actual samples.

[0031] Table 2 Spiking recovery rates (% ± standard deviation) and detection limits of TIM and DIN in sediment

[0032] a: Mean ± relative standard deviation (%) (n = 3) Example 2 A method for detecting dinotefuran and tilmicosin in a wetland system, comprising the following steps: (1) Sample pretreatment: The wetland plant Cyperus alternifolius was dried, cut into pieces, and ground by a medium cell grinder at a frequency of 120 Hz for 30 min to obtain a powder.

[0033] (2) Drug extraction: Weigh 0.2 g of the pretreated Cyperus alternifolius powder sample, add 5 mL of 5% formic acid-acetonitrile (formic acid accounts for 5% of the volume of acetonitrile) for extraction, and vortex the mixture for 1 min; then add 0.2 g of anhydrous magnesium sulfate and 0.2 g of sodium chloride, vortex again for 1 min, and then centrifuge at 8000 rpm for 10 min to collect the supernatant; repeat the extraction twice, combine the supernatants obtained after the two extractions, then add 0.1 g of amorphous C18 packing (40 - 60 μm), 0.08 g of PSA and 0.07 g of GCB mixed dispersive solid-phase extraction reagent, vortex and mix again for 1 min, and then centrifuge at 8000 rpm for 10 min to collect the supernatant; the supernatant is evaporated to dryness under a nitrogen stream, and the residue is dissolved in 1 mL of methanol and filtered through a 0.22 μm PTFE membrane for subsequent analysis.

[0034] (3) Preparation of matrix-matched standard working curve: Accurately weigh the standard substances of dinotefuran and tilmicosin separately, and prepare standard stock solutions with a concentration of 1000 mg / L in methanol respectively; use blank plants as samples, extract them according to the method described in step (2), and the obtained solution is used as the matrix solution; then use the matrix solution as the solvent, add different amounts of the standard stock solution, and configure external standard standard working curves with concentrations of 1.0 μg / L, 5.0 μg / L, 10.0 μg / L, 50 μg / L, 100 μg / L, and 500 μg / L.

[0035] (4) Quantitative detection of pesticide DIN and veterinary drug TIM: The above extraction solution was measured under the same chromatographic - mass spectrometric conditions as in step (4) of Example 1. Taking the peak area of the quantitative ion pair of the target drug and the corresponding drug integration peak area value Y as the ordinate, and the relative concentration X of the standard curve working solution as the abscissa, a matrix - matched working curve was established; the concentration of the target drug in the sample solution was obtained, and thus the content of the target drug in the sediment sample was obtained. The results showed that the retention times of TIM and DIN were 8.36 min and 4.62 min respectively; the standard curves of TIM and DIN were respectively fitted as Y = 8080.38 + 137125*X and Y = -185557 + 34295.9*X, and the correlation coefficients were 0.9957 and 0.9988 respectively.

[0036] (5) Spike recovery rate and repeatability: The recovery rate was determined by adding the standard in parallel three times, and the spiked concentration was investigated. The spiking method was as follows: add an appropriate amount of the mixed standard intermediate solution of the two target drugs to the plant sample without the target drug, so that the spiked concentrations of the two target drugs in the plant sample were both 500 ng / g; extract and detect according to the above steps, compare the measured concentration with the theoretical added concentration, and investigate the method repeatability by calculating the relative standard deviation of 3 parallel spiked samples. The spike recovery rates of the two target drugs in plants by the method of the present invention are shown in Table 3. It can be seen that the recovery rates of the two target drugs DIN and TIM in plants are 109.33% and 85.67% respectively; the relative standard deviation RSD of the parallel samples is less than 10%, indicating that the recovery rate of this method is high and the repeatability is good, and it can be used for the detection of actual samples.

[0037] Table 3 Spike recovery rates (% ± standard deviation) and detection limits of TIM and DIN in plants

[0038] a: Mean ± relative standard deviation (%) (n = 3) Comparative Example 1 Replace the 10% ammonia water - acetonitrile in step (2) of Example 1 with 5% formic acid - acetonitrile, 10% formic acid - acetonitrile, 15% formic acid - acetonitrile, 5% ethyl formate, 10% ethyl formate, and 15% ethyl formate, and the remaining operations are the same as in Example 1; replace the 5% formic acid - acetonitrile in step (2) of Example 2 with 5% ammonia water - acetonitrile and 10% ammonia water - acetonitrile, and the remaining operations are the same as in Example 2. The extraction recovery rates of the target substances using different ratios of acidity - alkalinity and different types of organic extraction solvents are shown in Tables 4 and 5.

[0039] Table 4 Spiked recovery rates of TIM and DIN in sediment (% ± standard deviation)

[0040] a: Mean ± relative standard deviation (%) (n = 3) Table 5 Spiked recovery rates of TIM and DIN in plants (% ± standard deviation)

[0041] a: Mean ± relative standard deviation (%) (n = 3) As can be seen from Tables 4 and 5, after changing to different acidity - alkalinity and different extractants, when extracting drugs from plants under alkaline conditions, the recovery rate of TIM is too low to meet the requirements; during the sediment extraction process, when extracting drugs under acidic + acetonitrile conditions, the recovery rate of DIN is too high to meet the requirements, and when extracting drugs under acidic + ethyl formate conditions, the recovery rate of TIM is unstable and also cannot accurately meet the extraction requirements.

[0042] Comparative Example 2 Replace the matrix solution for preparing the external standard working curve in step (3) of Example 1 and Example 2 with methanol, and the remaining operations are the same as in Example 1 and Example 2. The recovery rates are shown in Table 6.

[0043] Table 6 Spiked recovery rates of TIM and DIN in sediment and plants (% ± standard deviation)

[0044] a: Mean ± relative standard deviation (%) (n = 3) As can be seen from Table 6, the extraction recovery rate of the plant samples in Example 2 is significantly higher than that in Comparative Example 2; it is more conducive to drug extraction.

[0045] Although the specific implementation manners of the present invention have been described in detail in combination with the embodiments, it should not be construed as a limitation on the protection scope of this patent. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative efforts still fall within the protection scope of this patent.

Claims

1. A method for detecting dinotefuran and timicosin in a wetland system, characterized in that: The following steps are involved: S1: pre-treating the detection object in the wetland system to obtain a pre-treated sample; the detection object is wetland sediment or wetland plant; S2: extracting the pretreated sample to obtain an extract; S3: Dissolve the dinotefuran and tilmicosin standard substances in methanol to prepare a standard stock solution; extract the blank test object using the same extraction method as S2 to obtain a matrix solution; then add different amounts of the standard stock solution to the matrix solution to prepare an external standard working curve with concentrations of 1.0 μg / L, 5.0 μg / L, 10.0 μg / L, 50 μg / L, 100 μg / L, and 500 μg / L; S4: Detection of dinotefuran and tilmicosin in the extract by chromatography-mass spectrometry; S5: Establish a matrix matching working curve with the peak area of ​​the quantitative ion pair of the target drug and the corresponding drug integrated peak area value Y as the ordinate and the relative concentration X of the working solution of the external standard working curve as the abscissa; obtain the target drug concentration in the extract, thereby obtaining the target drug content in the test object.

2. The method for detecting dinotefuran and timicosin in a wetland system according to claim 1, characterized in that: The detection object is wetland sediment, and the pretreatment method thereof is: freezing the wetland sediment at -20°C for 24 hours, and then freeze-drying it at a pressure of 0.1 Pa for 48 hours.

3. The method for detecting dinotefuran and timicosin in a wetland system according to claim 2, characterized in that: The extraction method for pre-processing samples includes the following steps: S21: The pretreated sample was dispersed in an ammonia-acetonitrile extract and vortexed for 1 min; then centrifuged at 4200 rpm for 10 min to separate the supernatant and the lower solid; the lower solid was extracted again using the same extraction method, and the supernatants of the two extractions were combined; S22: Add C18 filler to the obtained supernatant, vortex oscillate for 1 minute, and then centrifuge at 4200 rpm for 10 minutes to collect the supernatant; then filter with a 0.22 μm PTFE filter membrane, and then evaporate to dryness under nitrogen flow conditions. Dissolve the residue with methanol and filter with a 0.22 μm PTFE filter membrane to obtain an extract.

4. The method for detecting dinotefuran and timicosin in a wetland system according to claim 3, characterized in that: The ammonia-acetonitrile extract is prepared by mixing ammonia and acetonitrile, wherein the ammonia accounts for 10% of the volume of the acetonitrile in the mixed solution.

5. The method for detecting dinotefuran and timicosin in a wetland system according to claim 4, characterized in that: The solid-liquid ratio of the pretreated sample to the ammonia-acetonitrile extract was 1 g:2 mL.

6. The method for detecting dinotefuran and timicosin in a wetland system according to claim 1, characterized in that: The detection object is wetland plants, and the pretreatment method is: the wetland plants are dried and then ground into powder.

7. The method for detecting dinotefuran and timicosin in a wetland system according to claim 6, characterized in that: The extraction method for pre-processing samples includes the following steps: S21: The pretreated sample was dispersed in formic acid-acetonitrile extract and vortexed for 1 min; magnesium sulfate and sodium chloride were then added, and vortexed for another 1 min, followed by centrifugation at 8000 rpm for 10 min to separate the supernatant and the lower solid; the lower solid was extracted again using the same extraction method, and the supernatants of the two extractions were combined; S22: C18 filler and PSA / GCB were added to the obtained supernatant, vortexed for 1 min, and then centrifuged at 8000 rpm for 10 min, and the supernatant was collected; and evaporated to dryness under nitrogen flow conditions, and the residue was dissolved with methanol and filtered with a 0.22 μm PTFE filter membrane to obtain an extract.

8. The method for detecting dinotefuran and timicosin in a wetland system according to claim 7, characterized in that: The formic acid-acetonitrile extract is prepared by mixing formic acid and acetonitrile, wherein the formic acid accounts for 5% of the volume of the acetonitrile in the mixed solution.

9. The method for detecting dinotefuran and timicosin in a wetland system according to claim 8, characterized in that: The solid-liquid ratio of the pretreated sample to the ammonia-acetonitrile extract was 0.2 g:5 mL; the mass ratio of the added magnesium sulfate and sodium chloride to the pretreated sample was 1:1:

1.

10. The method for detecting dinotefuran and timicosin in a wetland system according to claim 1, characterized in that: The chromatographic conditions for chromatography-mass spectrometry detection in S4 are: The chromatographic column was a Shim-pack Velox PFPP column, the column temperature was 30°C, the flow rate was 0.3 mL / min, and the injection volume was 5 μL; the mobile phase was a 0.1% formic acid aqueous solution as phase A, methanol as phase B, the total running time was 15 minutes, and gradient elution was used. The elution program was set as follows: 0-6 min, the methanol volume ratio increased linearly from 5% to 95%; 6-14 min, the methanol volume ratio was maintained at 95%; 14-15 min, the methanol volume ratio decreased linearly to 5%; The mass spectrometry conditions were: The ion source is an electrospray ion source, and the scanning mode is full scan. The parent ion, daughter ion, collision energy, and RFlens of dinotefuran and timicocin are as follows: 。

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