Solid phase microextraction adsorbents for pyrethroid pesticides

Abstract

The present application relates to a kind of pyrethroid pesticides solid phase microextraction adsorbent, it is characterized by 2,3,5,6-tetrafluoro-p-phenylenediamine and 2,4,6-trifluoro-1,3,5-triacetyl benzene as reactant monomer by condensation reaction obtained polymer.Its preparation process includes: solvent is put into reaction kettle, under continuous stirring, add reactant monomer mixture and catalyst, normal temperature reaction 10-15 hours, filter out solid, respectively with solvent and methanol wash after vacuum drying, obtain cluster polymer.The polymer has good adsorption selectivity to pyrethroid pesticides, can be used as the solid phase microextraction adsorbent of pyrethroid pesticides, for making solid phase microextraction probe.

Description

Technical Field

[0001] This invention relates to a solid-phase microextraction adsorbent for pyrethroid pesticides, particularly a polymer obtained by condensation reaction of 2,3,5,6-tetrafluoro-p-phenylenediamine and 2,4,6-trifluoro-1,3,5-triacetylbenzene as reactant monomers, belonging to the field of pesticide detection technology. Background Technology

[0002] Chemical pesticides play an increasingly important role in the production of agricultural products such as grains, vegetables, fruits, tea, and medicinal herbs. Pyrethroid pesticides are a class of insecticides synthesized artificially to mimic natural pyrethrin. Their active ingredient is natural pyrethrin, and they are a class of biomimetic broad-spectrum insecticides capable of controlling a variety of pests. Their insecticidal ability is 10 to 100 times higher than older generation insecticides such as organochlorines, organophosphates, and carbamates. They are highly effective and low-toxicity chemical pesticides, and are widely used as alternatives to organochlorine pesticides. These pesticides can enter the human body through the digestive tract, respiratory tract, and skin mucous membranes. Under the action of mixed-function oxidases and pyrethroid enzymes in liver microsomes, they undergo oxidation and hydrolysis reactions to produce water-soluble metabolites and conjugates of acids and alcohols, which are then excreted from the body. Although animal studies have shown that pyrethroids have no carcinogenic or teratogenic effects, some studies have indicated a risk of mutagenic effects during their biochemical processes in animals. Many countries have set strict limits on the residue levels of pyrethroid pesticides in food, therefore, the analysis and detection of pyrethroid pesticides has attracted much attention.

[0003] The residues of pyrethroid pesticides in food fall into the trace category, making direct analysis difficult. Enrichment is typically required before analysis. Currently, pyrethroid pesticide enrichment often utilizes C18 adsorbents through filtration columns. However, solid-phase microextraction (SPE) probes have limited adsorption capacity, and those made from ordinary C18 adsorbents cannot meet the enrichment requirements for trace pyrethroid pesticides in most foods. Invention patent 2019107354724 discloses a polymeric material with significantly improved pyrethroid pesticide enrichment capacity compared to ordinary C18 adsorbents. SPE probes made from this material have potential applications, but our experiments revealed significant shortcomings in their selectivity for pyrethroid pesticides. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of previous technologies and provide a solid-phase microextraction adsorbent with high selectivity and adsorption capacity for pyrethroid pesticides.

[0005] The solid-phase microextraction adsorbent of this invention is a covalent organic polymer, obtained by condensation reaction in a suitable solvent using 2,3,5,6-tetrafluoro-p-phenylenediamine and 2,4,6-trifluoro-1,3,5-triacetylbenzene as reactant monomers and a mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride as a catalyst. Studies have shown that this polymer exhibits good adsorption selectivity for pyrethroid pesticides and can be used as a solid-phase microextraction adsorbent for pyrethroid pesticides in food.

[0006] The structure of one reactant monomer of the present invention, 2,3,5,6-tetrafluoro-p-phenylenediamine, is shown in Formula I, and the structure of another reactant monomer of the present invention, 2,4,6-trifluoro-1,3,5-triacetylbenzene, is shown in Formula II.

[0007]

[0008] The specific preparation method of covalent organic polymer is as follows: The solvent is put into the reaction vessel, and the reactant monomer mixture and catalyst are added under continuous stirring. The mass ratio of solvent, reactant monomer mixture and catalyst is maintained at (20-30):1:(0.05-0.10). The reaction is carried out at room temperature for 10-15 hours. The solid is filtered out, washed with solvent and methanol respectively, and dried under vacuum at no more than 50°C for 6-8 hours to obtain a clustered polymer, whose repeating unit is shown in Formula III.

[0009]

[0010] The solvent is one or a mixture of several of 1,4-dioxane, o-xylene, m-xylene, p-xylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene; the reactant monomer mixture is a mixture of 2,3,5,6-tetrafluoro-p-phenylenediamine and 2,4,6-trifluoro-1,3,5-triacetylbenzene in a molar ratio of 1:1; and the catalyst is a mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:(0.8-1.5).

[0011] The obtained polymer can be used to make solid-phase microextraction probes. For example, after grinding and cleaning the stainless steel wire of the solid-phase microextraction device, the polymer of the present invention is adhered to the stainless steel wire with sealant. After curing, a solid-phase microextraction probe with high selectivity and adsorption capacity for pyrethroid pesticides is obtained. Detailed Implementation

[0012] Example 1

[0013] 1,4-Dioxane and o-xylene were added to a reactor at a mass ratio of 1:1. Under continuous stirring, a mixture of reactant monomers was added, along with a mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride at a molar ratio of 1:1. The mass ratio of solvent, reactant monomer mixture, and catalyst was maintained at 25:1:0.05. The reaction was carried out at room temperature for 12 hours. The solid was filtered off, washed with o-xylene and methanol respectively, and then dried under vacuum at 45°C for 8 hours to obtain a clustered polymer.

[0014] Spectroscopic analysis revealed that this clustered polymer has a network structure, with each mesh consisting of 12 reactant monomers linked in a rotationally symmetrical manner. Its repeating unit is shown in Formula IV.

[0015]

[0016] Example 2

[0017] 1,3,5-trimethylbenzene was added to a reaction vessel, and a mixture of reactant monomers was added under continuous stirring. A mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:1.2 was also added. The mass ratio of solvent, reactant monomer mixture and catalyst was maintained at 20:1:0.08, and the reaction was carried out at room temperature for 15 hours. The solid was filtered off, washed with 1,3,5-trimethylbenzene and methanol respectively, and then dried under vacuum at 40°C for 7 hours to obtain a clustered polymer.

[0018] Example 3

[0019] p-xylene was added to a reaction vessel, and a mixture of reactant monomers was added under continuous stirring. A mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:0.6 was also added. The mass ratio of solvent, reactant monomer mixture and catalyst was maintained at 26:1:0.06, and the reaction was carried out at room temperature for 12 hours. The solid was filtered out, washed with p-xylene and methanol respectively, and then dried under vacuum at 42°C for 6 hours to obtain a clustered polymer.

[0020] Example 4

[0021] xylene was added to a reaction vessel, and a mixture of reactant monomers was added under continuous stirring. A mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:1 was added, and the mass ratio of solvent, reactant monomer mixture and catalyst was maintained at 28:1:0.09. The reaction was carried out at room temperature for 10 hours. The solid was filtered out, washed with xylene and methanol respectively, and dried under vacuum at 48°C for 7 hours to obtain a clustered polymer.

[0022] Example 5

[0023] 1,2,3-Trimethylbenzene was added to a reaction vessel, and a mixture of reactant monomers was added under continuous stirring. A mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:1.4 was also added. The mass ratio of solvent, reactant monomer mixture and catalyst was maintained at 25:1:0.07, and the reaction was carried out at room temperature for 12 hours. The solid was filtered off, washed with trimethylbenzene and methanol respectively, and dried under vacuum at 41°C for 6 hours to obtain a clustered polymer.

[0024] Example 6

[0025] 1,2,4-Trimethylbenzene was added to a reaction vessel, and a mixture of reactant monomers was added under continuous stirring. A mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:1.2 was also added. The mass ratio of solvent, reactant monomer mixture and catalyst was maintained at 30:1:0.06, and the reaction was carried out at room temperature for 14 hours. The solid was filtered off, washed with trimethylbenzene and methanol respectively, and dried under vacuum at 40°C for 7 hours to obtain a clustered polymer.

[0026] Example 7

[0027] After the stainless steel wire of the solid phase microextraction device was polished and cleaned, sealant was evenly applied to the front surface of the stainless steel wire, about 2 cm in length. The polymer prepared in Example 1 was then adhered to the stainless steel wire through the sealant. After curing, a solid phase microextraction probe was obtained.

[0028] Example 8

[0029] Weigh 1g of apple and crush it, add 5.0mL of acetonitrile, vortex for 1 hour, filter, and collect the filtrate. Insert the solid-phase microextraction probe prepared in Example 7 into the apple extract, and perform gas chromatography-tandem mass spectrometry (GC-MS) to detect the solid-phase microextraction probe adsorbed with pyrethroid pesticides. The detection method was performed according to GB / T 5009.146-2008, "Determination of Multiple Residues of Organochlorine and Pyrethroid Pesticides in Plant-Based Foods," with a GC thermal desorption temperature of 268℃. The results showed that the pyrethroid compound content in the apple was 1.5 ng / g.

[0030] Example 9

[0031] After the stainless steel wire of the solid phase microextraction device was polished and cleaned, sealant was evenly applied to the front surface of the stainless steel wire, about 2 cm in length. The polymer prepared in Example 2 was then adhered to the stainless steel wire through the sealant. After curing, a solid phase microextraction probe was obtained.

[0032] Example 10

[0033] Weigh 1g of millet, pulverize it, add 5.0mL of acetonitrile, vortex for 1 hour, filter, and collect the filtrate. Insert the solid-phase microextraction probe prepared in Example 9 into the extract, and perform gas chromatography-tandem mass spectrometry (GC-MS / MS) to detect the solid-phase microextraction probe adsorbed with pyrethroid pesticides. The detection method was performed according to GB / T 5009.146-2008, "Determination of Multiple Residues of Organochlorine and Pyrethroid Pesticides in Plant-Based Foods," with a GC thermal desorption temperature of 268℃. The results showed that the pyrethroid compound content in millet was 0.7 ng / g.

Claims

1. A solid-phase microextraction adsorbent for pyrethroid pesticides, characterized in that... A polymer is obtained by condensation reaction of a mixture of 2,3,5,6-tetrafluoro-p-phenylenediamine and 2,4,6-trifluoro-1,3,5-triacetylbenzene in a molar ratio of 1:

1. The preparation method of the polymer is as follows: a solvent is added to a reaction vessel, and the mixture of reactant monomers and a catalyst are added under continuous stirring, maintaining the mass ratio of solvent, reactant monomer mixture and catalyst at (20-30):1:(0.05-0.10), and reacting at room temperature for 10-15 hours; the solid is filtered out, washed with solvent and methanol respectively, and dried under vacuum at no more than 50°C for 6-8 hours to obtain a clustered polymer.

2. The solid-phase microextraction adsorbent for pyrethroid pesticides according to claim 1, characterized in that... The solvent is one or a mixture of several of 1,4-dioxane, o-xylene, m-xylene, p-xylene, 1,2,3-trimethylene, 1,2,4-trimethylene, and 1,3,5-trimethylene.

3. The solid-phase microextraction adsorbent for pyrethroid pesticides according to claim 1, characterized in that... The catalyst is a mixture of zinc trifluoromethanesulfonate and trifluoroacetic anhydride in a molar ratio of 1:(0.8-1.5).

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