Hydrophobic eutectic solvent and application thereof in pyrethroid pesticide extraction

Abstract

The invention belongs to the technical field of pesticide residue detection, and particularly relates to a hydrophobic deep-eutectic solvent and application thereof in pyrethroid pesticide extraction. The hydrophobic deep-eutectic solvent provided by the invention comprises thymol serving as a hydrogen bond acceptor and coumarin or menthol serving as a hydrogen bond donor. Through the hydrophobic interaction between the hydrophobic deep-eutectic solvent and the hydrophobic pyrethroid pesticide, and the strong pi-pi action between the benzene ring structures of coumarin and thymol and the benzene ring of the pyrethroid pesticide, or the adsorption action between the aliphatic ring of menthol and the benzene ring of the pesticide, the pyrethroid pesticide can be prepared. The selective efficient enrichment of the pyrethroid pesticide can be realized through the combined action of the hydrophobic deep-eutectic solvent and the hydrophobic deep-eutectic solvent, the extraction efficiency of the pyrethroid pesticide by the hydrophobic deep-eutectic solvent can be greatly improved, and the detection sensitivity and the detection accuracy of the pyrethroid pesticide can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide residue detection, and in particular to a hydrophobic low eutectic solvent and application thereof in the extraction of pyrethroid pesticides. Background Art

[0002] Pyrethroid insecticides (PY) are the main insecticide category in the world. They are highly effective, low-toxic, low-residue, and easy to degrade. They are widely used in agricultural pest control, as well as in the control of sanitary pests and storage pests. At the same time, the problem of PY residues in the environment and agricultural products is becoming increasingly serious, causing serious harm to the ecological environment and human health, and also reducing the quality of agricultural products. More than 10 types of PY pesticides have been detected in my country, mainly including cypermethrin, deltamethrin, bifenthrin, cypervalerate, cypermethrin, permethrin, cyhalothrin, cyfluthrin, beta-cypermethrin, and phenothrin.

[0003] The main method reported for extracting pesticide residues from agricultural products is QuEChERS, which is the preferred method for rapid extraction and cleanup of food samples for pesticide residue analysis. However, it requires a large amount of organic solvent as an extractant, which inevitably pollutes the environment. In recent years, several pretreatment strategies have been developed for pre-concentration of pesticide residues, including solid phase extraction (SPE), magnetic solid phase extraction (MSPE), dispersive liquid-liquid microextraction (DLLME), liquid-liquid microextraction (LLME), etc.

[0004] A Chinese patent with authorization announcement number CN110231423B, which was authorized on April 22, 2022, discloses a method for determining pyrethroid pesticides in grain by dispersed liquid-liquid microextraction-high performance liquid chromatography. Thymol (thymol) or choline chloride is used as a hydrogen bond acceptor, and pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid or decanoic acid is used as a hydrogen bond donor. The hydrophobic low eutectic solvent formed by the mixture is used as an extractant, and is added to the supernatant obtained by vortex mixing of the sample to be tested and the dispersant, and dispersed liquid-liquid microextraction is carried out. After the extraction, the extract is centrifuged and ice-bathed, and the extracted phase is converted into a solid phase and then collected, and melted into a liquid at room temperature to obtain a solution of the sample to be tested. This method uses a hydrophobic low eutectic solvent for extraction, avoids the use of harmful organic solvents, reduces the adverse effects and damage to the ecological environment, and is more green and environmentally friendly.

[0005] However, the extraction efficiency of pyrethroid pesticides using hydrophobic low eutectic solvents in the above method is still low. Summary of the invention

[0006] The object of the present invention is to provide a hydrophobic deep eutectic solvent to solve the problem of low extraction efficiency of pyrethroid pesticides by existing hydrophobic deep eutectic solvents.

[0007] The second object of the present invention is to provide an application of a hydrophobic deep eutectic solvent in the extraction of pyrethroid pesticides, so as to solve the problem of low extraction efficiency of pyrethroid pesticides by existing hydrophobic deep eutectic solvents.

[0008] In order to solve the above technical problems, the technical solution of the hydrophobic deep eutectic solvent of the present invention is: A hydrophobic deep eutectic solvent comprising thymol as a hydrogen bond acceptor and coumarin or menthol as a hydrogen bond donor.

[0009] The present invention improves the prior art and provides a hydrophobic low eutectic solvent, which uses coumarin or menthol as a hydrogen bond donor and thymol as a hydrogen bond acceptor. Through the hydrophobic interaction between the hydrophobic low eutectic solvent and the hydrophobic pyrethroid pesticide, and the strong π-π interaction between the benzene ring structure of coumarin and thymol and the benzene ring of the pyrethroid pesticide, or the adsorption effect between the aliphatic ring of menthol and the benzene ring of the pyrethroid pesticide, the two work together to achieve selective and efficient enrichment of pyrethroid pesticides, greatly improve the extraction efficiency of the hydrophobic low eutectic solvent for pyrethroid pesticides, and help to further improve the detection sensitivity and detection accuracy of pyrethroid pesticides.

[0010] In order to further improve the extraction efficiency, preferably, when the hydrophobic deep eutectic solvent includes thymol as a hydrogen bond acceptor and menthol as a hydrogen bond donor, the molar ratio of thymol to menthol is 1:(1-1.5).

[0011] In order to further improve the extraction efficiency, preferably, when the hydrophobic deep eutectic solvent includes thymol as a hydrogen bond acceptor and coumarin as a hydrogen bond donor, the molar ratio of coumarin to thymol is 1:(1-4). Compared with the adsorption between the aliphatic ring of menthol and the benzene ring of pyrethroid pesticides, the strong π-π interaction between the benzene ring of coumarin and the benzene ring of pyrethroid pesticides is more conducive to improving the extraction efficiency.

[0012] In order to further improve the extraction efficiency, preferably, the molar ratio of coumarin to thymol is 1:(2-2.5).

[0013] In order to further improve the stability of the hydrophobic deep eutectic solvent, preferably, the hydrophobic deep eutectic solvent is thymol as a hydrogen bond acceptor and coumarin or menthol as a hydrogen bond donor, which are stirred at 80-100° C. until transparent and clear.

[0014] The technical solution of the application of the hydrophobic deep eutectic solvent in the extraction of pyrethroid pesticides of the present invention is: Application of a hydrophobic deep eutectic solvent in the extraction of pyrethroid pesticides.

[0015] The present invention utilizes the hydrophobic low eutectic solvent as an extractant to extract pyrethroid pesticides, and utilizes the hydrophobic interaction, strong π-π interaction or adsorption between the hydrophobic low eutectic solvent and the pyrethroid pesticides. The two work together to achieve selective and efficient enrichment of pyrethroid pesticides, thereby improving the extraction efficiency of pyrethroid pesticides.

[0016] In order to further reduce the amount of the hydrophobic deep eutectic solvent used as the extractant and simplify the extraction process, preferably, the following steps are included: the hydrophobic deep eutectic solvent is used as the extractant for liquid-liquid microextraction. It is understandable that the hydrophobic deep eutectic solvent can be used as an extractant in the QuEChERS technique for sample pretreatment, and can also be used in dispersed liquid-liquid microextraction and liquid-liquid microextraction techniques, but the QuEChERS technique requires the use of a large amount of hydrophobic deep eutectic solvent for extraction, and the dispersed liquid-liquid microextraction requires the addition of a dispersant, and the extraction process is relatively complicated.

[0017] In order to facilitate phase separation of the hydrophobic deep eutectic solvent, preferably, a magnetic substance is added to the hydrophobic deep eutectic solvent to form a magnetic fluid before liquid-liquid microextraction. The magnetism of the magnetic substance can make the hydrophobic deep eutectic solvent realize phase separation under the action of an external magnetic field, without the need to use an ice bath in the prior art to convert it into a solid phase for separation, thereby simplifying the phase separation step.

[0018] In order to further improve the extraction efficiency, preferably, the pyrethroid pesticides include tefluthrin, bioresmethrin, bifenthrin, cypermethrin, λ-cyhalothrin, trans-permethrin, cis-permethrin, cyhalothrin, cypermethrin, high-efficiency cypermethrin, flucythrin, etherpyrethrin, fluvalinate, cypermethrin, S-cypermethrin, and deltamethrin. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The bar graph shows the extraction efficiency of hydrophobic deep eutectic solvents with different composition formulations. DETAILED DESCRIPTION

[0020] The technical concept of the hydrophobic deep eutectic solvent of the present invention is as follows: The hydrophobic deep eutectic solvent in the prior art uses thymol as a hydrogen bond acceptor and an organic acid such as decanoic acid as a hydrogen bond donor. The π-π interaction between the benzene ring structure of thymol and the benzene ring of pyrethroid pesticides limits the selective adsorption capacity of the hydrophobic deep eutectic solvent for pyrethroid pesticides. The present invention uses thymol containing a benzene ring structure as a hydrogen bond acceptor, and coumarin containing a benzene ring structure or menthol containing an aliphatic ring as a hydrogen bond donor, so that the hydrophobic deep eutectic solvent forms a stronger π-π interaction or other adsorption effect with the benzene ring of pyrethroid pesticides, thereby improving the selective adsorption capacity of the hydrophobic deep eutectic solvent for pyrethroid pesticides, thereby improving the extraction efficiency of pyrethroid pesticides.

[0021] In a specific embodiment, the hydrophobic deep eutectic solvent is obtained by stirring thymol as a hydrogen bond acceptor and coumarin or menthol as a hydrogen bond donor at 80-100° C. for 30-60 minutes.

[0022] In a specific embodiment, when the hydrophobic low eutectic solvent is used as an extractant for liquid-liquid microextraction, the hydrophobic low eutectic solvent and the sample extract are mixed and then vortexed; the sample extract is the supernatant obtained by extracting and solid-liquid separation after mixing the solid phase sample and water.

[0023] 1. Specific embodiments of the hydrophobic deep eutectic solvent of the present invention Example 1 The hydrophobic deep eutectic solvent of this embodiment is composed of coumarin as a hydrogen bond donor and thymol as a hydrogen bond acceptor, and the molar ratio of coumarin to thymol is 1:1.

[0024] Preparation of a hydrophobic deep eutectic solvent: Coumarin and thymol in a molar ratio of 1:1 were magnetically stirred at 80° C. for 30 min to obtain a clear and transparent solution. The preparation methods of the hydrophobic deep eutectic solvents in the following examples are the same and will not be described in detail.

[0025] Example 2 The hydrophobic deep eutectic solvent of this embodiment is composed of coumarin as a hydrogen bond donor and thymol as a hydrogen bond acceptor, and the molar ratio of coumarin to thymol is 1:2.

[0026] Example 3 The hydrophobic deep eutectic solvent of this embodiment is composed of coumarin as a hydrogen bond donor and thymol as a hydrogen bond acceptor, and the molar ratio of coumarin to thymol is 1:3.

[0027] Example 4 The hydrophobic deep eutectic solvent of this embodiment is composed of coumarin as a hydrogen bond donor and thymol as a hydrogen bond acceptor, and the molar ratio of coumarin to thymol is 1:4.

[0028] Example 5 The hydrophobic deep eutectic solvent of this embodiment is composed of DL-menthol as a hydrogen bond donor and thymol as a hydrogen bond acceptor, and the molar ratio of coumarin to thymol is 1:1.

[0029] 2. Specific Examples of Application of the Hydrophobic Deep Eutectic Solvent of the Present Invention in Extraction of Pyrethroid Pesticides Example 6 The application of the hydrophobic deep eutectic solvent of this embodiment in the extraction of pyrethroid pesticides is as follows: 1) Sample pretreatment: Weigh 100 mg of tobacco leaf powder into a 50 mL centrifuge tube, add 10 mL of water and sonicate for 30 min, let stand for 30 min, centrifuge at 3000 rpm for 5 min, and use the supernatant after solid-liquid separation as the sample extract for later use.

[0030] 2) Liquid-liquid microextraction: 100 mg of magnetic nanoparticles were dispersed in the hydrophobic low eutectic solvent of Example 1-5 to obtain a magnetic fluid. 90 μL of the magnetic hydrophobic low eutectic solvent was added to 5 mL of the sample extract obtained in step 1), and the mixture was vortexed for 3.5 min. Phase separation was achieved using a magnet. 1 mL of dichloromethane solution was added for elution. The mixture was vortexed for 3 min, and 500 μL of the solution was filtered through a 0.22 μm organic phase membrane to obtain a sample solution to be tested, which was tested and analyzed using GC-MS / MS.

[0031] 3. Experimental Examples This experimental example illustrates the screening of the hydrophobic deep eutectic solvent component formula.

[0032] Hydrophobic low eutectic solvents (HDES) of different components were used to extract 16 pyrethroid pesticides. The extraction method was referred to Example 6. The extraction efficiency was evaluated by the spiked recovery rate obtained by GC-MS / MS test. The spiked recovery rate = [(X 1 -X 0 ) / m]*100%, where X 1 is the value of the spiked sample, X 0 is the sample measurement value, and m is the spiked amount. The 16 pyrethroid pesticides are tefluthrin, bioresmethrin, bifenthrin, cypermethrin, λ-cyhalothrin, trans-permethrin, cis-permethrin, cyhalothrin, cypermethrin, beta-cypermethrin, flucythrin, ethomethrin, fluvalinate, cypermethrin, S-cypermethrin, and deltamethrin. The composition formula of the hydrophobic deep eutectic solvent is shown in Table 1.

[0033] Table 1 Component formula of hydrophobic deep eutectic solvent The extraction efficiency bar graph of 16 pyrethroid pesticides extracted using the hydrophobic deep eutectic solvents in Table 1 is shown in Figure 1 As shown, Figure 1 a is a bar chart of the extraction efficiency of pyrethroid pesticides by hydrophobic deep eutectic solvents 1#, 5#~7#, Figure 1 b is a bar chart showing the extraction efficiency of pyrethroid pesticides by hydrophobic low eutectic solvents #1 to #4.

[0034] from Figure 1 It can be seen that the hydrophobic deep eutectic solvents composed of different components show different extraction effects on pyrethroid pesticides. Compared with MEN-DEC and THY-DEC, the hydrophobic deep eutectic solvents (COU-THY, THY-MEN) provided by the present invention show higher extraction efficiency, among which COU-THY shows higher extraction efficiency for 16 pyrethroid pesticides. In addition to tefluthrin, bioresmethrin, bifenthrin and cypermethrin, THY-MEN also shows higher extraction efficiency for cypermethrin, λ-cyfluthrin, trans-permethrin, cis-permethrin, cyfluthrin, high-efficiency cypermethrin, flucythrin, ethercypermethrin, fluvalinate, cypermethrin, S-cypermethrin and deltamethrin. The extraction capacity of COU-THY with different ratios was evaluated, and it was found that the highest extraction efficiency was shown when the molar ratio was 1:2.

[0035] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrophobic deep eutectic solvent, characterized in that: The hydrophobic deep eutectic solvent includes thymol as a hydrogen bond acceptor and coumarin or menthol as a hydrogen bond donor.

2. The hydrophobic deep eutectic solvent according to claim 1, characterized in that When the hydrophobic deep eutectic solvent comprises thymol as a hydrogen bond acceptor and menthol as a hydrogen bond donor, the molar ratio of thymol to menthol is 1:(1-1.5).

3. The hydrophobic deep eutectic solvent according to claim 1, characterized in that When the hydrophobic deep eutectic solvent includes thymol as a hydrogen bond acceptor and coumarin as a hydrogen bond donor, the molar ratio of coumarin to thymol is 1:(1-4).

4. The hydrophobic deep eutectic solvent according to claim 1 or 3, characterized in that The molar ratio of coumarin to thymol is 1:(2-2.5).

5. The hydrophobic deep eutectic solvent according to claim 1, characterized in that The hydrophobic deep eutectic solvent is thymol as a hydrogen bond acceptor and coumarin or menthol as a hydrogen bond donor, which are stirred at 80-100° C. until transparent and clear.

6. Use of the hydrophobic deep eutectic solvent according to any one of claims 1 to 5 in the extraction of pyrethroid pesticides.

7. Use of the hydrophobic deep eutectic solvent according to claim 6 in the extraction of pyrethroid pesticides, characterized in that: The method comprises the following steps: using the hydrophobic low eutectic solvent as an extractant to perform liquid-liquid microextraction.

8. Use of the hydrophobic deep eutectic solvent according to claim 7 in the extraction of pyrethroid pesticides, characterized in that: Before liquid-liquid microextraction, magnetic material is added to the hydrophobic deep eutectic solvent to form a magnetic fluid.

9. Use of the hydrophobic deep eutectic solvent according to claim 6 in the extraction of pyrethroid pesticides, characterized in that: The pyrethroid pesticides include tefluthrin, bioresmethrin, bifenthrin, cypermethrin, λ-cyhalothrin, trans-permethrin, cis-permethrin, cyhalothrin, cypermethrin, high-efficiency cypermethrin, flucythrin, ethomethrin, fluvalinate, cypermethrin, S-cypermethrin, and deltamethrin.

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