Preparation and application of mass spectrum ionization source element special for benzoylurea insecticide analysis

Abstract

The invention discloses preparation and application of a mass spectrum ionization source element special for benzoylurea insecticide analysis, and the ionization source element comprises a substrate layer which is paper; the adsorption layer covers at least part of the surface of the substrate, the adsorption layer is formed by a sulfonic acid functionalized covalent organic framework material and hydrogel, and the hydrogel is composed of water, sodium alginate, calcium ions and polyacrylic acid. The sulfonic acid functionalized covalent organic framework material is composed of repeated multi-element ring units as shown in a formula I which is described in the specification. The ionization source element is uniform in coating, good in benzoylurea enrichment effect and high in adsorption capacity, the ionization source element can serve as a fixed substrate, mass spectrometric detection is carried out through ionization and ionization, the detection steps are simple, the background noise of detection is low, sensitivity and accuracy are high, and the detection cost is low. The method is especially suitable for enrichment and detection of benzoylurea in a complex food matrix sample.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of analytical chemistry, in particular, to the preparation and application of a mass spectrometry ionization source element for benzoylurea insecticide analysis. BACKGROUND

[0002] Benzoylurea insecticides (BUs) are widely used in agricultural production as insect growth regulators, which inhibit insect reproduction by interfering with chitin synthesis. With high selectivity, good biological activity and rapid degradation characteristics, this class of pesticides plays an important role in the control of agricultural pests. However, its extensive use may lead to pesticide residues accumulating in food and the environment through the food chain, posing potential threats to the health of mammals and humans due to chronic exposure and long-term toxicity. There is an urgent need to develop high-sensitivity, rapid and suitable analysis methods for benzoylurea pesticide detection in complex food matrices.

[0003] Liquid chromatography tandem mass spectrometry (LC-MS / MS) is the standard detection method for benzoylurea insecticides, but the pretreatment is complex and the chromatographic separation time is long, which cannot meet the demand of rapid detection. Solid substrate electrospray ionization mass spectrometry (SSESI-MS) is an atmospheric pressure ionization technique that directly electrosprays samples on a solid carrier, and the extraction efficiency and enrichment effect of target compounds on the surface of the solid substrate are enhanced by coating modification. Therefore, it is of great practical significance and application value to develop a solid substrate ionization source element for specific enrichment of BUs and a corresponding direct mass spectrometry detection method. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present application is to innovatively combine a sulfonic acid functionalized covalent organic framework with a hydrogel and composite it on a paper substrate to construct a new adsorption material. The hydrogel not only imparts excellent hydrophilicity to the material, but also allows the sulfonic acid functionalized covalent organic framework to be coated on the paper substrate through physical methods, thereby eliminating the chemical reaction step and realizing integrated operation of "adsorption-desorption-ionization".

[0005] According to one aspect of the present application, a mass spectrometry ionization source element for benzoylurea insecticide analysis is provided. According to an embodiment of the present application, the ionization source element comprises: a substrate layer composed of a paper material; and an adsorption layer coated on at least part of the surface of the substrate, the adsorption layer being formed of a sulfonic acid functionalized covalent organic framework material and a hydrogel, wherein the hydrogel is composed of water, sodium alginate, calcium ions and polyacrylic acid, and the sulfonic acid functionalized covalent organic framework material is composed of a repeated polybasic ring unit represented by Formula I.

[0006]

[0007] The ionization source element according to the embodiment of the present application has a uniform coating, good benzoylurea enrichment effect, strong adsorption, and directly ionizes and ionizes for mass spectrometry detection by applying high voltage to the surface, so that the detection steps are simple, the background noise of detection is low, the sensitivity and accuracy are high, and it is especially suitable for the enrichment and detection of benzoylurea in complex food matrix samples.

[0008] In addition, the specific benzoylurea insecticide analysis special mass spectrometry ionization source element according to the above embodiment of the present application can also have the following additional technical features:

[0009] According to the embodiment of the present application, the paper material is qualitative filter paper.

[0010] According to the embodiment of the present application, the base layer has a conical tip, preferably an equilateral triangle.

[0011] According to the embodiment of the present application, the side length of the base layer is not greater than 2.0 cm, preferably an equilateral triangle with a side length of 1.3 cm and a thickness of 0.2 mm.

[0012] According to the embodiment of the present application, the hydrophilic contact angle of the adsorption layer is 25-26 degrees, preferably 25.14 degrees.

[0013] According to the embodiment of the present application, the benzoylurea insecticide is at least one selected from diflubenzuron (DIFL), flucycloxuron (PENF), fluroxuron (NOVA), flufenoxuron (FLUF) and flufenprox (FLUA).

[0014] According to another aspect of the present application, a method for preparing the aforementioned benzoylurea insecticide analysis special mass spectrometry ionization source element is provided. According to the embodiment of the present application, the method comprises: contacting an amino monomer and an aldehyde monomer and performing a first ultrasonic and Schiff base reaction to obtain a covalent organic framework; contacting the aforementioned covalent organic framework with 2-mercaptoethanesulfonic acid sodium and performing a second ultrasonic and click reaction to obtain a sulfonic acid functionalized covalent organic framework; mixing calcium ions and polyacrylic acid in water to obtain a calcium ion-polyacrylic acid mixture; mixing the sulfonic acid functionalized covalent organic framework, sodium alginate and water to perform a third ultrasonic to obtain a post-ultrasonic liquid; immersing paper in the post-ultrasonic liquid until saturation to obtain an immersed paper base; and contacting the immersed paper base with the calcium ion-polyacrylic acid mixture to perform a chain association reaction, solidification to form a composite covalent organic framework-hydrogel composite paper base (COF@HYD / PA), so as to obtain the ionization source element.

[0015] According to the preparation method of the embodiment of the present application, the ionization source element coating prepared by the method has uniform coating, strong adsorption of benzoylurea insecticide enrichment, and the preparation method has mild conditions, simple steps, low cost and good commercialization potential.

[0016] According to the embodiment of the present application, the contact of the amino monomer and the aldehyde monomer is carried out in a mixed solution of 1,4-dioxane and mesitylene, wherein the volume ratio of 1,4-dioxane and mesitylene is 1:1.

[0017] According to the embodiment of the present application, the aldehyde monomer is 1,4-dialdehyde-2,5-divinylbenzene (Dva), and the amino monomer is N,N-bis(4-aminophenyl)benzene-1,4-diamine (TAPA).

[0018] According to the embodiment of the present application, the ratio of the amino monomer, the aldehyde monomer and the mixed solution is 0.4 mmol:0.6 mmol:25-35 mL, preferably 0.4 mmol:0.6 mmol:30 mL.

[0019] According to the embodiment of the present application, the catalyst of the Schiff base reaction is acetic acid, and the initiator of the click reaction is azobisisobutyronitrile.

[0020] According to the embodiment of the present application, the volume ratio of the acetic acid to the mixed solution is 1:30.

[0021] According to the embodiment of the present application, the contact of the covalent organic framework and 2-mercaptoethanesulfonic acid sodium is carried out in an acetonitrile solution.

[0022] According to the embodiment of the present application, the ratio of the covalent organic framework, 2-mercaptoethanesulfonic acid sodium and acetonitrile is 40 mg:36 mg:10-20 mL, preferably 40 mg:36 mg:15 mL.

[0023] According to the embodiment of the present application, the calcium ion is calcium chloride.

[0024] According to the embodiment of the present application, the ratio of the calcium chloride and the polyacrylic acid to water is 225 mg:0.6 mmol:25-35 mL, preferably 225 mg:0.6 mmol:30 mL.

[0025] According to the embodiment of the present application, the ratio of the sulfonic acid functionalized covalent organic framework, the sodium alginate and water is 25 mg:20 mg:1 mL.

[0026] According to the embodiment of the present application, the time of the first ultrasonic, the second ultrasonic and the third ultrasonic is independently 10-20 minutes, preferably 15 minutes.

[0027] According to an embodiment of the present invention, the Schiff base reaction is carried out at a temperature of 55-65°C for 5-7 hours, preferably 6 hours, and at a reaction temperature of 60°C.

[0028] According to an embodiment of the present invention, the temperature of the click reaction is 65-75°C, preferably 70°C, the time is 10-14 hours, preferably 12 hours, and the reaction temperature is 70°C.

[0029] According to another aspect of the present invention, an integrated separation and ionization mass spectrometry device is provided. According to an embodiment of the present invention, the device includes: the aforementioned ionization source element specifically designed for the analysis of benzoylurea pesticides; an open-type mass spectrometer detector including an inlet, the inlet being disposed opposite to the tip of the ionization source element; and a high-voltage power supply connected to the ionization source element. Thus, the aforementioned ionization source element specifically designed for the analysis of benzoylurea pesticides is directly connected to the high-voltage power supply. Under the action of the high voltage, the target analyte on the ionization source element is ionized under the action of the elution solvent. The generated ions directly enter the mass spectrometer inlet to obtain the acquired signal. The detection procedure is simple, and the background noise of the detection is low, making it particularly suitable for the enrichment and detection of benzoylurea pesticides in complex samples.

[0030] According to another aspect of the present invention, a method for enriching and purifying benzoylurea insecticides is provided. According to an embodiment of the present invention, the method includes: pretreating a sample to be tested to obtain a test solution; and subjecting the test solution to oscillating contact treatment with a benzoylurea insecticide-specific mass spectrometry ionization source element to obtain an ionization source element with surface adsorption of the benzoylurea insecticide. Therefore, this purification method exhibits good specificity and strong adsorption capacity for benzoylurea insecticides, which is beneficial for the sufficient enrichment of complex matrices, such as benzoylurea insecticides in food. Furthermore, the enrichment and purification method of the present invention is simple to operate, requires no complex sample pretreatment process, and has high sample extraction efficiency.

[0031] According to an embodiment of the present invention, the rotational speed of the oscillating contact treatment is 500-700 rpm, and the time is 40 minutes.

[0032] According to another aspect of the present invention, the present invention provides a method for qualitative / quantitative detection of benzoylurea insecticides. According to an embodiment of the present invention, the method includes: enriching benzoylurea insecticides in a test sample using the aforementioned method for enriching and purifying benzoylurea insecticides to obtain an ionization source element for surface enrichment of benzoylurea insecticides; and detecting the ionization source element for surface enrichment of benzoylurea insecticides using the aforementioned integrated separation and ionization mass spectrometry device to perform qualitative / quantitative detection of the benzoylurea insecticides. Therefore, the aforementioned ionization source element has good specificity and strong adsorption for benzoylurea pesticides in complex matrices, which is conducive to fully enriching benzoylurea pesticides in complex matrices. Furthermore, the ionization source element for enriching benzoylurea pesticides is directly connected to a high-voltage power supply. Under the action of high voltage, the target substance on the ionization source element is ionized by the elution solvent. The generated ions directly enter the mass spectrometer through the inlet of the mass spectrometer detector to obtain the acquired signal. The detection procedure is simple, the background noise is low, and the detection sensitivity is high, making it particularly suitable for the rapid and accurate analysis of trace amounts of benzoylurea pesticides.

[0033] According to an embodiment of the present invention, the detection conditions of the integrated separation and ionization mass spectrometry device are as follows: high voltage power supply voltage: +3.5kV; ionization elution solvent: methanol solution.

[0034] According to an embodiment of the present invention, the detection conditions of the mass spectrometer detector are as follows: detection mode: multiple reaction monitoring (MRM); electrospray ionization source: ESI+; nebulizing gas flow rate: 3 L / min; drying gas flow rate: 10 L / min; heating gas flow rate: 10 L / min; interface temperature: 300 °C; DL temperature: 250 °C; heating block temperature: 400 °C.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 The diagram shows a scanning electron microscope (SEM) image of an ionization source element according to an embodiment of the present invention, wherein A and B are SEM images of COF(TAPA-Dva-SO3H); C and D are SEM images of an unmodified paper substrate; and E and F are SEM images of the ionization source element COF@HYD / PA.

[0038] Figure 2Characterization diagrams of an ionization source element according to an embodiment of the present invention are shown, wherein (A) and (B) are infrared spectra; (C) is a thermogravimetric analysis curve; and (D) is an N2 adsorption-desorption isotherm.

[0039] Figure 3 The X-ray photoelectron spectrum of the present invention is shown, wherein (A) is the X-ray photoelectron spectrum of the ionization source element COF@HYD / PA; (B), (C), (D), (E) and (F) are high-resolution XPS spectra of C1s, O1s, Ca2p, Na1s and S2p of the ionization source element COF@HYD / PA, respectively.

[0040] Figure 4 The image shows contact angles according to an embodiment of the present invention, wherein A is the contact angle of the ionization source element COF@HYD / PA; and B is the contact angle of COF(TAPA-Dva-SO3H).

[0041] Figure 5 A schematic diagram showing the optimized results of enrichment and ionization conditions according to an embodiment of the present invention is provided.

[0042] Figure 6 The matrix-matched standard curves of five benzoylurea insecticides in milk according to an embodiment of the present invention are shown. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and do not require that this invention must be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0045] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0046] According to one aspect of the present invention, a dedicated mass spectrometry ionization source element for the analysis of benzoylurea pesticides is provided. The ionization source element according to embodiments of the present invention has a uniform coating, exhibits good enrichment effect on benzoylurea pesticides, strong adsorption capacity, and can serve as a fixed substrate for mass spectrometry detection via ionization. The detection procedure is simple, with low background noise, high sensitivity and accuracy, making it particularly suitable for the enrichment and detection of benzoylurea pesticides in complex food matrix samples.

[0047] To facilitate understanding of this ionization source element, it is explained herein. According to an embodiment of the present invention, the ionization source element includes:

[0048] 100 basal layer

[0049] According to an embodiment of the present invention, the substrate is formed of a paper material. The inventors have found that using a paper base as a solid substrate is inexpensive, and the rough surface of the paper provides greater friction, which facilitates the fixation of the hydrogel.

[0050] According to an embodiment of the present invention, the paper material is qualitative filter paper. Therefore, the substrate formed from the qualitative filter paper has good processing properties, is easy to cut, inexpensive, and has high friction.

[0051] According to an embodiment of the present invention, the substrate layer has a tapered tip, that is, the substrate has a pointed shape in its top view. This facilitates open-type solid-substrate electrospray mass spectrometry analysis. The ionization source element is fixed at the horizontal front end of the mass spectrometer inlet. By applying a spray solvent, benzoylurea adsorbed on the substrate surface can be eluted, and then ionized at the tip by a high-voltage power supply to form a Taylor cone spray, which can then directly enter the mass spectrometer for detection. According to an embodiment of the present invention, the substrate is an equilateral triangle.

[0052] According to an embodiment of the present invention, the side length of the substrate layer is no greater than 2.0 cm, preferably an equilateral triangle with a side length of 1.3 cm and a thickness of 0.2 mm. Thus, a spray Taylor cone is formed at the apex of the triangle. If the angle is too large, the elution solvent will be hindered from spray formation due to surface tension; if the angle is too small, the substrate area will be small, affecting the substrate's adsorption capacity. At this size, the efficiency of elution solvent spray formation is higher.

[0053] Adsorption layer 200

[0054] According to embodiments of the present invention, the adsorption layer is coated on at least a portion of the surface of the substrate. The adsorption layer is formed from a sulfonic acid-functionalized covalent organic framework material and a hydrogel, wherein the sulfonic acid-functionalized covalent organic framework material is composed of repeating multi-ring units as shown in Formula I. The adsorption efficiency of the adsorption layer in embodiments of the present invention is significantly improved, possibly due to π-π stacking, hydrogen bonding, pore structure, electrostatic attraction, and van der Waals forces. First, since both benzoylurea and this sulfonic acid-functionalized covalent organic framework material possess aromatic rings, π-π interactions exist between them, significantly enhancing the adsorption effect. Second, the sulfonic acid groups of the sulfonic acid-functionalized covalent organic framework material in this embodiment form hydrogen bonds with the amino and carbonyl groups in benzoylurea. Subsequently, the sulfonic acid-functionalized covalent organic framework material of this embodiment has a rich porous structure, allowing benzoylurea to enter and be adsorbed. The adsorption effect is particularly significant when the molecular size of the target analyte matches the pore size of the material. Furthermore, the surface of the sulfonic acid-functionalized covalent organic framework material of this embodiment carries a negative charge, enabling electrostatic interactions with weakly acidic benzoylurea under neutral and alkaline conditions, further enhancing the adsorption effect. Finally, the sulfonic acid-functionalized covalent organic framework material of this embodiment has a large specific surface area and can exert a certain force on benzoylurea through van der Waals forces. Although the effect of van der Waals forces is weak, it still contributes to the adsorption effect.

[0055] According to an embodiment of the present invention, the hydrophilic contact angle of the adsorption layer is 25-26 degrees, preferably 25.14 degrees. Therefore, the adsorption layer has good hydrophilicity and can adsorb benzoylurea in aqueous solution.

[0056] According to embodiments of the present invention, benzoylurea is at least one selected from diflubenzuron (DIFL), fluorouracil (PENF), fluorouracil (NOVA), flufenoxuron (FLUF), and pyrimethanil (FLUA).

[0057] According to another aspect of the present invention, the present invention provides a method for preparing a dedicated mass spectrometry ionization source element for the analysis of benzoylurea insecticides. The preparation method according to the embodiments of the present invention produces an ionization source element with a uniform coating, good specificity for enriching benzoylurea insecticides, strong adsorption capacity, and the preparation method is mild, simple, and low in cost, possessing good commercialization potential.

[0058] To facilitate understanding of the method for preparing the aforementioned mass spectrometry ionization source element for the analysis of benzoylurea insecticides, the method is explained herein. According to an embodiment of the present invention, the method includes:

[0059] S100 Schiff base reaction

[0060] According to an embodiment of the present invention, an amino monomer and an aldehyde monomer are contacted and subjected to a first sonication and Schiff base reaction to obtain a covalent organic framework.

[0061] According to an embodiment of the present invention, the contact between the amino monomer and the aldehyde monomer is carried out in a mixed solution of 1,4-dioxane and mesitylene. That is, the amino monomer and the aldehyde monomer are contacted with a mixed solution of 1,4-dioxane and mesitylene in which the amino monomer and the aldehyde monomer are dissolved. According to an embodiment of the present invention, the volume ratio of 1,4-dioxane to mesitylene is 1:1. Therefore, the dissolution effect on the amino monomer and the aldehyde monomer is good.

[0062] According to embodiments of the present invention, the aldehyde monomer is 1,4-dialdehyde-2,5-divinylbenzene (Dva), and the amino monomer is N,N-bis(4-aminophenyl)benzene-1,4-diamine (TAPA). Specifically, COFs generally have BO, C=N, CN, and C=C bond types, among which the C=N bond type has mild synthesis conditions, good reproducibility, and chemical stability of the product; therefore, this type of synthesis is chosen in this embodiment. Regarding the selection of amino monomers, this embodiment mainly selects TAPA and TAPM, and the aldehyde monomers mainly select DHTA, TFPA, and Dva. Preferably, the TAPA-Dva combination has the highest enrichment efficiency. Dva has an alkenyl group, which facilitates a "thiol-alkene" click reaction with sodium 2-mercaptoethanesulfonate, thereby introducing a sulfonic acid group onto the COF and increasing the affinity for the target analyte.

[0063] According to embodiments of the present invention, the ratio of the amino monomer, the aldehyde monomer, and the mixed solution is 0.4 mmol: 0.6 mmol: 25-35 mL, preferably 0.4 mmol: 0.6 mmol: 30 mL. This ratio helps maintain a similar number of amino and aldehyde groups in the amino and aldehyde monomers, ensuring a more complete reaction and reducing monomer waste. Furthermore, within this ratio range, the mixed solution is better able to fully dissolve and disperse the amino and aldehyde monomers.

[0064] According to an embodiment of the present invention, the duration of the first ultrasound is 15 minutes. This facilitates the complete dissolution of the monomer in the mixed solution.

[0065] According to an embodiment of the present invention, the Schiff base reaction is carried out at a temperature of 55–65°C for 5–7 hours, preferably 6 hours. This facilitates a highly efficient and complete reaction, resulting in a high product yield.

[0066] According to an embodiment of the present invention, the catalyst for the Schiff base reaction is acetic acid, and the volume ratio of acetic acid to the mixed solution is 1:30. Therefore, the catalytic effect is good and the reaction efficiency is high.

[0067] According to an embodiment of the present invention, the reaction product was washed three times with methanol and acetonitrile and dried in a vacuum oven at 60°C for 24 hours to obtain a covalent organic framework material.

[0068] S200 Click Response

[0069] According to an embodiment of the present invention, the above-mentioned covalent organic framework is ground into powder, contacted with sodium 2-mercaptoethanesulfonate, and subjected to a second ultrasonic and click reaction to obtain a sulfonic acid functionalized covalent organic framework.

[0070] According to an embodiment of the present invention, the contact between the covalent organic framework and sodium 2-mercaptoethanesulfonate is carried out in an acetonitrile solution. That is, the covalent organic framework is contacted with sodium 2-mercaptoethanesulfonate.

[0071] According to an embodiment of the present invention, the ratio of the covalent organic framework and sodium 2-mercaptoethanesulfonate to acetonitrile is 40 mg:36 mg:10-20 mL, preferably 40 mg:36 mg:15 mL. Therefore, within this ratio range, it is beneficial for the complete dissolution of sodium 2-mercaptoethanesulfonate and the full conduct of the click reaction, and the reaction efficiency is not affected by excessively low system concentration.

[0072] According to an embodiment of the present invention, the ultrasonication time is 15 minutes. This facilitates the complete dissolution of the reaction substrate in acetonitrile.

[0073] According to an embodiment of the present invention, the covalent organic framework is TAPA-Dva. Since the chemical structure of benzoylurea insecticides contains fluorine functional groups, the inventors synthesized a sulfonic acid-functionalized covalent organic framework by introducing sulfonic acid groups to enhance its adsorption.

[0074] According to an embodiment of the present invention, the click reaction is carried out at a temperature of 65–75°C for 10–14 hours, preferably 12 hours, and at a reaction temperature of 70°C. This facilitates a highly efficient and complete reaction, resulting in a high product yield.

[0075] According to an embodiment of the present invention, the initiator of the click reaction is azobisisobutyronitrile (AIBN), and the ratio of AIBN to acetonitrile is 4 mg: 15 mL. Therefore, the initiation effect is good and the reaction efficiency is high.

[0076] S300 chain association reaction

[0077] According to an embodiment of the present invention, calcium chloride and polyacrylic acid are mixed in water to obtain a calcium ion-polyacrylic acid curing solution. This step is to prepare the curing solution for subsequent curing of sodium alginate (the precursor of the hydrogel). Calcium ions in CaCl2 are key to the crosslinking of sodium alginate because the carboxyl groups of sodium alginate form ionic bonds with calcium ions, forming an "egg-box" structure, thereby curing the gel. PAA has two functions: first, to adjust the pH and prevent COF from becoming unstable in an alkaline environment; second, the carboxyl groups of PAA itself may interact with calcium ions or the sulfonic acid groups of COF, enhancing the mechanical properties of the hydrogel.

[0078] According to an embodiment of the present invention, the ratio of calcium ions to polyacrylic acid and water is 225 mg: 0.6 mmol: 25-35 mL, preferably 225 mg: 0.6 mmol: 30 mL. This concentration provides a suitable ion concentration, allowing for effective subsequent curing.

[0079] According to an embodiment of the present invention, the sulfonic acid functionalized covalent organic framework, sodium alginate, and water are mixed and subjected to a third ultrasonication to obtain an ultrasonic post-liquid; paper is immersed in the ultrasonic post-liquid until fully saturated to obtain an impregnated paper substrate.

[0080] According to an embodiment of the present invention, the ratio of the sulfonic acid-functionalized covalent organic framework, the sodium alginate, and water is 25 mg:20 mg:1 mL. In this embodiment, the specific ratios were determined to ensure a complete reaction; the inventors experimented with various ratios to determine the exact reaction proportions. Ultrasonic treatment was used to disperse the COF particles, ensuring uniform distribution in the solution. Sodium alginate, as a precursor to the hydrogel, provides the framework for subsequent cross-linking. After mixing, a suspension is formed, allowing the COF to be uniformly loaded into the sodium alginate matrix, preventing aggregation that could affect performance.

[0081] Filter paper is used as a porous substrate because capillary action allows the mixture to fully penetrate between the fibers after immersion in the suspension. Complete saturation is crucial to ensure that COF-sodium alginate is evenly distributed throughout the paper substrate, rather than remaining only on the surface. The cellulose skeleton of the filter paper also provides additional support, preventing gel shrinkage and deformation.

[0082] According to an embodiment of the present invention, the impregnated paper substrate is transferred to the calcium ion-polyacrylic acid curing solution and left to stand for 30 minutes (the standing time is long enough to ensure uniform curing and avoid external hardening while the interior remains liquid) to carry out a chain association reaction and cure to form a composite covalent organic framework-hydrogel composite paper substrate (COF@HYD / PA). The paper substrate is then removed and thoroughly washed with ultrapure water and air-dried at room temperature for 24 hours to obtain the ionization source element.

[0083] According to another aspect of the present invention, an integrated separation and ionization mass spectrometry device is provided. According to an embodiment of the present invention, the device includes: the aforementioned ionization source element specifically designed for the analysis of benzoylurea pesticides; an open-type mass spectrometer detector including an inlet, the inlet being disposed opposite to the tip of the ionization source element; and a high-voltage power supply connected to the ionization source element. Thus, the aforementioned ionization source element specifically designed for the analysis of benzoylurea pesticides is directly connected to the high-voltage power supply. Under the action of the high voltage, the target analyte on the ionization source element is ionized under the action of the elution solvent. The generated ions directly enter the mass spectrometer inlet to obtain the acquired signal. The detection procedure is simple, and the background noise of the detection is low, making it particularly suitable for the enrichment and detection of benzoylurea pesticides in complex samples.

[0084] According to another aspect of the present invention, a method for enriching and purifying o-benzoylurea insecticides is provided. According to an embodiment of the present invention, the method includes: pretreating a sample to be tested to obtain a test solution; and subjecting the test solution to an oscillating contact treatment with a benzoylurea insecticide-specific mass spectrometry ionization source element to obtain an ionization source element with surface adsorption of the benzoylurea insecticide. Therefore, this purification method exhibits good specificity and strong adsorption capacity for benzoylurea insecticides, which is beneficial for the sufficient enrichment of complex matrices, such as benzoylurea insecticides in food. Furthermore, the enrichment and purification method of the embodiments of the present invention is simple to operate, requires no complex sample pretreatment process, and has high sample extraction efficiency.

[0085] According to an embodiment of the present invention, the rotation speed of the oscillating contact treatment is 500-700 rpm, and the time is 40 minutes. This facilitates the ionization source element to fully adsorb benzoylurea pesticides in the test solution.

[0086] According to another aspect of the present invention, the present invention provides a method for qualitative / quantitative detection of benzoylurea insecticides. According to an embodiment of the present invention, the method includes: enriching benzoylurea insecticides in a test sample using the aforementioned method for enriching and purifying benzoylurea insecticides to obtain an ionization source element for surface enrichment of benzoylurea insecticides; and detecting the ionization source element for surface enrichment of benzoylurea insecticides using the aforementioned integrated separation and ionization mass spectrometry device to perform qualitative / quantitative detection of the benzoylurea insecticides. Therefore, the aforementioned ionization source element has good specificity and strong adsorption for benzoylurea pesticides in complex matrices, which is conducive to fully enriching benzoylurea pesticides in complex matrices. Furthermore, the ionization source element for enriching benzoylurea pesticides is directly connected to a high-voltage power supply. Under the action of high voltage, the target substance on the ionization source element is ionized by the elution solvent. The generated ions directly enter the mass spectrometer through the inlet of the mass spectrometer detector to obtain the acquired signal. The detection procedure is simple, the background noise is low, and the detection sensitivity is high, making it particularly suitable for the rapid and accurate analysis of trace amounts of benzoylurea pesticides.

[0087] According to an embodiment of the present invention, the detection conditions of the integrated separation and ionization mass spectrometry device are as follows: high voltage power supply voltage: +3.5kV; ionization elution solvent: methanol solution. Therefore, when the high voltage power supply voltage is +3.5kV, the signal response is strong; and the methanol solution, as the ionization elution solvent, provides excellent elution performance and a high signal response.

[0088] According to an embodiment of the present invention, the detection conditions of the mass spectrometer detector are as follows: detection mode: multiple reaction monitoring (MRM); electrospray ionization source and ionization mode: ESI+; nebulizing gas flow rate: 3 L / min; drying gas flow rate: 10 L / min; heating gas flow rate: 10 L / min; interface temperature: 300℃; DL temperature: 250℃; heating block temperature: 400℃. Therefore, under the above conditions, the detection of benzoylurea insecticides exhibits high target analyte response values, low background noise, and high detection sensitivity and accuracy, making it particularly suitable for rapid and accurate analysis of trace amounts of benzoylurea insecticides.

[0089] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and should not be construed as limiting the present invention.

[0090] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products, such as those purchased from Sigma.

[0091] The materials and reagents used in the embodiments of this invention are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] Example 1

[0096] According to an embodiment of the present invention, a method for preparing an ionization source element is used, with COF(TAPA-Dva-SO3H) as a sulfonic acid-functionalized covalent organic framework, and a hydrogel composite coating and an ionization source element are prepared together with sodium alginate solution and calcium ion-polyacrylic acid solution. The specific method is as follows:

[0097] 1. A uniform suspension was prepared by mixing 25 mg COF (TAPA-Dva-SO3H) and 20 mg sodium alginate with 1 mL of water and sonicating for 10 minutes.

[0098] 2. Then prepare 30 mL of 0.02 mol / L polyacrylic acid (PAA) solution containing 225 mg CaCl2 as the curing solution;

[0099] 3. Immerse the pre-cut equilateral triangular qualitative filter paper (side length 1.3cm) into the COF-sodium alginate suspension until completely saturated;

[0100] 4. Transfer the saturated filter paper to the curing solution and let it stand for 30 minutes to fully cure it; remove the molded paper substrate with tweezers and wash it thoroughly with ultrapure water, then air dry it at room temperature for 24 hours to obtain an equilateral triangular COF(TAPA-Dva-SO3H) hydrogel composite paper substrate (COF@HYD / PA) with good mechanical stability and uniform size (side length 1.3cm).

[0101] Example 2

[0102] Detailed characterization experiments were conducted on the ionization source element (COF@HYD / PA) prepared in Example 1 to demonstrate the successful preparation of the material and its excellent physicochemical properties. The specific details are as follows:

[0103] 1. The surface morphology of the sulfonic acid-functionalized covalent organic framework, the unmodified paper substrate, and the ionization source element COF@HYD / PA was characterized, providing evidence for the successful composite of COFs on the paper substrate surface. COF(TAPA-Dva-SO3H)( Figure 1 A and B exhibit spherical structures with diameters of 150-300 nm. Compared to unmodified paper substrates ( Figure 1 C, D), COF@HYD / PA( Figure 1 E and F show significant morphological changes, indicating successful loading of the COF-hydrogel composite on a paper substrate.

[0104] 2. FT-IR spectroscopy further confirmed the successful synthesis of COFs. A comparison of COF(TAPA-Dva-SO3H) with...

[0105] Fourier transform infrared (FTIR) spectroscopy of COF(TAPA-Dva) confirmed the Schiff base reaction. A characteristic peak of the NH stretching vibration of TAPA (3408.0 cm⁻¹) was observed in COF(TAPA-Dva). -1 and 3330.7cm -1 ) and the C=O stretching vibration peak of Dva (1687.5 cm⁻¹) ( Figure 2 A). These characteristic peaks disappear in COF(TAPA-Dva-SO3H), while at 1621.9 cm⁻¹... -1 A new characteristic peak of C=N stretching vibration appears at this location. Figure 2 B) confirms the occurrence of the Schiff base reaction. The S2p of XPS is...

[0106] The presence of a distinct sulfonic acid group characteristic peak in the range of 168.0-169.5 eV indicates that a click reaction has occurred (the click reaction is for adding sulfonic acid groups to the COF).

[0107] 3. Through thermogravimetric analysis (TGA), Figure 2 C) Characterizing the thermal stability of the materials; COF remained stable below 437℃, while HYD / PA remained stable below 320℃. In comparison, COF@HYD / PA exhibited superior thermal stability, maintaining structural integrity up to 440℃. When the temperature exceeded 320℃, the mass loss rate of HYD / PA was significantly higher than that of COF@HYD / PA, further confirming that the introduction of COF composite material effectively improved the thermal stability of the paper substrate.

[0108] 4. The BET specific surface area of ​​COF@HYD / PA is 18.069 m². 2 / g, pore size is 19.9nm ( Figure 2 D), whose type IV(a) adsorption temperature characteristics confirm the mesoporous nature of the material.

[0109] 5. Characterization of COF@HYD / PA by X-ray photoelectron spectroscopy (XPS) Figure 3 A) Confirmed that the composite material contains C, O, Ca, Na, and S elements. High-resolution C1s spectrum ( Figure 3 B) Three characteristic peaks were observed at 284.4 eV, 286.5 eV, and 288.2 eV, corresponding to C=C / C–C bonds, C=N / C–N bonds, and C=O / C–O bonds, respectively, further verifying the successful loading of COF into the hydrogel. O 1s spectrum ( Figure 3 The characteristic peaks at 531.4 eV and 532.8 eV in C) are attributed to O–H and O–C bonds, consistent with sodium alginate and polyacrylic acid components. (Ca 2p spectrum) Figure 3 D) shows 347.9 eV (Ca2p 3 / 2 ) and 351.5 eV (Ca 2p 1 / 2 The two main peaks confirm that Ca 2+ The cross-linking effect on the alginate hydrogel network. The Na 1s spectrum shows a characteristic peak at 1071.8 eV ( Figure 3 E), confirming the introduction of sodium alginate. Furthermore, the S2p spectrum clearly shows the characteristic peak of the sulfonic acid group (-SO3H). Figure 3 F) indicates that the functional group was successfully introduced into COF@HYD / PA. The above results collectively confirm the integrity of the chemical composition and structure of COF@HYD / PA.

[0110] 6. The hydrophilicity of COF(TAPA-Dva-SO3H) and COF@HYD / PA was investigated using contact angle testing. For example... Figure 4 As shown, the water contact angle of COF(TAPA-Dva-SO3H) is 86.67°, while the contact angle of COF@HYD / PA is significantly reduced to 25.14°. The results indicate that the introduction of sodium alginate hydrogel significantly improves the hydrophilicity of the material.

[0111] Example 3

[0112] In this embodiment, the ionization source element prepared in Example 1 was used to optimize the mass spectrometry detection parameters for benzoylurea insecticides in milk samples, as detailed below:

[0113] 1. Experimental Methods

[0114] (1) Take 2 mL of milk and place it in a 50 mL centrifuge tube. Add 8 mL of acetonitrile and mix by vortexing for 5 min, followed by ultrasonic extraction for 10 min. Next, centrifuge at 10000 rpm / min for 10 min at 4 °C, collect the supernatant, and dry it to near dryness using nitrogen at 40 °C. Then, dissolve the residue in 5 mL of deionized water, filter it through a 0.22 μm microporous membrane, and adjust the pH of the solution to 5.0 using formic acid and ammonia water. Finally, use it for the next step of processing.

[0115] (2) Add one COF@HYD / PA tablet to the sample solution (5 mL) and vortex extract for 40 min. Then remove the supernatant with a pipette. Use tweezers to remove the COF@HYD / PA after adsorbing benzoylurea and place it on paper to absorb the solution on the paper substrate surface. Mount the treated COF@HYD / PA on a self-made three-dimensional moving platform, and align one of the apexes of the triangle with the mass spectrometer inlet. The apex is located about 5 mm from the inlet, and a high voltage of +3.5 kV is applied to the substrate. Then, 15 μL of methanol solution is evenly dropped onto the paper substrate surface for 10 seconds to generate electrospray at the apex to ionize the analyte, which is then analyzed by mass spectrometry.

[0116] Mass spectrometry conditions included: detection mode: multiple reaction monitoring (MRM); electrospray ionization source: ESI+; nebulizer gas flow rate: 3 L / min; drying gas flow rate: 10 L / min; heating gas flow rate: 10 L / min; interface temperature: 300℃; DL temperature: 250℃; heating block temperature: 400℃.

[0117] 2. Experimental Results

[0118] (1) The MRM mass spectrometry parameters of the five benzoylurea insecticides after optimization are shown in Table 2, and the peak area of ​​the quantitative ions is used as the evaluation index.

[0119] Table 2:

[0120]

[0121] Note: * indicates quantitative ions.

[0122] Example 4

[0123] In this embodiment, the effects of extraction conditions such as sample pH, ionic strength, and adsorption time, as well as ionization conditions such as applied voltage and elution solvent, on the detection results were investigated. Taking the analysis of five benzoylureas in milk samples as an example, five spiked samples of the benzoylureas to be tested were prepared and analyzed three times in parallel using the mass spectrometry detection conditions of Example 2.

[0124] 1. pH and ionic strength optimization

[0125] The pH value of the extraction solvent significantly affects the extraction efficiency by altering the ionization state of benzoylurea pesticides and the charge characteristics of the adsorbent surface. Therefore, the sample pH was adjusted to the range of 3-10 using 1 mol / L HCl and 1 mol / L NaOH. Figure 5 As shown in Figure A, all five benzoylureas reached their maximum extraction efficiency at pH 7. When pH < 7, hydrogen ions compete with the target analyte for active adsorption sites, leading to a decrease in binding capacity. Under pH 7 conditions, the strong hydrogen bonding between COF@HYD / PA and benzoylurea facilitates optimal adsorption. When pH > 7, the decrease in peak area is attributed to the alkaline hydrolysis of benzoylurea.

[0126] The effect of adding NaCl to adjust the ion concentration (0-40 mmol / L) was investigated on ionic strength. Figure 5 As shown in Figure B, the peak areas of all analytes decreased with increasing ionic strength, a phenomenon likely caused by sodium ions occupying electrostatic adsorption sites. Furthermore, the addition of NaCl may have increased solution viscosity and reduced the analyte diffusion rate, further weakening the adsorption efficiency. Therefore, NaCl was not added in subsequent experiments.

[0127] 2. Optimized extraction time

[0128] The effect of extraction time (5-50 minutes) on the extraction efficiency of five benzoylurea insecticides was investigated. Figure 5 C) The results showed that the extraction efficiency increased within 5-40 minutes and then stabilized, indicating that the system reached adsorption equilibrium at 40 minutes. Therefore, 40 minutes was selected as the optimal extraction time for subsequent experiments.

[0129] 3. Optimization of spraying conditions

[0130] Open-type mass spectrometry (AIMS) performance is influenced by both the spray solvent and the applied voltage. The spray solvent determines the elution efficiency of the analyte from the substrate. This example evaluates the elution performance of solvent systems including methanol (MeOH), acetonitrile (ACN), ethyl acetate (EA), isopropanol (IPA), and an acetonitrile / methanol (1:1, v / v) mixture. Figure 5 D). Methanol exhibits the best elution efficiency, while ethyl acetate performs the worst. Therefore, methanol was selected as the preferred solvent.

[0131] 4. Optimization of spray voltage

[0132] Spray voltage plays a crucial role in regulating ionization efficiency. Testing was conducted in the +2 to +5 kV voltage range under positive ion mode. Figure 5E) Findings: When the voltage is < +3kV, insufficient electrostatic force prevents effective electrospray formation, resulting in a weak mass spectrometry signal; when the voltage is increased to the +3 to +3.5kV range, the peak areas of all analytes are significantly improved; however, voltages exceeding +3.5kV cause rapid solvent evaporation and uneven analyte distribution, leading to a decrease in signal intensity. Therefore, +3.5kV was ultimately selected as the preferred spray voltage.

[0133] 5. Detection limit, linear range, and repeatability of mass spectrometry detection methods

[0134] Five benzoylurea standard solutions of different concentrations were prepared using a blank milk matrix solution to obtain standard curves. The LODs, LOQs, and precision of the method were investigated. The results are as follows: Figure 6 As shown in Table 3, the five benzoylurea assays exhibited excellent linearity in the concentration range of 0.1–100 μg / kg (R0). 2 The limit of detection (LOD) and limit of quantitation (LOQ) are 0.05–0.56 μg / kg and 0.15–1.69 μg / kg, respectively. Therefore, this element exhibits good repeatability in the detection of benzoylurea compounds, and the detection limit meets the requirements, demonstrating promising application prospects.

[0135] Table 3

[0136]

[0137] 6. Matrix effect

[0138] When analyzing complex matrix samples using an open-type mass spectrometry ion source, matrix effects caused by ion suppression or enhancement may lead to decreased signal intensity, increased detection limits, and reduced analytical accuracy. The matrix effect (ME%) is estimated using formula (3.1):

[0139] ME=(k2 / k1-1)×100%(3.1)

[0140] Where k2 and k1 represent the slopes of the matrix calibration curve and the solvent calibration curve, respectively. Standard curves were established by adding 0.1–100 ng / mL of five benzoylurea to blank milk samples and aqueous solutions. Matrix effects can be positive or negative, and can be classified into three categories based on their degree of influence: strong matrix effect (>50% or <-50%), moderate matrix effect (20%–50% or -50%–-20%), and slight matrix effect (-20%–20%).

[157] As shown in Table 4, the ME value range of this method is -10.06% to 15.66%, indicating that the matrix effect has a negligible impact on the detection results.

[0141] Table 4

[0142]

[0143] 7. Recovery rate of mass spectrometry detection method at different spiking concentrations

[0144] The established analytical method was applied to the detection of five benzoylureas in four commercially available milk samples purchased from a local supermarket. The target analytes were not detected in any samples (content was below the method detection limit or no residue was found). To verify the accuracy of the method, a spiked recovery experiment was conducted: three concentration levels (10, 20, and 50 μg / kg) of the target analytes were added to blank milk samples for detection. As shown in Table 5, the recoveries ranged from 74.6% to 112.2%, and the standard deviation (SD) was ≤6.5%, confirming the reliability and applicability of this method for the detection of benzoylureas in complex milk matrices.

[0145] Table 5

[0146]

[0147] ND = not detected.

[0148] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0149] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A mass spectrometry ionization source element for analyzing benzoylurea insecticides, characterized in that, include: A base layer, wherein the base layer is made of paper material; as well as An adsorption layer is formed on at least a portion of the surface of the substrate, the adsorption layer being formed of a sulfonic acid-functionalized covalent organic framework material and a hydrogel, wherein the hydrogel is composed of water, sodium alginate, calcium ions and polyacrylic acid, and the sulfonic acid-functionalized covalent organic framework material is composed of repeating multi-ring units as shown in Formula I.

2. The ionization source element according to claim 1, characterized in that, The paper material is qualitative filter paper. Optionally, the base layer has a tapered tip, preferably an equilateral triangle. Optionally, the side length of the base layer is no greater than 2.0 cm, preferably an equilateral triangle with a side length of 1.3 cm and a thickness of 0.2 mm.

3. The ionization source element according to claim 1, characterized in that, The hydrophilic contact angle of the adsorption layer is 25-26 degrees, preferably 25.14 degrees. Optionally, the benzoylurea insecticide is selected from at least one of diflubenzuron (DIFL), fluoroquinolones (PENF), fluoroacetate (NOVA), flufenoxuron (FLUF), and pyrimethanil (FLUA).

4. A method for preparing a dedicated mass spectrometry ionization source element for the analysis of benzoylurea insecticides according to any one of claims 1-3, characterized in that, include: The amino monomer and the aldehyde monomer are contacted and subjected to a first sonication and Schiff base reaction to obtain a covalent organic framework. The above covalent organic framework was contacted with sodium 2-mercaptoethanesulfonate and subjected to a second ultrasonic and click reaction to obtain a sulfonic acid-functionalized covalent organic framework. Calcium ions are mixed with polyacrylic acid in water to obtain a calcium ion-polyacrylic acid mixture; The sulfonic acid-functionalized covalent organic framework, sodium alginate, and water were mixed and subjected to a third ultrasound to obtain a post-ultrasound solution. The paper is immersed in the ultrasonic post-saturation solution until it is fully saturated in order to obtain the immersed paper substrate; as well as The impregnated paper substrate is brought into contact with the calcium ion-polyacrylic acid mixture to undergo a chain association reaction and solidify to form a composite covalent organic framework-hydrogel composite paper substrate (COF@HYD / PA) in order to obtain the ionization source element.

5. The method according to claim 4, characterized in that, The contact between the amino monomer and the aldehyde monomer is carried out in a mixed solution of 1,4-dioxane and mesitylene, wherein the volume ratio of 1,4-dioxane and mesitylene is 1:

1. Optionally, the aldehyde monomer is 1,4-dialdehyde-2,5-divinylbenzene (Dva), and the amino monomer is N,N-bis(4-aminophenyl)benzene-1,4-diamine (TAPA). Optionally, the ratio of the amino monomer, the aldehyde monomer, and the mixed solution is 0.4 mmol:0.6 mmol:25-35 mL, preferably 0.4 mmol:0.6 mmol:30 mL. Optionally, the catalyst for the Schiff base reaction is acetic acid, and the initiator for the click reaction is azobisisobutyronitrile (AIBN). Optionally, the volume ratio of acetic acid to the mixed solution is 1:

30.

6. The method according to claim 4, characterized in that, The contact between the covalent organic framework and sodium 2-mercaptoethanesulfonate is carried out in an acetonitrile solution. Optionally, the ratio of the covalent organic framework and sodium 2-mercaptoethanesulfonate to acetonitrile is 40 mg:36 mg:10-20 mL, preferably 40 mg:36 mg:15 mL. Optionally, the calcium ions are calcium chloride. Optionally, the ratio of calcium chloride and polyacrylic acid to water is 225 mg: 0.6 mmol: 25-35 mL, preferably 225 mg: 0.6 mmol: 30 mL.

7. The method according to claim 4, characterized in that, The sulfonic acid-functionalized covalent organic framework and the sodium alginate in water are in a ratio of 25 mg:20 mg:1 mL. Optionally, the duration of the first ultrasound, the second ultrasound, and the third ultrasound is independently 10-20 minutes, preferably 15 minutes. Optionally, the Schiff base reaction is carried out at a temperature of 55–65°C for 5–7 hours, preferably 6 hours at a temperature of 60°C. Optionally, the temperature of the click reaction is 65-75°C, preferably 70°C, the time is 10-14 hours, preferably 12 hours, and the reaction temperature is 70°C.

8. A mass spectrometry device integrating separation and ionization, characterized in that, include: The mass spectrometry ionization source element for analyzing benzoylurea insecticides as described in any one of claims 1-3; An open-type mass spectrometer detector, the open-type mass spectrometer detector including an inlet, the inlet being disposed opposite to the tip of the ionization source element; and A high-voltage power supply, which is connected to the ionization source element.

9. A method for enriching and purifying benzoylurea insecticides, characterized in that, include: The sample to be tested is pretreated to obtain the test solution; as well as The test solution is subjected to oscillating contact treatment with the ionization source element for benzoylurea insecticide analysis as described in any one of claims 1-3, in order to obtain an ionization source element with the benzoylurea insecticide adsorbed on its surface. Optionally, the rotational speed of the oscillating contact treatment is 500-700 rpm, and the time is 40 minutes.

10. A method for qualitative / quantitative detection of benzoylurea insecticides, characterized in that, include: The method for enriching and purifying benzoylurea insecticides as described in claim 9 is used to enrich benzoylurea insecticides in the test sample in order to obtain an ionization source element for surface enrichment of benzoylurea insecticides. as well as The ionization source element enriched with benzoylurea insecticides on its surface is detected using the integrated separation and ionization mass spectrometry device described in claim 8, in order to perform qualitative / quantitative detection of the benzoylurea insecticides. Optionally, the detection conditions of the integrated separation and ionization mass spectrometry device are as follows: High voltage power supply voltage: +3.5kV; Ionization elution solvent: methanol solution; Optionally, the detection conditions of the mass spectrometer detector are: Detection method: Multiple reaction monitoring (MRM); Electrospray ionization source: ESI+; Atomizing gas flow rate: 3L / min; Drying gas flow rate: 10 L / min; Heating gas flow rate: 10L / min; Interface temperature: 300℃; DL temperature: 250℃; Heating block temperature: 400℃.

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