A method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent

Abstract

A method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent relates to the field of drinking water and food detection, and includes the following operation steps: a. adding a hydrophobic deep eutectic solvent to a sample solution to obtain a mixed solution A; the deep eutectic solvent is prepared from a hydrogen bond acceptor and a hydrogen bond donor; the hydrogen bond acceptor is one of dipropylamine, triethylamine, N,N-dimethylcyclohexylamine, and N,N-dimethylbenzylamine; the hydrogen bond donor is hexafluoroisopropanol; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (2 to 1):(1 to 5); the volume ratio of the deep eutectic solvent to the sample solution is (0.04 to 0.08):1. This method also avoids the large-scale use of traditional organic solvents, follows the standards of contemporary green analytical chemistry, is sensitive, simple, and environmentally friendly, and is suitable for the detection and analysis of triazole insecticides in drinking water and beverages.

Description

Technical Field

[0001] The present invention relates to the technical field of drinking water and food detection, and in particular to a method for extracting and analyzing triazole fungicides by using a switchable polarity deep eutectic solvent. Background Art

[0002] Fungicides are one of the most widely used pesticides in agriculture. They are directly sprayed on crops to prevent and control fungal attacks, thereby improving the yield and quality of products. Among them, triazole fungicides (TFs) have been widely used to control powdery mildew, rust and other fungal pests on grains, fruits, vegetables, lawn shrubs and trees due to their high chemical and photochemical stability, low biodegradability and easy transport in the environment. However, studies have shown that triazole fungicides are endocrine disruptors and harmful to human health. Long-term exposure to excessive amounts of triazole fungicides can have many adverse effects on human health, such as nausea, vomiting, respiratory depression, mental changes, acute kidney injury and other serious health problems. Due to their stable physical and chemical properties, the residues of TFs and their by-products are easily persistent in water samples. Therefore, monitoring the content levels of triazole fungicides in drinking water and beverages has received extensive attention.

[0003] In existing analytical techniques, the pretreatment techniques for TFs in drinking water and beverages include liquid-liquid extraction, solid-phase extraction, dispersive liquid-liquid microextraction and stir bar sorptive extraction, etc. These methods not only require a large amount of organic solvents, which are likely to cause secondary environmental pollution, but also have low detection sensitivity and often cannot meet the requirements of analytical determination.

[0004] For example, the Chinese invention patent with the publication number "CN201811522873.3" discloses a method for analyzing triazole pesticide residues in water, providing a new method for analyzing triazole pesticide residues in water based on a carbon dioxide bubbling-assisted demulsification-deep eutectic solvent aqueous two-phase system. The basic concept of the present invention makes full use of carbon dioxide bubbling-assisted demulsification, enabling the emulsion to quickly become clear without additional centrifugation equipment. The deep eutectic solvent aqueous two-phase system has the advantages of being green and environmentally friendly, having good biocompatibility, low cost, rapid phase formation and high extraction efficiency. However, the above method for analyzing triazole pesticide residues in water requires the addition of a large amount of deep eutectic solvent during use, which does not conform to the development strategy of green environmental protection. Summary of the Invention

[0005] In view of this, it is necessary to provide a method for extracting and analyzing triazole fungicides by using a switchable polarity deep eutectic solvent.

[0006] The solution of the present invention to solve its technical problems is:

[0007] A method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent, comprising the following steps:

[0008] a. Add a hydrophobic deep eutectic solvent to the sample solution to obtain a mixed solution A; the deep eutectic solvent is made from a hydrogen bond acceptor and a hydrogen bond donor;

[0009] Among them, the hydrogen bond acceptor is one of dipropylamine, triethylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine; the hydrogen bond donor is hexafluoroisopropanol;

[0010] The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (2-1):(1-5);

[0011] The volume ratio of the deep eutectic solvent to the sample solution is (0.04-0.08):1.

[0012] Preferably, it further comprises the following steps:

[0013] b. Add an acidic solution to the mixed solution A to obtain a mixed solution B;

[0014] c. Add an alkaline solution to the mixed solution B for extraction to obtain a mixed solution C;

[0015] d. Perform induced separation on the mixed solution C to separate out the lower layer solution rich in triazole fungicides;

[0016] e. After diluting the separated lower layer solution rich in triazole fungicides, inject it into a high performance liquid chromatograph for content analysis.

[0017] Preferably, when the hydrogen bond acceptor is dipropylamine, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (3-5):1.

[0018] Preferably, the acidic solution is one of sulfuric acid, hydrochloric acid, and nitric acid.

[0019] Preferably, when the acidic solution is a 6.0M sulfuric acid solution, the volume ratio of the acidic solution to the deep eutectic solvent is (2.5-3.0):1.

[0020] Preferably, the alkaline solution is one of sodium carbonate, sodium hydroxide, and potassium hydroxide.

[0021] Preferably, the triazole fungicide is one or more of myclobutanil, flusilazole, hexaconazole, and bitertanol.

[0022] Preferably, the conditions of the high performance liquid chromatograph are as follows: the chromatographic column is a Waters XBridge-C18 column (150 mm × 4.6 mm); the mobile phase is a gradient elution of water-methanol (35.5:64.5, v / v); the flow rate is 1.0 mL·min -1 ; the detection wavelength is 220 nm; the column temperature is 30 °C, and the injection volume is 10 μL.

[0023] Beneficial effects: The method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent according to the present invention adopts a switchable polarity deep eutectic solvent microextraction technique, uses hexafluoroisopropanol as a hydrogen bond donor and an amine substance as a hydrogen bond acceptor to detect the content of triazole substances in drinking water and beverages. During the detection process, only a small amount of deep eutectic solvent is required to achieve good detection accuracy and high recovery rate, while improving the detection efficiency. It is a green and environmentally friendly method for detecting triazole fungicides. In particular, it is found during the experiment that the detection rates of hexaconazole and bitertanol are relatively high. It should also be noted that during the detection process, the density of hexafluoroisopropanol is greater than that of water, making it easier to separate during centrifugation. This method also avoids the large use of traditional organic solvents, follows the standards of contemporary green analytical chemistry, is sensitive, simple, green and environmentally friendly, and is suitable for the detection and analysis of triazole fungicides in drinking water and beverages. Description of the Drawings

[0024] Figure 1 It is an infrared identification diagram of a switchable polarity deep eutectic solvent (Note: Identification diagram: dipropylamine (a); hexafluoroisopropanol (b); deep eutectic solvent (c); deep eutectic solvent plus acidic solution (d) and deep eutectic solvent plus basic solution (e)).

[0025] Figure 2 It is a schematic diagram of liquid phase microextraction based on a switchable polarity deep eutectic solvent.

[0026] Figure 3 It is a hydrogen nuclear magnetic resonance identification diagram of a switchable polarity deep eutectic solvent (Note: 1H NMR identification diagram: dipropylamine (a); hexafluoroisopropanol (b); deep eutectic solvent (c); deep eutectic solvent plus acidic solution (d) and deep eutectic solvent plus basic solution (e)).

[0027] Figure 4 It is a diagram for optimizing the extraction efficiency of triazole pesticides residues (Note: (A) type of deep eutectic solvent; (B) molar ratio of deep eutectic solvent; (C) volume of deep eutectic solvent; (D) volume of sulfuric acid solution and (E) volume of sodium carbonate solution).

[0028] Figure 5 It is a high performance liquid chromatography diagram (Note: (A) standard sample solution (1.0 μg / mL), (B) blank sample and (C) simulated sample (100 μg / L)). Detailed implementation manners

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0030] A method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent includes the following steps:

[0031] a. Add a hydrophobic deep eutectic solvent to the sample solution to obtain a mixed solution A; the deep eutectic solvent is prepared from a hydrogen bond acceptor and a hydrogen bond donor; wherein, the hydrogen bond acceptor is one of dipropylamine, triethylamine, N,N-dimethylcyclohexylamine, and N,N-dimethylbenzylamine; the hydrogen bond donor is hexafluoroisopropanol;

[0032] The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (2-1):(1-5);

[0033] The volume ratio of the deep eutectic solvent to the sample solution is (0.04-0.08):1.

[0034] In a preferred implementation manner, the hydrogen bond acceptor is dipropylamine, and the molar ratio of dipropylamine to hexafluoroisopropanol is (3-5):1. Preferably, the molar ratio of dipropylamine to hexafluoroisopropanol is 4:1.

[0035] In the present invention, a hydrophobic deep eutectic solvent system with hexafluoroisopropanol as the hydrogen bond donor and amine substances as the hydrogen bond acceptor is constructed. When detecting triazole fungicides in water bodies or solutions, only 4%-8% of the deep eutectic solvent of the volume of the sample to be tested needs to be added, and it has high detection accuracy and detection efficiency. It is a green and environmentally friendly detection method for triazole fungicides.

[0036] In some specific implementation manners, the method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent further includes the following steps:

[0037] b. Add an acidic solution to the mixed solution A to obtain a mixed solution B.

[0038] Specifically, the acidic solution is one of sulfuric acid, hydrochloric acid, and nitric acid. In one specific implementation manner, the acidic solution is selected as a 6M sulfuric acid solution, and the added volume of the sulfuric acid solution is 2.5-3 times the added volume of the deep eutectic solvent. Preferably, the added volume of the sulfuric acid solution is 2.5 times the added volume of the deep eutectic solvent.

[0039] An acidic solution is added to the mixed solution A to change the eutectic solvent system from hydrophobic to hydrophilic, and the eutectic solvent is fully mixed with the sample solution to facilitate the enrichment of triazole fungicides in the sample solution.

[0040] c. A basic solution is added to the mixed solution B for extraction to obtain a mixed solution C.

[0041] Specifically, the selected basic solution is one of sodium carbonate, sodium hydroxide, and potassium hydroxide. Preferably, the basic solution is a 4M sodium carbonate solution. The volume ratio of the added volume of the sodium carbonate solution to the added volume of the sulfuric acid solution is (2 - 3):1. Preferably, the volume ratio of the added volume of the sodium carbonate solution to the added volume of the sulfuric acid solution is 7:3.

[0042] A basic solution is added to the mixed solution B to change the eutectic solvent system from hydrophilic to hydrophobic, and the solvent is quickly separated from water. The triazole fungicides in the sample solution are enriched in the eutectic solvent system.

[0043] d. The mixed solution C is subjected to induced separation to separate the lower layer solution rich in triazole fungicides.

[0044] Specifically, the mixed solution C is centrifuged. The relatively large eutectic solvent system is located at the bottom of the centrifuge tube, facilitating the separation of the lower layer solution rich in triazole fungicides from the centrifuge tube and improving the detection efficiency and accuracy.

[0045] e. After diluting the separated lower layer solution rich in triazole fungicides, it is injected into a high-performance liquid chromatograph for analysis of its content.

[0046] Specifically, the conditions of the selected high-performance liquid chromatograph are as follows: the chromatographic column is a Waters XBridge-C18 column (150 mm × 4.6 mm); the mobile phase is a gradient elution of water - methanol (35.5:64.5, v / v); the flow rate is 1.0 mL·min -1 ; the detection wavelength is 220 nm; the column temperature is 30 °C, and the injection volume is 10 μL.

[0047] In a method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent, the preparation of the deep eutectic solvent uses one of dipropylamine, triethylamine, N,N-dimethylcyclohexylamine, and N,N-dimethylbenzylamine as a hydrogen bond acceptor, hexafluoroisopropanol as a hydrogen bond donor, and mixes them in an appropriate molar ratio. The optimal choice is that the molar ratio of hexafluoroisopropanol to dipropylamine is 1:4. Stir with a magnetic stirrer until the mixture becomes a homogeneous, transparent, and clear liquid to prepare four switchable polarity deep eutectic solvents. Then, take a certain amount of sample solution, add the deep eutectic solvent to change the polarity of the sample solution to hydrophobicity. At this time, the substances in the solution are mutually incompatible. Immediately add an acidic solvent to change the polarity of the solution to hydrophilicity, enabling the substances in the sample solution to fuse with each other, laying the foundation for extraction. After the extraction is completed, add an alkaline solution again. At this time, the polarity of the sample solution becomes hydrophobic again. Then, centrifuge the extracted solution. During centrifugation, because the density of hexafluoroisopropanol is greater than that of water, the target detection substance will be at the bottom of the solution, facilitating liquid extraction. The obtained solution is diluted with an organic acid solution, and after dilution, the content is analyzed by injecting it into a high-performance liquid chromatograph. During the detection process, by adding a small amount of the deep eutectic solvent, harmful components in the triazole fungicides are detected, with high speed and efficiency, reducing the waste of the deep eutectic solvent during the detection process, which conforms to the ecological concept of green development.

[0048] The following further illustrates the present invention through examples, but the present invention is not limited thereto.

[0049] 1. Preparation and identification of switchable polarity deep eutectic solvents

[0050] Preparation of switchable polarity deep eutectic solvents: Use one of dipropylamine, triethylamine, N,N-dimethylcyclohexylamine, and N,N-dimethylbenzylamine as a hydrogen bond acceptor, hexafluoroisopropanol as a hydrogen bond donor, mix them in an appropriate molar ratio, and stir with a magnetic stirrer until the mixture becomes a homogeneous, transparent, and clear liquid to prepare four switchable polarity deep eutectic solvents.

[0051] Identify the change in its polarity by means of FT-IR and 1H-NMR, etc. Taking dipropylamine (EPA) as an example, explain its identification process. IR spectra of EPA, HFIP, DES, and DES before and after switching polarity: As Figure 1 shown, by comparing the IR spectra of EPA and HFIP, it is found that the O-H of the synthesized DES's IR spectrum redshifts to 3436 cm -1 and the peak shape broadens. This is because the formation of internal hydrogen bonds in DES causes changes in the electron cloud density of oxygen atoms, resulting in a decrease in the force constant of the bond. In addition, compared with the IR spectra of its single components, no peaks disappear and no new peaks appear in DES, indicating that no chemical reactions occur during the preparation of DES. After adding an acid solution to switch the solution polarity, the stretching vibration peak of O-H shifts from 3436 cm-1 Red-shifted to 3395 cm -1 , and the spectral band broadened. After adding the alkaline solution, the polarity of the solution switched back to the original hydrophobicity, and the IR spectrum was basically consistent with that of DES, indicating that the bond energy of DES was stable before and after the polarity switch. Comparing the 1H-NMR spectra of EPA (see attachment Figure 3 ), the chemical shift of the C-H protons of DES shifted to a lower field, which was due to the high electronegativity of -CF 3 reducing the electron cloud density around the C-H protons, resulting in an increase in their chemical shift. After adding acid, a large number of active H proton signals appeared at a chemical shift of 4.99 ppm, and these proton signals may come from H 2 O. After adding the alkaline solution to adjust the solution polarity, the proton resonance absorption peaks of the H spectrum were consistent with those of DES, and the signal intensity did not weaken, indicating that the hydrogen bond network of DES could still maintain good stability after the hydrophilic-hydrophobic switch.

[0052] In the present invention, when not particularly emphasized, the eutectic solvent used is a dipropylamine-hexafluoroisopropanol system synthesized at a molar ratio of 1:2.

[0053] 2. Preparation of standard sample solution

[0054] Take 0.1 ml / L of water, and add 0.1 μg of myclobutanil, 0.1 μg of flusilazole, 0.1 μg of hexaconazole, and 0.1 μg of bitertanol respectively, and mix well to prepare a 1.0 μg / mL standard sample solution.

[0055] 3. Experimental procedure:

[0056] Take 10 mL of the standard sample solution, add the hydrophobic eutectic solvent; add the acidic solution to change the polarity of the solution to hydrophilic, add the alkaline solution, and the polarity of the solution switches back to the original hydrophobicity to achieve homogeneous extraction; after the extraction is completed, the lower layer solution obtained after centrifugation is diluted with the organic acid solution and then injected into the high performance liquid chromatograph for content analysis. The separation and extraction schematic diagram is as Figure 2 shown.

[0057] 4. Investigation and optimization of extraction conditions

[0058] A: Types of extractants

[0059] (1) Experimental method: Take 10 mL of the standard sample solution and add four different hydrophobic deep eutectic solvents (dipropylamine - hexafluoroisopropanol, triethylamine - hexafluoroisopropanol, N,N - dimethylcyclohexylamine - hexafluoroisopropanol, and N,N - dimethylbenzylamine - hexafluoroisopropanol), all synthesized at a molar ratio of 1:2. Add 1200 μL (6 M) of sulfuric acid solution. The hydrophobic deep eutectic solvent is transformed into a hydrophilic one to obtain a homogeneous solution. Then, add 2800 μL (4 M) of sodium carbonate solution to induce phase separation. After centrifuging for 3 min, the lower - layer hydrophobic deep eutectic solvent is obtained. The content of triazole pesticides in the lower - layer solution is determined by high - performance liquid chromatography.

[0060] The experimental results are as Figure 4 shown in Figure A. The results show that dipropylamine - hexafluoroisopropanol has the best extraction effect on triazole pesticides, which may be related to the hydrogen - bond interaction and hydrophobic interaction of the switchable deep eutectic solvent. Therefore, dipropylamine - hexafluoroisopropanol is preferably used as the extractant.

[0061] B: Molar ratio of deep eutectic solvent

[0062] Experimental method: The same as the method in Example 1, except that dipropylamine and hexafluoroisopropanol are used to prepare the switchable - polarity deep eutectic solvent at different molar ratios (1:2, 2:1, 3:1, 4:1, and 5:1).

[0063] (2) The experimental results are as Figure 4 shown in Figure B. The results show that: as the proportion of dipropylamine increases, the peak areas of the target analytes flusilazole, hexaconazole, and bitertanol gradually increase. When the molar ratio of dipropylamine to hexafluoroisopropanol is 4:1, the extraction effect is the best. When the proportion of dipropylamine continues to increase, the peak area of the target compound decreases. This may be because the molar ratio of the hydrogen - bond acceptor to the hydrogen - bond donor affects the surface tension and dissociation degree of the deep eutectic solvent during the extraction process. Therefore, dipropylamine - hexafluoroisopropanol prepared at a molar ratio of 4:1 is used for further research. It should be noted that for myclobutanil, when the molar ratio of dipropylamine to hexafluoroisopropanol is (3 - 4):1, the peak area of the target compound shows a decline, and when the molar ratio of dipropylamine to hexafluoroisopropanol is 5:1, it rises again.

[0064] C: Volume of deep eutectic solvent

[0065] (1) Experimental method: The same as the method in Example 1, except that the dipropylamine - hexafluoroisopropanol deep eutectic solvent is used at different volumes (400 - 800 μL).

[0066] (2) Experimental results: As Figure 4As shown in C. The results show that when the volume of the extractant increased from 400 μL to 800 μL, the peak area of the target compound decreased due to dilution. Therefore, 400 μL of the switchable deep eutectic solvent was used for subsequent experiments.

[0067] D: Optimization of the volume of sulfuric acid

[0068] (1) Experimental method: The same as the method in Example 1, except that sulfuric acid was used with different volumes (600 - 1500 μL).

[0069] (2) Experimental results: As Figure 4 shown in D. The results show that the peak area increased significantly with the increase in the volume of sulfuric acid and decreased slightly when the volume of sulfuric acid reached 1200 μL. This indicates that 1200 μL of sulfuric acid is sufficient to convert the hydrophobic deep eutectic solvent into a hydrophilic one. More sulfuric acid will reduce the pH value and have a negative impact on the extraction of triazole pesticides residues. Therefore, 1200 μL of sulfuric acid was used as the optimal volume in subsequent studies.

[0070] E: Optimization of the volume of sodium carbonate

[0071] (1) Experimental method: The same as the method in Example 1, except that sodium carbonate was used with different volumes (2800 - 4000 μL).

[0072] (2) Experimental results: As Figure 4 shown in E. The results show that due to the dilution effect, the peak area decreased with the increase in the amount of sodium carbonate added, resulting in a decrease in extraction efficiency. Therefore, 2800 μL of sodium carbonate solution was used for further experiments.

[0073] Using the optimal conditions, by purchasing beverages locally, detecting them, and conducting spiked recovery experiments, the relevant data obtained are shown in Table 1.

[0074] Example 1:

[0075] Beverages (orange juice and grape juice) were purchased from a local supermarket. After centrifugation, they were filtered through a 0.45 μm filter membrane. 10 mL of the beverage sample solution was added to a 15 mL centrifuge tube. After adding 600 μL of dipropylamine - hexafluoroisopropanol, 1000 μL (6 M) of sulfuric acid solution was added, and the hydrophobic deep eutectic solvent was converted into a hydrophilic one to obtain a homogeneous solution; finally, 3000 μL (4 M) of sodium carbonate solution was added to induce layering. After centrifugation for 3 min, the lower - layer hydrophobic deep eutectic solvent was obtained. 30 μL of formic acid was used to dilute the lower - layer solution for injection analysis.

[0076] Example 2:

[0077] Drinking water was taken from this laboratory. After centrifugation, it was filtered through a 0.45 μm filter membrane. 10 mL of the sample solution was added to a 15 mL centrifuge tube. After adding 400 μL of N,N-dimethylbenzylamine-hexafluoroisopropanol, 800 μL (6 M) of hydrochloric acid solution was added, and the hydrophobic deep eutectic solvent was transformed into a hydrophilic one to obtain a homogeneous solution. Finally, 2800 μL (4 M) of sodium hydroxide solution was added to induce stratification. After centrifuging for 3 min, the lower-layer hydrophobic deep eutectic solvent was obtained. The lower-layer solution was taken and diluted with 50 μL of acetic acid and then injected for analysis.

[0078] Example 3:

[0079] Beverages (orange juice and grape juice) were purchased from a local supermarket. After centrifugation, they were filtered through a 0.45 μm filter membrane. 10 mL of the sample solution was added to a 15 mL centrifuge tube. After adding 500 μL of triethylamine-hexafluoroisopropanol, 1200 μL (6 M) of hydrochloric acid solution was added, and the hydrophobic deep eutectic solvent was transformed into a hydrophilic one to obtain a homogeneous solution. Finally, 3500 μL (4 M) of sodium carbonate solution was added to induce stratification. After centrifuging for 3 min, the lower-layer hydrophobic deep eutectic solvent was obtained. The lower-layer solution was taken and diluted with 25 μL of formic acid and then injected for analysis.

[0080] The chromatographic conditions for the above examples were as follows: the chromatographic column was a Waters XBridge-C18 column (150 mm × 4.6 mm); the mobile phase was a gradient elution of water-methanol (35.5:64.5, v / v); the flow rate was 1.0 mL·min -1 ; the detection wavelength was 220 nm; the column temperature was 30 °C, and the injection volume was 10 μL; the total time for the extraction process in the above 3 examples was 5 min, which greatly improved the extraction efficiency.

[0081] Table 1 Spike recovery rates of triazole herbicides in spiked samples (μg L -1 ).

[0082]

[0083] According to Table 1, using the detection scheme provided by the present invention, the recovery rates of myclobutanil, flusilazole, hexaconazole, and bitertanol were good.

[0084] The detection limit parameters of the experiments in the present invention were demonstrated by methodology, and the results are shown in Table 2.

[0085] Table 2 Detection limit parameters

[0086]

[0087] From Table 2, by applying the method provided by the present invention to detect triazole fungicides in water bodies or solutions, the lower detection limit is 1-2 μg L -1 , with high sensitivity and accuracy.

[0088] The present invention also compares the method of the present invention with some known methods, and the comparison results are shown in Table 3 below.

[0089] Advantages and disadvantages of the methods of the published literature and the method provided by the present invention in Table 3

[0090]

[0091] In the table, SBSE-DLLME: Stir bar sorptive extraction with DLLME (Stir bar sorptive extraction with dispersive liquid-liquid microextraction);

[0092] DLLME: Dispersive liquid–liquid microextraction (Dispersive liquid-liquid microextraction);

[0093] UA-SHS-HLLME: Ultrasonic assisted switchable hydrophilic solvent homogeneous liquid–liquid microextraction (Ultrasonic assisted switchable hydrophilic solvent homogeneous liquid-liquid microextraction);

[0094] SPME: Solid-phase microextraction (Solid-phase microextraction).

[0095] As can be seen from Table 3, compared with the technical solutions disclosed in the literature, the detection time of the technical solution of the present invention is roughly the same, the recovery rate is also within the range of the literature, and the detection limit is also roughly the same. However, in the detection process of the present invention, the usage amount of the eutectic solvent is reasonably optimized, greatly reducing the usage amount of the eutectic solvent. During the detection process, very little eutectic solvent can be used to achieve good detection results; and it is found in the experiment that the detection rates of hexaconazole and bitertanol are relatively high. In addition, the detection lower limit of triazole insecticides (including myclobutanil, flusilazole, hexaconazole and bitertanol) is 1-2 μg / L, which is higher than that recorded in the published literature. At the same time, only a very small amount of eutectic solvent is used as an alternative extraction solvent throughout the extraction process, which is green and environmentally friendly.

[0096] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited by this. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent, characterized in that, it includes the following steps: a. Add a hydrophobic deep eutectic solvent to the sample solution to obtain a mixed solution A; the deep eutectic solvent is made of a hydrogen bond acceptor and a hydrogen bond donor; wherein, the hydrogen bond acceptor is one of dipropylamine, triethylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine; the hydrogen bond donor is hexafluoroisopropanol; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (2-1):(1-5); the volume ratio of the deep eutectic solvent to the sample solution is (0.04-0.08):1; b. Add an acidic solution to the mixed solution A to obtain a mixed solution B, and the acidic solution is one of sulfuric acid, hydrochloric acid, and nitric acid; c. Add an alkaline solution to the mixed solution B for extraction to obtain a mixed solution C, and the alkaline solution is one of sodium carbonate, sodium hydroxide, and potassium hydroxide; d. Perform induced separation on the mixed solution C to separate out the lower layer solution rich in triazole fungicides; e. After diluting the separated lower layer solution rich in triazole fungicides, it is injected into a high performance liquid chromatograph for content analysis. The conditions of the high performance liquid chromatograph are as follows: the chromatographic column is a Waters XBridge-C18 column, 150 mm × 4.6 mm; the mobile phase is a water-methanol gradient elution, 35.5:64.5, v / v; the flow rate is 1.0 mL·min -1 ; the detection wavelength is 220 nm; the column temperature is 30 °C, and the injection volume is 10 μL; the triazole fungicide is one or more of myclobutanil, flusilazole, hexaconazole, and bitertanol.

2. The method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent according to claim 1, characterized in that: when the hydrogen bond acceptor is dipropylamine, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (3-5):

1.

3. The method for extracting and analyzing triazole fungicides using a switchable polarity deep eutectic solvent according to claim 1, characterized in that: when the acidic solution is a 6.0M sulfuric acid solution, the volume ratio of the acidic solution to the deep eutectic solvent is (2.5-3.0):1.

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