CN114660198B - Method for detecting rhodamine B based on solid-phase microextraction film enrichment - Google Patents
Method for detecting rhodamine B based on solid-phase microextraction film enrichment Download PDFInfo
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Abstract
The invention discloses a method for detecting rhodamine B based on solid-phase microextraction film enrichment, and belongs to the technical field of analysis and detection. The invention adopts a COF-117 modified film of a COFs material with rich ureido, negative charge in the state of aqueous solution and a large pi system to prepare the solid-phase microextraction film. The solid phase microextraction film has good adsorption effect on rhodamine B, has anti-interference capability during enrichment, and can effectively simplify the pretreatment step of a sample matrix. The method can quantitatively detect rhodamine B based on the solid-phase microextraction film, has high sensitivity, the detection limit is 0.007 mug/L, and the recovery rate is stable.
Description
Technical Field
The invention relates to a method for detecting rhodamine B based on solid-phase microextraction film enrichment, belonging to the technical field of analysis and detection.
Background
Rhodamine B (RB) is a synthetic azo dye, originally applied to the textile and plastics industry as an industrial colorant. Studies show that rhodamine B has carcinogenicity, reproductive toxicity and neurotoxicity for human and animals, so that the development of the human is slowed down. The cancer risk assessment of chemicals according to the world health organization international cancer Institute (IARC) shows that: chronic or acute poisoning may occur when inhaled and skin comes into contact with rhodamine dyes. Rhodamine B is specifically prescribed in the list of non-edible substances and abusable food additives varieties (first lot) that may be illegally added in foods to prohibit the use in foods. However, illicit merchants illegally add rhodamine B to foods in order to increase the color of the foods and improve the appearance of the foods. Therefore, in order to ensure the health and safety of people, it is important to establish a rapid and reliable detection method of rhodamine B in foods.
The current analysis method for detecting rhodamine B mainly comprises a chromatography (high performance liquid chromatography is connected with various detectors or mass spectrometry technologies) method, a visible spectrophotometry method and a fluorescence spectrophotometry fluorescence method. However, due to the complexity of the food matrix and the low concentration of contaminants in the food, it is often necessary to pretreat the food to remove matrix interference and increase the sensitivity of the detection prior to detection of rhodamine B using an instrumental method. Thus, there is a need to develop pretreatment methods that can be reused, reduce pretreatment steps, and that can selectively enrich rhodamine B to achieve more accurate detection of trace concentrations.
Currently, commonly used pretreatment methods for detecting rhodamine B include gel chromatography purification, solid-phase extraction column purification, liquid-liquid extraction technology, solid-phase microextraction, matrix dispersion solid-phase extraction, magnetic solid-phase microextraction and the like. However, the organic solvents required for gel chromatography purification and solid phase extraction column purification are complex and the detection time is long; liquid-liquid extraction requires the consumption of more organic reagents.
As one of the solid-phase microextraction modes, the membrane microextraction has the advantages of simple operation, high preconcentration coefficient and high phase separation speed, has higher specific surface area to volume ratio, and can provide higher extraction efficiency and faster balancing time. Therefore, the film microextraction is used as a small, convenient and environment-friendly analysis method, and the use amount and the sample amount of the organic reagent are obviously reduced, so that the analysis cost and the analysis time are saved. The selection of an appropriate adsorbent is critical as the core of the extraction mode. The adsorbent currently applied to solid phase extraction, magnetic solid phase extraction and solid phase microextraction comprises ionic liquid-cyclodextrin crosslinked polymer, functionalized magnetic graphene oxide, functionalized carbon nano tube, molecularly imprinted polymer and other materials. However, magnetic graphene oxide and functionalized carbon nanotubes are not selective to analytical targets; although the molecular engram polymer has good selectivity, the material has high price, the synthesis is complex, and the cost is high.
Disclosure of Invention
To solve the above problems, the present invention provides a method for in situ growth of covalent organic framework films on most polymer films and use in conjunction with high performance liquid chromatography. According to the invention, the polytetrafluoroethylene membrane is adopted as a basal membrane, dopamine is polymerized into polydopamine on the surface of the membrane, a functional group is provided for uniform growth of COFs on the polytetrafluoroethylene membrane, and a COFs composite membrane is synthesized and used for membrane solid-phase microextraction of rhodamine B. The method successfully combines the advantages of simple operation, high pre-enrichment coefficient, high phase separation speed, high specific surface area and volume ratio, large specific surface area of COFs and strong adsorption capacity of the film solid-phase microextraction. The polydopamine coating is formed on the surface of the film, so that a site is provided for the COFs to grow on the surface of the film and form a composite film, and the COFs and the polymer film are combined more uniformly and firmly. The COF-117 and rhodamine B have electrostatic interaction, hydrogen bond interaction and pi-pi acting force, so that the prepared COFs composite film has good adsorption effect on rhodamine B, has anti-interference capability during enrichment, and can effectively simplify the pretreatment step of a sample matrix; greatly improves the enrichment capability of rhodamine B and reduces the detection limit of rhodamine B.
The first object of the invention is to provide a solid-phase microextraction film for enrichment detection, which is prepared by the following method:
(1) Immersing the film in absolute ethyl alcohol for ultrasonic treatment, then immersing in a dopamine solution, and reacting at 50-70 ℃ to obtain the film with the polydopamine attached to the surface;
(2) Placing the obtained film with the polydopamine attached to the surface into a 1,3, 5-trialdehyde phloroglucinol solution for reaction at 80-100 ℃;
(3) After the reaction is finished, cleaning the film and drying; then mixing with 1,3, 5-trialdehyde phloroglucinol, 1' - (1, 4 phenylene) diurea, acetic acid and organic solvent, and reacting at 80-100 ℃ to obtain the film modified with COF-117.
In one embodiment of the present invention, in step (1), the medium environment of the dopamine solution is 0.009mol/L Tris-HCl solution with pH=8.5.
In one embodiment of the present invention, in step (1), the concentration of dopamine in the dopamine solution is 3-8g/L; particularly preferably 4g/L.
In one embodiment of the invention, in step (1), the reaction time is from 4 to 6 hours.
In one embodiment of the invention, in step (1), the film is selected from: polytetrafluoroethylene film, polydimethylsiloxane film, polyacrylonitrile film.
In one embodiment of the invention, in step (2), the concentration of the 1,3, 5-trialdehyde phloroglucinol solution is 1mg/mL.
In one embodiment of the present invention, in step (2), the solvent of the 1,3, 5-trialdehyde phloroglucinol solution is dioxane.
In one embodiment of the invention, in step (2), the reaction time is 1 to 3 hours.
In one embodiment of the present invention, in step (3), after the completion of the reaction, the film is washed with N, N-dimethylformamide, ethanol and distilled water in this order.
In one embodiment of the present invention, in step (3), the mass ratio of 1,3, 5-trialdehyde phloroglucinol to 1,1' - (1, 4 phenylene) diurea is 1: (1.2-1.5).
In one embodiment of the present invention, in step (3), the concentration of 1,3, 5-trialdehyde phloroglucinol relative to the organic solvent is 20mg/mL.
In one embodiment of the invention, in step (3), the concentration of acetic acid relative to the organic solvent is 0.6mmol/mL.
In one embodiment of the present invention, in step (3), the organic solvent is a mixed system of N-methyl-2-pyrrolidone and 1,2, 4-trichlorobenzene; the volume ratio of the N-methyl-2-pyrrolidone to the 1,2, 4-trichlorobenzene is 4:1.
in one embodiment of the invention, in step (3), the reaction time is 20 to 30 hours.
The second object of the invention is to provide a method for enriching and extracting rhodamine B based on the solid-phase microextraction film, which comprises the following steps:
pretreating a sample to obtain a sample solution, and controlling the concentration of NaCl in the solution to be 0.5mol/L and the pH to be 3; and then adding the solid-phase microextraction film into the sample solution, fully mixing, extracting and enriching, taking out the film after the extraction and enrichment are finished, eluting with an eluent to obtain an eluent, and removing the eluent to obtain rhodamine B.
In one embodiment of the present invention, if the sample is chilli powder, the corresponding enrichment process specifically includes:
(1) Extracting rhodamine B in the chilli powder by using an organic reagent to obtain an extracting solution containing the rhodamine B. Blowing the extracting solution containing rhodamine B to near dryness by using a nitrogen blow dryer, re-dissolving by using 3mL of NaCl solution with the concentration of 0.5mol/L, and adjusting the pH value to 3;
(2) Putting a piece of COFs composite film into the sample solution and vibrating;
(3) And adding 1mL of eluent to elute the COFs composite membrane to obtain eluent, and filtering the eluent to be detected.
In one embodiment of the present invention, the organic solvent in the step (1) includes acetonitrile, methanol, a mixture of acetonitrile and water, and a mixture of methanol and water.
In one embodiment of the present invention, the eluent comprises one of acetonitrile, ethanol, and methanol.
In one embodiment of the invention, the eluent may also be ethanol or a mixture of methanol and formic acid.
In one embodiment of the invention, the filter is a 0.22 or 0.45 μm microporous filter.
The second object of the present invention is to provide a method for quantitatively determining rhodamine B based on the solid-phase microextraction film described above, comprising:
(1) Preparing a series of rhodamine B standard sample solutions with known concentration by using 0.5mol/L NaCl solution with pH value of 3; then the solid phase microextraction film is respectively added into the standard sample solution, fully mixed, extracted and enriched, after the completion, the film is taken out, eluted by an eluent to obtain eluent, concentrated and dried, and 200 mu L of methanol/formic acid (v/v, 9/1) is used for constant volume, and the film is filtered to obtain corresponding sample liquid;
(2) Detecting the obtained test sample liquid by using high performance liquid chromatography, and acquiring corresponding high performance liquid chromatography data; and the peak area is linearly related to the concentration of the corresponding rhodamine B standard sample solution, so that a quantitative detection model is obtained.
In one embodiment of the present invention, if the sample is chilli powder, the corresponding quantitative detection process specifically includes:
(1) Treating a chilli powder sample:
extracting rhodamine B in a chilli powder sample by using methanol/0.1% formic acid (v/v, 1/1) vortex oscillation to obtain an extracting solution containing the rhodamine B, blowing the extracting solution to be near dry by using a nitrogen blow-drying device, re-dissolving by using 3mL of NaCl solution with the concentration of 0.5mol/L, and adjusting the pH value to be 3; and (5) carrying out subsequent membrane solid-phase microextraction treatment.
(2) Film solid phase microextraction:
the film solid phase microextraction method is used to obtain the liquid to be tested containing rhodamine B.
(3) High performance liquid chromatography detection:
and detecting the standard sample and the sample to be detected respectively by using liquid chromatography, recording the chromatograms, integrating by using a chromatograph with software to obtain peak areas, drawing a rhodamine B standard curve, and calculating to obtain the rhodamine B content in the sample to be detected.
In one embodiment of the present invention, the chromatographic column used for the high performance liquid chromatography detection is a C18 column.
In one embodiment of the present invention, the specific conditions of the liquid chromatography include: the mobile phase is methanol: 0.1% formic acid aqueous solution (v: v, 70:30), column temperature of 35 ℃, fluorescence detector excitation wavelength of 553nm, emission wavelength of 574nm, sample injection amount of 10. Mu.L, flow rate of 1mL/min.
The invention has the beneficial effects that:
(1) The method fully combines the advantages of simple operation, high preconcentration coefficient, high phase separation speed and high specific surface area and volume ratio of the film solid-phase microextraction and the characteristics of large specific surface area and strong adsorption capacity of the COF material.
(2) The COFs material adopted by the method is COF-117, has rich ureido, is negatively charged in an aqueous solution state, has a large pi system, has electrostatic interaction with rhodamine B, hydrogen bond interaction and pi-pi acting force, ensures that the prepared solid-phase microextraction film has good adsorption effect on rhodamine B, has anti-interference capability in enrichment, and can effectively simplify the pretreatment step of a sample matrix.
(3) Compared with polymer films such as a polydimethylsiloxane film or a polyacrylonitrile film, the polytetrafluoroethylene film has good chemical stability and mechanical stability, is not easy to break and is not interfered by most organic reagents.
(4) The method adopts an in-situ growth mode to prepare the COFs composite membrane, and adopts a mode of firstly modifying dopamine on the surface of the membrane, so that sites which are beneficial to the growth of the COFs exist on the surface of the membrane, the combination of the COFs membrane and the polytetrafluoroethylene membrane is firmer, the COFs composite membrane is not easy to fall off in the use process, and the service life of the prepared solid-phase micro-membrane is prolonged.
(5) The membrane solid-phase microextraction process in the method is simple to operate, and is convenient and quick.
(6) The method has high sensitivity, the detection limit is 0.007 mug/L, the linear correlation between the rhodamine B peak area and the concentration is good, and the recovery rate is stable.
Drawings
Fig. 1 is a flowchart for preparing COFs composite film of example 1.
Fig. 2 is an electron microscopic image of the COFs composite film of example 1.
FIG. 3 is a graph showing the optimization of the extraction conditions for membrane solid phase microextraction in example 2.
FIG. 4 is an optimized view of the conditions for membrane solid phase microextraction elution in example 2.
Fig. 5 is a Tp concentration optimization chart of example 2.
FIG. 6 is a graph of the linear relationship between rhodamine B concentration and absorbance thereof in example 2.
Detailed Description
The following description of the preferred embodiments of the present invention is provided for better illustration of the invention, and should not be construed as limiting the invention.
Example 1: preparation of COFs composite film
20 polytetrafluoroethylene films with the diameter of 13mm are immersed in absolute ethyl alcohol for ultrasonic treatment for 20min, then immersed in 4g/L of Tris-HCl dopamine solution with the pH of 8.5, oscillated for 5 hours under the water bath condition of 60 ℃, and then the surfaces are washed by distilled water and freeze-dried for standby. The prepared polytetrafluoroethylene film with the polydopamine attached on the surface is placed in a 50mL round bottom flask of 1,3, 5-trialdehyde phloroglucinol solution (1 mg/mL Tp) dissolved in dioxane, the film is reacted for 1 hour at 90 ℃, the film is taken out, and the composite film is sequentially washed by N, N-dimethylformamide, ethanol and distilled water, and the composite film is frozen and dried for later use. 10 pieces of the above film were taken, and trialdehyde phloroglucinol (Tp) (40 mg), 1' - (1, 4 phenylene) diurea (BDU) (55.5 mg), N-methyl-2-pyrrolidone (1.6 mL), 1,2, 4-trichlorobenzene (0.4 mL), acetic acid (6 m,0.2 mL) were added to react with a 35mL Schlenk tube at 85 ℃ for 24 hours. And after the film is taken out, the film is sequentially washed by N, N-dimethylformamide, ethanol and distilled water, and then is freeze-dried, so that a film product with the modified COF-117, namely a COF-117 composite film is obtained.
Example 2: enrichment of rhodamine B by solid-phase microextraction of COFs composite film
When rhodamine B in chilli powder is extracted by using a film solid-phase microextraction mode, the extraction time, the pH value of the solution, the salt ion concentration, the elution time, the type of eluting solvent and the volume of the eluting solvent, and the COFs composite film have influence on the extraction result. The experiment optimizes the extraction time, solution pH, ionic strength, elution time, eluting solvent type, eluting solvent volume, and COFs composite film, respectively.
The enrichment conditions were optimized with 10ppb rhodamine B solution: controlling the NaCl concentration and pH of the solution; and then adding the solid-phase microextraction film into the sample solution, fully mixing, extracting and enriching, taking out the film after the extraction and enrichment are finished, and eluting with an eluent to obtain an eluent.
Extraction conditions:
the optimal extraction time is within the range of 5-25min, the pH of the solution is 3, the NaCl concentration is 0.5mol/L, the elution time is 2min, and the eluting solvent is methanol/formic acid (v/v, 9/1) and the volume of the eluting solvent is 1mL.
The pH optimization range of the solution is 3-11, the extraction time is 20min, the NaCl concentration is 0.5mol/L, the elution time is 2min, and the eluting solvent is methanol/formic acid (v/v, 9/1) and the volume of the eluting solvent is 1mL.
The optimal range of NaCl concentration is between 0 and 2mol/L, the extraction time is 20min, the pH of the solution is 3, the elution time is 2min, and the eluting solvent is methanol/formic acid (v/v, 9/1) and the volume of the eluting solvent is 1mL.
Each condition is repeated for 3 times, and an error bar is made, so that the accuracy of experimental data is ensured.
The results are shown in FIG. 3. The extraction time is preferably 20min; the pH of the solution is preferably 3; the NaCl concentration is preferably 0.5mol/L.
(II) elution conditions:
the optimized eluting time is 1-10min, the extracting time is 20min, the pH of the solution is 3, the NaCl concentration is 0.5mol/L, and the eluting solvent is methanol/formic acid (v/v, 9/1) and the volume of the eluting solvent is 1mL.
The eluting solvent type is selected: 1% formic acid+methanol, 10% acetic acid+ethanol, methanol, ethanol, acetonitrile; the extraction time is 20min, the pH of the solution is 3, the NaCl concentration is 0.5mol/L, the elution time is 2min, and the volume of the eluting solvent is 1mL.
The volume optimization range of the eluting solvent is between 0.5 and 1.5mL, the extraction time is 20min, the pH of the solution is 3, the NaCl concentration is 0.5mol/L, the eluting time is 2min, and the eluting solvent is methanol/formic acid (v/v, 9/1); .
Each condition is repeated for 3 times, and an error bar is made, so that the accuracy of experimental data is ensured.
The results are shown in FIG. 4. The eluting solvent is preferably methanol/formic acid (v/v, 9/1); the volume of the eluting solvent is preferably 1mL, and the eluting time is preferably 2min.
(III) optimizing the COFs composite film:
the concentration of Tp affects the preparation of COF composite films by affecting the number of site formations for subsequent COF-117 in situ growth. The optimal Tp concentration is discussed and determined by exploring the effect of the composite membrane on RB extraction. The experiments discussed the different extraction effects of RB at Tp concentrations of 0mg/mL, 1mg/mL, 2mg/mL, 3mg/mL, 4mg/mL and 5 mg/mL. As a result, the pre-grafted Tp provides nucleation sites for the growth of the COF-117 on the surface of the film, is a necessary condition for synthesizing a uniform and good-effect composite film, and has the best extraction effect of the COF-117-PTFE film on RB when the concentration of Tp is 1mg/mL.
The ureido organic framework COF-117 has good adsorption effect on rhodamine B due to the rich ureido functional groups on the surface. TpPa-1, tpBD and COF-117 are prepared by respectively reacting the same monomer (Tp) with another monomer with similar structure.
Adsorption thermodynamic experiment steps: preparing RB solutions with different initial concentrations by using ultrapure water, accurately transferring 5mL of RB solution with a certain concentration into a centrifuge tube at room temperature, adding 0.005g of adsorbent COF-117, placing the centrifuge tube on an oscillator, oscillating for a certain time, centrifuging to obtain supernatant, measuring absorbance of the supernatant by using an ultraviolet spectrophotometer UV-vis, calculating concentration of RB solution before and after adsorption according to linear relation between RB solution and absorbance, and calculating adsorption amounts of TpPa-1, tpBD and COF-117 to RB according to a formula, wherein the results are shown in table 1.
TABLE 1 comparison of adsorption capacities of TpPa-1, tpBD and COF-117
| Material name | TpPa-1 | TpBD | COF-117 |
| Maximum adsorption capacity (mg g) -1 ) | 5.285 | 30.864 | 57.471 |
Experimental results show that the adsorption effect of COF-117 on rhodamine B is best by comparing the maximum adsorption capacities of three different covalent organic framework materials on RB.
Example 3 quantitative detection of rhodamine B based on COFs composite film solid-phase microextraction
(1) Preparation of standard solution: methanol is adopted to prepare rhodamine B standard solution, and the rhodamine B standard solution is diluted to 1ppm in a gradient way for standby.
(2) Preparation of a standard sample: and diluting the rhodamine B standard solution with ultrapure water to prepare 0.1-200ppb of rhodamine B solution.
(3) Membrane solid phase microextraction:
putting 1 piece of COFs composite film into 3mL of rhodamine B solution, and oscillating and extracting for 20min by a shaking table;
(4) Eluting the object to be detected:
taking 1mL of methanol/formic acid (v/v, 9/1) as eluent, and fully eluting the film in the eluent;
(5) Drying with nitrogen and fixing volume:
blowing the eluent to near dryness by using a nitrogen blow-drying device, fixing the volume by 200 mu L of methanol/formic acid (v/v, 9/1), and passing through a microporous filter membrane of 0.22 mu m to be detected;
(6) High performance liquid chromatography detection:
and C18 chromatography is used for detecting a sample to be detected, a chromatogram is recorded, and the peak area is obtained through integration of the chromatograph with software.
Chromatographic conditions: c18 chromatographic detection:
mobile phase: methanol: 0.1% formic acid in water (v: v, 70:30);
column temperature: 35 ℃;
excitation wavelength: 553nm;
emission wavelength: 574nm;
sample injection amount: 10. Mu.L;
flow rate: 1mL/min;
the peak area was integrated by chromatograph from the provided software to obtain a standard curve of rhodamine B after enrichment, as shown in table 2.
TABLE 2 Standard curve for enrichment of rhodamine B by thin film solid phase microextraction
| Target object | Linear range (mu g L) -1 ) | Linear equation | Correlation coefficient |
| Rhodamine B | 0.1-100 | y＝759577x+576567 | 0.9994 |
Results: the rhodamine B peak area and the concentration have good linear correlation, and the detection limit is 0.007 mug/L.
Example 4: labeling recovery rate detection and method adaptability verification of rhodamine B in chilli powder
(1) Adding a standard to the chilli powder:
the standard 5 mug/kg and 50 mug/kg of the two concentrations are added to 1g of the chilli powder sample respectively for standby.
(2) Sample preparation:
1g of chilli powder is added with 5mL of methanol/0.1% formic acid (1/1, v/v) for vortex extraction for 15min, centrifugation is carried out at 8000rpm for 5min, supernatant is taken, residues are added with 5mL of methanol/0.1% formic acid (1/1, v/v) for vortex extraction for 15min, centrifugation is carried out at 8000rpm for 5min, and the two supernatants are combined for detection.
(3) Membrane solid phase microextraction:
taking 1 piece of COFs composite film, placing the film in 3mL of sample solution, and oscillating and extracting for 20min by a shaking table;
(4) Eluting the object to be detected:
taking 1mL of methanol/formic acid (v/v, 9/1) as eluent, and fully eluting the film in the eluent;
(5) Drying with nitrogen and fixing volume:
blowing the eluent to near dryness by using a nitrogen blow-drying device, fixing the volume by 200 mu L of methanol/formic acid (v/v, 9/1), and passing through a microporous filter membrane of 0.22 mu m to be detected;
(6) High performance liquid chromatography detection
And C18 chromatography is used for detecting a sample to be detected, a chromatogram is recorded, and the peak area is obtained through integration of the chromatograph with software.
Chromatographic conditions: c18 chromatographic detection:
mobile phase: methanol: 0.1% formic acid in water (v: v, 70:30);
column temperature: 35 ℃;
excitation wavelength: 553nm;
emission wavelength: 574nm;
sample injection amount: 10. Mu.L;
flow rate: 1mL/min;
after quantitative calculation, the standard adding recovery rate range of rhodamine B in 5 mug/kg and 50 mug/kg of chilli powder sample is 90.6-103.3%, 82.3-98.5% respectively, and the method has good stability.
Claims (8)
1. A method for quantitatively determining rhodamine B, comprising:
preparing a series of rhodamine B standard sample solutions with known concentration by using 0.5mol/L NaCl solution with pH value of 3; respectively adding solid-phase microextraction films into standard sample solutions, fully mixing, extracting and enriching, taking out the films after the completion, eluting with an eluent to obtain an eluent, concentrating and drying, and carrying out constant volume with 200 mu L of methanol/formic acid v/v and 9/1, and carrying out membrane filtration to obtain corresponding sample solutions; the eluent is methanol/formic acid v/v,9/1;
detecting the obtained test sample liquid by using high performance liquid chromatography, and acquiring corresponding high performance liquid chromatography data; the peak area is linearly related with the concentration of the corresponding rhodamine B standard sample solution to obtain a quantitative detection model;
the solid phase microextraction film is prepared by the following method:
(1) Immersing the film in absolute ethyl alcohol for ultrasonic treatment, then immersing in a dopamine solution, and reacting at 50-70 ℃ to obtain the film with the polydopamine attached to the surface;
(2) Placing the obtained film with the polydopamine attached to the surface into a 1,3, 5-trialdehyde phloroglucinol solution for reaction at 80-100 ℃;
(3) After the reaction is finished, cleaning the film and drying; then mixing with 1,3, 5-trialdehyde phloroglucinol, 1' - (1, 4 phenylene) diurea, acetic acid and organic solvent, and reacting at 80-100 ℃ to obtain the film modified with COF-117.
2. The method of claim 1, wherein in step (1), the medium environment of the dopamine solution is 0.009mol/L Tris-HCl solution with ph=8.5.
3. The method of claim 1, wherein in step (1), the concentration of dopamine in the dopamine solution is 3-8g/L.
4. The method of claim 1, wherein in step (1), the film is selected from the group consisting of: polytetrafluoroethylene film, polydimethylsiloxane film, polyacrylonitrile film.
5. The method according to claim 1, wherein in step (2), the concentration of the 1,3, 5-trialdehyde phloroglucinol solution is 1mg/mL.
6. The method according to claim 1, wherein in the step (3), the mass ratio of 1,3, 5-trialdehyde phloroglucinol to 1,1' - (1, 4 phenylene) diurea is 1: (1.2-1.5).
7. The method according to claim 1, wherein in step (3), the concentration of 1,3, 5-trialdehyde phloroglucinol relative to the organic solvent is 20mg/mL.
8. The process according to claim 1, wherein in step (3), the concentration of acetic acid relative to the organic solvent is 0.6mmol/mL.
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| CN107413313A (en) * | 2017-07-18 | 2017-12-01 | 武汉大学 | A kind of Magnetic solid phases extractant based on covalent organic framework material and its preparation method and application |
| CN108579708A (en) * | 2018-04-28 | 2018-09-28 | 江南大学 | A kind of polycyclic aromatic hydrocarbon enrichment detection solid-phase micro-extraction fibre and production method |
| CN110975843A (en) * | 2019-12-17 | 2020-04-10 | 中国科学技术大学 | Preparation method and application of covalent organic framework based heavy metal ion adsorption separation membrane |
| CN111346523A (en) * | 2020-03-12 | 2020-06-30 | 广州大学 | Multifunctional bio-based composite microporous membrane and preparation method thereof |
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Patent Citations (4)
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| CN107413313A (en) * | 2017-07-18 | 2017-12-01 | 武汉大学 | A kind of Magnetic solid phases extractant based on covalent organic framework material and its preparation method and application |
| CN108579708A (en) * | 2018-04-28 | 2018-09-28 | 江南大学 | A kind of polycyclic aromatic hydrocarbon enrichment detection solid-phase micro-extraction fibre and production method |
| CN110975843A (en) * | 2019-12-17 | 2020-04-10 | 中国科学技术大学 | Preparation method and application of covalent organic framework based heavy metal ion adsorption separation membrane |
| CN111346523A (en) * | 2020-03-12 | 2020-06-30 | 广州大学 | Multifunctional bio-based composite microporous membrane and preparation method thereof |
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| Polydopamine-modulated covalent organic framework membranes for molecular separation;Jianliang Shen等;《Journal of Materials Chemistry A》;20190704;18063-18071 * |
| Urea-Linked Covalent Organic Frameworks;Chenfei Zhao等;《Journal of the American Chemical Society》;20181115;第140卷;16438-16441 * |
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