A packing material for a strong polar solid phase extraction column, a preparation method thereof and an application thereof

Abstract

The present invention belongs to the technical field of fillers for solid-phase extraction columns, and discloses a strongly polar solid-phase extraction column filler, a preparation method thereof and an application thereof. The method includes: Step S1, adding magnesium carbonate into water for dispersion and dissolution; adding a mixed solution of divinylbenzene, azobisisobutyronitrile, tetraethoxysilane, aviation kerosene and xylene, stirring and then raising the temperature to adjust the pH of the reaction system; supplementing azobisisobutyronitrile, and reacting to obtain seed balls; Step S2, adding an amphoteric ion surfactant into water for dispersion, adding sodium metasilicate pentahydrate, then adding the seed balls, adjusting the pH, and etching for 10-25 minutes; adding an aqueous magnesium sulfate solution to obtain the filler. The solid-phase extraction filler prepared by the present invention has adjustable particle size, a relatively large particle size, can be used for short-time sample loading of high-viscosity and large-volume samples, and has high recovery rates for some of the four major types of agricultural residues such as organophosphorus, organochlorine, pyrethroids and carbamates. The filler of the present invention has good stability, good reproducibility and is easy to produce in large quantities.

Description

Technical Field

[0001] The present invention belongs to the technical field of fillers for solid-phase extraction columns, and particularly relates to a strongly polar solid-phase extraction column filler, a preparation method thereof, and an application thereof. Background Art

[0002] The commonly used magnesium oxide composite polar silica adsorbent Florisil on the market for separating target substances such as organochlorine pesticides, amines, polychlorinated biphenyls (PCBs), ketones, and organic acids is a highly selective adsorbent widely used in pretreatment and chromatographic analysis. Currently, all global Florisil fillers are sourced from U.S. Silica Company in the United States, and the difference between each brand lies in purchasing through different distributors.

[0003] At present, domestic manufacturers have relatively weak industrial control technologies for silica spheres and background contents, and cannot develop stable products comparable to Florisil. Due to the monopoly of this technology by foreign countries, the cost of imported materials is increasing day by day, and the purchase channels may be cut off at any time. Therefore, it is urgent to develop alternative materials with low price and excellent performance as soon as possible. Summary of the Invention

[0004] In view of the above technical problems, the present invention has developed a high-performance strongly polar solid-phase extraction column filler and a preparation method thereof, innovatively using core-shell structured organic-inorganic composite microspheres. The core layer can adjust the particle size and specific surface area, and the shell layer combines with the silanol groups of the core layer to provide strong polarity, which can be used for the separation of organochlorine pesticides, amines, polychlorinated biphenyls (PCBs), and ketones. The polymer microspheres prepared by this method have the advantages of uniform particle size and adjustable specific surface area, and are very suitable for the sample loading method with high viscosity and large volume, saving detection costs and improving efficiency.

[0005] In the first aspect of the present invention, a preparation method of a strongly polar solid-phase extraction column filler is provided, including the following steps:

[0006] Step S1, adding light magnesium carbonate into water, dispersing and dissolving it; then adding a mixed solution of divinylbenzene, azobisisobutyronitrile, tetraethoxysilane, aviation kerosene, and xylene, stirring and heating to 65°C - 80°C. After reaching 65 - 80°C, adding an alkali to adjust the pH of the reaction system between 10 and 12; adding azobisisobutyronitrile after a predetermined time, reacting for another predetermined time to obtain a solid, washing and drying the solid to obtain seed spheres for standby;

[0007] Step S2: Add zwitterionic surfactant into water. After stirring and dispersing, add sodium metasilicate pentahydrate. After stirring and dispersing again, add the seed balls. Add alkali to adjust the pH of the reaction system between 12 and 14, and etch for 10 to 25 minutes. Then, dropwise add an aqueous solution of magnesium sulfate. After the reaction between sodium metasilicate and magnesium sulfate, deposition occurs on the surface of the seed balls to obtain the packing material of the strong polar solid-phase extraction column.

[0008] Further, in step S1, the mass ratio of divinylbenzene to aviation kerosene to xylene is 50:(1 - 5):(30 - 70); the mass ratio of light magnesium carbonate to water to divinylbenzene is (5 - 25):(230 - 450):50; the total mass ratio of initiator azobisisobutyronitrile to tetraethoxysilane to divinylbenzene is (8 - 32):(42 - 95):50, where the mass ratio of azobisisobutyronitrile added for the first time to azobisisobutyronitrile added for the second time is 2:1.

[0009] Further, in step S2, the zwitterionic surfactant is of the betaine type. The mass ratio of the zwitterionic surfactant to the seed balls is 0.5 - 3:50. The mass ratio of the seed balls to sodium metasilicate pentahydrate to magnesium sulfate is 500:(140 - 188):(20 - 104), where the mass ratio of sodium metasilicate pentahydrate to water in the sodium metasilicate pentahydrate solution is 1:(12 - 20).

[0010] Further, the alkali is any one of sodium hydroxide, sodium bicarbonate, or potassium hydroxide.

[0011] Further, in step S1, the alkali is an alkali solution with a concentration of 1 mol / L to 5.5 mol / L; in step S2, the alkali is an alkali solution with a concentration of 2.5 mol / L to 10 mol / L, and the mass ratio of magnesium sulfate to water in the aqueous solution of magnesium sulfate is 1:4 - 7.

[0012] Further, in step S1, the rotation speed is controlled at 350 - 550 revolutions per minute, and light magnesium carbonate is added to water. After 2 - 3 hours, add azobisisobutyronitrile. Stop the reaction after 6 - 10 hours. Wash the solid twice with hot water, dilute hydrochloric acid, and ethanol respectively, and then dry at 65 - 80 °C for 6 - 10 hours to obtain the seed balls.

[0013] Further, the reaction temperature in step S2 is 20 °C - 35 °C, the stirring is mechanical stirring, the stirring and dispersing time is 0.5 h - 2 h, the reaction time is 1 - 4 h, and the stirring speed is 450 - 650 revolutions per minute.

[0014] Further, the seed balls are organic-inorganic composite porous balls with a particle size of 60 - 100 mesh and a BET of 250 m 2 / g - 450 m 2 / g, with a pore size of 100 Å to 210 Å.

[0015] In the second aspect of the present invention, a strongly polar solid-phase extraction column packing is provided, which is prepared by the above method. The polarity of the obtained packing is 7 to 8.5. The particle size of the packing is mainly determined by the seed balls, and the particle size of the packing is basically the same as that of the seed balls.

[0016] In the third aspect of the present invention, the application of the above packing as a solid-phase extraction column packing in the separation of organochlorine pesticide residues, amines, polychlorinated biphenyls (PCBs), and ketones is provided.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] (1) The specific surface area and particle size of the seed balls of the present invention can be regulated, so the specific surface area and particle size of the packing prepared from the seed balls can also be regulated.

[0019] (2) The solid-phase extraction packing prepared by the present invention belongs to a magnesium silicate adsorbent, with a relatively large particle size, 60 to 100 mesh, which can be used for short-time sample loading of high-viscosity and large-volume samples, and has a high recovery rate for some pesticide residues in four categories, namely organophosphorus, organochlorine, pyrethroids, and carbamates.

[0020] (3) The packing of the present invention has good stability, good reproducibility, and is easy to produce in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the particle size diagram of the seed balls prepared in Example 1 of the present invention;

[0022] Figure 2 It is the particle size diagram of the seed balls prepared in Comparative Example 2 of the present invention;

[0023] Figure 3 It is the nitrogen adsorption and desorption curve diagram of the seed balls prepared in Example 1 of the present invention;

[0024] Figure 4 It is the SEM diagram of the polar adsorption packing prepared in Example 1 of the present invention;

[0025] Figure 5 It is the gas chromatogram of the standard product malathion. DETAILED DESCRIPTION OF THE INVENTION

[0026] The technical solutions of the present invention will be further described below with reference to the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0027] Unless otherwise specified, the raw materials and materials used in the embodiments of the present invention are purchased through general commercial channels.

[0028] The source information of relevant raw materials, materials, and instruments involved in the following examples or comparative examples is as follows:

[0029] Commercially available magnesium silicate small column: Florisil small column from U.S. silica company;

[0030] Sodium metasilicate pentahydrate, sodium hydroxide, magnesium carbonate, magnesium sulfate, azobisisobutyronitrile, etc. were purchased from Aladdin Reagent (Shanghai) Co., Ltd.;

[0031] AB23 type laboratory pH meter (Orion Instruments Co., Ltd., USA);

[0032] Nano ZS type nano laser particle size analyzer (Malvern Instruments Ltd., UK);

[0033] ASAP 2460 type physical adsorption analyzer (Micromeritics Instrument Corporation, USA);

[0034] QSightTM 220 type liquid chromatography - mass spectrometry instrument (PerkinElmer Instruments Ltd., USA).

[0035] <Example 1>

[0036] This example provides a strongly polar solid - phase extraction column packing and its preparation method.

[0037] Step S1, Seed - ball - 1: Add 5 g of light magnesium carbonate to a 1 L three - necked flask containing 230 mL of deionized water, with a mechanical stirring speed of 400 revolutions per minute. After the magnesium carbonate is fully dispersed and dissolved, then add 50 g of divinylbenzene, 2.67 g of azobisisobutyronitrile, 42 g of tetraethoxysilane, 1 g of aviation kerosene, and 30 g of xylene. Stir for half an hour and then heat up to 75 °C. After reaching 75 °C, add 1 mL (1 mol / L) NaOH aqueous solution. After 2 hours, add 1.33 g of azobisisobutyronitrile. After reacting for 8 hours, stop. Wash the solid with 1 mol / L dilute hydrochloric acid, hot water, and ethanol twice each, and then dry at 65 °C for 6 hours to obtain the seed - ball for standby.

[0038] Step S2: Add 0.5 g of sulfobetaine into 168 mL of deionized water, with the mechanical stirring speed at 450 revolutions per minute and the oil bath temperature controlled at 35°C. After stirring and dispersing for 30 minutes, add 14 g of sodium metasilicate pentahydrate, stir and disperse for 30 minutes, add 50 g of seed balls into the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system between 12 and 14 with 2.5 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add dropwise an aqueous solution of magnesium sulfate (2 g of magnesium sulfate dissolved in 8 g of water), and start timing for 2 hours after the addition is completed, so that sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seed balls. After the reaction ends, the product is filtered by a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in an oven at 60°C for 6 hours to obtain the packing material for a strong polar solid-phase extraction column, denoted as Product-1.

[0039] <Example 2>

[0040] This example provides a packing material for a strong polar solid-phase extraction column and a preparation method thereof.

[0041] Step S1, Seed Balls-2: Add 15 g of light magnesium carbonate into a 1 L three-necked flask containing 340 mL of deionized water, with the mechanical stirring speed at 400 revolutions per minute. After the magnesium carbonate is fully dispersed and dissolved, then add 50 g of divinylbenzene, 6.67 g of azobisisobutyronitrile, 68.5 g of tetraethoxysilane, 3 g of aviation kerosene and 50 g of xylene, stir for half an hour and then heat up to 75°C. After reaching 75°C, add 1 mL (3.25 mol / L) of NaOH aqueous solution. After 2 hours, add 3.33 g of azobisisobutyronitrile. After reacting for 8 hours, stop, wash the solid twice with 1 mol / L dilute hydrochloric acid, hot water and ethanol respectively, and dry at 65°C for 6 hours to obtain the seed balls for standby.

[0042] Step S2: Add 1.75 g of sulfobetaine into 300 mL of deionized water, with the mechanical stirring speed at 450 revolutions per minute and the oil bath temperature controlled at 35°C. After stirring and dispersing for 30 minutes, add 16.4 g of sodium metasilicate pentahydrate, stir for 30 minutes, add 50 g of seed balls into the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system between 12 and 14 with 6.25 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add dropwise an aqueous solution of magnesium sulfate (6.2 g of magnesium sulfate dissolved in 34.1 g of water), and start timing for 2 hours after the addition is completed, so that sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seed balls. After the reaction ends, the product is filtered by a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in an oven at 60°C for 6 hours to obtain the packing material for a strong polar solid-phase extraction column, denoted as Product-2.

[0043] <Example 3>

[0044] This embodiment provides a strongly polar solid-phase extraction column packing and a preparation method thereof.

[0045] Step S1, seed ball - 3: Add 25 g of light magnesium carbonate into a 1-L three-necked flask containing 450 mL of deionized water. The mechanical stirring speed is 400 revolutions per minute. After the magnesium carbonate is fully dispersed and dissolved, then add 50 g of divinylbenzene, 10.67 g of azobisisobutyronitrile, 95 g of tetraethoxysilane, 5 g of aviation kerosene, and 70 g of xylene. Stir for half an hour and then heat up to 75 °C. After reaching 75 °C, add 2.5 mL (5.5 mol / L) of NaOH aqueous solution. After 2 hours, add 5.33 g of azobisisobutyronitrile. After reacting for 8 hours, stop. Wash the solid with 1 mol / L dilute hydrochloric acid, hot water, and ethanol twice each, and then dry at 65 °C for 6 hours to obtain the seed ball for standby.

[0046] Step S2: Add 3 g of sulfobetaine into 376 mL of deionized water. The mechanical stirring speed is 450 revolutions per minute, and the oil bath temperature is controlled at 35 °C. After stirring and dispersing for 30 minutes, add 18.8 g of sodium metasilicate pentahydrate and stir for 30 minutes. Add 50 g of the seed ball into the sodium metasilicate pentahydrate solution, and adjust the pH of the reaction system to be between 12 and 14 with 10 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly dropwise add magnesium sulfate aqueous solution (10.4 g of magnesium sulfate dissolved in 72.8 g of water). After the dropping is completed, start timing for 2 hours. After the reaction of sodium metasilicate and magnesium sulfate, deposition occurs on the surface of the seed ball. After the reaction ends, the product is filtered by a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in an oven at 60 °C for 6 hours to obtain the strongly polar solid-phase extraction column packing, denoted as product - 3.

[0047] <Comparative Example 1>

[0048] This embodiment provides a strongly polar solid-phase extraction column packing and a preparation method thereof.

[0049] Step S1, seed ball - 4: Add 35 g of light magnesium carbonate into a 1-L three-necked flask containing 450 mL of deionized water. The mechanical stirring speed is 400 revolutions per minute. After the magnesium carbonate is fully dispersed and dissolved, then add 50 g of divinylbenzene, 14 g of azobisisobutyronitrile, 125 g of tetraethoxysilane, and 70 g of xylene. Stir for half an hour and then heat up to 75 °C. After reaching 75 °C, add 2.5 mL (5.5 mol / L) of NaOH aqueous solution. After reacting for 8 hours, stop. Wash with 200 mL of 1 mol / L dilute hydrochloric acid, hot water, and ethanol twice each, and then dry in an oven at 65 °C for 6 hours for standby.

[0050] Step S2: Add 3 g of sulfobetaine into 300 mL of deionized water, with the mechanical stirring speed at 450 revolutions per minute and the oil bath temperature controlled at 35°C. After stirring and dispersing for 30 minutes, add 28.8 g of sodium metasilicate pentahydrate and stir for 30 minutes. Then add 50 g of seed balls into the sodium metasilicate pentahydrate solution, and adjust the pH of the reaction system between 12 and 14 with 2.5 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes. After that, uniformly add dropwise an aqueous magnesium sulfate solution (40 g of magnesium sulfate dissolved in 160 g of water). After the addition is completed, start timing for 2 hours. After the reaction of sodium metasilicate and magnesium sulfate, deposition occurs on the surface of the seed balls. After the reaction ends, filter the product through a Buchner funnel, wash the filter cake twice with 150 mL of methanol, and dry it in an oven at 60°C for 6 hours to obtain the packing material for a strong polar solid-phase extraction column, denoted as Product-4.

[0051] <Comparative Example 2>

[0052] This example provides a packing material for a strong polar solid-phase extraction column and a preparation method thereof.

[0053] Step S1: Seed balls - 5: Add 4 g of light magnesium carbonate into a 1-L three-necked flask containing 230 mL of deionized water, with the mechanical stirring speed at 200 revolutions per minute. After the magnesium carbonate is fully dispersed and dissolved, then add 50 g of divinylbenzene, 2.67 g of azobisisobutyronitrile, 42 g of tetraethoxysilane, 1 g of aviation kerosene, and 30 g of xylene. Stir for half an hour and then heat up to 75°C. After reaching 75°C, add 1 mL (1 mol / L) of sodium hydroxide aqueous solution. After 2 hours, add 1.33 g of azobisisobutyronitrile. After reacting for 8 hours, stop. Wash the solid twice with 1 mol / L dilute hydrochloric acid, hot water, and ethanol respectively, and then dry it at 65°C for 6 hours to obtain the seed balls for standby.

[0054] Step S2: Add 0.5 g of sulfobetaine into 168 mL of deionized water, with the mechanical stirring speed at 450 revolutions per minute and the oil bath temperature controlled at 35°C. After stirring and dispersing for 30 minutes, add 14 g of sodium metasilicate pentahydrate and stir and disperse for 30 minutes. Then add 50 g of seed balls into the sodium metasilicate pentahydrate solution, and adjust the pH of the reaction system between 12 and 14 with 2.5 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes. After that, uniformly add dropwise an aqueous magnesium sulfate solution (2 g of magnesium sulfate dissolved in 8 g of water). After the addition is completed, start timing for 2 hours to make the reaction of sodium metasilicate and magnesium sulfate deposit on the surface of the seed balls. After the reaction ends, filter the product through a Buchner funnel, wash the filter cake twice with 150 mL of methanol, and dry it in an oven at 60°C for 6 hours to obtain the packing material for a strong polar solid-phase extraction column, denoted as Product-5.

[0055] <Test Example 1>

[0056] Disperse the seed balls prepared in Example 1 in ethanol, measure the particle size of the microspheres using a nano laser particle size analyzer, and take the data closest to the average value after measuring 3 times. The results are shown in Figure 1 .

[0057] From Figure 1 it can be seen that the seed balls in Example 1 have good particle size uniformity, showing a single-peak distribution, and D(50) is 250 microns (i.e., 60 mesh).

[0058] Test the seed balls prepared in Comparative Example 2 using the same method, and the results are shown in Figure 2 .

[0059] From Figure 2 it can be seen that the stirring speed in the S1 stage of Comparative Example 2 is reduced, and at the same time, the dosage of the dispersant magnesium carbonate is reduced. The final particle size D(50) of the seed balls is 345 microns, and the particle size is too large, which will lead to a decrease in the specific surface area of the filler. At the same time, when the particle size of the filler is too large during the pretreatment, the flow rate through the column is too fast, which will cause incomplete sample loading and result in a low recovery rate.

[0060] The N2 adsorption-desorption experiment was carried out on a Micromertics ASAP 2460 type physical adsorption instrument. The sample (seed balls prepared in Example 1) was vacuum-activated at 373 K for 3 h, and then the nitrogen adsorption experiment was carried out at 77 K. The results are shown in Figure 3 .

[0061] From Figure 3 it can be seen that the adsorption-desorption curve of Example 1 shows that the seed balls mainly have a relatively uniform mesoporous structure. In the low-pressure region, the adsorption-desorption curves coincide and rise slowly, with almost no micropores. In the high-pressure region, due to capillary condensation, the isotherm rises rapidly, showing a closed hysteresis loop.

[0062] Use a Hitachi field emission scanning electron microscope S-4800 with an acceleration voltage of 25 KV to characterize the surface morphology of the polar adsorption filler prepared in Example 1, and the results are shown in Figure 4 .

[0063] From Figure 4 it can be seen that the prepared filler particles are relatively uniform.

[0064] Calculate the specific surface area of the sample by the BET method and the pore size distribution by the BJH method; test the seed balls prepared in Examples 1 to 3 and Comparative Example 1, and the particle size and BET data are shown in Table 1 below.

[0065] Table 1. Particle size and BET data of seed balls

[0066]

[0067] As can be seen from Table 1, the seed balls with a particle size in the range of 60 to 100 mesh were prepared in Examples 1, 2, and 3. By adjusting the dosages of the dispersant magnesium carbonate, the pore-forming agents kerosene and xylene in Step S1 differently, the particle size and specific surface area of the prepared seed balls can be changed, thereby adjusting the physical parameters of the pore-adjusted seed balls. Generally speaking, the larger the particle size of the seed balls, the larger the particle size of the corresponding prepared polar adsorption filler, and the faster the flow rate when the prepared pretreatment small column passes through the solvent. However, if the particle size of the seed balls is too large, the corresponding specific surface area will decrease, affecting the recovery rate of the filler. Therefore, it is necessary to strictly limit the ratio of each reaction monomer within the preferred range. In Comparative Example 1, the addition amount of the dispersant magnesium carbonate was too high, and at the same time, the bad pore-forming agent kerosene was removed. Therefore, the particle size of the prepared seed balls was too small and not in the range of 60 to 100 mesh. When performing pretreatment injection, it was easy to become blocked, and negative pressure was required to reach the column passing flow rate of Examples 1 to 3, seriously reducing the pretreatment efficiency. At the same time, the bad pore-forming agent was not added, resulting in a smaller pore size of the seed balls and a larger specific surface area, and the overall adsorption performance of the filler was too strong, which instead reduced the recovery rate and made it difficult to elute the target substance.

[0068] <Application Example 1>

[0069] The solid-phase extraction column fillers prepared in Examples 1 to 3 were packed into columns. The capacity of the solid-phase extraction column was 3 mL, and each small column was filled with 250 mg of filler. The specific operation steps are as follows:

[0070] Step 1. Activation and equilibration: 5 mL of n-hexane;

[0071] Step 2. Sample loading: 5 mL of n-hexane, 5 mL of fenvalerate sample loading solution (accurately pipette 1 mL of fenvalerate standard stock solution at 10 μg / mL into a 50 mL volumetric flask, dilute to the mark with n-hexane to prepare a concentration of 0.2 μg / mL, shake well and set aside);

[0072] Step 3. Rinsing: 8 mL of n-hexane;

[0073] Step 4. Elution: 2 × 4 mL of ether, acetone and n-hexane (ether:acetone:n-hexane = 2:2:1), dry with nitrogen, and dilute to 1 mL with acetone and n-hexane (acetone:n-hexane = 1:1).

[0074] In this test example, the standard product was fenvalerate, and the detection instrument was GC-MS. Instrument reference conditions: Chromatographic column: CD-5MS, 30 mm × 0.25 mm × 0.25 mm, temperature programming: initial temperature 40°C, hold for 2 min, increase the temperature to 300°C at a rate of 8°C / min, hold for 5 min; Scanning mode: SIM; Monitoring ions: Quantitative ion (m / z) 125, qualitative ions (m / z) 167, 225; Ion source temperature: 280°C; Carrier gas: He, 1.0 mL / min; Injection volume: 1.0 μL.

[0075] Take 1 μL of the blank test solution and 3 test sample solutions and inject them into the GC-MS. The recovery rate is calculated as follows:

[0076]

[0077] P——recovery rate, unit: %;

[0078] C2——sample concentration, unit: μg / mL;

[0079] C1——blank concentration, unit: μg / mL;

[0080] C3——Concentration of spiked sample, unit: μg / mL.

[0081] The results are retained to 2 significant figures. The test results are shown in Table 2.

[0082] Table 2 Recovery of standard cypermethrin on polar magnesium silicate column

[0083]

[0084] The test results in Table 2 show that the recovery rates of Examples 1, 2, and 3 are comparable to those of commercial polar magnesium silicate solid phase extraction columns, indicating good application performance. The recovery rate of fenvalerate in Comparative Example 1 is relatively low at 75.6%, which does not meet application requirements.

[0085] <Application Example 2>

[0086] Tea extraction: Take 1 g of tea powder sample in a 50 mL centrifuge tube, add 10 mL of n-hexane and acetone (n-hexane: acetone = 1:1), homogenize (first mix at 2500 rpm for 5 min, then centrifuge at 8000 rpm for 5 min), repeat the extraction twice, combine the extracts, centrifuge (8000 rpm, 5 min), take the supernatant, and blow nitrogen to 1 mL at 35°C for purification.

[0087] The solid phase extraction column filler prepared in Examples 1 to 3 was loaded into the column. The capacity of the solid phase extraction column was 3 mL, and each column was loaded with 250 mg of filler. The specific operation steps were as follows:

[0088] Purification: The CNWBOND Carbon-GCB SPE cartridge was pre-activated with 5 mL of n-hexane and acetone (n-hexane:acetone = 1:1). The concentrated extract was added to the activated SPE cartridge, and the filtrate was collected. Then, it was eluted with 10 mL of n-hexane and acetone (n-hexane:acetone = 1:1). The loaded filtrate and the eluate were mixed and concentrated to about 2 mL under nitrogen at 40 °C. For Examples 1-3 and the reference cartridge, it was first activated with 5 mL of n-hexane. When the solvent level reached the upper surface of the column, the above purification solution was added to the activated cartridge, and the filtrate was collected. Then, it was eluted with 8 mL of ether, acetone, and n-hexane (ether:acetone:n-hexane = 2:2:1). The eluate was collected and mixed with the loaded filtrate, dried under nitrogen at 40 °C, and redissolved in 1 mL of n-hexane for injection and detection.

[0089] In this test example, the reference standards were 14 kinds of pesticide residues such as heptachlor and chlorpyrifos. Among them, the gas chromatogram of the injection of the malathion reference standard is shown in Figure 5 . The concentration for machine detection was 400 ppb, and the detection instrument was GC-MS. Instrument reference conditions: Gas phase conditions: CD-5MS, 30 m × 0.32 mm, 0.25 µm; injection port temperature 250 °C; splitless; column temperature: 300 °C, held for 5 min. Mass spectrometry conditions: interface temperature 280 °C, ion source temperature 250 °C. The test results are shown in Table 3.

[0090] Table 3 Recovery rates of pesticide residues in tea matrix by polar magnesium silicate filler

[0091]

[0092] The test results in Table 3 show that the magnesium silicate solid-phase extraction cartridges prepared in Examples 1, 2, and 3 can be compared with commercial magnesium silicate cartridges in terms of the recovery rates of 14 kinds of pesticide residues in the tea matrix, indicating good application performance.

[0093] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a strong polar solid phase extraction column packing, characterized in that, It includes the following steps: Step S1: Add light magnesium carbonate into water, disperse and dissolve it; then add a mixed solution of divinylbenzene, azobisisobutyronitrile, tetraethoxysilane, aviation kerosene and xylene, stir and heat up to 65°C - 80°C. After reaching 65°C - 80°C, add an alkali to adjust the pH of the reaction system between 10 and 12; add azobisisobutyronitrile again after 2 - 3 hours. After the reaction, obtain a solid, wash and dry the solid to obtain seeds for use; Step S2: Add an amphoteric ion surfactant to water for dispersion, add sodium metasilicate pentahydrate, stir and disperse, then add the seeds, add an alkali to adjust the pH of the reaction system between 12 and 14, and etch for 10 - 25 minutes; then dropwise add an aqueous magnesium sulfate solution. After the reaction between sodium metasilicate and magnesium sulfate, deposition occurs on the surface of the seeds to obtain a strong polar solid phase extraction column packing; Among them, in step S1, the mass ratio of divinylbenzene, aviation kerosene and xylene is 50:(1 - 5):(30 - 70); the mass ratio of light magnesium carbonate, water and divinylbenzene is (5 - 25):(230 - 450):50; the total mass ratio of azobisisobutyronitrile, tetraethoxysilane and divinylbenzene is (8 - 32):(42 - 95):50, and the mass ratio of the first - added azobisisobutyronitrile to the second - added azobisisobutyronitrile is 2:1; In step S2, the amphoteric ion surfactant is of the betaine type, the mass ratio of the amphoteric ion surfactant to the seeds is 0.5 - 3:50, the mass ratio of the seeds, sodium metasilicate pentahydrate and magnesium sulfate is 500:(140 - 188):(20 - 104), and the mass ratio of sodium metasilicate pentahydrate to water in the sodium metasilicate pentahydrate solution is 1:(12 - 20); The seed bulb is an organic-inorganic composite porous sphere with a particle size of 60 to 100 mesh, a BET of 250 m 2 / g to 450 m 2 / g, and a pore diameter of 100 Å to 210 Å.

2. The preparation method of the strong polar solid phase extraction column packing as described in claim 1, characterized in that, The alkali is any one of sodium hydroxide, sodium bicarbonate or potassium hydroxide.

3. The preparation method of the strong polar solid phase extraction column packing according to claim 1, characterized in that In step S1, the alkali is an alkali solution with a concentration of 1mol / L - 5.5mol / L; in step S2, the alkali is an alkali solution with a concentration of 2.5mol / L - 10mol / L, and the mass ratio of magnesium sulfate to water in the aqueous magnesium sulfate solution is 1:(4 - 7).

4. The preparation method of the strongly polar solid-phase extraction column packing according to claim 1, characterized in that, In step S1, the rotation speed is controlled at 350 - 550 revolutions per minute, and the light magnesium carbonate is added into water; add azobisisobutyronitrile again after 2 - 3 hours, stop the reaction after 6 - 10 hours, wash the solid 2 times each with hot water, dilute hydrochloric acid and ethanol, and dry at 65°C - 80°C for 6 - 10 hours to obtain the seeds.

5. The preparation method of the strong polar solid phase extraction column packing according to claim 1, characterized in that, The reaction temperature in step S2 is 20°C - 35°C, the stirring and dispersing time is 0.5h - 2h, the reaction time is 1h - 4h, and the stirring speed is 450 - 650 revolutions per minute.

6. A packing material for a strong polar solid phase extraction column, characterized in that, It is prepared by the preparation method of the strong polar solid phase extraction column packing described in any one of claims 1 - 5.

7. An application of the strong polar solid phase extraction column packing as described in claim 6 as a solid phase extraction column packing in the separation of organochlorine pesticide residues, amines, polychlorinated biphenyls and ketones.

Images