A method for analyzing the content of organophosphate pollutants

Abstract

The present application discloses a method for analyzing the content of organophosphate pollutants. The analytical method of the present application can realize efficient and accurate analysis of the three occurrence forms of organophosphate pollutants, avoiding the defect of evaluating ecological risks based on the total concentration of organophosphate pollutants. The analytical method of the present application adopts a magnetic solid phase extraction material with efficient adsorption for organophosphates. After adsorption, the magnetic solid phase extraction material can be efficiently separated by magnetic separation, making the analysis operation simpler and faster. The analytical method of the present application adopts a multi-step continuous extraction and analysis method of magnetic solid phase extraction adsorption, organic solvent extraction, acidic dissolution and then magnetic solid phase extraction. The acidic dissolution extraction of bound organophosphates avoids the decomposition of the target object caused by traditional alkaline and thermal hydrolysis, which helps to protect the original chemical structure of the target analyte during the extraction process, thereby improving the accuracy of the analysis results.

Description

Technical Field

[0001] The present application belongs to the technical field of environmental pollutant analysis and detection, and specifically relates to a method for analyzing the content of organic phosphate pollutants. Background Art

[0002] Organophosphate pollutants include organophosphate pesticides and organophosphate flame retardants. Among them, organophosphate pesticides are a type of pollutant that has received widespread attention, while organophosphate flame retardants are new organic pollutants that are frequently added to daily necessities to meet fire protection requirements. Since organophosphate flame retardants are physically added to flammable components, they are easily released during use and enter soil and water sediments. These two types of pollutants can enter the human body through atmospheric inhalation, drinking water, and food chain transmission, seriously interfering with human metabolism, reproduction, and endocrine systems. In order to achieve chemical control of these two types of substances, ecological risk assessments are required. At present, most of the ecological risk assessments of these two types of substances are based on the analysis of the total amount of occurrence in environmental samples, which often leads to overestimation of risks and excessive control and governance.

[0003] Soil and sediment are highly heterogeneous and complex systems composed of organic matter, minerals and other components. After entering into them, organophosphates can continuously undergo adsorption-desorption, complexation-dissociation and other reactions with organic matter or minerals, and undergo continuous multi-level micro-interface migration and distribution, thereby forming different occurrence forms. Different forms determine their migration and transformation processes and ecological risks in environmental media. According to the chemical extraction capacity, the occurrence forms of organophosphates in soil and sediments can generally be divided into active state, adsorbed state and bound state. The first two refer to the parts that can be directly extracted by chemical reagents and whose chemical structure has not changed. The bound state refers to the part that cannot be directly extracted by chemical reagents. Only the dissolved or rapidly desorbed parts can be absorbed and utilized by organisms. Therefore, it is very necessary to detect and analyze the content of different occurrence forms of organophosphates in the above-mentioned environmental samples, which plays an important role in understanding their environmental behavior and ecological risks.

[0004] At present, the continuous extraction method is commonly used to analyze the occurrence forms of organic pollutants. First, Tenax resin (2,6-diphenyl-p-phenylene oxide) is used to extract the active state, then a suitable organic solvent is used to extract the adsorbed state, and finally heating is used under alkaline conditions to extract the bound state (patent CN105548389). However, this method has the following problems in the extraction of organophosphate pollutants in soil and sediments:

[0005] (1) Tenax resin is highly hydrophobic. After being added to an aqueous solution, it tends to float on the surface of the solution and is difficult to completely disperse in the aqueous solution. It cannot fully contact with the organophosphates in the soil particles, resulting in insufficient extraction of the organophosphates.

[0006] (2) Tenax resin is difficult to achieve efficient separation from environmental samples during use, resulting in cumbersome operation steps in the active state extraction process and reduced recovery rate;

[0007] (3) According to the chemical properties of organophosphate pollutants, the phosphate groups in them are very easy to hydrolyze under alkaline conditions. For example, the half-life of TBPP in an alkaline solution at room temperature with a pH of 12 is only 0.96 hours (Environ. Sci. Technol. 2018, 52, 1997). The hydrolysis rate may be higher under heating conditions. Therefore, the above-mentioned alkaline-thermal hydrolysis method is obviously not suitable for the extraction of bound substances of this type.

[0008] It can be seen from this that it is necessary to redevelop a set of appropriate occurrence form content analysis methods for organophosphate pollutants in environmental samples. Summary of the invention

[0009] The purpose of this application is to overcome the shortcomings of the prior art and provide an analytical method for the content of organophosphate pollutants to solve the technical problems that the existing total concentration evaluation of organophosphate pollutants is not scientific enough, and the continuous extraction method is not suitable for Tenax resin and alkaline thermal hydrolysis extraction for such substances, resulting in a cumbersome organophosphate extraction and analysis process and a low extraction rate.

[0010] In order to achieve the above application purpose, the present application provides a method for analyzing the content of organophosphate pollutants, comprising the following steps:

[0011] The method comprises the following steps: using a magnetic solid phase extraction material to adsorb active organic phosphate in a first sample to be tested, wherein the first sample to be tested is a water-containing mixture system; separating the adsorbed magnetic solid phase extraction material to obtain a sample to be tested after a single treatment, eluting the active organic phosphate adsorbed on the magnetic solid phase extraction material and detecting its content; the magnetic solid phase extraction material is Fe3O4@SiO2@HLB-WAX with a core-shell structure;

[0012] The sample to be tested after the first treatment is subjected to solid-liquid separation to obtain a solid second sample to be tested; a methanol solution containing aqueous ammonia is added to the second sample to be tested, and the adsorbed organic phosphate is extracted and then subjected to solid-liquid separation to obtain a solid third sample to be tested, and the content of the adsorbed organic phosphate in the extract is detected;

[0013] Inorganic acid is added to the third sample to be tested to dissolve the bound organic phosphate, and after the solution is adjusted to neutral, the magnetic solid phase extraction material is added to the solution to adsorb the dissolved bound organic phosphate, the adsorbed magnetic solid phase extraction material is separated, the bound organic phosphate adsorbed on the magnetic solid phase extraction material is eluted and its content is detected.

[0014] Furthermore, the magnetic solid phase extraction material is prepared by the following method:

[0015] Preparation of Fe3O4 magnetic nanoparticles;

[0016] Modifying the surface of the Fe3O4 magnetic nanoparticles with a SiO2 shell to obtain Fe3O4@SiO2;

[0017] Modify the surface of the Fe3O4@SiO2 with 3-(methacryloyloxy)propyltrimethoxysilane to obtain Fe3O4@SiO2@MPS;

[0018] The Fe3O4@SiO2@MPS is placed in a mixture system containing azobisisobutyronitrile, divinylbenzene, vinylpyrrolidone, and 4-chloromethylstyrene for a first reaction, and piperazine is added to the system after the first reaction for a second reaction to separate the prepared magnetic solid phase extraction material Fe3O4@SiO2@HLB-WAX.

[0019] Furthermore, the temperature of the first reaction is 65-70° C., and the time is 18-24 hours.

[0020] Furthermore, the temperature of the second reaction is 80-90° C., and the time is 12-15 hours.

[0021] Furthermore, in the first reaction, the dosage ratio of the Fe3O4@SiO2@MPS, the azobisisobutyronitrile, the divinylbenzene, the vinylpyrrolidone and the 4-chloromethylstyrene is: (3-5) g: (650-700) mg: (2.6-3.0) mL: (2.4-3.0) mL: (3.0-3.5) mL.

[0022] Furthermore, in the second reaction, the mass ratio of the amount of piperazine to the amount of Fe3O4@SiO2@MPS is: (2.5-3): (3-5).

[0023] Furthermore, the step of adding an inorganic acid to the third sample to dissolve the bound organic phosphate comprises the following steps:

[0024] Adding 1-1.5M CaCl2 to the third sample to be tested to dissolve it, obtaining a solid fourth sample to be tested and a first dissolving solution after solid-liquid separation, adjusting the first dissolving solution to neutrality, adding the magnetic solid phase extraction material to adsorb the dissolved first bound organic phosphate and detecting its content;

[0025] Adding 0.5-1.0M HCl to the fourth sample to be tested to dissolve it, obtaining a solid fifth sample to be tested and a second dissolved solution after solid-liquid separation, adjusting the second dissolved solution to neutrality, adding the magnetic solid phase extraction material to adsorb the dissolved second bound organic phosphate and detecting its content;

[0026] Adding 5-5.5M HCl to the fifth sample to be tested to dissolve it, obtaining a solid sixth sample to be tested and a third dissolving solution after solid-liquid separation, adjusting the third dissolving solution to neutrality, adding the magnetic solid phase extraction material to adsorb the dissolved third bound organic phosphate and detecting its content;

[0027] A mixed acid solution of 1.3-1.5M HF and 1.8-2.0M H2SO4 is added to the sixth sample to be tested for dissolution, and a fourth solution is obtained after solid-liquid separation. After the fourth solution is adjusted to neutral, the magnetic solid phase extraction material is added to adsorb the dissolved fourth bound organic phosphate and detect its content.

[0028] Furthermore, the volume fraction of aqueous ammonia in the methanol solution containing aqueous ammonia is 5-10%.

[0029] Furthermore, the first sample to be tested contains contaminated soil or contaminated sediment.

[0030] Furthermore, a microbial inhibitor is added to the first sample to be tested.

[0031] Compared with the prior art, this application has the following technical effects:

[0032] The analytical method for the content of organophosphate pollutants in the present application can realize efficient and accurate analysis of the three occurrence forms of organophosphate pollutants, avoiding the defect of evaluating ecological risks based on the total concentration of organophosphate pollutants.

[0033] The present invention discloses a method for analyzing the content of organic phosphate pollutants by using a magnetic solid phase extraction material that has high adsorption capacity for organic phosphates. After adsorption, the magnetic solid phase extraction material can be efficiently separated by magnetic separation, making the analysis operation simpler and faster.

[0034] The present application discloses a method for analyzing the content of an organic phosphate pollutant, which adopts a multi-step continuous extraction analysis method of magnetic solid phase extraction adsorption, organic solvent extraction, acidic dissolution and then magnetic solid phase extraction. The acidic dissolution extraction of bound organic phosphate avoids the decomposition of the target substance caused by traditional alkaline and thermal hydrolysis, helps to protect the original chemical structure of the target analyte during the extraction process, and thus improves the accuracy of the analysis results. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0037] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0038] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0039] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0040] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0041] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0042] The present application embodiment provides a method for analyzing the content of organophosphate pollutants, comprising the following steps:

[0043] (1) using a magnetic solid phase extraction material to adsorb active organic phosphate in a first sample to be tested, wherein the first sample to be tested is a water-containing mixture system; separating the adsorbed magnetic solid phase extraction material to obtain a sample to be tested after a single treatment, eluting the active organic phosphate adsorbed on the magnetic solid phase extraction material and detecting its content; the magnetic solid phase extraction material is a core-shell structured Fe3O4@SiO2@HLB-WAX;

[0044] (2) performing solid-liquid separation on the sample to be tested after the first treatment to obtain a solid second sample to be tested; adding a methanol solution containing aqueous ammonia to the second sample to extract the adsorbed organic phosphate and then performing solid-liquid separation to obtain a solid third sample to be tested, and detecting the content of the adsorbed organic phosphate in the extract;

[0045] (3) adding an inorganic acid to the third sample to be tested to dissolve the bound organophosphate, adjusting the solution to neutrality, adding a magnetic solid phase extraction material to the solution to adsorb the dissolved bound organophosphate, separating the adsorbed magnetic solid phase extraction material, eluting the bound organophosphate adsorbed on the magnetic solid phase extraction material and detecting its content.

[0046] The first sample to be tested in the embodiment of the present application contains contaminated soil or contaminated sediment. In order to prevent the microorganisms in the contaminated soil or contaminated sediment from affecting the analysis results during the analysis, a microbial inhibitor, such as sodium azide, can be added to the first sample to be tested during the analysis.

[0047] The method for analyzing the content of organophosphate pollutants in an embodiment of the present application can realize efficient and accurate analysis of the three occurrence forms of organophosphate pollutants, namely, active state, adsorbed state and bound state, avoiding the defect of evaluating ecological risks based on the total concentration of organophosphate pollutants.

[0048] A method for analyzing the content of organic phosphate pollutants in an embodiment of the present application uses a magnetic solid-phase extraction material that has high adsorption capacity for organic phosphates. After adsorption, the magnetic solid-phase extraction material can be efficiently separated by magnetic separation, making the analysis operation simpler and faster, and greatly reducing the equipment and labor costs required for the analysis and processing.

[0049] An analysis method for the content of organic phosphate pollutants in an embodiment of the present application adopts a multi-step continuous extraction analysis method of magnetic solid phase extraction adsorption, organic solvent extraction, acidic dissolution and then magnetic solid phase extraction. The acidic dissolution extraction of bound organic phosphates avoids the decomposition of the target object caused by traditional alkaline and thermal hydrolysis, helps to protect the original chemical structure of the target analyte during the extraction process, and thus improves the accuracy of the analysis results.

[0050] In the above step (1), the magnetic solid phase extraction material Fe3O4@SiO2@HLB-WAX can be prepared by the following method:

[0051] (11) Fe3O4 magnetic nanoparticles can be prepared by conventional hydrothermal method. In the embodiment of the present application, Fe3O4 magnetic nanoparticles are prepared by the following method: 1.35g FeCl3·6H2O is dissolved in 40mL ethylene glycol, and stirred until the solution becomes clear and bright yellow, and then 3.6g NaAc powder and 1.0g polyethylene glycol particles are added. The obtained mixed solution is stirred for 1 hour until the NaAc powder and polyethylene glycol particles are completely dissolved, and then the solution is poured into a 50mL stainless steel reactor. The reactor is placed in an oven and heated at 200°C for 8h. The reactor is taken out and cooled to room temperature, and the prepared black Fe3O4 magnetic nanoparticles are recovered with a magnet, and then the product is washed three times with 100mL water and 100mL ethanol alternately. Finally, the product is dried under vacuum at 60°C.

[0052] (12) Fe3O4@SiO2 can be prepared by coating the surface of Fe3O4 magnetic nanoparticles with SiO2 shells using a conventional one-pot method. In the present embodiment, Fe3O4@SiO2 is prepared by the following method: 0.10 g of Fe3O4 magnetic nanoparticles is firstly treated with 50 mL of 0.1 mol L -1 The HCl solution was ultrasonically treated for 10 minutes, then washed with ultrapure water, and then ultrasonically dispersed in a mixed solution of 80 mL ethanol, 20 mL ultrapure water, and 1.0 mL 28 wt% ammonia. 0.03 g TEOS was then added dropwise to the above solution. After the reaction system was stirred at room temperature for 6 hours, the Fe3O4@SiO2 magnetic nanoparticles were separated in an external magnetic field, washed several times with ethanol and ultrapure water, and dried under vacuum conditions at 60 °C.

[0053] (13) Fe3O4@SiO2@MPS was obtained by modifying the surface of Fe3O4@SiO2 with 3-(methacryloyloxy)propyltrimethoxysilane (MPS). In the present embodiment, Fe3O4@SiO2@MPS was prepared by the following method: 3 g of Fe3O4@SiO2 magnetic particles were dispersed in 400 mL of ethanol / H2O (v / v, 3:1). Under nitrogen atmosphere at room temperature, a mixed solution of 8 mL of ammonia water, 8 mL of MPS and 10 mL of ethanol was added to the above suspension in sequence. The reaction was then stirred continuously at 60°C for 12 h to obtain the obtained product.

[0054] (14) Fe3O4@SiO2@MPS was placed in a mixture system containing azobisisobutyronitrile (AIBN), divinylbenzene (DVB), vinylpyrrolidone (NVP), and 4-chloromethylstyrene (4-VBC) for a first reaction, and piperazine was added to the system after the first reaction for a second reaction to separate the prepared magnetic solid phase extraction material Fe3O4@SiO2@HLB-WAX.

[0055] In the embodiment of the present application, the temperature of the first reaction is 65-70°C and the time is 18-24 hours. In the first reaction, the dosage ratio of Fe3O4@SiO2@MPS, azobisisobutyronitrile, divinylbenzene, vinylpyrrolidone and 4-chloromethylstyrene can be controlled as follows: (3-5) g: (650-700) mg: (2.6-3.0) mL: (2.4-3.0) mL: (3-3.5) mL.

[0056] The temperature of the second reaction is 80-90°C and the time is 12-15 hours. In the second reaction, the mass ratio of piperazine to Fe3O4@SiO2@MPS can be controlled to be: (2.5-3): (3-5).

[0057] In the embodiment of the present application, Fe3O4@SiO2-@HLB-WAX can be prepared by the following method: First, 3g of Fe3O4@SiO2@MPS nanoparticles are dispersed in 500mL of acetonitrile and ultrasonically treated for 15min. 650mgAIBN, 2.6mL of DVB, 2.4mL of NVP and 3mL of 4-VBC are added in sequence under nitrogen protection. Before the reaction starts, nitrogen is continuously introduced into the mixed solution while stirring for 2h. Then the temperature is raised to 70°C for 24h. 2.5g of piperazine is added to the solution, and the temperature is raised to 80°C. The solution is stirred and reacted for 12h. After the reaction stops, the Fe3O4@SiO2-@HLB-WAX magnetic nanoparticles are recovered by an external magnetic field, and water and ethanol are used to wash alternately 3 to 5 times, and finally dried at 60°C for 24h under vacuum conditions.

[0058] The Fe3O4@SiO2@HLB-WAX material prepared in the embodiment of the present application contains both hydrophilic and hydrophobic functional groups on its surface, which can overcome the defect that Tenax resin is difficult to fully disperse in water. The Fe3O4@SiO2-@HLB-WAX material prepared in the embodiment of the present application has a core-shell structure, with Fe3O4 magnetic nanoparticles in the middle, and a SiO2 layer wrapped outside to protect the magnetism of Fe3O4. The outermost layer is modified with appropriate functional groups according to the properties of the sample matrix and the target organic phosphate to be adsorbed to meet the high adsorption efficiency required for analysis. For organophosphate pollutants, the weak anionic amphiphilic polymer (HLB-WAX) on the surface of the Fe3O4@SiO2@HLB-WAX material of the embodiment of the present application shows good affinity for such substances, especially hydroxyl organophosphates. The hydrophilic groups in HLB-WAX will help it to disperse in the first sample to be tested, that is, the suspension of soil or sediment, and the amino groups in HLB-WAX will form electrostatic interactions with the hydroxyl groups in the organophosphates to achieve specific enrichment of hydroxyl organophosphate pollutants; and the hydrophobic functional groups in HLB-WAX will combine with weakly polar organophosphates to achieve specific enrichment of this part of organophosphates. Therefore, the Fe3O4@SiO2-@HLB-WAX material of the embodiment of the present application can meet the requirements of multi-targeted and efficient adsorption of various forms of organophosphates in contaminated soil or sediments.

[0059] In the above step (2), the volume fraction of aqueous ammonia in the methanol solution containing aqueous ammonia is 5 to 10%.

[0060] In the above step (3), adding an inorganic acid to the third sample to dissolve the bound organic phosphate specifically comprises the following steps:

[0061] 1-1.5M (i.e., 1-1.5mol / L) CaCl2 is added to the third sample to be tested for dissolution, and a solid fourth sample to be tested and a first dissolving solution are obtained after solid-liquid separation. After the first dissolving solution is adjusted to neutrality, a magnetic solid phase extraction material is added to adsorb the dissolved first bound organic phosphate and detect its content; the first bound organic phosphate is a portion bound to the surface adsorbed iron;

[0062] 0.5-1.0M HCl is added to the fourth sample to be tested to dissolve it, and after solid-liquid separation, a solid fifth sample to be tested and a second dissolved solution are obtained, and after the second dissolved solution is adjusted to neutrality, a magnetic solid phase extraction material is added to adsorb the dissolved second bound organic phosphate and detect its content; the second bound organic phosphate is a part bound to low crystallinity minerals (such as ferrihydrite, siderite and green rust-like minerals);

[0063] Add 5-5.5M HCl to the fifth sample to be tested to dissolve it, obtain a solid sixth sample to be tested and a third solution after solid-liquid separation, adjust the third solution to neutrality, add a magnetic solid phase extraction material to adsorb the dissolved third bound organic phosphate and detect its content; the third bound organic phosphate is a part bound to a high-crystallinity iron-containing mineral (such as hematite);

[0064] A mixed acid solution of 1.3-1.5M HF and 1.8-2.0M H2SO4 (in the mixed acid solution, the volume ratio of HF and H2SO4 is 1:1) is added to the sixth sample to be tested for dissolution, and a fourth dissolved solution is obtained after solid-liquid separation. After the fourth dissolved solution is adjusted to neutral, a magnetic solid phase extraction material is added to adsorb the dissolved fourth bound organophosphate and detect its content. The fourth bound organophosphate is the part bound to the iron-containing silicate and the clay mineral.

[0065] Organophosphates that enter the soil or sediment will combine with soil organic carbon under long-term aging and eventually become part of the soil organic carbon. The stability of soil organic carbon is mainly controlled by the physical closure of soil aggregates and the binding of iron minerals, among which iron-bound organic carbon is the key factor for its long-term storage. However, active iron in the soil is easily dissolved and recrystallized under the action of farmland cultivation, river dredging, and estuary tides, causing the sequestration or release of soil organic matter, and also causing the sequestration or release of organophosphate pollutants that enter the soil organic matter, resulting in changes in their occurrence forms. Therefore, quantitative analysis of organophosphates in different iron-bound states is very necessary and is a key indicator for conducting precise ecological risk assessments.

[0066] The embodiment of the present application adopts a continuous extraction method of multi-step acid dissolution, which can not only completely extract all iron-bound organophosphates, but also avoid the hydrolysis of organophosphates caused by traditional alkaline and thermal hydrolysis methods, protect their original molecular structure information, and provide scientific and reliable data support for accurate ecological risk assessment.

[0067] The following is a specific example to illustrate a method for analyzing the content of an organophosphate pollutant in an embodiment of the present application.

[0068] The present application example provides a method for analyzing the content of organic phosphate pollutants, which is as follows:

[0069] Determination of three occurrence forms of tris(2-chloro-ethyl) phosphate (TCEP) in the soil around a certain organic phosphate flame retardant production plant:

[0070] (1) Preparation of TCEP-spiked soil: 1 mL of 60 mg / L TCEP methanol standard solution was evenly added to 20 g of unpolluted Qinghai-Tibet Plateau soil and aged at room temperature for 10 days. At the same time, 1 kg of soil from the vicinity of an organophosphate flame retardant production plant was collected as the test sample.

[0071] (2) Active TCEP magnetic solid phase extraction: Weigh 5g of the above-mentioned contaminated spiked soil sample and place it in a stoppered conical flask, add 15mL of ultrapure water, 20mg of sodium azide and 30mg of magnetic solid phase extraction material Fe3O4@SiO2@HLB-WAX. The sample bottle is kept shaking at 200rpm and 25℃ in the dark. After 2h, the magnetic solid phase extraction material is separated from the reaction system using an external magnetic field, and then 2mL of methanol is used to elute the organic phosphate adsorbed on the magnetic solid phase extraction material under ultrasonic conditions. This process is repeated 3 times. The extract is concentrated into a sample bottle, blown to near dryness with nitrogen, and finally fixed to 1mL with methanol or acetonitrile.

[0072] (3) Extraction of adsorbed TCEP: Soil particles were separated by centrifugation from the residual suspension in the previous step. 10 mL of 5% NH3·H2O in methanol was added twice, shaken for 30 min, centrifuged and filtered, and the methanol solution was concentrated by nitrogen blow-through to obtain slowly desorbed TCEP. 10 mL of 5% NH3·H2O in methanol was added twice to the remaining portion, and ultrasonic extraction was performed for 30 min to stabilize the adsorbed TCEP. The extraction was repeated three times, and the extracts were concentrated on a rotary evaporator to near dryness, and then fixed to 1 mL with methanol.

[0073] (4) Continuous extraction of bound TCEP: 10 mL of 1 M CaCl2, 0.5 M HCl, 5 M HCl, 1.3 M HF, and 1.8 M H2SO4 solutions were used to dissolve the organic phosphates bound to surface adsorbed iron, low-crystallinity minerals (such as ferrihydrite, siderite, and green rust), high-crystallinity iron-containing minerals (such as hematite), and iron-containing silicates and clay minerals, respectively. After each dissolution step, NaOH solution was used to adjust the pH value to close to 7. Then, magnetic solid phase extraction material was added to the solution and shaken for 2 h. After magnetic separation, 2 mL of methanol was added to elute the organic phosphate bound to the magnetic nanomaterial. This step was repeated 3 times. The extract was concentrated to near dryness by nitrogen blowing, and finally the volume was fixed to 1 mL with methanol.

[0074] (5) TCEP content determination method: The TCEP content in the fixed volume solutions of steps (2), (3) and (4) was quantitatively determined by gas chromatography-mass spectrometry.

[0075] Instrument model: gas chromatography-triple quadrupole tandem mass spectrometry (Agilent 7890A, Agilent 7010); chromatographic conditions: chromatographic column specifications are 30m×0.25mm id×0.25μm; carrier gas is high-purity helium (>99.999%); column flow rate is 1mL / min. The chromatographic temperature program is an initial temperature of 50℃ for 2min, then increased to 80℃ at 20℃ / min, then increased to 250℃ at 5℃ / min, and increased to 300℃ at 15℃ / min, and finally maintained for 10min. Automatic injection without splitting, injection volume 1μL. Mass spectrometry conditions: electron impact source (EI) detector, mass spectrometry ion source energy is 70eV, and the analysis method is multiple reaction monitoring mode. The ion source temperature is 250℃, and the transmission line is 230℃.

[0076] (6) Quality control of the above continuous extraction method: To ensure the credibility of the above extraction method, the TCEP contents extracted in steps 2 to 4 were added together and divided by the total concentration of standard TCEP added to the sample. The recovery rate of TCEP was calculated to be 92.5%.

[0077] (7) Actual soil sample test results: The sample to be tested was tested according to the above steps (2) to (5). The test results are as follows:

[0078] The active TCEP in the soil around the organophosphate flame retardant production plant was 20.82 ng / g dw, the adsorbed TCEP was 53.21 ng / g dw, the total iron-bound amount was 14.3 ng / g dw, and the organophosphates bound to surface adsorbed iron, low-crystallinity minerals (such as ferrihydrite, siderite and green rust-like minerals), high-crystallinity iron-containing minerals (such as hematite), and iron-containing silicates and clay minerals were 2.86 ng / g dw, 6.15 ng / g dw, 2.1 ng / g dw and 3.19 ng / g dw, respectively.

[0079] The embodiment of the present application adopts an analytical processing method of multi-step continuous extraction using magnetic solid phase extraction, organic solvent extraction, acidic dissolution followed by magnetic solid phase extraction, combined with gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry detection to establish an analytical method for the content of different occurrence forms of organophosphate pollutants in soil or sediment.

Claims

1. A method for analyzing the content of organophosphate pollutants, characterized in that: The following steps are involved: The method comprises the following steps: using a magnetic solid phase extraction material to adsorb active organic phosphate in a first sample to be tested, wherein the first sample to be tested is a water-containing mixture system; separating the adsorbed magnetic solid phase extraction material to obtain a sample to be tested after a single treatment, eluting the active organic phosphate adsorbed on the magnetic solid phase extraction material and detecting its content; the magnetic solid phase extraction material is Fe3O4@SiO2@HLB-WAX with a core-shell structure; The magnetic solid phase extraction material is prepared by the following method: Preparation of Fe3O4 magnetic nanoparticles; Modifying the surface of the Fe3O4 magnetic nanoparticles with a SiO2 shell to obtain Fe3O4@SiO2; Modify the surface of the Fe3O4@SiO2 with 3-(methacryloyloxy)propyltrimethoxysilane to obtain Fe3O4@SiO2@MPS; The Fe3O4@SiO2@MPS is placed in a mixture system containing azobisisobutyronitrile, divinylbenzene, vinylpyrrolidone, and 4-chloromethylstyrene for a first reaction, piperazine is added to the system after the first reaction for a second reaction, and the prepared magnetic solid phase extraction material Fe3O4@SiO2@HLB-WAX is separated; The sample to be tested after the first treatment is subjected to solid-liquid separation to obtain a solid second sample to be tested; a methanol solution containing aqueous ammonia is added to the second sample to be tested, and the adsorbed organic phosphate is extracted and then subjected to solid-liquid separation to obtain a solid third sample to be tested, and the content of the adsorbed organic phosphate in the extract is detected; Adding an inorganic acid to the third sample to be tested to dissolve the bound organic phosphate, adjusting the solution to neutrality, adding the magnetic solid phase extraction material to the solution to adsorb the dissolved bound organic phosphate, separating the adsorbed magnetic solid phase extraction material, eluting the bound organic phosphate adsorbed on the magnetic solid phase extraction material and detecting its content; The step of adding an inorganic acid to the third sample to dissolve the bound organic phosphate comprises the following steps: Adding 1-1.5 M CaCl2 to the third sample to be tested to dissolve it, obtaining a solid fourth sample to be tested and a first dissolving solution after solid-liquid separation, adjusting the first dissolving solution to neutrality, adding the magnetic solid phase extraction material to adsorb the dissolved first bound organic phosphate and detecting its content; Adding 0.5-1.0 M HCl to the fourth sample to be tested to dissolve it, obtaining a solid fifth sample to be tested and a second dissolved solution after solid-liquid separation, adjusting the second dissolved solution to neutrality, adding the magnetic solid phase extraction material to adsorb the dissolved second bound organic phosphate and detecting its content; Adding 5-5.5 M HCl to the fifth sample to be tested to dissolve it, obtaining a solid sixth sample to be tested and a third dissolving solution after solid-liquid separation, adjusting the third dissolving solution to neutrality, adding the magnetic solid phase extraction material to adsorb the dissolved third bound organic phosphate and detecting its content; A mixed acid solution of 1.3-1.5 M HF and 1.8-2.0 M H2SO4 is added to the sixth sample to be tested for dissolution, and a fourth solution is obtained after solid-liquid separation. After the fourth solution is adjusted to neutral, the magnetic solid phase extraction material is added to adsorb the dissolved fourth bound organic phosphate and detect its content.

2. The method for analyzing the content of organophosphate pollutants according to claim 1, characterized in that: The temperature of the first reaction is 65-70°C and the time is 18-24 h.

3. The method for analyzing the content of organophosphate pollutants according to claim 1, characterized in that: The temperature of the second reaction is 80-90°C and the time is 12-15 hours.

4. The method for analyzing the content of organic phosphate pollutants according to claim 1, characterized in that: In the first reaction, the dosage ratio of the Fe3O4@SiO2@MPS, the azobisisobutyronitrile, the divinylbenzene, the vinylpyrrolidone and the 4-chloromethylstyrene is: (3~5) g: (650~700) mg: (2.6~3.0) mL: (2.4~3.0) mL: (3.0~3.5) mL.

5. The method for analyzing the content of organic phosphate pollutants according to claim 1, characterized in that: In the second reaction, the mass ratio of the amount of piperazine to the amount of Fe3O4@SiO2@MPS is: (2.5-3): (3-5).

6. The method for analyzing the content of organic phosphate pollutants according to claim 1, characterized in that: The volume fraction of ammonia water in the ammonia-containing methanol solution is 5-10%.

7. The method for analyzing the content of organic phosphate pollutants according to any one of claims 1 to 6, characterized in that: The first sample to be tested contains contaminated soil or contaminated sediment.

8. The method for analyzing the content of organic phosphate pollutants according to claim 7, characterized in that: A microbial inhibitor is also added to the first sample to be tested.