Strong-polarity solid-phase extraction column filler as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of fillers of solid-phase extraction columns, and discloses a strong-polarity solid-phase extraction column filler, and a preparation method and application thereof. The method comprises the following steps: S1, adding magnesium carbonate into water for dispersing and dissolving; adding a mixed solution of divinyl benzene, azodiisobutyronitrile, tetraethoxysilane, aviation kerosene and xylene, stirring, and heating to adjust the pH value of a reaction system; supplementing azodiisobutyronitrile, and reacting to obtain seed balls; s2, adding a zwitterionic surfactant into water for dispersion, adding sodium metasilicate pentahydrate, then adding the seed balls, adjusting the pH value, and etching for 10-25 minutes; adding a magnesium sulfate aqueous solution to obtain the filler. The solid-phase extraction filler prepared by the method is adjustable and large in particle size, can be used for short-time sample loading of high-viscosity large-volume samples, and is high in recovery rate of part of pesticide residues of four major types including organic phosphorus, organochlorine, pyrethroid and carbamic acid ester. The filler is good in stability, good in reproducibility and easy to produce on a large scale.

Description

Technical Field

[0001] The invention belongs to the technical field of solid phase extraction column fillers, and in particular relates to a strong polar solid phase extraction column filler, a preparation method and application thereof. Background Art

[0002] Florisil is a polar silica gel adsorbent with magnesium oxide composite, which is commonly used in the market to separate organochlorine pesticide residues, amines, polychlorinated biphenyls (PCBs), ketones and organic acids. Florisil is a highly selective adsorbent widely used in pretreatment and chromatographic analysis. Currently, all the global Florisil fillers come from US silica company in the United States, and different brands are purchased through different distributors.

[0003] At present, domestic manufacturers have weak industrial control technology for silica gel bulbs and background content, and cannot develop stable products comparable to Florisil. Since this technology is monopolized by foreign countries, the cost of imported materials is increasing, and the purchase channel may be cut off at any time. Therefore, it is urgent to develop alternative materials with low prices 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, highly polar solid phase extraction column filler and its preparation method, which innovatively uses organic-inorganic composite microspheres with a core-shell structure, the core layer can adjust the particle size and specific surface area, and the silanol groups of the shell layer combined with the core layer provide strong polarity, which can be used for the separation of organochlorine pesticide residues, 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, which are very suitable for high-viscosity and large-volume loading methods, saving detection costs and improving efficiency.

[0005] In a first aspect, the present invention provides a method for preparing a highly polar solid phase extraction column filler, comprising the following steps: Step S1, adding light magnesium carbonate into water to disperse and dissolve; then adding a mixed solution of divinylbenzene, azobisisobutyronitrile, tetraethoxysilane, aviation kerosene and xylene, stirring and heating to 65°C-80°C, adding alkali to adjust the pH of the reaction system to between 10 and 12 after reaching 65-80°C; adding azobisisobutyronitrile after a predetermined time, reacting for another predetermined time to obtain a solid, washing and drying the solid to obtain a seed ball for standby use; Step S2, adding a zwitterionic surfactant to water, stirring and dispersing, adding sodium metasilicate pentahydrate, stirring and dispersing, adding the ball, adding alkali to adjust the pH of the reaction system to between 12 and 14, etching for 10 to 25 minutes; then dripping magnesium sulfate aqueous solution, sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the ball to obtain a strong polar solid phase extraction column filler.

[0006] Furthermore, 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 mass ratio of the total amount of initiator azobisisobutyronitrile to tetraethoxysilane to divinylbenzene is (8-32):(42-95):50, wherein the mass ratio of azobisisobutyronitrile added for the first time to azobisisobutyronitrile added for the second time is 2:1.

[0007] Furthermore, in step S2, the zwitterionic surfactant is a betaine type, the mass ratio of the zwitterionic surfactant to the bulbs is 0.5~3:50, the mass ratio of the bulbs to 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).

[0008] Furthermore, the alkali is any one of sodium hydroxide, sodium bicarbonate or potassium hydroxide.

[0009] Furthermore, in step S1, the alkali is an alkaline solution, and the concentration of the alkaline solution is 1 mol / L~5.5 mol / L; in step S2, the alkali is an alkaline solution, and the concentration of the alkaline solution is 2.5 mol / L~10 mol / L, and the mass ratio of magnesium sulfate to water in the magnesium sulfate aqueous solution is 1:4~7.

[0010] Furthermore, in step S1, the rotation speed is controlled at 350-550 rpm, and light magnesium carbonate is added to water; azobisisobutyronitrile is added after 2-3 hours, and the reaction is stopped after 6-10 hours. The solid is washed twice with hot water, dilute hydrochloric acid and ethanol respectively, and then dried at 65-80°C for 6-10 hours to obtain a bulb.

[0011] Furthermore, the reaction temperature in step S2 is 20° C. to 35° C., the stirring is mechanical stirring, the stirring and dispersion time is 0.5 h to 2 h, the reaction time is 1 to 4 h, and the stirring speed is 450 to 650 rpm.

[0012] Furthermore, the ball is an organic-inorganic composite porous ball with a particle size of 60-100 mesh and a BET of 250m 2 / g~450m 2 / g, pore size is 100 Å~210 Å.

[0013] In a second aspect, the present invention provides a highly polar solid phase extraction column filler prepared by the above method. The polarity of the obtained filler is 7 to 8.5. The particle size of the filler is mainly determined by the seed ball, and the particle size of the filler is substantially consistent with the particle size of the seed ball.

[0014] The third aspect of the present invention provides the use of the above filler as a solid phase extraction column filler in the separation of organochlorine pesticide residues, amines, polychlorinated biphenyls (PCBs) and ketones.

[0015] Compared with the prior art, the present invention has at least the following advantages: (1) The specific surface area and particle size of the seed balls of the present invention can be controlled, and thus the specific surface area and particle size of the filler prepared from the seed balls can also be controlled.

[0016] (2) The solid phase extraction filler prepared by the present invention is a magnesium silicate adsorbent with a relatively large particle size of 60-100 mesh, which can be used for short-term loading of high-viscosity and large-volume samples, and has a high recovery rate for some pesticide residues of four major categories, namely, organophosphorus, organochlorine, pyrethroids, and carbamate esters.

[0017] (3) The filler of the present invention has good stability and reproducibility and is easy to produce in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram of the particle size of the bulbs prepared in Example 1 of the present invention; Figure 2 This is a diagram of the particle size of the bulbs prepared in Comparative Example 2 of the present invention; Figure 3 This is a nitrogen adsorption-desorption curve diagram of the seed ball prepared in Example 1 of the present invention; Figure 4 This is a SEM image of the polar adsorption filler prepared in Example 1 of the present invention; Figure 5 This is the gas chromatogram of standard malathion. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0020] Unless otherwise specified, the raw materials and materials used in the examples of the present invention are purchased through general commercial channels.

[0021] The sources of the raw materials, materials and instruments involved in the following examples or comparative examples are as follows: Commercial magnesium silicate columns: Florisil columns from US silica company; Sodium metasilicate pentahydrate, sodium hydroxide, magnesium carbonate, magnesium sulfate, and azobisisobutyronitrile were purchased from Aladdin Reagent (Shanghai) Co., Ltd.; AB23 laboratory pH meter (Ohaus Instruments, Inc., USA); Nano ZS nanometer laser particle size analyzer (Malvern Instruments Ltd., UK); ASAP 2460 physical adsorption analyzer (Micromeritics Instruments, USA); QSightTM 220 LC-MS / MS instrument (PerkinElmer Instruments, Inc., USA).

[0022] <Example 1> This embodiment provides a highly polar solid phase extraction column filler and a preparation method thereof.

[0023] Step S1, seed ball-1: add 5g of light magnesium carbonate to a 1L three-necked flask containing 230mL of deionized water, and the mechanical stirring speed is 400 rpm. After the magnesium carbonate is fully dispersed and dissolved, add 50g of divinylbenzene, 2.67g of azobisisobutyronitrile, 42g of tetraethoxysilane, 1g of aviation kerosene and 30g of xylene. After stirring for half an hour, heat to 75°C, and add 1 mL (1 mol / L) NaOH aqueous solution after reaching 75°C. Add 1.33g of azobisisobutyronitrile after 2 hours. After 8 hours of reaction, stop, wash the solid with 1 mol / L dilute hydrochloric acid, hot water and ethanol twice each, and dry at 65°C for 6 hours to obtain seed balls for standby use.

[0024] Step S2, add 0.5g of sulfobetaine to 168mL of deionized water, the mechanical stirring speed is 450 rpm, and the oil bath temperature is controlled at 35°C. After stirring and dispersing for 30 minutes, add 14g of sodium metasilicate pentahydrate, stir and disperse for 30 minutes, add 50g of seeds to the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system to between 12 and 14 with 2.5 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add magnesium sulfate aqueous solution (2g magnesium sulfate dissolved in 8g water), after the addition is complete, start timing for 2 hours, so that sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seeds. After the reaction is completed, the product is filtered through a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in a 60°C oven for 6 hours to obtain a strong polar solid phase extraction column filler, which is recorded as product-1.

[0025] <Example 2> This embodiment provides a highly polar solid phase extraction column filler and a preparation method thereof.

[0026] Step S1, seed ball-2: add 15g of light magnesium carbonate to a 1L three-necked flask containing 340mL of deionized water, and the mechanical stirring speed is 400 rpm. After the magnesium carbonate is fully dispersed and dissolved, add 50g of divinylbenzene, 6.67g of azobisisobutyronitrile, 68.5g of tetraethoxysilane, 3g of aviation kerosene and 50g of xylene. After stirring for half an hour, heat to 75°C, and add 1 mL (3.25 mol / L) NaOH aqueous solution after reaching 75°C. Add 3.33g of azobisisobutyronitrile after 2 hours. After 8 hours of reaction, stop, wash the solid with 1 mol / L dilute hydrochloric acid, hot water and ethanol twice each, and dry at 65°C for 6 hours to obtain seed balls for standby use.

[0027] Step S2, add 1.75g ​​of sulfobetaine to 300mL of deionized water, the mechanical stirring speed is 450 rpm, and the oil bath temperature is controlled at 35°C. After stirring and dispersing for 30 minutes, add 16.4g of sodium metasilicate pentahydrate, stir for 30 minutes, add 50g of seeds to the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system to between 12 and 14 with 6.25 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add magnesium sulfate aqueous solution (6.2g magnesium sulfate dissolved in 34.1g water), after the addition is complete, start timing for 2 hours, sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seeds. After the reaction is completed, the product is filtered through a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in a 60°C oven for 6 hours to obtain a strong polar solid phase extraction column filler, which is recorded as product-2.

[0028] <Example 3> This embodiment provides a highly polar solid phase extraction column filler and a preparation method thereof.

[0029] Step S1, seed ball-3: Add 25g of light magnesium carbonate to a 1L three-necked flask containing 450mL of deionized water, and the mechanical stirring speed is 400 rpm. After the magnesium carbonate is fully dispersed and dissolved, add 50g of divinylbenzene, 10.67g of azobisisobutyronitrile, 95g of tetraethoxysilane, 5g of aviation kerosene and 70g of xylene. After stirring for half an hour, heat to 75°C, and add 2.5 mL (5.5 mol / L) NaOH aqueous solution after reaching 75°C. Add 5.33g of azobisisobutyronitrile after 2 hours. After 8 hours of reaction, stop, wash the solid with 1 mol / L dilute hydrochloric acid, hot water and ethanol twice each, and dry at 65°C for 6 hours to obtain seed balls for standby use.

[0030] Step S2, add 3g of sulfobetaine to 376mL of deionized water, the mechanical stirring speed is 450 rpm, and the oil bath temperature is controlled at 35°C. After stirring and dispersing for 30 minutes, add 18.8g of sodium metasilicate pentahydrate, stir for 30 minutes, add 50g of seeds to the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system to between 12 and 14 with 10 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add magnesium sulfate aqueous solution (10.4g magnesium sulfate dissolved in 72.8g water), after the addition is complete, start timing for 2 hours, sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seeds. After the reaction is completed, the product is filtered through a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in a 60°C oven for 6 hours to obtain a strong polar solid phase extraction column filler, which is recorded as product-3.

[0031] <Comparative Example 1> This embodiment provides a highly polar solid phase extraction column filler and a preparation method thereof.

[0032] Step S1, seed ball-4: add 35g of light magnesium carbonate to a 1L three-necked flask containing 450mL of deionized water, and stir mechanically at a speed of 400 rpm. After the magnesium carbonate is fully dispersed and dissolved, add 50g of divinylbenzene, 14g of azobisisobutyronitrile, 125g of tetraethoxysilane, and 70g of xylene. Stir for half an hour and then heat to 75°C. After reaching 75°C, add 2.5mL (5.5 mol / L) NaOH aqueous solution. After reacting for 8 hours, stop, wash twice with 1 mol / L dilute hydrochloric acid, hot water, and ethanol 200mL each, and dry in an oven at 65°C for 6 hours for standby use.

[0033] Step S2, add 3g of sulfobetaine to 300mL of deionized water, the mechanical stirring speed is 450 rpm, and the oil bath temperature is controlled at 35°C. After stirring and dispersing for 30 minutes, add 28.8g of sodium metasilicate pentahydrate, stir for 30 minutes, add 50g of seeds to the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system to between 12 and 14 with 2.5 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add magnesium sulfate aqueous solution (40g magnesium sulfate dissolved in 160g water), after the addition is complete, start timing for 2 hours, sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seeds. After the reaction is completed, the product is filtered through a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in a 60°C oven for 6 hours to obtain a strong polar solid phase extraction column filler, which is recorded as product-4.

[0034] <Comparative Example 2> This embodiment provides a highly polar solid phase extraction column filler and a preparation method thereof.

[0035] Step S1, seed ball-5: Add 4g of light magnesium carbonate to a 1L three-necked flask containing 230mL of deionized water, and stir mechanically at a speed of 200 rpm. After the magnesium carbonate is fully dispersed and dissolved, add 50g of divinylbenzene, 2.67g of azobisisobutyronitrile, 42g of tetraethoxysilane, 1g of aviation kerosene and 30g of xylene. After stirring for half an hour, heat to 75°C, and add 1 mL (1 mol / L) NaOH aqueous solution after reaching 75°C. Add 1.33g of azobisisobutyronitrile after 2 hours. After reacting for 8 hours, stop, wash the solid with 1 mol / L dilute hydrochloric acid, hot water and ethanol twice each, and dry at 65°C for 6 hours to obtain seed balls for standby use.

[0036] Step S2, add 0.5g of sulfobetaine to 168mL of deionized water, the mechanical stirring speed is 450 rpm, and the oil bath temperature is controlled at 35°C. After stirring and dispersing for 30 minutes, add 14g of sodium metasilicate pentahydrate, stir and disperse for 30 minutes, add 50g of seeds to the sodium metasilicate pentahydrate solution, adjust the pH of the reaction system to between 12 and 14 with 2.5 mol / L sodium hydroxide aqueous solution, and etch for 10 minutes; then uniformly add magnesium sulfate aqueous solution (2g magnesium sulfate dissolved in 8g water), after the addition is complete, start timing for 2 hours, so that sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seeds. After the reaction is completed, the product is filtered through a Buchner funnel, the filter cake is washed twice with 150 mL of methanol, and dried in a 60°C oven for 6 hours to obtain a strong polar solid phase extraction column filler, which is recorded as product-5.

[0037] <Test Example 1> The microspheres prepared in Example 1 were dispersed in ethanol, and the particle size of the microspheres was measured using a nano-laser particle size analyzer. The data closest to the average value was taken after three measurements. Figure 1 .

[0038] from Figure 1 It can be seen that the particle size uniformity of the seed balls in Example 1 is good, with a single peak distribution, and D (50) is 250 μm (i.e. 60 mesh).

[0039] The same method was used to test the bulbs prepared in Comparative Example 2. The results are shown in Figure 2 .

[0040] from Figure 2 It can be seen that the stirring speed of the S1 stage of comparative example 2 is reduced, and the amount of dispersant magnesium carbonate is reduced. The final particle size D (50) of the ball 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, the filler particle size is too large during pretreatment, and the flow rate through the column is too fast, which will cause incomplete sample loading and result in a low recovery rate.

[0041] The N2 adsorption-desorption experiment was carried out on a Micromertics ASAP 2460 physical adsorption instrument. The sample (the seed ball 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 .

[0042] from Figure 3 It can be seen that the adsorption-desorption curve of Example 1 shows that the seed ball is mainly a relatively uniform mesoporous structure. In the low-pressure area, the adsorption-desorption curves overlap and rise slowly, with almost no micropores. In the high-pressure area, due to the occurrence of capillary condensation, the isotherm rises rapidly and a closed hysteresis loop appears.

[0043] The surface morphology of the polar adsorption filler prepared in Example 1 was characterized using a Hitachi field emission scanning electron microscope S-4800 with an accelerating voltage of 25 KV. Figure 4 .

[0044] from Figure 4 It can be seen that the prepared filler particles are relatively uniform.

[0045] The specific surface area of ​​the sample was measured by the BET method, and the pore size distribution was calculated by the BJH method. The bulbs prepared in Examples 1 to 3 and Comparative Example 1 were tested, and the particle size and BET data are shown in Table 1 below.

[0046] Table 1. Bulb size and BET data

[0047] As can be seen from Table 1, Examples 1, 2, and 3 all prepared balls with a particle size in the range of 60 to 100 mesh. The amount of dispersant magnesium carbonate, porogen kerosene, and xylene in the adjustment step S1 is different, so that the particle size and specific surface area of ​​the prepared balls can be changed, thereby adjusting the physical parameters of the pore balls. Generally speaking, the larger the particle size of the balls, the larger the particle size of the corresponding polar adsorption filler prepared, and the faster the flow rate when the prepared pre-treatment column is solvent-passed, but the particle size of the balls is too large, and the corresponding specific surface area will decrease accordingly, affecting the recovery rate of the filler. Therefore, it is necessary to strictly limit the ratio of each reaction monomer within the preferred range. The amount of dispersant magnesium carbonate added in Comparative Example 1 is too high, and the bad porogen kerosene is removed at the same time, so the particle size of the prepared balls is small, not in the range of 60 to 100 mesh, and it is easy to be blocked when doing pre-treatment injection. Negative pressure is required to reach the column flow rate of Examples 1 to 3, which seriously reduces the pre-treatment efficiency. At the same time, poor porogens were not added, resulting in smaller pore size of the bulbs, larger specific surface area, and too strong overall adsorption performance of the filler, which in turn reduced the recovery rate and made it difficult to elute the target.

[0048] <Application Example 1> 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: Step 1, activation balance: 5 mL of n-hexane; Step 2: Sample loading: 5 mL of n-hexane, 5 mL of fenvalerate loading solution (precisely pipette 1 mL of fenvalerate standard stock solution 10 μg / mL into a 50 mL volumetric flask, dilute to the mark with n-hexane to a concentration of 0.2 μg / mL, and shake well for later use); Step 3, elution: 8 mL of n-hexane; Step 4: Elution: 2*4mL of ether, acetone and n-hexane (ether acetone n-hexane = 2:2:1), blow dry with nitrogen, and make up to 1mL with acetone and n-hexane (acetone: n-hexane = 1:1).

[0049] In this test example, the standard product is cypermethrin, and the detection instrument is GC-MS. Instrument reference conditions: Chromatographic column: CD-5MS, 30mm*0.25mm*0.25mm, heating program: initial temperature 40℃, hold for 2min, heat to 300℃ at 8℃ / min, hold for 5min; scanning mode: SIM; monitoring ions: quantitative ion (m / z) 125, qualitative ion (m / z) 167, 225; ion source temperature: 280℃; carrier gas: He, 1.0mL / min; injection volume: 1.0µL.

[0050] Take 1 μL of the blank test solution and 3 test solution and inject them into the GC-MS. The recovery rate is calculated as follows:

[0051] P——recovery rate, unit: %; C2——sample concentration, unit: μg / mL; C1——blank concentration, unit: μg / mL; C3——Concentration of spiked sample, unit: μg / mL.

[0052] The results are retained to 2 significant figures. The test results are shown in Table 2.

[0053] Table 2 Recovery of standard cypermethrin on polar magnesium silicate column

[0054] 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.

[0055] <Application Example 2> 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.

[0056] 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: Purification: CNWBOND Carbon-GCB SPE column was activated with 5 mL of n-hexane and acetone (n-hexane:acetone=1:1) in advance, the concentrated extract was added to the activated SPE column, the filtrate was collected, and then eluted with 10 mL of n-hexane and acetone (n-hexane:acetone=1:1); the sample filtrate and the eluent were mixed and concentrated to about 2 mL with nitrogen at 40°C; Examples 1 to 3 and the reference column were first activated with 5 mL of n-hexane, and when the solvent liquid level reached the upper surface of the column, the above-mentioned purification solution was added to the activated column, the filtrate was collected, and then eluted with 8 mL of ether, acetone and n-hexane (ether:acetone:n-hexane=2:2:1), the eluent was collected and mixed with the sample filtrate, dried with nitrogen at 40°C, and redissolved in 1 mL of n-hexane, and injected for detection.

[0057] In this test example, the standard samples are 14 kinds of pesticide residues such as heptachlor and chlorpyrifos. The gas chromatogram of the injection of malathion standard sample is shown in Figure 5 The detection concentration 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; no split; column temperature: 300°C, maintained for 5 min. Mass spectrometry conditions: interface temperature 280°C, ion source temperature 250°C. The test results are shown in Table 3.

[0058] Table 3 Recovery rate of polar magnesium silicate filler for pesticide residues in tea matrix

[0059] The test results in Table 3 show that the recovery rates of the magnesium silicate solid phase extraction columns prepared in Examples 1, 2 and 3 for 14 pesticide residues in tea matrix are comparable to those of commercial magnesium silicate columns, indicating that they have good application performance. The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a highly polar solid phase extraction column filler, characterized in that: The following steps are involved: Step S1, adding light magnesium carbonate into water to disperse and dissolve; then adding a mixed solution of divinylbenzene, azobisisobutyronitrile, tetraethoxysilane, aviation kerosene and xylene, stirring and heating to 65°C-80°C, adding alkali to adjust the pH of the reaction system to between 10 and 12 after reaching 65°C-80°C; adding azobisisobutyronitrile after 2-3 hours, obtaining a solid after reaction, washing and drying the solid to obtain a seed ball for standby use; Step S2, adding a zwitterionic surfactant to water for dispersion, adding sodium metasilicate pentahydrate, adding the seed ball after stirring and dispersing, adding alkali to adjust the pH of the reaction system to between 12 and 14, and etching for 10 to 25 minutes; then dripping a magnesium sulfate aqueous solution, sodium metasilicate reacts with magnesium sulfate and deposits on the surface of the seed ball to obtain a strong polar solid phase extraction column filler; Wherein, 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 mass ratio of the total amount of azobisisobutyronitrile to tetraethoxysilane to divinylbenzene is (8-32):(42-95):50, wherein the mass ratio of azobisisobutyronitrile added for the first time to azobisisobutyronitrile added for the second time is 2:1; In step S2, the zwitterionic surfactant is a betaine type, the mass ratio of the zwitterionic surfactant to the bulb is 0.5~3:50, the mass ratio of the bulb to sodium metasilicate pentahydrate and magnesium sulfate is 500:(140~188):(20~104), wherein the mass ratio of sodium metasilicate pentahydrate to water in the sodium metasilicate pentahydrate solution is 1:(12~20).

2. The method for preparing the highly polar solid phase extraction column filler according to claim 1, characterized in that: The alkali is any one of sodium hydroxide, sodium bicarbonate or potassium hydroxide.

3. The method for preparing the highly polar solid phase extraction column filler according to claim 1, characterized in that: In step S1, the alkali is an alkaline solution, and the concentration of the alkaline solution is 1 mol / L~5.5 mol / L; in step S2, the alkali is an alkaline solution, and the concentration of the alkaline solution is 2.5 mol / L~10 mol / L, and the mass ratio of magnesium sulfate to water in the magnesium sulfate aqueous solution is 1:(4~7).

4. The method for preparing the highly polar solid phase extraction column filler according to claim 1, characterized in that: In step S1, the rotation speed is controlled at 350-550 rpm, and the light magnesium carbonate is added to water; azobisisobutyronitrile is added after 2-3 hours, and the reaction is stopped after 6-10 hours. The solid is washed twice with hot water, dilute hydrochloric acid and ethanol respectively, and then dried at 65°C-80°C for 6-10 hours to obtain the seed ball.

5. The method for preparing the highly polar solid phase extraction column filler according to claim 1, characterized in that: The reaction temperature in step S2 is 20° C. to 35° C., the stirring and dispersing time is 0.5 h to 2 h, the reaction time is 1 h to 4 h, and the stirring speed is 450 to 650 rpm.

6. The method for preparing the highly polar solid phase extraction column filler according to claim 1, characterized in that: The ball is an organic-inorganic composite porous ball with a particle size of 60-100 mesh and a BET of 250m 2 / g~450m 2 / g, pore size is 100 Å~210 Å.

7. A highly polar solid phase extraction column filler, characterized in that: The highly polar solid phase extraction column filler is prepared by the preparation method of any one of claims 1 to 6.

8. Use of the highly polar solid phase extraction column filler as claimed in claim 7 as a solid phase extraction column filler in the separation of organochlorine pesticide residues, amines, polychlorinated biphenyls and ketones.

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