A method for determining benzene series pollutants in water sample by solid phase microextraction

Abstract

The application discloses a kind of determination methods of solid phase microextraction of benzene series pollutants in water sample, belong to chemical analysis detection and sample pre-treatment technical field.The application is used to solve the technical problems of the drawbacks of weak mechanical force of conventional extraction fiber in prior art, leading to poor stability of extraction head;And the drawbacks of weak adsorption force between metal matrix extraction head and coating material, a kind of determination methods of solid phase microextraction of benzene series pollutants in water sample, comprising the following steps: S1, collecting contaminated water source in headspace bottle, oscillation is shaken evenly, and sample liquid is obtained;S2, headspace bottle constant temperature water bath, insert the extraction handle of extraction head equipped with coating layer, detect the adsorption concentration of benzene series pollutants in water sample.The extraction head used in the above determination method is prepared by mixing modified fiber activated by high-temperature carbonization and water vapor, cuparene, and high pressure;The combined fiber is inserted into a polysiloxane-epoxy resin adhesive solution, dried and cured to prepare the extraction head coated with coating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical analysis detection and sample pretreatment, and particularly relates to a solid phase microextraction determination method of benzene series pollutants in water samples. BACKGROUND

[0002] As the main component of gasoline and the chemical synthesis raw material, benzene series pollutants are also common organic water pollutants in the environment. Among them, polychlorinated biphenyls, as a representative of benzene series pollutants, have the characteristics of high persistence, difficult volatilization and high hazard; therefore, accurate measurement of benzene series pollutants represented by polychlorinated biphenyls in environmental samples is the goal that analysts constantly pursue.

[0003] As a sample pretreatment method, solid phase microextraction (SPME) has the advantages of simple operation, short time consumption and small sample consumption; if the solid phase microextraction method is applied to the determination of benzene series pollutants, rapid, efficient and sensitive analysis of benzene series pollutants can be achieved; among them, the material of the extraction head, the shape and structure of the extraction head, and the coating material used are crucial to the analysis of target substances. However, the common coating material cannot specifically extract benzene series pollutants represented by polychlorinated biphenyls.

[0004] Patent application CN115282640A discloses a molecularly imprinted solid phase microextraction fiber coating and its preparation method and application. 4,4'-dichlorobenzyl biphenyl is used as a template molecule, and is polymerized in situ with a functional monomer to prepare a molecularly imprinted solid phase microextraction fiber coating with rough surface and uniform thickness. The above-mentioned molecularly imprinted solid phase microextraction fiber contains various functional groups such as mercapto and phenyl, thereby having good strong specific adsorption function for polychlorinated biphenyls. However, the material and composition of the extraction fiber are not disclosed in the above-mentioned prior art. The conventional extraction fiber has the disadvantage of weak mechanical force, resulting in poor stability of the extraction head; and the extraction head of the metal substrate has the disadvantage of weak adsorption force between the coating material; selecting and designing a suitable extraction fiber material is important for extraction sensitivity, stability and accuracy.

[0005] In view of the above technical defects, a solution is proposed. SUMMARY

[0006] The present application aims to provide a solid phase microextraction determination method of benzene series pollutants in water samples, which solves the technical problems of weak mechanical force and poor stability of the organic extraction head in the prior art of solid phase microextraction technology, and the common coating material cannot specifically extract benzene series pollutants represented by polychlorinated biphenyls.

[0007] The object of the present application can be achieved by the following technical solutions:

[0008] A determination method of benzene series pollutants in water sample by solid phase microextraction, comprising the following steps:

[0009] S1, collecting contaminated water in a headspace bottle, then sealing with a sealing film, oscillating and shaking evenly to obtain a sample solution;

[0010] S2, constant temperature water bath of the headspace bottle, inserting the extraction handle provided with the coated extraction head, exposing the coated extraction head, and then rapidly inserting into the sample inlet of the gas chromatograph mass spectrometer for determination, and the adsorption concentration of benzene series pollutants in the water sample can be detected.

[0011] Further, the preparation method of the coated extraction head comprises the following steps:

[0012] A1, heating ethylenediamine to 100-110 DEG C, then adding polyacrylonitrile fiber and H2O2 solution, mixing, reacting at 70-80 DEG C for 5-6 h, then taking out the fiber solid; the fiber solid is washed with deionized water until the fiber solid is neutral, and dried at 50-60 DEG C for 10-12 h to obtain modified polyacrylonitrile fiber;

[0013] The polyacrylonitrile fiber is aminated to obtain the modified polyacrylonitrile fiber.

[0014] A2, mixing the modified polyacrylonitrile fiber, graphite and additives to obtain raw materials;

[0015] A3, transferring the raw materials to a resistance furnace, heating the raw materials from room temperature to 800-850 DEG C at a heating rate of 10-20 DEG C / min under nitrogen atmosphere, then constant temperature reaction for 2-3 h, and water vapor is introduced during the heating process; then stop heating, and the raw materials are naturally cooled to room temperature to obtain activated fiber; mixing the activated fiber and calixarene, and then preparing a combined fiber with a diameter of 0.2-025 mm and a length of 1-2 cm under high pressure conditions;

[0016] The modified polyacrylonitrile fiber, graphite and kaolin clay as inorganic materials are mixed and calcined at high temperature, and the activated fiber is obtained by activating with high-temperature water vapor during the high-temperature calcination process, so that the functional groups such as hydroxyl groups are introduced on the surface of the fiber. The activated fiber and calixarene are mixed to prepare a combined fiber.

[0017] A4, the combined fiber is installed in a solid phase microextraction sampling device, then the combined fiber is inserted into a polysiloxane-epoxy resin adhesive solution and dried and cured to prepare a coated extraction head.

[0018] Further, in step A1, the concentration of the H2O2 solution is 30-40%wt; the amount ratio of ethylenediamine, polyacrylonitrile fiber and H2O2 solution is 20-30 mL:3-5 g:1-2 mL; in step A2, the auxiliary agent is kaolin; the weight ratio of modified polyacrylonitrile fiber, graphite and auxiliary agent is 30-40:40-50:5-10.

[0019] Further, in step A3, the rate of water vapor is 50 mL / min, and the time of water vapor is 3-5 min; the weight ratio of activated fiber and calixarene is 50-60:10-20, and the pressing pressure is 10-20 MPa; in step A4, the insertion time is 20-30 min, the drying and curing temperature is 120-180℃, and the drying and curing time is 2-3 h.

[0020] Further, the preparation method of the polysiloxane-epoxy resin viscous solution comprises the following steps:

[0021] B1, 2-chloroethyl triethoxysilane and solid phase transfer catalyst are sequentially added into a high-pressure reaction kettle, hydrogen sulfide gas is introduced into the high-pressure reaction kettle until the pressure of the high-pressure reaction kettle is 305-345 kPa, and then the introduction of hydrogen sulfide gas is stopped; the high-pressure reaction kettle is stirred uniformly, and a mixture is obtained; sodium hydrosulfide solution is introduced into the mixture, and constant temperature reaction is carried out at 75-80℃ for 4-5 h to obtain a reaction product; the reaction product is cooled to room temperature, and the organic liquid phase is collected, which is the synthesized mercaptoethyl triethoxysilane;

[0022] Sodium hydrosulfide solution is used as a catalyst, 2-chloroethyl triethoxysilane and hydrogen sulfide gas are reacted to prepare mercaptoethyl triethoxysilane, and the reaction formula is as follows:

[0023]

[0024] B2, isocyanuric acid triglycidyl ester is added into DMF, and stirred until isocyanuric acid triglycidyl ester is completely dissolved to obtain an isocyanuric acid triglycidyl ester solution; then mercaptoethyl triethoxysilane, isocyanuric acid triglycidyl ester solution and curing agent are uniformly mixed and rotary evaporated to obtain a polysiloxane-epoxy resin viscous solution.

[0025] Isocyanuric acid triglycidyl ester and mercaptoethyl triethoxysilane can occur crosslinking reaction under high temperature conditions, and a curing agent is used for curing to prepare a polysiloxane-epoxy resin viscous solution.

[0026] Further, in step B1, the solid phase transfer catalyst is tetrabutylammonium bromide; the ratio of the amount of 2-chloroethyltriethoxysilane to the solid phase transfer catalyst is 22.6-45.2 g:0.3-0.48 g; the concentration of sodium hydrosulfide solution is 50-60 %wt, and the ratio of the amount of the mixture to the sodium hydrosulfide solution is 45 g:30-40 g.

[0027] Further, in step B2, the ratio of the amount of isocyanuric acid triglycidyl ester to DMF is 3-5 g:20-30 mL; the curing agent is any one of curing agent HT901, curing agent HT933 or curing agent HT906, and the ratio of the amount of mercaptoethyltriethoxysilane, isocyanuric acid triglycidyl ester solution and the curing agent is 20-25 g:20-30 mL:0.5-1 g; the time length for rotary evaporation concentration is 20-30 min, and the temperature for rotary evaporation concentration is 80-90 °C.

[0028] Further, in step S2, the temperature of the constant temperature water bath is 60-65 °C, and the equilibrium time length is 30-40 min.

[0029] The present application has the following advantages:

[0030] 1, The present application adopts solid phase microextraction method to determine benzene series pollutants. The present application uses modified fiber as extraction head, and then coats the extraction head with synthesized polysiloxane-epoxy resin adhesive solution, so that the prepared extraction device has the advantages of high sensitivity, good accuracy and stable detection results. The polyacrylonitrile fiber contains rich nitrile functional groups. If the polyacrylonitrile fiber is mixed with inorganic materials such as graphite and kaolin, the components of the raw materials can be adsorbed to each other. Then the above raw materials are subjected to high temperature calcination, carbonization and pressing to prepare the extraction head. The above extraction head and the coating material modified epoxy resin can be adhered by electrostatic adsorption, reaction and other ways, so as to improve the bonding density and stability of the synthesized extraction head and the coating. Further, the mixed raw materials prepared by modified polyacrylonitrile fiber, graphite and kaolin additives are carbonized. The carbonized fiber and inorganic materials have larger specific surface area, faster adsorption speed and larger extraction amount. In addition, high temperature steam activation can enrich the number of hydroxyl functional groups contained in the extraction head. Calixarene is the third generation of macrocyclic compounds, which has a unique hydrophobic cavity size, a hydrophilic carboxyl group at the upper end and a hydrophobic alkyl chain at the lower end. It can be self-assembled with the activated fiber to form an extraction head containing a porous structure.

[0031] 2、The present application uses epoxy resin as the coating material of the synthetic extraction head, and because it has multiple epoxy groups, it has a greater crosslinking density with curing agents and the like, so that the isocyanuric acid triglycidyl ester has excellent high-temperature resistance and chemical stability. The present application uses mercaptoethyl triethoxysilane to modify the isocyanuric acid triglycidyl ester, and a polysiloxane-epoxy resin viscous solution is prepared. Polysiloxane, as an organic polymer, has the advantages of high viscosity, good wettability, and easy to be coated. By using a physical coating method to coat the extraction head, excellent film-forming properties are obtained. 2-Chloroethyl triethoxysilane is reacted to prepare mercaptoethyl triethoxysilane; the mercaptoethyl triethoxysilane can react with the isocyanuric acid triglycidyl ester under high temperature conditions, thereby preparing a polysiloxane-epoxy resin viscous solution. The synthetic extraction head is inserted into the polysiloxane-epoxy resin viscous solution, and various functional groups are reacted by organic reaction, so that the prepared extraction device has the advantages of high sensitivity, accuracy, and high stability for detecting benzene series pollutants in water samples. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be clearly and completely described below in combination with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] The isocyanuric acid triglycidyl ester used in the embodiments 1-3 of the present application is purchased from Nanjing Bermuda Biotechnology Co., Ltd., and the EINECS number is 219-514-3; the curing agent HT901, the curing agent HT933 and the curing agent HT906 used in the embodiments 1-3 of the present application are purchased from Jiaxing Dongzhen Chemical Product Co., Ltd.; the polyacrylonitrile fiber used in the embodiments 4-6 of the present application is purchased from Changzhou Tianyi Engineering Fiber Co., Ltd., and the density is 1.18 g / cm 3 ; the graphite used in the embodiments 4-6 of the present application is purchased from Lingshou County Jushun Mineral Product Co., Ltd., and the crystal particle size is 0.5 mm; the kaolin used in the embodiments 4-6 of the present application is purchased from Lingshou County Changhe Mineral Product Processing Factory, and the article number is h8955555; the calixarene used in the embodiments 4-6 of the present application is 4-tert-butyl calix【6】arene, and the article number is PA22231, which is purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.; the bisphenol A type epoxy resin used in Comparative Example 2 is purchased from Zibo Linzi Shuangli Resin Factory, and the article number is 005, and the brand is 604.

[0034] Embodiment 1

[0035] The present embodiment provides a preparation method of a polysiloxane-epoxy resin viscous solution for a solid-phase microextraction fiber coating of benzene series pollutants in water samples, comprising the following steps:

[0036] B1, select 500 mL, laboratory use stainless steel high pressure reactor, to the high pressure reactor in turn 22.6 g of 2-chloroethyl triethoxysilane, 0.3 g of solid phase transfer catalyst tetrabutylammonium bromide, then into the high pressure reactor into hydrogen sulfide gas, until the pressure of the high pressure reactor is 305 kPa, stop hydrogen sulfide gas; the high pressure reactor is stirred by stirring device, so that the above-mentioned reactants are mixed, to obtain a mixture, reserve 45 g of the mixture to continue the reaction. Again 30 g, 50% wt of sodium hydrosulfide solution into the above-mentioned high pressure reactor; the high pressure reactor is heated by jacket electric heating mode at 75 DEG C constant temperature reaction 4 h, to obtain the reactant; after the high pressure reactor is cooled to room temperature, the organic liquid phase is collected, which is the synthesis of mercaptoethyl triethoxysilane.

[0037] B2, 3 g of isocyanuric acid triglycidyl ester is added to 20 mL of DMF, and stirred until completely dissolved to obtain isocyanuric acid triglycidyl ester solution. Then 20 g of mercaptoethyl triethoxysilane, 20 mL of isocyanuric acid triglycidyl ester solution and 0.5 g of curing agent HT901 are mixed, and the part of DMF solvent is concentrated by rotary evaporation. The rotary evaporation concentration temperature is 80 DEG C, and the rotary evaporation concentration time is 20 min, to obtain a polysiloxane-epoxy resin viscous solution.

[0038] Example 2

[0039] The present embodiment provides a preparation method of a polysiloxane-epoxy resin viscous solution for coating of a solid phase microextraction fiber for benzene series pollutants in water samples, comprising the following steps:

[0040] B1, select 500 mL, laboratory use stainless steel high pressure reactor, to the high pressure reactor in turn 22.6 g of 2-chloroethyl triethoxysilane, 0.3 g of solid phase transfer catalyst tetrabutylammonium bromide, then into the high pressure reactor into hydrogen sulfide gas, until the pressure of the high pressure reactor is 305 kPa, stop hydrogen sulfide gas; the high pressure reactor is stirred by stirring device, so that the above-mentioned reactants are mixed, to obtain a mixture, reserve 45 g of the mixture to continue the reaction. Again 30 g, 50% wt of sodium hydrosulfide solution into the above-mentioned high pressure reactor; the high pressure reactor is heated by jacket electric heating mode at 75 DEG C constant temperature reaction 4 h, to obtain the reactant; after the high pressure reactor is cooled to room temperature, the organic liquid phase is collected, which is the synthesis of mercaptoethyl triethoxysilane.

[0041] B2, 4 g of trioxane isocyanurate is added to 25 mL of DMF and stirred until completely dissolved to obtain a trioxane isocyanurate solution. Then 22 g of mercaptoethyl triethoxysilane, 25 mL of trioxane isocyanurate solution and 0.8 g of curing agent HT933 are uniformly mixed, and part of the DMF solvent is concentrated by rotary evaporation. The rotary evaporation concentration temperature is 85°C, and the rotary evaporation concentration time is 25 min, to obtain a polysiloxane-epoxy resin viscous solution.

[0042] Example 3

[0043] The present embodiment provides a preparation method of a polysiloxane-epoxy resin viscous solution for coating a solid-phase microextraction fiber coating for benzene series pollutants in water samples, comprising the following steps:

[0044] B1, select a 500 mL laboratory stainless steel high-pressure reaction kettle, and sequentially add 45.2 g of 2-chloroethyl triethoxysilane and 0.48 g of solid phase transfer catalyst tetrabutylammonium bromide to the high-pressure reaction kettle. Then, hydrogen sulfide gas is introduced into the high-pressure reaction kettle until the pressure of the high-pressure reaction kettle reaches 345 kPa, and the introduction of hydrogen sulfide gas is stopped. The high-pressure reaction kettle is stirred by a stirring device to mix the above-mentioned reactants, and 45 g of the mixture is reserved for further reaction. Then, 40 g of 60%wt sodium hydrosulfide solution is introduced into the high-pressure reaction kettle. The high-pressure reaction kettle is heated at 80°C by a jacketed electric heating method for 5 h to obtain a reaction product. Then, the high-pressure reaction kettle is naturally cooled to room temperature, and the organic liquid phase is collected, which is the synthesized mercaptoethyl triethoxysilane.

[0045] B2, 5 g of trioxane isocyanurate is added to 30 mL of DMF and stirred until completely dissolved to obtain a trioxane isocyanurate solution. Then 25 g of mercaptoethyl triethoxysilane, 30 mL of trioxane isocyanurate solution and 1 g of curing agent HT906 are uniformly mixed, and part of the DMF solvent is concentrated by rotary evaporation. The rotary evaporation concentration temperature is 90°C, and the rotary evaporation concentration time is 30 min, to obtain a polysiloxane-epoxy resin viscous solution.

[0046] Example 4

[0047] The present embodiment provides a preparation method of a coated extraction head for solid-phase microextraction of benzene series pollutants in water samples:

[0048] A1, add 20 mL of ethylenediamine to a 250 mL three-necked flask, and heat it to 100℃ in a water bath; add 3 g of polyacrylonitrile fiber and 1 mL of 30%wt H2O2 solution to the three-necked flask, mix well, and react at 70℃ for 5 h; take out the fiber solid, wash it with deionized water until the pH value of the liquid drops on the surface of the fiber solid is neutral; then dry the fiber in an oven at 50℃ for 10 h to obtain modified polyacrylonitrile fiber.

[0049] A2, mix 30 parts of modified polyacrylonitrile fiber, 40 parts of graphite, and 5 parts of auxiliary kaolin according to weight parts, grind to 200 mesh, and obtain raw materials.

[0050] A3, take 5 g of raw materials into a quartz boat, place the quartz boat in a small tube furnace (inner diameter of 40 mm, length of 600 mm), replace the air in the tube furnace with nitrogen, and then heat the tube furnace; the heating rate is 10℃ / min, heat to 800℃, and keep constant temperature for 2 h; during the heating process, water vapor is continuously introduced into the tube furnace at a rate of 50 mL / min; then stop heating, and naturally cool to room temperature to obtain activated fiber. Mix 50 parts of activated fiber and 10 parts of calixarene according to weight parts, and then press into an extraction head with a diameter of 0.2 mm and a length of 1 cm under a pressure of 10 MPa.

[0051] A4, place the above extraction head in a solid-phase microextraction sampling device, and then insert the extraction head into the polysiloxane-epoxy resin adhesive solution of Example 1 for 20 min, and dry and cure at 120℃ for 2 h to obtain an extraction head coated with a coating layer.

[0052] Example 5

[0053] The present embodiment provides a method for preparing an extraction head coated with a coating layer for solid-phase microextraction of benzene series pollutants in water samples:

[0054] A1, add 20 mL of ethylenediamine to a 250 mL three-necked flask, and heat it to 100℃ in a water bath; add 3 g of polyacrylonitrile fiber and 1 mL of 30%wt H2O2 solution to the three-necked flask, mix well, and react at 70℃ for 5 h; take out the fiber solid, wash it with deionized water until the pH value of the liquid drops on the surface of the fiber solid is neutral; then dry the fiber in an oven at 50℃ for 10 h to obtain modified polyacrylonitrile fiber.

[0055] A2, mix 30 parts of modified polyacrylonitrile fiber, 40 parts of graphite, and 5 parts of auxiliary kaolin according to weight parts, grind to 200 mesh, and obtain raw materials.

[0056] A3, 8 g of the raw material was weighed into a quartz boat, the quartz boat was placed in a small tube furnace (inner diameter of 40 mm, length of 600 mm), nitrogen was introduced to replace the air in the tube furnace, and then the tube furnace was heated; the heating rate was 12 ℃ / min, heated to 830 ℃, and then kept constant for 2.5 h; during the heating process, water vapor was introduced into the tube furnace at a rate of 80 mL / min; then stop heating, and then naturally cool to room temperature to obtain the activated fiber. According to the weight parts, 55 parts of the activated fiber and 15 parts of the calixarene were uniformly mixed, and then pressed into an extraction head with a diameter of 0.22 mm and a length of 1.5 cm under 15 MPa.

[0057] A4, the extraction head was placed in a solid phase microextraction sampling device, and then the extraction head was inserted into the polysiloxane-epoxy resin viscous solution prepared in Example 2 for 25 min, and then dried and cured at 150 ℃ for 2.3 h to prepare a coated extraction head.

[0058] Example 6

[0059] The present embodiment provides a method for preparing a coated extraction head for solid phase microextraction of benzene series pollutants in water samples:

[0060] A1, 30 mL of ethylenediamine was added to a 250 mL three-necked flask, and then heated to 110 ℃ in a water bath; 5 g of polyacrylonitrile fiber and 2 mL of 40%wt H2O2 solution were added to the three-necked flask and mixed uniformly, and then reacted at 80 ℃ for 6 h; the fiber solid was taken out and washed with deionized water until the pH value of the liquid drops on the surface of the fiber solid was neutral; then the fiber was dried in an oven at 60 ℃ for 12 h to obtain a solid modified polyacrylonitrile fiber.

[0061] A2, according to the weight parts, 40 parts of the modified polyacrylonitrile fiber, 50 parts of graphite and 10 parts of the auxiliary agent kaolin were uniformly mixed to obtain the raw material.

[0062] A3, 10 g of the raw material was weighed into a quartz boat, the quartz boat was placed in a small tube furnace (inner diameter of 40 mm, length of 600 mm), nitrogen was introduced to replace the air in the tube furnace, and then the tube furnace was heated, the heating rate was 20 ℃ / min, heated to 850 ℃, and then kept constant for 3 h; during the heating process, water vapor was introduced into the tube furnace at a rate of 50 mL / min for 5 min; then stop heating, and then naturally cool to room temperature to obtain the activated fiber. According to the weight parts, 60 parts of the activated fiber and 20 parts of the calixarene were uniformly mixed, and then pressed into an extraction head with a diameter of 0.25 mm and a length of 2 cm under 20 MPa.

[0063] A4, the extraction head is installed in a solid phase microextraction sampling device, then the extraction head is inserted into the polysiloxane-epoxy resin viscous solution prepared in Example 3 for 30 min, and dried and cured at 180℃ for 3 h to prepare the extraction head coated with a coating layer.

[0064] Example 7

[0065] The embodiment provides a determination method of solid phase microextraction of benzene series pollutants in a water sample, and comprises the following steps:

[0066] S1, 10.00 mL of a water sample polluted by a chemical plant is taken, insoluble impurities in the water sample are removed by using a microporous filter membrane with a pore size of 0.5 μm, then 5.00 mL of the water sample is stored in a 20 mL polytetrafluoroethylene headspace bottle, the headspace bottle cap is tightened, a sealing film is sealed, and the sample solution is obtained by oscillation and shaking.

[0067] S2, then the headspace bottle is placed in a constant temperature water bath pot at 60℃, an extraction handle provided with a solid phase microextraction head is inserted, the extraction head is exposed, and after 30 min of balance, the extraction head is quickly inserted into a sample inlet of a gas chromatograph mass spectrometer for determination, and the adsorption concentration of the benzene series pollutants in the water sample can be detected.

[0068] Example 8

[0069] The embodiment provides a determination method of solid phase microextraction of benzene series pollutants in a water sample, and comprises the following steps:

[0070] S1, 10.00 mL of a water sample polluted by a chemical plant is taken, insoluble impurities in the water sample are removed by using a microporous filter membrane with a pore size of 0.5 μm, then 5.00 mL of the water sample is stored in a 20 mL polytetrafluoroethylene headspace bottle, the headspace bottle cap is tightened, a sealing film is sealed, and the sample solution is obtained by oscillation and shaking.

[0071] S2, then the headspace bottle is placed in a constant temperature water bath pot at 62℃, an extraction handle provided with a solid phase microextraction head is inserted, the extraction head is exposed, and after 35 min of balance, the extraction head is quickly inserted into a sample inlet of a gas chromatograph mass spectrometer for determination, and the adsorption concentration of the benzene series pollutants in the water sample can be detected.

[0072] Example 9

[0073] The embodiment provides a determination method of solid phase microextraction of benzene series pollutants in a water sample, and comprises the following steps:

[0074] S1, 10.00 mL of a water sample polluted by a chemical plant is taken, insoluble impurities in the water sample are removed by using a microporous filter membrane with a pore size of 0.5 μm, then 5.00 mL of the water sample is stored in a 20 mL polytetrafluoroethylene headspace bottle, the headspace bottle cap is tightened, a sealing film is sealed, and the sample solution is obtained by oscillation and shaking.

[0075] S2, then put the headspace bottle into a constant temperature water bath at 65℃, insert the extraction handle equipped with a solid phase microextraction head, expose the extraction head, after equilibration for 40 min, quickly insert into the sample inlet of a gas chromatograph mass spectrometer for determination, and the adsorbed concentration of benzene series pollutants in the water sample can be detected.

[0076] Comparative Example 1

[0077] The difference between the present comparative example and Example 9 is that, in the preparation of the coated extraction head, the fiber is not activated by water vapor in the carbonization process.

[0078] Comparative Example 2

[0079] The difference between the present comparative example and Example 9 is that, in the preparation of the polysiloxane-epoxy resin viscous solution, the same mass of bisphenol A type epoxy resin is used to replace isocyanuric acid triglycidyl ester.

[0080] Comparative Example 3

[0081] The difference between the present comparative example and Example 9 is that, in the preparation of the polysiloxane-epoxy resin viscous solution, step B1 is cancelled, and 2-chloroethyl triethoxysilane is used to replace mercaptoethyl triethoxysilane in the same amount.

[0082] Performance test:

[0083] The solid phase microextraction water samples prepared in Examples 7-9 and Comparative Examples 1-3 are subjected to quantitative analysis evaluation; the linear correlation coefficient (R) value, method detection limit and linear range value are recorded. Then, the solid microextraction method in Examples 7-9 and Comparative Examples 1-3 is used to test the recovery rate of PCBs with a concentration of 120 ng / L in water, and the specific test results are shown in the following table.

[0084] Table 1 - Performance test data table of samples

[0085]

[0086] Data analysis: by comparing and analyzing the data in Table 1, the solid phase microextraction method for benzene series pollutants in water samples adopted in the present application has good ability to extract benzene series pollutants in water samples, and exhibits a wide linear range, low detection limit and good reproducibility (high linear correlation coefficient R value).

[0087] However, in Comparative Example 1, the fiber is not activated by water vapor in the carbonization process when preparing the extraction head, and the number of functional groups such as hydroxyl groups contained on the surface thereof is reduced; the activated modified polyacrylonitrile fiber has better adsorption performance with calixarene and the organic material attached to the extraction head, so that the detection degree of benzene series pollutants is more sensitive and accurate.

[0088] In the comparative example 2, when preparing the polysiloxane-epoxy resin viscous solution, the isocyanuric acid triglycidyl ester is replaced by the same mass of bisphenol A type epoxy resin; the mercaptoethyl triethoxysilane has stronger reactivity and higher adsorption with the isocyanuric acid triglycidyl ester, which shows that the prepared polysiloxane-epoxy resin viscous solution has higher solidification degree and viscosity on the extraction head.

[0089] In the comparative example 3, when preparing the polysiloxane-epoxy resin viscous solution, the step B1 is cancelled, and the mercaptoethyl triethoxysilane is replaced by the same amount of 2-chloroethyl triethoxysilane; the 2-chloroethyl triethoxysilane does not react with the isocyanuric acid triglycidyl ester; the grafted siloxane has good epoxy resin film forming property and better adsorption performance. It shows that the prepared extraction head has better sensitivity for adsorbing organic materials and more accurate detection data.

[0090] The above is only an example and description of the structure of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace, as long as it does not deviate from the structure of the invention or exceed the scope defined by the claims.

[0091] In the description of the specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0092] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details, nor limit the application to the specific embodiments. Obviously, many modifications and changes can be made according to the content of the specification. The specification selects and describes these embodiments in order to better explain the principles and practical application of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for the determination of benzene series pollutants in water samples by solid phase microextraction, characterized by, The method comprises the following steps: S1, collecting the contaminated water in a headspace bottle, then sealing the bottle with a sealing film, shaking to obtain a sample solution; S2, placing the headspace bottle in a constant temperature water bath, inserting an extraction handle provided with a coated extraction head, exposing the coated extraction head, and then rapidly inserting the coated extraction head into a sample inlet of a gas chromatograph mass spectrometer for determination after equilibrium, and detecting the adsorption concentration of benzene series pollutants in the water sample; The preparation method of the coated extraction head comprises the following steps: A1, heating ethylenediamine to 100-110 DEG C, then adding polyacrylonitrile fiber and H2O2 solution, mixing, reacting at 70-80 DEG C for 5-6 h, then taking out the fiber solid; the fiber solid is washed with deionized water until the fiber solid is neutral, and then dried at 50-60 DEG C for 10-12 h to obtain modified polyacrylonitrile fiber; A2, mixing the modified polyacrylonitrile fiber, graphite and additives to obtain a raw material; A3, transferring the raw material to a resistance furnace, heating the raw material from room temperature to 800-850 DEG C at a heating rate of 10-20 DEG C / min under a nitrogen atmosphere, then constant temperature reaction for 2-3 h, and water vapor is introduced during the heating process; then stop heating, and the raw material is naturally cooled to room temperature to obtain activated fiber; mixing the activated fiber and calixarene, and then pressing into an extraction head with a diameter of 0.2-0.25 mm and a length of 1-2 cm; A4, the extraction head is installed in a solid phase microextraction sampling device, then the extraction head is inserted into a polysiloxane-epoxy resin viscous solution and dried and cured to obtain a coated extraction head; The preparation method of the polysiloxane-epoxy resin viscous solution comprises the following steps: B1, 2-chloroethyl triethoxysilane and solid phase transfer catalyst are sequentially added to a high-pressure reaction kettle, hydrogen sulfide gas is introduced into the high-pressure reaction kettle until the pressure of the high-pressure reaction kettle is 305-345 kPa, then the introduction of hydrogen sulfide gas is stopped; the mixture is obtained by stirring uniformly in the high-pressure reaction kettle; sodium hydrosulfide solution is introduced into the mixture, and constant temperature reaction is carried out at 75-80 DEG C for 4-5 h to obtain a reaction product; the reaction product is cooled to room temperature, and the organic liquid phase is collected, which is the synthesized mercaptoethyl triethoxysilane; B2, isocyanuric acid triglycidyl ester is added to DMF, stirred until isocyanuric acid triglycidyl ester is completely dissolved to obtain an isocyanuric acid triglycidyl ester solution; then mixing mercaptoethyl triethoxysilane, isocyanuric acid triglycidyl ester solution and curing agent, rotary evaporation to obtain a polysiloxane-epoxy resin viscous solution.

2. The method according to claim 1, wherein the method is characterized by, In step A1, the concentration of H2O2 solution is 30-40 wt%; The amount ratio of ethylenediamine, polyacrylonitrile fiber and H2O2 solution is 20-30 mL:3-5 g:1-2 mL; in step A2, the additive is kaolin; the weight ratio of modified polyacrylonitrile fiber, graphite and additive is 30-40:40-50:5-10.

3. The method according to claim 1, wherein the method is characterized by, In step A3, the rate of water vapor introduction is 50 mL / min, and the time of water vapor introduction is 3-5 min; the weight ratio of activated fiber and calixarene is 50-60:10-20, and the pressing pressure is 10-20 MPa; In step A4, the insertion time is 20-30 min, the temperature for drying and curing is 120-180℃, and the time for drying and curing is 2-3 h.

4. The method according to claim 1, wherein the method is characterized by, In step B1, the solid phase transfer catalyst is tetrabutylammonium bromide; the ratio of 2-chloroethyltriethoxysilane to the solid phase transfer catalyst is 22.6-45.2 g:0.3-0.48 g; the concentration of sodium hydrosulfide solution is 50-60% wt, and the ratio of the mixture to sodium hydrosulfide solution is 45 g:30-40 g.

5. The method according to claim 1, wherein the method is characterized by, In step B2, the ratio of isocyanuric acid triglycidyl ester to DMF is 3-5 g:20-30 mL; the curing agent is any one of curing agent HT901, curing agent HT933 or curing agent HT906, and the ratio of mercaptoethyltriethoxysilane, isocyanuric acid triglycidyl ester solution and the curing agent is 20-25 g:20-30 mL:0.5-1 g; the time for rotary evaporation concentration is 20-30 min, and the temperature for rotary evaporation concentration is 80-90℃.

6. The method according to claim 1, wherein the method is characterized by, In step S2, the temperature of the constant temperature water bath is 60-65℃, and the time for equilibration is 30-40 min.

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