A method for detecting residual pesticides based on VA-DES-DLLME and application thereof

Abstract

This invention discloses a VA-DES-DLLME-based method for detecting pesticide residues and its application, belonging to the fields of chemical analysis and pesticide residue detection technology. This invention uses a eutectic solvent composed of menthol or ethanolamine as hydrogen bond donors and thymol as hydrogen bond acceptors as the extraction solvent, combined with vortex-assisted dispersion liquid-liquid microextraction (VA-DES-DLLME) technology, to obtain a novel pesticide residue detection method—a VA-DES-DLLME-based method for detecting pesticide residues. The provided VA-DES-DLLME-based method for detecting pesticide residues exhibits good extraction efficiency for pesticides containing high charge density halogens. Using this VA-DES-DLLME-based method for detecting pesticide residues containing high charge density halogens offers advantages such as low limit of quantitation, high recovery rate, good linearity, and low reagent consumption.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis and pesticide residue detection technology, specifically relating to a method for detecting pesticide residues based on VA-DES-DLLME and its application. Background Technology

[0002] With increasing consumer awareness of food safety and the rapid development of the global fruit and vegetable processing industry, the quality and safety of fruit juice, as an important natural beverage, are receiving growing attention. Pesticide residues are one of the core indicators of fruit juice safety, directly impacting consumer health.

[0003] In the fruit juice processing chain, pesticide residues mainly originate from two sources: first, pesticides such as insecticides, fungicides, and herbicides applied directly to the raw fruit during cultivation; and second, secondary pollution caused by incomplete cleaning of raw materials, leading to the concentration or transformation of pesticide residues during processing. Because fruit juice production involves multiple stages such as pressing, clarification, concentration, and sterilization, the migration, accumulation, and degradation of pesticide residues are complex, resulting in significant differences in residue levels between the final product and the original fruit.

[0004] Currently, international organizations (such as FAO / WHO, EU, and US EPA) have set strict limits on maximum residue limits (MRLs) for pesticides in various fruit juices. Detection technologies have also evolved from traditional chromatography to higher sensitivity, higher throughput, and automation. Mainstream methods include gas chromatography-mass spectrometry (GC-MS / MS), liquid chromatography-tandem mass spectrometry (LC-MS / MS), and high-throughput screening methods based on QuEChERS (rapid, simple, economical, efficient, stable, and safe) pretreatment technology, which have been developed in recent years.

[0005] However, fruit juice matrices are complex, rich in sugars, organic acids, pigments, pectin, and other interfering substances, posing challenges to the extraction, purification, and detection of pesticide residues. Existing detection methods still suffer from cumbersome pretreatment processes and significant matrix effects. Therefore, developing rapid, accurate, multi-residue, and low-cost pesticide residue detection technologies suitable for fruit juice matrices remains a key research focus in the field of food safety analysis. Summary of the Invention

[0006] The purpose of this invention is to provide a method for detecting pesticide residues based on VA-DES-DLLME and its application. By using a eutectic solvent (DES) composed of menthol or ethanolamine as hydrogen bond donors and thymol as hydrogen bond acceptors as the extraction solvent, and combining it with vortex-assisted dispersion liquid-liquid microextraction (VA-DLLME) technology, a novel method for detecting pesticide residues—a vortex-assisted eutectic solvent dispersion liquid-liquid microextraction (VA-DES-DLLME) method—is obtained. The provided VA-DES-DLLME-based method for detecting pesticide residues exhibits good extraction efficiency for pesticides containing high charge density halogens. Using this method, the detection of pesticides containing high charge density halogens has a low limit of quantitation (0.005~0.01 mg·kg⁻¹). -1 High recovery rate (76%~120%), good linearity (R0.05). 2 The advantages of >0.9751 and low reagent consumption.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a method for detecting pesticide residues based on VA-DES-DLLME, comprising the following steps: The sample solution to be extracted was mixed with a eutectic solvent, and then vortexed to separate the eutectic solvent. The residual pesticide content in the separated eutectic solvent was determined using an analytical instrument. The hydrogen bond donor (HBA) of the eutectic solvent is menthol or ethanolamine (ETA), and the hydrogen bond acceptor (HBD) is thymol. The pesticides include: chlorantraniliprole, trifluopyridine, or trifluralin.

[0008] Preferably, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is (1~2):(1~2).

[0009] Preferably, the volume ratio of the sample solution to be extracted to the eutectic solvent is 10:1.

[0010] Preferably, when the hydrogen bond donor is menthol, the vortex extraction time is 0.5 min; when the hydrogen bond donor is ethanolamine, the vortex extraction time is 1 min.

[0011] Preferably, the analytical instrument includes a high-performance liquid chromatography-mass spectrometry (HPLC-MS) system.

[0012] The second technical solution of the present invention provides an application of the above-mentioned VA-DES-DLLME-based pesticide residue detection method in the detection of pesticide residues in agricultural and sideline products.

[0013] Preferably, the agricultural product includes fruit juice.

[0014] The method for detecting pesticide residues in fruit juice based on VA-DES-DLLME provided by this invention can eliminate the interference of complex matrices in the fruit juice on the results of pesticide residue detection, and has high accuracy and low limit of quantification.

[0015] The beneficial technical effects of the present invention are as follows: This invention utilizes a eutectic solvent composed of menthol or ethanolamine as hydrogen bond donors and thymol as hydrogen bond acceptors as the extraction solvent, combined with vortex-assisted dispersion liquid-liquid microextraction (VA-DES-DLLME) technology, to obtain a novel method for pesticide residue detection—a pesticide residue detection method based on vortex-assisted eutectic solvent dispersion liquid-liquid microextraction (VA-DES-DLLME). The provided VA-DES-DLLME-based pesticide residue detection method exhibits excellent extraction performance for pesticides containing high charge density halogens. Using this invention's VA-DES-DLLME-based pesticide residue detection method, the detection of pesticides containing high charge density halogens has a low limit of quantitation (0.005~0.01 mg·kg⁻¹). -1 High recovery rate (76%~120%), good linearity (R0.05). 2 The advantages of >0.9751 and low reagent consumption. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the vortex-assisted DES dispersion liquid-liquid microextraction process in Example 1.

[0018] Figure 2 The density measurement results of the six types of DES in Example 1 are shown.

[0019] Figure 3 The viscosity measurement results are for the six DES types in Example 1.

[0020] Figure 4 The images show the FT-IR spectra of the six DES in Example 1; where A is the FT-IR spectrum of menthol, thymol and menthol-based DES, and B is the FT-IR spectrum of ethanolamine, thymol and ethanolamine-based DES.

[0021] Figure 5Differential scanning calorimetry (DSC) images of the three monomers and six DES in Example 1.

[0022] Figure 6 The effect of DES dosage on the absolute recovery rate of the target analyte during the optimization of detection conditions.

[0023] Figure 7 The effect of NaCl concentration on the absolute recovery rate of the target analyte during the optimization of detection conditions.

[0024] Figure 8 The effect of vortex time on the absolute recovery rate of the target analyte during the optimization of detection conditions. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0026] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0027] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0030] Unless otherwise specified, room temperature in this invention refers to a temperature of 20±10℃.

[0031] The pesticide standards chlorantraniliprole (98.1%) and trifluralin (98.6%) used in this invention were purchased from Beijing Qincheng Yixin Technology Co., Ltd. (Beijing), and trifluralin (99.9%) was provided by Syngenta Crop Protection.

[0032] The fruit juices (apple juice, grape juice, peach juice, Huiyuan brand) used in this invention were purchased from a local supermarket.

[0033] The pesticide standard was dissolved in acetonitrile and accurately prepared to a concentration of 1000 mg·L⁻¹. -1 The mixed standard stock solution is stored in a light-protected environment at -18℃; the standard working solution is obtained by diluting the standard stock solution with acetonitrile to a suitable concentration and is prepared on-site before each test.

[0034] Example 1 (1) The required mass was calculated according to the molar ratio of hydrogen bond acceptor (ethanolamine or menthol) to hydrogen bond donor (thymol) of 1:2, 1:1, and 2:1, respectively. The two components were weighed into a round-bottom flask and stirred for 2 hours in a water bath at 80°C to obtain transparent and clear DES. After cooling to room temperature, no solid precipitated. Thus, six target DES were obtained for use. For ease of description, DES using ethanolamine as hydrogen bond acceptor are collectively referred to as "ethanolamine DES", and DES using menthol as hydrogen bond acceptor are collectively referred to as "menthol DES".

[0035] (2) Transfer 1.5 mL of sample solution to a 2 mL plastic centrifuge tube, then add 0.15 mL of DES extraction reagent. Use vortex-assisted extraction to fully disperse DES into the sample to achieve good extraction results. The vortexing times are 0.5 min (chlorantraniliprole and trifluralin) and 1 min (trifluralin). Then centrifuge at 10000 rpm for 2 min to obtain the upper DES enriched phase containing pesticide residues. Transfer the DES enriched phase to another 2 mL centrifuge tube, dilute 5 times with acetonitrile, filter through a 0.22 μm organic filter membrane, and transfer to a vial for analysis. The flowchart of vortex-assisted DES dispersion liquid-liquid microextraction (VA-DES-DLLME) is shown below. Figure 1 .

[0036] (3) The filtrate obtained in step (2) was detected using HPLC-MS under the following conditions: Chromatographic column: C18-WP column (2.1 mm × 50 mm, 3 µm); mobile phase set to isocratic elution: acetonitrile: 0.1 wt% formic acid water = 80:20 (v / v); flow rate: 0.3 mL·min -1 Injection volume: 5 µL; Ion source: Electrospray ionization (ESI); Scan mode: Positive ion mode; Detection mode: Multiple reaction monitoring (MRM); Nitrogen flow rate: 8 L / min -1 The settings for pesticide MRM detection parameters are shown in Table 1.

[0037] Table 1. MRM parameter settings for three pesticides The densities of the six DES types in Example 1 were measured, and the results are shown in Table 2 and... Figure 2 .

[0038] The viscosities of the six DES types in Example 1 were measured, and the results are shown in Table 2 and... Figure 3 .

[0039] Table 2. Composition ratios, density, and viscosity properties of six types of DES Density is an important physical property of eutectic solvents, determining the collection method of eutectic solvents during dispersion-liquid microextraction. According to Table 2, at 303 K, the density of ethanolamine-based DES decreases with increasing thymol content, from 1.023 g·cm³. -3 Decreased to 0.970 g·cm⁻¹ -3 The densities of [ETA][Thymol]1:1 and [ETA][Thymol]1:2 are both less than that of water. The densities of menthol derivatives (DES) range from 0.920 to 0.962 g·cm³. -3 Between these values, the values ​​are all less than water. According to... Figure 2 It can be seen that the density variation of DES is negligible in the range of 283~323K.

[0040] Viscosity is a crucial factor affecting the dispersion of DES in liquid environments. High-viscosity DES is detrimental to the mass transfer efficiency of the target analyte, while low viscosity helps improve the extraction efficiency. Viscosity is influenced by multiple factors, including the length of the alkyl chain in the component and the halogen elements in the quaternary ammonium salt. For nonionic DES, intermolecular interactions are a significant factor affecting viscosity. Compared to ionic DES, nonionic DES exhibits significantly lower viscosity. As shown in Table 2, at 303 K, ethanolamine-based eutectic solvents have higher viscosities (101.3–115.4 mPa·s), while menthol-based eutectic solvents have lower viscosities (33.2–53.9 mPa·s). Furthermore, the viscosity of both types of DES decreases with increasing thymol content. Figure 3 It can be seen that within the temperature range of 293K to 333K, the viscosity of all six DES types decreases with increasing temperature. This is related to the increase in kinetic energy due to molecule absorption, leading to increased intermolecular migration rates and ultimately reduced viscosity. Finally, at 333K, the viscosity of all six DES types is less than 100 mPa·s, with menthol-based DES exhibiting the smallest viscosity range of 8.4–13.3 mPa·s. The relationship between temperature and DES viscosity was fitted using the Arrhenius equation (Table 2). The viscosity activation energies for ethanolamine and menthol-based DES ranged from 6.84 to 8.69 kJ·mol⁻¹. -1 6.55~7.70 kJ·mol-1 Viscous activation energy characterizes the sensitivity of liquid viscosity to temperature changes. It can be seen that the viscosity activation energy and viscosity of the two types of DES show the same trend: ethanolamine DES > menthol DES. At low temperatures, the higher the viscosity of the DES, the greater its response to temperature.

[0041] Infrared analysis was performed on the six DES types in Example 1, and the resulting FT-IR spectra are shown below. Figure 4 Wherein, A is the FT-IR spectrum of menthol, thymol and menthol-based DES, and B is the FT-IR spectrum of ethanolamine, thymol and ethanolamine-based DES.

[0042] The success of DES preparation depends on whether hydrogen bonds are formed between the components of DES. Figure 4 Infrared spectra show that all three monomers are in the range of 3500~3000 cm⁻¹. -1 A broad OH stretching vibration absorption peak appeared at 806 cm⁻¹, indicating the existence of hydrogen bonds between monomeric components. The selected monomer possesses the ability to form intermolecular hydrogen bonds, providing structural support for the successful preparation of DES. Comparing the spectra of thymol monomer and DES, thymol exhibits a peak at 806 cm⁻¹. -1 A strong bending vibration absorption peak belonging to the CH group of the benzene ring appeared at the peak. Since only thymol has a benzene ring structure among the three components, this peak was identified as a unique peak of thymol. The benzene ring CH peak was observed in all nine DES samples, indicating the presence of thymol in the DES.

[0043] from Figure 4 As can be seen in A, menthol is at 2930 cm⁻¹ -1 An absorption peak for the stretching vibration of the methylene group (CH) was observed. In menthol-based DES, the absorption intensity of this peak gradually decreased with the decrease of the menthol proportion, indicating not only the presence of menthol in the DES but also reflecting the change in component ratio. Simultaneously, due to the newly formed hydrogen bond between menthol and thymol, the position of the broad OH peak in the DES showed a blue shift compared to the menthol and thymol monomers, indicating stronger intermolecular hydrogen bonding. Thus, menthol-based DES were successfully prepared.

[0044] from Figure 4 As can be seen in B, the ethanolamine monomer, due to the presence of an amino group, is at 3353 cm⁻¹ -1 and 3286cm -1 The stretching vibrations of the NH bond were observed at the two peaks. Since only ethanolamine has an amino group among the four components, these two peaks were identified as unique peaks of ethanolamine. Unique peaks of ethanolamine and thymol were observed in all ethanolamine-based DES. The NH stretching vibration peak underwent a blue shift due to the influence of hydrogen bonding, while the CH on the benzene ring was not significantly affected.

[0045] The melting points of the three monomers and six DES in Example 1 were determined using differential scanning calorimetry: The method is as follows: Weigh approximately 0.3 g of sample into a crucible for differential scanning calorimetry (DSC) measurement. Set the initial temperature to 253 K and the heating rate to 10 K·min. -1 The termination temperature is 398K.

[0046] Differential scanning calorimetry (DSC) images of three monomers and six DESs are shown below. Figure 5 .

[0047] Figure 5 The results show that menthol, ethanolamine, and thymol exhibit endothermic reactions at 318 K, 283 K, and 324 K, respectively. These temperatures correspond to the melting points of the three monomers, consistent with the fact that menthol and thymol are crystalline solids at room temperature, while ethanolamine is a liquid. However, as the temperature increases from 253 K at 10 K·min... -1 The melting rate increased to 398 K, and no endothermic phenomenon occurred in the six DES. Since the prepared DES were liquid at room temperature, it is speculated that the melting points of the six prepared DES were all below 253 K, which meets the requirement of liquid form of the extractant in the dispersion liquid-liquid microextraction process. In addition, under different molar ratios, none of the prepared DES showed endothermic phenomena at the melting point of the monomer, indicating that all components participated in the preparation of the new compound system. The formation of hydrogen bonds in DES did not have a fixed ratio and form, but rather formed different new substances in the form of hydrogen bond networks.

[0048] To obtain optimal extraction and detection conditions, based on the COSMO-RS screening results, menthol:thymol with a molar ratio of 2:1 was used to extract chlorantraniliprole and trifluopyridine, and ethanolamine:thymol with a molar ratio of 2:1 was used to extract trifluopyridine.

[0049] Absolute recovery (AR) is used as the evaluation criterion for extraction efficiency. The calculation method for AR is as follows: In the above formula, C DES This indicates the concentration of pesticide residues in the DES enrichment phase (mg·L). -1 ); V DES The volume (mL) of the DES-enriched phase is indicated. C S This indicates the concentration of pesticide residues in the sample (mg·L). -1 ); V S Indicates the sample volume (mL).

[0050] (1) Dosage of DES The amount of eutectic solvent used is a crucial factor affecting extraction efficiency. Adding 0.1 mg / kg solvent to 1.5 mL of sample solution (blank water sample) is recommended. -1 The effect of DES extractant dosage of 50 μL, 100 μL, 150 μL, and 200 μL on extraction efficiency was investigated under the condition of pesticide volume.

[0051] The effect of DES dosage on the absolute recovery of the target analyte is shown in [reference needed]. Figure 6 .

[0052] Depend on Figure 6 It can be seen that the extraction results of [MENTH][Thymol]-1 for chlorantraniliprole and trifluralin show the same trend, that is, with the increase of volume, the recovery rate gradually decreases, possibly due to dilution. When the amount of [MENTH][Thymol]-1 is 150 μL, the actual absolute recoveries of chlorantraniliprole and trifluralin are 90% and 91%, respectively, which meet the analytical requirements. Similarly, when [ETA][Thymol]-1 is used to extract trifluralin, the recovery rate decreases with the increase of DES volume. When the DES volume is 200 μL, the recovery rate drops to 56%. When the DES volume is 50 μL, 100 μL, and 150 μL, the recovery rates of trifluralin are 82%, 78%, and 71%, respectively, all of which meet the analytical requirements. Since some [ETA][Thymol]-1 is lost during the extraction process, and too low a DES dosage will make it difficult to collect the DES-enriched phase, 150 μL of DES was selected for extraction and detection of the target analyte in subsequent experiments.

[0053] (2) Salt content The salt content of the extraction environment typically reduces the solubility of the target analyte in water through salting out, thereby improving extraction efficiency. Therefore, to investigate the effect of NaCl concentration on the recovery rate of the target analyte, 0.1 mg / kg NaCl was added to the sample solution (blank water sample). -1 A certain amount of NaCl was added to the pesticide to obtain NaCl concentrations of 0.1, 1, and 10 mg·L⁻¹. -1 Water samples were used as extraction environments under different salt content conditions.

[0054] The effect of NaCl concentration on the absolute recovery of the target analyte is shown in [reference]. Figure 7 .

[0055] from Figure 7As can be seen, the absolute recoveries of chlorantraniliprole and trifluralin initially increased and then decreased with increasing NaCl concentration. This may be because at low NaCl concentrations, the salt mainly acts as a salting-out agent, promoting pesticide recovery. However, high NaCl concentrations cause salting-out in the DES phase, reducing the extraction efficiency of DES. Therefore, to ensure the extraction efficiency of the target pesticides, a sample environment without added NaCl is sufficient for analysis. Furthermore, the absolute recovery rate of trifluralin remained relatively stable within the range of 80%–85% at different NaCl concentrations, indicating that trifluralin is less affected by salting-out. In conclusion, it is unnecessary to add NaCl to alter the sample environment in subsequent experiments.

[0056] (3) Vortex time The vortexing time determines the degree of dispersion of the DES phase, thus affecting the extraction efficiency. Within a certain time range, the mass transfer of pesticides can reach equilibrium, resulting in good extraction efficiency; further increases in time will not improve the extraction efficiency. To ensure sufficient mass transfer of pesticides in the DES phase and minimize time costs, this invention selected vortexing times of 0.5, 1, 2, and 3 minutes to test the vortexing time.

[0057] The effect of vortex time on the absolute recovery rate of the target analyte is shown in the figure. Figure 8 .

[0058] from Figure 8 As can be seen, the absolute recovery rate of chlorantraniliprole reached 106% at a vortex time of 0.5 min, and increased slightly with the extension of vortex time. At this time, the absolute recovery rate of trifluralinamide was 107%, which met the analytical requirements. The absolute recovery rate of trifluralinamide continued to increase with time, which may be due to the fact that the increase of vortex time promoted the extraction of impurities in the matrix, resulting in the absolute recovery rate being severely affected by the matrix effect. Therefore, 0.5 min was selected as the extraction time for trifluralinamide and chlorantraniliprole. When [ETA][Thymol]-1 was used as the extractant to extract trifluralinamide, the absolute recovery rate showed a trend of first increasing and then decreasing with the increase of vortex time, reaching the optimal recovery rate of 78% at 1 min of vortexing, which was longer than the vortex time when [MENTH][Thymol]-1 was used as the extractant. This is likely because [ETA][Thymol]-1 has a higher viscosity (115.4 mPa·s, 303 K) than [MENTH][Thymol]-1 (53.9 mPa·s, 303 K), requiring more time to achieve good dispersion. In subsequent experiments, [MENTH][Thymol]-1 was used as the extractant with a vortex-assisted time of 0.5 min, while [ETA][Thymol]-1 was used with a vortex-assisted time of 1 min.

[0059] Validation of the optimized method After optimization, the extraction conditions for VA-DES-DLLME were determined as follows: [MENTH][Thymol]-1 was used as the extractant for chlorantraniliprole and trifluralin, and [ETA][Thymol]-1 was used as the extractant for trifluralin; the extractant volume was 150 μL, and the vortexing time was 0.5 min (using [MENTH][Thymol]-1 as the extractant) or 1 min (using [ETA][Thymol]-1 as the extractant); no salt was added; the sample solution volume was 1.5 mL; and centrifugation was performed at 10,000 rpm for 1 min. To verify the application value of the optimized conditions obtained in the method optimization experiment, grape juice, peach juice, and apple juice were selected to further test the applicability of the method.

[0060] A matrix blank extract of the fruit juice was used as a diluent to prepare a matrix blank gradient standard solution for determination, with concentrations of 0.0005, 0.005, 0.01, 0.05, 0.1, and 0.2 mg·L⁻¹. -1 At least four points are used to ensure that the linear relationship covers two orders of magnitude. A matrix calibration curve is plotted with the measured concentration on the x-axis and the peak area on the y-axis.

[0061] The linear range, correlation coefficient, and limit of quantitation of the three pesticides in fruit juice and acetonitrile are shown in Table 3.

[0062] Table 3. Linear range, correlation coefficient, and limit of quantitation for the VA-DES-DLLME method. Table 3 shows that this method has good linearity against the three pesticides in the three fruit juices, with correlation coefficients R0. 2 The matrix effect was between 0.9754 and 0.9994. The matrix effect was obtained by the ratio of the slope of the matrix-matched standard curve to the slope of the acetonitrile-prepared standard curve. Matrix effects of pesticides were observed in apple juice, grape juice, and peach juice, at 818%–1847%, 975%–2175%, and 65%–72%, respectively. A matrix effect greater than 100% was considered matrix-enhanced, less than 80% was considered matrix-weakened, and a matrix effect in the range of 80%–120% was considered negligible. Therefore, the detection of chlorantraniliprole and trifluralin showed matrix enhancement, while the detection of trifluralin showed matrix weakening. In this invention, a matrix-matched standard solution is required for quantification.

[0063] Further designs were developed with concentrations of 0.005, 0.01, and 0.1 mg·L⁻¹. -1As added levels, recovery levels were determined, with each added level repeated three times. Precision (RSD) is expressed as the relative standard deviation of the recovery rate. The addition and recovery of pesticide residues in the three fruit juices are shown in Table 4.

[0064] Table 4 Recovery rates of additives in juice samples (n=3) Table 4 shows that the recoveries of chlorantraniliprole, trifluralinamide, and trifluralinamide in the three fruit juices were 79%–98%, 76%–105%, and 95%–120%, respectively, with relative standard deviations of 1%–16%, 6%–29%, and 1%–24%, respectively, meeting the analytical requirements. The minimum spiked concentration for each group was used as the limit of quantitation (LOQ) for this method. The results showed that the LOQ for chlorantraniliprole and trifluralinamide in all three fruit juices was 0.005 mg·L⁻¹. -1 The LOQ for trifluralin in apple and peach juice is 0.005 mg·L⁻¹. -1 The concentration in grape juice is 0.01 mg / L. -1 .

[0065] The VA-DES-DLLME detection method of this invention uses the AGREE evaluation system. The parameters in the AGREE evaluation system are designed as follows: (1) No external batch pretreatment of samples is required; (2) The sample volume is 1.5 mL; (3) The detection equipment is non-in-situ offline processing; (4) The processing steps are ≤3 (vortexing for 1 min and centrifugation for 2 min); (5) Semi-automated & small-scale processing; (6) No derivatization is required; (7) The waste liquid generated is 0.5 mL; (8) 3 target substances can be detected each time, and 20 samples can be analyzed per hour; (9) The maximum energy consumption is HPLC-MS / MS, and each sample consumes 0.1 kWh; (10) Some solvents are natural products; (11) 0.5 mL of toxic solvent is used; (12) Aquatic toxic, explosive and flammable solvent (acetonitrile) is used.

[0066] For ease of comparison, the AGREE analysis results of the traditional QuEChERS and DES-QuEChERS detection methods are shown in Table 5.

[0067] Table 5 AGREE Analysis Results Table 5 shows the detection steps for traditional QuEChERS: Weigh 10.00 ± 0.02 g of the homogenate sample, add 10.0 mL of acetonitrile, vortex for 3 min, add 3.00 g of NaCl, vortex again for 2 min, centrifuge at 3800 rpm for 5 min, and transfer 1.00 mL to a pre-weighed 2 mL centrifuge tube containing the purification agent. Vortex the centrifuge tube for 2 min, centrifuge at 10000 rpm for 1 min, and filter the supernatant through a 0.22 μm filter membrane into a vial for analysis.

[0068] The detection steps for DES-QuEChERS are as follows: Weigh 5.0 g of the homogenized sample into a 50 mL centrifuge tube, add 48% (2.4 mL) pure water, 18% (0.9 g) NaCl and 1 mL of eutectic solvent extraction solution, vortex extract for 1 min, centrifuge at 3800 rpm for 2 min to obtain the upper DES enriched phase, transfer 100 μL of the DES enriched phase to a 2 mL centrifuge tube, add 900 μL of acetonitrile for dilution before HPLC-MS / MS detection.

[0069] The results showed that the VA-DES-DLLME detection method achieved an average score of 0.71, which was 0.22 and 0.08 higher than that of conventional QuEChERS and DES-QuEChERS, respectively. Its higher score compared to DES-QuEChERS is mainly due to the reduced sample size to 1.5 mL, which earned the method a "miniaturized" score. Furthermore, the reduced sample volume also reduced the required DES extraction reagent.

[0070] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for detecting pesticide residues based on VA-DES-DLLME, characterized in that, Includes the following steps: The sample solution to be extracted was mixed with a eutectic solvent, and then vortexed to separate the eutectic solvent. The residual pesticide content in the separated eutectic solvent was determined using an analytical instrument. The hydrogen bond donor of the eutectic solvent is menthol or ethanolamine, and the hydrogen bond acceptor is thymol. The pesticides include: chlorantraniliprole, trifluopyridine, or trifluralin.

2. The method for detecting pesticide residues based on VA-DES-DLLME according to claim 1, characterized in that, The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is (1~2):(1~2).

3. The method for detecting pesticide residues based on VA-DES-DLLME according to claim 1, characterized in that, The volume ratio of the sample solution to be extracted to the eutectic solvent is 10:

1.

4. The method for detecting residual pesticides based on VA-DES-DLLME according to claim 1, characterized in that, When the hydrogen bond donor is menthol, the vortex extraction time is 0.5 min; when the hydrogen bond donor is ethanolamine, the vortex extraction time is 1 min.

5. The method for detecting pesticide residues based on VA-DES-DLLME according to claim 1, characterized in that, The analytical instruments include a high-performance liquid chromatography-mass spectrometry system.

6. The application of the VA-DES-DLLME-based pesticide residue detection method according to any one of claims 1 to 5 in the detection of pesticide residues in agricultural and sideline products.

7. Use according to claim 6, characterized in that, The agricultural products mentioned include fruit juice.

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