A magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI), its preparation method and application

Abstract

A magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III), and Cr(VI), its preparation method, and applications are disclosed. This invention relates to the field of sample pretreatment and utilizes ethylene boric anhydride pyridine solution and 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt as bifunctional monomers, prepared via in-situ polymerization. The adsorbent can simultaneously enrich four triazole pesticides and two forms of Cr through multiple interactions including B-N coordination, hydrogen bonding, and π-π stacking. Furthermore, the prepared adsorbent possesses advantages such as simple operation, low cost, long service life, low consumption of organic reagents, environmental friendliness, and high enrichment efficiency. Therefore, the magnetic porous monolithic adsorbent prepared in this invention has significant practical application value.

Description

Technical Field

[0001] This invention relates to the field of sample pretreatment, and more particularly to a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI), its preparation method and application. Background Technology

[0002] Triazole pesticides are widely used for disease control in various crops, vegetables, and fruits. However, during production and application, triazole pesticides inevitably seep into aquatic ecosystems such as rivers and lakes. Studies have shown that triazole compounds, due to their potential mutagenic and carcinogenic properties, can significantly interfere with the human endocrine system. Cr originates from various industrial wastewater and exhaust emissions; for example, the production processes of leather tanning, smelting, and electroplating industries generate large amounts of Cr-containing wastewater. Cr exists in the environment mainly in two forms: Cr(III) and Cr(VI). Cr(III) is one of the essential trace elements for the human body, participating in various biological processes, while Cr(VI), due to its strong oxidizing properties and high permeability, can induce mutations and is carcinogenic. Therefore, speciation analysis of Cr is essential. Based on practical needs, there is an urgent need to develop sensitive and reliable methods to detect triazole pesticides and different forms of Cr in environmental samples.

[0003] Currently, the commonly used methods for determining triazole pesticides are gas chromatography and high-performance liquid chromatography. Commonly used speciation analysis methods for Cr include flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry, and inductively coupled plasma mass spectrometry. There are no literature reports on methods that can simultaneously enrich and detect triazole pesticides and different speciations of chromium. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems in the prior art and provide a magnetic porous monolithic adsorbent and its preparation method that can simultaneously and efficiently extract triazole pesticides and different forms of Cr from environmental samples. Using ethylene boric anhydride pyridine solution (VAP) and 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (MAT) as bifunctional monomers, a magnetic porous monolithic adsorbent was prepared in situ in a capillary, achieving for the first time the simultaneous and efficient enrichment of triazole pesticides and different forms of Cr.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) includes the following steps:

[0007] 1) Mix the functional monomers, crosslinking agents, porogens, initiators and magnetic nanoparticles in a certain proportion and sonicate them into a homogeneous solution;

[0008] 2) Pour the prepolymer solution mixed in step 1) into a container, seal it, and initiate the polymerization reaction at a certain temperature;

[0009] 3) After the polymerization reaction is complete, rinse it with a certain volume of methanol or acetonitrile, and then rinse it again with methanol or acetonitrile to activate it before use;

[0010] The functional units are VAP and MAT;

[0011] The crosslinking agents are ethylene glycol dimethacrylate (EDMA) and divinylbenzene (DVB);

[0012] The pore-forming agents are n-propanol and 1,4-butanediol.

[0013] The amount of VAP and MAT added is 10% to 30% of the total mass of the prepolymer solution, and the mass ratio of VAP to MAT is 1:4 to 4:1.

[0014] The amount of EDMA and DVB added is 10% to 30% of the total mass of the prepolymer solution, and the mass ratio of EDMA to DVB is 1:3 to 3:1.

[0015] The amount of n-propanol and 1,4-butanediol added is 40% to 90% of the total mass of the prepolymer solution, and the mass ratio of n-propanol to 1,4-butanediol is 1:3 to 3:1.

[0016] The initiator is azobisisobutyronitrile (AIBN); the amount of AIBN added is 0.2–4.0 mg / 100 mg prepolymer solution.

[0017] The magnetic nanoparticles are modified Fe3O4 nanoparticles; the magnetic nanoparticles are added at a mass of 0.5–5.0 mg / 100 mg prepolymer solution.

[0018] In step 2), the polymerization temperature is 60–80°C and the polymerization time is 8–24 h.

[0019] In step 3), the specified volume is 1.0 to 10 mL.

[0020] The adsorbent prepared in this invention can simultaneously enrich four triazole pesticides and two forms of Cr through multiple interactions such as BN coordination, hydrogen bonding and π-π stacking.

[0021] Since the concentration of pollutants in the environment is very low and the actual sample substrate is relatively complex, this invention performs enrichment pretreatment on the sample, and utilizes the reaction of complexing agents with Cr to generate complexes with ultraviolet absorption. Then, high performance liquid chromatography coupled with an ultraviolet detector is used for determination. Through optimization of the chromatographic method, the simultaneous determination of triazole pesticides and different forms of Cr can be achieved.

[0022] Specifically, the magnetic porous monolithic adsorbent is used to pre-adsorb samples containing triazole pesticides, Cr(III) and Cr(VI), followed by desorption, and finally the triazole pesticides and different forms of Cr are analyzed simultaneously by chromatographic detection.

[0023] In this invention, a complexing agent is used during the adsorption pretreatment to convert Cr(III) and Cr(VI) into metal-organic complexes that can be detected by HPLC-DAD. Ultrapure water and acetonitrile are used as the mobile phase, and a gradient elution program is set: 0–11.0 min, 53% acetonitrile; 11.0–15.0 min, 53%–70% acetonitrile; 15.0–18.0 min, 70% acetonitrile; 18.0–22.0 min, 70%–53% acetonitrile; 22.0–25.0 min, 53% acetonitrile, enabling the simultaneous detection of triazole pesticides and different forms of Cr.

[0024] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0025] This invention represents the first synthesis of a magnetic porous monolithic adsorbent capable of simultaneously and efficiently extracting triazole pesticides and different forms of Cr. Because the adsorbent is rich in boron, nitrogen, and aromatic functional groups, it achieves simultaneous and efficient extraction of triazole pesticides and Cr complexes through BN coordination, hydrogen bonding, and π-π stacking interactions. Furthermore, the prepared adsorbent possesses advantages such as simple operation, low cost, long service life, low consumption of organic reagents, environmental friendliness, and high enrichment efficiency. Therefore, the magnetic porous monolithic adsorbent prepared in this invention has significant practical application value. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the synthesis reaction of the magnetic porous monolithic adsorbent in Example 2.

[0027] Figure 2 The image shows the infrared spectrum of the magnetic porous monolithic adsorbent in Example 6.

[0028] Figure 3 This is a scanning electron microscope image of the magnetic porous monolithic adsorbent in Example 6.

[0029] Figure 4 This is a transmission electron microscope (TEM) image of the magnetic porous monolithic adsorbent in Example 6.

[0030] Figure 5 This is a diagram showing the service life of the magnetic porous monolithic adsorbent in Example 6.

[0031] Figure 6 The following are high-performance liquid chromatograms of the spiked samples in Example 10 before direct injection (a), after extraction with magnetic porous monolithic material (without magnetic field) (b), and after extraction with magnetic porous monolithic material (with magnetic field applied) (c). Detailed Implementation

[0032] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] Synthesis of magnetic nanoparticles:

[0035] First, 5.4 g of FeCl3·6H2O and 1.98 g of FeCl2·4H2O were dissolved in 100 mL of ultrapure water. The solution was placed in an 80 °C water bath and stirred continuously for 2 h. When the water bath temperature was raised to 60 °C, 10 mL of ethylenediamine was added, and nitrogen gas was continuously introduced during the reaction. After the reaction was complete, the obtained Fe3O4 was washed with methanol, ultrapure water, and acetone, respectively, and then dissolved in 150 mL of ultrapure water to obtain a Fe3O4 solution. The solution containing 1 g of Fe3O4 particles was dispersed in 100 mL of isopropanol, and 5 mL of tetraethyl orthosilicate and 60 mL of 25% ammonia water were added. The mixture was reacted at room temperature for 12 h to obtain Fe3O4@SiO2 particles. Fe3O4@SiO2 (1g), methanol (10mL), triethylamine (1mL) and 3-(isobutenoyloxy)propyltrimethoxysilane (1mL) were mixed and shaken on a shaker for 12h. This step can introduce double bonds on the particles. The particles were washed with methanol and dried at 60℃ to obtain the modified Fe3O4 nanoparticles.

[0036] Example 2

[0037] Preparation of magnetic porous monolithic adsorbent:

[0038] The synthesis reaction equation for magnetic porous monolithic adsorbents is as follows: Figure 1As shown, VAP and MAT were used as functional monomers, EDMA and DVB as crosslinking agents, n-propanol and 1,4-butanediol as porogens, and AIBN as an initiator. The above reagents were combined with magnetic nanoparticles to form a prepolymerization solution. The composition of the prepolymerization solution, by mass percentage, was 10% functional monomers, 20% crosslinking agents, and 70% porogens. The composition of the functional monomers, by mass percentage, was 50% VAP and 50% MAT. The composition of the crosslinking agents, by mass percentage, was 40% EDMA and 60% DVB. The composition of the porogens, by mass percentage, was 50% n-propanol and 50% 1,4-butanediol. The mass of AIBN added was 1.0 mg / 100 mg of the prepolymerization solution. The mass of the magnetic nanoparticles added was 0.5 mg / 100 mg of the prepolymerization solution. The mixed prepolymerization solution was injected into a tubular container, sealed, and reacted at 70°C for 10 h. After the polymerization reaction was completed, it was rinsed with 1.0 mL of methanol.

[0039] Example 3

[0040] Preparation of magnetic porous monolithic adsorbent:

[0041] Using VAP and MAT as functional monomers, EDMA and DVB as crosslinking agents, n-propanol and 1,4-butanediol as porogens, and AIBN as an initiator, a prepolymerization solution was prepared by combining the above reagents with magnetic nanoparticles. The prepolymerization solution consisted of the following composition by mass percentage: 20% functional monomers, 20% crosslinking agents, and 60% porogens; 40% VAP and 60% MAT; 60% EDMA and 40% DVB; 70% n-propanol and 30% 1,4-butanediol; 2.0 mg of AIBN per 100 mg of the prepolymerization solution; and 1.5 mg of magnetic nanoparticles per 100 mg of the prepolymerization solution. The mixed prepolymerization solution was injected into a tubular container, sealed, and reacted at 60°C for 24 h. After the polymerization reaction was complete, the solution was rinsed with 2.0 mL of acetonitrile.

[0042] Example 4

[0043] Preparation of magnetic porous monolithic adsorbent:

[0044] Using VAP and MAT as functional monomers, EDMA and DVB as crosslinking agents, n-propanol and 1,4-butanediol as porogens, and AIBN as an initiator, a prepolymerization solution was prepared by combining the above reagents with magnetic nanoparticles. The prepolymerization solution consisted of 15% functional monomers, 25% crosslinking agents, and 60% porogens by mass percentage. Specifically, the functional monomers comprised 30% VAP and 70% MAT by mass percentage; the crosslinking agents comprised 50% EDMA and 50% DVB by mass percentage; the porogens comprised 40% n-propanol and 60% 1,4-butanediol by mass percentage; AIBN was added at a concentration of 1.5 mg / 100 mg of the prepolymerization solution; and the magnetic nanoparticles were added at a concentration of 1.0 mg / 100 mg of the prepolymerization solution. The mixed prepolymerization solution was injected into a tubular container, sealed, and reacted at 80°C for 8 hours. After the polymerization reaction was complete, the container was rinsed with 2.0 mL of methanol.

[0045] Example 5

[0046] Preparation of magnetic porous monolithic adsorbent:

[0047] Using VAP and MAT as functional monomers, EDMA and DVB as crosslinking agents, n-propanol and 1,4-butanediol as porogens, and AIBN as an initiator, a prepolymerization solution was prepared by combining the above reagents with magnetic nanoparticles. The prepolymerization solution consisted of 20% functional monomers, 10% crosslinking agents, and 70% porogens by mass percentage. Specifically, the functional monomers comprised 60% VAP and 40% MAT by mass percentage; the crosslinking agents comprised 30% EDMA and 70% DVB by mass percentage; the porogens comprised 50% n-propanol and 50% 1,4-butanediol by mass percentage; and AIBN was added at a concentration of 2.0 mg / 100 mg of the prepolymerization solution. The magnetic nanoparticles were also added at a concentration of 2.0 mg / 100 mg of the prepolymerization solution. The mixed prepolymerization solution was injected into a tubular container, sealed, and reacted at 70°C for 24 h. After the polymerization reaction was complete, the container was rinsed with 4.0 mL of methanol.

[0048] Example 6

[0049] Preparation of magnetic porous monolithic adsorbent:

[0050] Using VAP and MAT as functional monomers, EDMA and DVB as crosslinking agents, n-propanol and 1,4-butanediol as porogens, and AIBN as an initiator, a prepolymerization solution was prepared by combining the above reagents with magnetic nanoparticles. The prepolymerization solution consisted of 16% functional monomers, 19% crosslinking agents, and 65% porogens by mass percentage. Specifically, the functional monomers comprised 25% VAP and 75% MAT by mass percentage; the crosslinking agents comprised 50% EDMA and 50% DVB by mass percentage; and the porogens comprised 50% n-propanol and 50% 1,4-butanediol by mass percentage. The AIBN concentration was 2.0 mg / 100 mg of the prepolymerization solution, and the magnetic nanoparticles concentration was 2.5 mg / 100 mg of the prepolymerization solution. The mixed prepolymerization solution was injected into a tubular container, sealed, and reacted at 70°C for 12 h. After polymerization, the solution was rinsed with 5.0 mL of acetonitrile.

[0051] Figure 2 The infrared spectrum of the magnetic porous monolithic adsorbent prepared in this embodiment is shown, with 2936 cm⁻¹. -1 The absorption peak is due to the stretching vibration of alkyl groups, at 1728 cm⁻¹. -1 The absorption peak at 1638 cm⁻¹ is a characteristic peak of the carbonyl group in EDMA. -1 The absorption peak is attributed to the stretching vibration of the C=C functional group, 1458 cm⁻¹. -1 The absorption peak is attributed to the stretching vibration of the benzene ring, 1109 cm⁻¹. -1 and 1167cm -1 The absorption peak is attributed to the stretching vibration of CN in VAP and MAT, 712 cm⁻¹ -1 The absorption peak at 573 cm⁻¹ is attributed to the stretching vibration of the CF on the MAT. -1 The absorption peak at that point corresponds to the stretching vibration of Fe-O. Figure 3 The scanning electron microscope image of the magnetic porous monolithic adsorbent prepared in this embodiment shows a clear porous structure. Figure 4 The image shows a transmission electron microscope (TEM) image of the magnetic porous monolithic adsorbent prepared in this embodiment, in which magnetic nanoparticles are uniformly dispersed in the porous monolithic material. Figure 5 The graph shows the service life of the magnetic porous monolithic adsorbent. After 120 cycles of adsorption and desorption, the adsorption performance remains good.

[0052] Example 7

[0053] Preparation of magnetic porous monolithic adsorbent:

[0054] Using VAP and MAT as functional monomers, EDMA and DVB as crosslinking agents, n-propanol and 1,4-butanediol as porogens, and AIBN as an initiator, a prepolymerization solution was prepared by combining the above reagents with magnetic nanoparticles. The prepolymerization solution consisted of the following composition by mass percentage: 4% functional monomers, 6% crosslinking agents, and 90% porogens; 25% VAP and 75% MAT; 75% EDMA and 25% DVB; 30% n-propanol and 70% 1,4-butanediol; 4.0 mg AIBN per 100 mg of the prepolymerization solution; and 5.0 mg of the magnetic nanoparticles per 100 mg of the prepolymerization solution. The mixed prepolymerization solution was injected into a tubular container, sealed, and reacted at 70°C for 18 hours. After the polymerization reaction was complete, the solution was rinsed with 10 mL of acetonitrile.

[0055] Example 8

[0056] Comparison of the performance of magnetic porous monolithic adsorbents under different preparation conditions:

[0057] The porous monolithic adsorbents prepared in Examples 2-7 were used for the enrichment of triazole pesticides and different forms of Cr. Sample solutions containing 100 μg / L of target compounds were prepared. The target compounds included four triazole pesticides (triazole (TRN), cyproconazole (MYC), triadimefon (TRF), and hexaconazole (HEX)) and two forms of Cr (Cr(III) and Cr(VI)). Specific extraction conditions were as follows: sample volume 3.0 mL, adsorption flow rate 0.10 mL / min, acetonitrile as desorption solvent 100 μL, desorption flow rate 0.06 mL / min, and no pH adjustment of the sample solution. Under these conditions, the enrichment efficiency of the adsorbent for the target analyte in Example 2 was 28.9%–51.0%; in Example 3, it was 24.0%–52.8%; in Example 4, it was 33.0%–51.4%; in Example 5, it was 30.6%–60.7%; in Example 6, it was 39.5%–65.5%; and in Example 7, it was 35.9%–57.1%. The porous monolithic adsorbent prepared in Example 6 exhibited the best enrichment performance for triazole pesticides and different forms of Cr.

[0058] Example 9

[0059] Application of the magnetic field-assisted in-tube solid-phase microextraction-chromatography coupled device based on the adsorbent of this invention:

[0060] The online coupling device consists of two parts: an extraction unit and a chromatographic detection unit. The extraction unit includes two high-pressure constant flow pumps, a six-way valve, and a capillary microextraction column containing a magnetic porous monolithic adsorbent. The chromatographic detection unit comprises a six-way valve, a quantitative loop, and a high-performance liquid chromatograph containing a high-pressure pump and a diode array detector. The two six-way valves are connected via PEEK tubing, and online adsorption, desorption, and detection of samples are achieved by switching valve positions. The capillary microextraction column is wrapped with a magnetic coil that can be connected to a DC power supply. During adsorption and desorption, by controlling the magnitude and direction of the current, the magnetic coil generates a magnetic field of a certain strength and direction. This induces a magnetic field gradient in the magnetic nanoparticles within the capillary microextraction column, improving the extraction efficiency of the target analyte.

[0061] To meet the requirements of chromatographic separation and detection, pyrrolidine dithiocarbamate (APD) was added to the sample solution before extraction to react simultaneously with Cr(III) and Cr(VI) to form Cr(III)-APD and Cr(VI)-APD complexes, respectively. The complexation reaction equations are shown below:

[0062]

[0063] During adsorption, the magnetic field direction within the capillary microextraction column is aligned with the flow direction of the sample solution, with a magnetic field strength of 20 Gs. Simultaneously, 8.0 mL of sample solution is introduced into the capillary microextraction column at a flow rate of 0.25 mL / min to adsorb the target analyte. After adsorption, the magnetic field direction within the capillary microextraction column is reversed, with a magnetic field strength of 40 Gs. 110 μL of acetonitrile is then introduced into the capillary microextraction column at a flow rate of 0.04 mL / min to desorb the target analyte. The eluent is stored in a quantitative loop. After desorption, the eluent is carried into the chromatographic column using the chromatographic mobile phase and finally analyzed by a diode array detector.

[0064] Example 10

[0065] Prepare 8.0 mL water samples containing TRN, MYC, TRF, HEX, Cr(III), and Cr(VI) (containing 40 mg / L of complexing agent APD) (the concentration of each target analyte was 100 μg / L). Using the magnetic porous monolithic adsorbent prepared in Example 6, online extraction and detection were performed according to the magnetic field-assisted in-tube solid-phase microextraction-chromatography (SPE-GC) system described in Example 9.

[0066] The instruments used for chromatographic analysis were an HPLC system and a DAD detector (model 1260, Agilent Technologies, USA). The high-performance liquid chromatography (HPLC) conditions included the column, mobile phase A, mobile phase B, elution program, and detection wavelength. The column was a ThermoHypersil BDS C18 column (250 mm × 4.6 mm id, 5 μm particle size). Mobile phase A was ultrapure water, and mobile phase B was acetonitrile. Gradient elution was used: 0–11.0 min, 53% B; 11.0–15.0 min, 53%–70% B; 15.0–18.0 min, 70% B; 18.0–22.0 min, 70%–53% B; 22.0–25.0 min, 53% B. The injection volume was 110 μL, the flow rate was 1.0 mL / min, and the detection wavelengths for TRN, MYC, TRF, and HEX were 223 nm, while the detection wavelengths for Cr(III)-APD and Cr(VI)-APD were 254 nm. Figure 6 The figures show the high-performance liquid chromatography (HPLC) chromatograms at 223 nm for four triazoles and two Cr complexes spiked with 100 ppb before extraction (a), after extraction with magnetic porous monolithic material (without magnetic field) (b), and after extraction with magnetic porous monolithic material (with magnetic field applied) (c). Under no magnetic field conditions, the enrichment efficiency for the target analytes ranged from 46.2% to 75.3%; after applying a magnetic field, the peak height of the target analytes increased significantly, and the enrichment efficiency improved to 80.5%–98.0%.

Claims

1. A method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI), characterized in that, Includes the following steps: 1) Mix the functional monomers, crosslinking agents, porogens, initiators and magnetic nanoparticles in a certain proportion and sonicate them into a homogeneous solution; 2) Pour the prepolymer solution mixed in step 1) into a container, seal it, and initiate the polymerization reaction at a certain temperature; 3) After the polymerization reaction is complete, rinse it with a certain volume of methanol or acetonitrile, and then rinse it again with methanol or acetonitrile to activate it before use; The functional monomers are ethylene boric anhydride pyridine solute VAP and 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt MAT; The crosslinking agent is ethylene glycol dimethacrylate (EDMA) and divinylbenzene (DVB); The pore-forming agent is n-propanol and 1,4-butanediol; The magnetic nanoparticles are synthesized as follows: Fe3O4@SiO2, methanol, triethylamine and 3-(isobutenoyloxy)propyltrimethoxysilane are mixed and shaken on a shaker. This step introduces double bonds on the particles. The particles are then washed with methanol and dried to obtain the modified Fe3O4 nanoparticles.

2. The method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) as described in claim 1, characterized in that: The amount of VAP and MAT added is 10% to 30% of the total mass of the prepolymer solution, and the mass ratio of VAP to MAT is 1:4 to 4:

1.

3. The method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) as described in claim 1, characterized in that: The amount of EDMA and DVB added is 10% to 30% of the total mass of the prepolymer solution, and the mass ratio of EDMA to DVB is 1:3 to 3:

1.

4. The method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) as described in claim 1, characterized in that: The amount of n-propanol and 1,4-butanediol added is 40% to 90% of the total mass of the prepolymerization solution, and the mass ratio of n-propanol to 1,4-butanediol is 1:3 to 3:

1.

5. A method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) as described in claim 1, characterized in that: The initiator is azobisisobutyronitrile (AIBN); the mass of AIBN added is 0.2~4.0 mg / 100 mg of prepolymer solution.

6. A method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) as described in claim 1, characterized in that: The magnetic nanoparticles were added at a mass of 0.5~5.0 mg / 100 mg of prepolymer solution.

7. A method for preparing a magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI) as described in claim 1, characterized in that: In step 2), the polymerization temperature is 60~80℃ and the polymerization time is 8~24 h; in step 3), the certain volume is 1.0~10 mL.

8. A magnetic porous monolithic adsorbent capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI), characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the magnetic porous monolithic adsorbent as described in claim 8, capable of simultaneously enriching triazole pesticides, Cr(III) and Cr(VI), characterized in that: The magnetic porous monolithic adsorbent is used to pre-adsorb samples containing triazole pesticides, Cr(III) and Cr(VI), followed by desorption, and finally the triazole pesticides and different forms of Cr are analyzed simultaneously by chromatographic detection.

10. The application as described in claim 9, characterized in that: During the pretreatment for adsorption, a complexing agent was used to convert Cr(III) and Cr(VI) into metal-organic complexes that can be detected by HPLC-DAD; a gradient elution program was set with ultrapure water and acetonitrile as the mobile phase: 0~11.0 min, 53% acetonitrile; 11.0~15.0 min, 53%~70% acetonitrile; 15.0~18.0 min, 70% acetonitrile; 18.0~22.0 min, 70%~53% acetonitrile; 22.0~25.0 min, 53% acetonitrile, to achieve simultaneous detection of triazole pesticides and different forms of Cr.

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