A post-printing modified molecularly imprinted solid phase microextraction fiber and a preparation method and a preparation device thereof

Abstract

The application belongs to the technical field of molecular recognition adsorption separation functional materials, and discloses an imprinted post-modified molecular imprinting solid-phase microextraction fiber and a preparation method and a preparation device thereof. The preparation method of the imprinted post-modified molecular imprinting solid-phase microextraction fiber is to modify the molecular imprinting solid-phase microextraction fiber by a derivatization reagent. The molecular imprinting solid-phase microextraction fiber is a chloramphenicol molecular imprinting solid-phase microextraction fiber, and the derivatization reagent includes trifluoroacetic anhydride, benzoyl chloride, sulfamic acid, tert-butyl isocyanate, 3,5-dimethylphenyl isocyanate or succinic anhydride. The application utilizes the derivatization reagent to modify the molecular imprinting solid-phase microextraction fiber after imprinting, introduces high-affinity binding sites into the cavity of the molecular imprinting polymer, and thus improves the extraction amount of the molecular imprinting polymer on the target analyte.

Description

Technical Field

[0001] This invention relates to the field of molecular recognition adsorption and separation functional materials technology, and in particular to a molecularly imprinted solid-phase microextraction fiber modified by imprinting, its preparation method and preparation device. Background Technology

[0002] Molecularly imprinted polymers (MIMs) are widely used as molecular recognition materials. However, MIMs often possess heterogeneous affinity binding sites. These heterogeneous affinity binding sites have several negative impacts on MIMs, including affecting imprinting capacity and selectivity, reducing recognition and imprinting efficiency, increasing the risk of template leakage, reducing binding affinity, potentially increasing the hydrophobicity of MIMs, leading to incompatibility with aqueous media, and resulting in low analyte extraction yields, thus limiting their applications. Summary of the Invention

[0003] The purpose of this invention is to provide a molecularly imprinted solid-phase microextraction fiber modified by imprinting, as well as its preparation method and apparatus, to solve the problem of low extraction yield of existing molecularly imprinted polymers.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification, comprising the following steps:

[0006] Molecularly imprinted solid-phase microextraction fibers and a first derivatization reagent are mixed and subjected to a first reaction to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting.

[0007] or,

[0008] Molecularly imprinted solid-phase microextraction fibers, a second derivatization reagent, and a first solvent are mixed and a second reaction is carried out to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting.

[0009] or,

[0010] Molecularly imprinted solid-phase microextraction fibers, a third derivatization reagent, a second solvent, and a catalyst are mixed and subjected to a third reaction to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting.

[0011] The molecularly imprinted solid-phase microextraction fiber is a chloramphenicol molecularly imprinted solid-phase microextraction fiber.

[0012] The first derivatizing reagent includes trifluoroacetic anhydride;

[0013] The second derivatizing agent includes benzoyl chloride, aminosulfonic acid, tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate;

[0014] The third derivatizing reagent includes succinic anhydride.

[0015] Preferably, in the above-mentioned method for preparing a molecularly imprinted solid-phase microextraction fiber modified by imprinting, the ratio of the second derivatizing reagent to the first solvent is 2.95-22.77 g: 28.2-45 mL;

[0016] The ratio of the third derivatizing reagent, the second solvent, and the catalyst is 1.00–1.10 g: 42–45 mL: 0.8–0.9 g.

[0017] Preferably, in the above-mentioned method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification, the temperature of the first reaction is 20-25°C, and the time of the first reaction is 1 hour.

[0018] When the second derivatizing reagent is benzoyl chloride, the temperature of the second reaction is 80℃, and the reaction time is 23-25h;

[0019] When the second derivatizing reagent is aminosulfonic acid, the temperature of the second reaction is 70°C, and the reaction time is 3-5 hours.

[0020] When the second derivatizing reagent is tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the temperature of the second reaction is 80°C and the time of the second reaction is 9-11 h.

[0021] The temperature of the third reaction is 20–25°C, and the time of the third reaction is 47–49 h.

[0022] Preferably, in the above-mentioned method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification, when the second derivatizing reagent is benzoyl chloride, the first solvent is pyridine;

[0023] When the second derivatizing agent is aminosulfonic acid, tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the first solvent is N,N-dimethylformamide;

[0024] The second solvent is N,N-dimethylformamide;

[0025] The catalyst is 4-dimethylaminopyridine.

[0026] The present invention also provides a method for preparing molecularly imprinted solid-phase microextraction fibers modified by imprinting.

[0027] The present invention also provides an apparatus for preparing molecularly imprinted solid-phase microextraction fibers modified by imprinting, comprising a cotton thread 1, a rubber band 2, a condenser 3, a glass stopper 4, a three-necked flask 5, molecularly imprinted solid-phase microextraction fibers 6, and a stir bar 7; one end of the cotton thread 1 is fixed to the opening of the condenser 3 by the rubber band 2, and the other end passes through the interior of the condenser 3, suspending and fixing the molecularly imprinted solid-phase microextraction fibers 6 in the three-necked flask 5; the condenser 3 is installed on the top of the three-necked flask 5; the three-necked flask 5 contains a second derivatizing reagent or a third derivatizing reagent.

[0028] Preferably, in the above-mentioned apparatus for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification, the two necks of the three-necked flask 5 are sealed by the glass stopper 4; the stir bar 7 is placed in the three-necked flask 5.

[0029] The three-necked flask 5 also contains a first solvent or a second solvent and a catalyst.

[0030] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0031] The method for preparing post-imprinted molecularly imprinted solid-phase microextraction (SPE) fibers provided by this invention facilitates the preparation of various post-imprinted SPE fibers. This includes post-imprinting modification of the SPE fiber coating using derivatizing reagents such as trifluoroacetic anhydride, benzoyl chloride, tert-butyl isocyanate, 3,5-dimethylphenyl isocyanate, aminosulfonic acid, and succinic anhydride. This modification modifies the hydroxyl groups on the functional monomers within the cavity of the molecularly imprinted polymer, introducing different groups and altering the affinity of the binding sites for the analyte to obtain high-affinity binding sites, thereby increasing the extraction yield of the target analyte by the molecularly imprinted polymer. The method for preparing post-imprinted molecularly imprinted SPE fibers provided by this invention has a wide range of applications and a simple operation process. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0033] Figure 1 The diagram shows the preparation apparatus of the present invention; wherein, 1 is cotton thread; 2 is rubber band; 3 is condenser; 4 is glass stopper; 5 is three-necked flask; 6 is molecularly imprinted solid-phase microextraction fiber; and 7 is stir bar. Detailed Implementation

[0034] This invention provides a method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification, comprising the following steps:

[0035] Molecularly imprinted solid-phase microextraction fibers and a first derivatization reagent are mixed and subjected to a first reaction to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting.

[0036] or,

[0037] Molecularly imprinted solid-phase microextraction fibers, a second derivatization reagent, and a first solvent are mixed and a second reaction is carried out to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting.

[0038] or,

[0039] Molecularly imprinted solid-phase microextraction fibers, a third derivatization reagent, a second solvent, and a catalyst are mixed and subjected to a third reaction to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting.

[0040] The molecularly imprinted solid-phase microextraction fiber is preferably a chloramphenicol molecularly imprinted solid-phase microextraction fiber;

[0041] The first derivatizing reagent includes trifluoroacetic anhydride;

[0042] The second derivatizing agent includes benzoyl chloride, aminosulfonic acid, tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate;

[0043] The third derivatizing reagent includes succinic anhydride.

[0044] In this invention, the coating of the molecularly imprinted solid-phase microextraction fiber is simply immersed in the first derivatization reagent.

[0045] In this invention, the preferred ratio of the second derivatizing reagent to the first solvent is 2.95–22.77 g: 28.2–45 mL;

[0046] The coating of the molecularly imprinted solid-phase microextraction fiber can be immersed in a mixture of the second derivatization reagent and the first solvent.

[0047] In this invention, the preferred ratio of the third derivatizing reagent, the second solvent, and the catalyst is 1.00–1.10 g: 42–45 mL: 0.8–0.9 g, more preferably 1.08 g: 45 mL: 0.8784 g;

[0048] The coating of the molecularly imprinted solid-phase microextraction fiber is immersed in a mixture of a third derivatizing reagent, a second solvent, and a catalyst.

[0049] In this invention, the molecularly imprinted solid-phase microextraction fiber is a chloramphenicol molecularly imprinted solid-phase microextraction fiber.

[0050] In this invention, the preparation method of the chloramphenicol molecularly imprinted solid-phase microextraction fiber includes the following steps:

[0051] (1) The template molecule chloramphenicol, the functional monomer-derived β-cyclodextrin and dimethyl sulfoxide were mixed and subjected to a prepolymerization reaction to obtain a prepolymer;

[0052] (2) Mix the prepolymer, crosslinking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile, and then pass nitrogen gas to remove oxygen to obtain a mixed solution;

[0053] (3) The mixed solution is injected into a glass capillary with one end sealed. Then, a silanized glass capillary with one end sealed is inserted into the glass capillary with one end sealed. The gap between the glass capillary with one end sealed and the silanized glass capillary with one end sealed is sealed with raw rubber tape to isolate the air and carry out the polymerization reaction. After the polymerization reaction is completed, the glass capillary with one end sealed is removed to obtain the fiber. The coating on the fiber is cut to 1.8 cm. Then, the template molecules are washed away by magnetic stirring in a mixed solution of methanol and acetic acid to obtain chloramphenicol molecularly imprinted solid-phase microextraction fiber.

[0054] In this invention, the method for preparing the derivatized β-cyclodextrin in step (1) includes the following steps:

[0055] Mono(6-ethylenediamine-6-deoxy)-β-cyclodextrin, sodium bicarbonate solution, and 1,2-hydroxy-7-octene were mixed and reacted. After the reaction was completed, the pH of the resulting solution was adjusted to 7 with HCl solution, and then the crude product was obtained by vacuum drying.

[0056] The crude product was dissolved in N,N-dimethylformamide, and the solution was filtered to remove sodium chloride. Then, diethyl ether was added to the filtered solution to collect DMF, and acetone was added to collect the precipitate. The precipitate was dissolved in water at 70°C, diethyl ether was added to collect the aqueous phase, and acetone was added to collect the precipitate. This purification process was repeated twice. The obtained precipitate was dissolved in methanol and placed in a water bath at 70°C. Finally, acetone was added at room temperature to collect the precipitate. This purification process was repeated twice again. The obtained product was dried to obtain derivatized β-cyclodextrin.

[0057] The ratio of mono(6-ethylenediamine-6-deoxy)-β-cyclodextrin, sodium bicarbonate solution, and 1,2-hydroxy-7-octene was 3 mmol: 40 mL: 2.3 g.

[0058] The concentration of the sodium bicarbonate solution is 0.1 mol / L;

[0059] The reaction temperature is 70°C, and the reaction time is 10 hours.

[0060] The ratio of mono(6-ethylenediamine-6-deoxy)-β-cyclodextrin to N,N-dimethylformamide is 3 mmol: 20 mL;

[0061] The drying temperature is 45°C, and the drying time is 7 hours.

[0062] The mono(6-ethylenediamine-6-deoxy)-β-cyclodextrin was prepared with reference to patent CN104031179A.

[0063] In this invention, the ratio of the template molecule chloramphenicol, the functional monomer-derived β-cyclodextrin, and dimethyl sulfoxide in step (1) is 1 mmol: 4 mmol: 5 mL.

[0064] In this invention, the temperature of the prepolymerization reaction in step (1) is 20-25°C, and the time of the prepolymerization reaction is 12h.

[0065] In this invention, the ratio of the template molecule chloramphenicol in step (1) to the crosslinking agent ethylene glycol dimethacrylate and the initiator azobisisobutyronitrile in step (2) is 1 mmol: 60 mmol: 20 mg.

[0066] In this invention, the diameter of the glass capillary with one end sealed in step (3) is 1.8 to 2.2 mm, and the diameter of the silanized glass capillary with one end sealed is 0.9 to 1.1 mm.

[0067] In this invention, the specific process of the polymerization reaction described in step (3) is carried out in a constant temperature water bath.

[0068] In this invention, the polymerization reaction in step (3) is carried out at a temperature of 60°C and for a duration of 23-25 ​​hours.

[0069] In this invention, the volume ratio of methanol to acetic acid in the mixed solution of methanol and acetic acid in step (3) is 9:1.

[0070] In this invention, the temperature of the first reaction is preferably 20-25°C; the time of the first reaction is preferably 1 hour.

[0071] When the second derivatizing reagent is benzoyl chloride, the preferred temperature of the second reaction is 80°C, and the preferred reaction time is 23–25 h.

[0072] When the second derivatizing reagent is aminosulfonic acid, the preferred temperature for the second reaction is 70°C, and the preferred reaction time is 3 to 5 hours.

[0073] When the second derivatizing reagent is tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the temperature of the second reaction is preferably 80°C, and the reaction time is preferably 8 to 11 hours.

[0074] The temperature of the third reaction is 20–25°C, and the time of the third reaction is 47–49 h.

[0075] In this invention, when the second derivatizing agent is benzoyl chloride, the first solvent is preferably pyridine;

[0076] When the second derivatizing agent is aminosulfonic acid, tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the first solvent is preferably N,N-dimethylformamide.

[0077] In this invention, the second solvent is preferably N,N-dimethylformamide;

[0078] The catalyst is preferably 4-dimethylaminopyridine.

[0079] In this invention, washing is also included after the reaction is completed;

[0080] When the derivatizing reagent is trifluoroacetic anhydride, the washing solvent is acetonitrile solution;

[0081] When the derivatizing reagent is succinic anhydride, the washing solvent is ethanol;

[0082] When the derivatizing agent is benzoyl chloride, aminosulfonic acid, tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the washing solvent is methanol.

[0083] The present invention also provides a method for preparing molecularly imprinted solid-phase microextraction fibers modified by imprinting.

[0084] The present invention also provides an apparatus for preparing molecularly imprinted solid-phase microextraction fibers modified by imprinting, comprising a cotton thread 1, a rubber band 2, a condenser 3, a glass stopper 4, a three-necked flask 5, molecularly imprinted solid-phase microextraction fibers 6, and a stir bar 7; one end of the cotton thread 1 is fixed to the opening of the condenser 3 by the rubber band 2, and the other end passes through the interior of the condenser 3, suspending and fixing the molecularly imprinted solid-phase microextraction fibers 6 in the three-necked flask 5; the condenser 3 is installed on the top of the three-necked flask 5; the three-necked flask 5 contains a second derivatizing reagent or a third derivatizing reagent.

[0085] In this invention, the two necks of the three-necked flask 5 are sealed by the glass stopper 4; the stir bar 7 is placed inside the three-necked flask 5.

[0086] The three-necked flask 5 also contains a first solvent or a second solvent and a catalyst.

[0087] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0088] The preparation method of the derivatized β-cyclodextrin in the following examples includes the following steps:

[0089] 3 mmol of mono(6-ethylenediamine-6-deoxy)-β-cyclodextrin and 40 mL of 0.1 mol / L sodium bicarbonate solution were added to a 250 mL single-necked round-bottom flask, followed by the addition of 2.3 g of 1,2-hydroxy-7-octene. The mixture was then placed in a water bath at 70 °C and reacted for 10 h. After the reaction was completed, the pH of the solution was adjusted to 7 using 1 mol / L HCl solution. The solution was then dried under reduced pressure at 45 °C to obtain the crude product.

[0090] The crude product was dissolved in 20 mL of N,N-dimethylformamide, and the solution was filtered to remove sodium chloride. Then, 100 mL of diethyl ether was added, DMF was collected, 100 mL of acetone was added, the product precipitated and collected. The precipitate was then dissolved in 10 mL of water at 70 °C, 100 mL of diethyl ether was added and the aqueous phase was collected. Another 100 mL of acetone was added and the precipitate was collected. This purification process was repeated twice. The product was dissolved in 10 mL of methanol and placed in a water bath at 70 °C. Finally, 100 mL of acetone was added at room temperature and the precipitate was collected. This purification process was repeated twice again. The product was dried at 45 °C for 7 hours to obtain the derivatized β-cyclodextrin.

[0091] Example 1

[0092] The preparation method of chloramphenicol molecularly imprinted solid-phase microextraction fiber includes the following steps:

[0093] (1) The template molecule chloramphenicol, the functional monomer-derived β-cyclodextrin and dimethyl sulfoxide were mixed and prepolymerized at 20°C for 12 h to obtain a prepolymer; wherein the ratio of the template molecule chloramphenicol, the functional monomer-derived β-cyclodextrin and dimethyl sulfoxide was 1 mmol: 4 mmol: 5 mL.

[0094] (2) The prepolymer, crosslinking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile are mixed and then nitrogen gas is introduced to remove oxygen to obtain a mixed solution; wherein, the ratio of template molecule chloramphenicol, crosslinking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile is 1 mmol: 60 mmol: 20 mg;

[0095] (3) The mixed solution was injected into a glass capillary with a diameter of 2.0 mm and one end sealed. Then, a silanized glass capillary with a diameter of 1.0 mm and one end sealed was inserted into the glass capillary with one end sealed. The gap between the glass capillary with one end sealed and the silanized glass capillary with one end sealed was sealed with raw rubber tape to isolate the air. The polymerization reaction was carried out in a constant temperature water bath at 60°C for 24 h. After the polymerization reaction was completed, the glass capillary with one end sealed was removed to obtain the fiber. The molecularly imprinted polymer coating on the fiber was cut to 1.8 cm. Then, the template molecules were washed away by magnetic stirring in a mixed solution of methanol and acetic acid (methanol:acetic acid = 9:1, v / v) to obtain chloramphenicol molecularly imprinted solid phase microextraction fiber.

[0096] The preparation method of non-molecularly imprinted solid-phase microextraction fibers is the same as that of chloramphenicol molecularly imprinted solid-phase microextraction fibers, the only difference being that the template molecule chloramphenicol is not added.

[0097] High-performance liquid chromatography (HPLC) was used to analyze chloramphenicol standard solutions with concentrations of 0.01 mg / L, 0.05 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, 10 mg / L, 25 mg / L, and 50 mg / L. A standard curve was established, and the equation for the chloramphenicol standard curve was y = 0.56895C - 0.0276, R0. 2 =0.99996.

[0098] Chloramphenicol molecularly imprinted solid-phase microextraction fiber and non-molecularly imprinted solid-phase microextraction fiber were used to extract 50 mL and 100 μg / L chloramphenicol aqueous solutions, respectively.

[0099] The specific process of extraction using chloramphenicol molecularly imprinted solid-phase microextraction fiber is as follows: 50 mL of 100 μg / L chloramphenicol aqueous solution is added to the extraction flask, a stir bar is placed in the flask, and the upper end of the chloramphenicol molecularly imprinted solid-phase microextraction fiber is fixed with a screw cap with a silicone gasket, leaving the other part of the chloramphenicol molecularly imprinted solid-phase microextraction fiber suspended in the solution. The extraction flask is placed on a stirring table and stirred for extraction. The extraction time is 120 min, followed by ultrasonic desorption in 240 μL of chromatographic methanol for 5 min.

[0100] The specific process of extraction using non-molecularly imprinted solid-phase microextraction fibers is the same as described above, except that the chloramphenicol molecularly imprinted solid-phase microextraction fibers are replaced with non-molecularly imprinted solid-phase microextraction fibers.

[0101] The desorbed liquid was analyzed using a high-performance liquid chromatography (HPLC) analyzer. The HPLC analysis conditions were as follows: C18 column, mobile phase acetonitrile:water = 35:65 (v / v), flow rate 1 mL / min, column temperature 30℃, injection volume 20 μL, and detection wavelength 273 nm.

[0102] The results showed that the extraction amount of chloramphenicol by the molecularly imprinted solid-phase microextraction fiber was 0.9524 μg, while the extraction amount of chloramphenicol by the non-molecularly imprinted solid-phase microextraction fiber was 0.64 μg.

[0103] Example 2

[0104] Place a stir bar 7 into a three-necked flask 5, and seal both sides of the flask 5 with glass stoppers 4; then add 4.2 mL of 3,5-dimethylphenyl isocyanate and 42 mL of N,N-dimethylformamide to the three-necked flask 5 to obtain a mixed solution;

[0105] Ten fibers 6, after the template molecules were washed away in Example 1, are fixed at one end of cotton thread 1. The other end of the cotton thread is passed through the condenser tube 3. Then, the other end of the cotton thread is fixed to the opening of the condenser tube 3 with rubber band 2. At this time, the fibers 6 after the template molecules were washed away in Example 1 are located in the center of the three-necked flask 5 and the chloramphenicol molecular imprint solid phase microextraction fiber coating is immersed in the mixed solution. The condenser tube 3 is installed on the top of the three-necked flask 5.

[0106] The device was placed on a magnetic stirrer, heated to 80°C, and stirred under reflux for 10 hours. After the reaction was completed, it was cooled to room temperature. The chloramphenicol molecularly imprinted solid-phase microextraction fiber was then removed and washed with methanol to obtain the chloramphenicol molecularly imprinted solid-phase microextraction fiber modified with the imprint.

[0107] Example 3

[0108] An inner tube was placed in a liquid chromatography vial, and 250 μL of trifluoroacetic anhydride was injected into the inner tube. One chloramphenicol molecularly imprinted solid-phase microextraction fiber from Example 1 was then placed inside. The gap between the chloramphenicol molecularly imprinted solid-phase microextraction fiber and the inner tube was sealed with raw rubber tape to reduce reagent evaporation. The reaction was carried out at 25°C for 1 hour. After the reaction, the chloramphenicol molecularly imprinted solid-phase microextraction fiber was removed and washed with acetonitrile to obtain the imprinted and modified chloramphenicol molecularly imprinted solid-phase microextraction fiber.

[0109] Example 4

[0110] Place a stir bar 7 into a three-necked flask 5, and seal the two necks of the three-necked flask 5 with glass stoppers 4; then add 3.4 mL of tert-butyl isocyanate and 42 mL of N,N-dimethylformamide into the three-necked flask 5 to obtain a mixed solution;

[0111] Ten fibers 6, after the template molecules were washed away in Example 1, are fixed at one end of cotton thread 1. The other end of the cotton thread is passed through the condenser tube 3. Then, the other end of the cotton thread is fixed to the opening of the condenser tube 3 with rubber band 2. At this time, the fibers 6 after the template molecules were washed away in Example 1 are located in the center of the three-necked flask 5 and the chloramphenicol molecular imprint solid phase microextraction fiber coating is immersed in the mixed solution. The condenser tube 3 is installed on the top of the three-necked flask 5.

[0112] The device was placed on a magnetic stirrer, heated to 80°C, and stirred under reflux for 10 hours. After the reaction was completed, it was cooled to room temperature. The chloramphenicol molecularly imprinted solid-phase microextraction fiber was then removed and washed with methanol to obtain the chloramphenicol molecularly imprinted solid-phase microextraction fiber modified with the imprint.

[0113] Example 5

[0114] Place a stir bar 7 into a three-necked flask 5, and seal the two necks of the three-necked flask 5 with glass stoppers 4; then add 5.46g of aminosulfonic acid and 45mL of N,N-dimethylformamide to the three-necked flask 5 to obtain a mixed solution.

[0115] Ten fibers 6, after the template molecules were washed away in Example 1, are fixed at one end of cotton thread 1. The other end of the cotton thread is passed through the condenser tube 3. Then, the other end of the cotton thread is fixed to the opening of the condenser tube 3 with rubber band 2. At this time, the fibers 6 after the template molecules were washed away in Example 1 are located in the center of the three-necked flask 5 and the chloramphenicol molecular imprint solid phase microextraction fiber coating is immersed in the mixed solution. The condenser tube 3 is installed on the top of the three-necked flask 5.

[0116] The device was placed on a magnetic stirrer, heated to 70°C, stirred and refluxed for 4 hours, and then cooled to room temperature. The chloramphenicol molecularly imprinted solid-phase microextraction fiber was taken out and washed with methanol to obtain the chloramphenicol molecularly imprinted solid-phase microextraction fiber modified by imprinting.

[0117] Example 6

[0118] Place a stir bar 7 into a three-necked flask 5, and seal both sides of the flask 5 with glass stoppers 4; then add 28.2 mL of pyridine and 18.8 mL of benzoyl chloride to the three-necked flask 5 to obtain a mixed solution;

[0119] Ten fibers 6, after the template molecules were washed away in Example 1, are fixed at one end of cotton thread 1. The other end of the cotton thread is passed through the condenser tube 3. Then, the other end of the cotton thread is fixed to the opening of the condenser tube 3 with rubber band 2. At this time, the fibers 6 after the template molecules were washed away in Example 1 are located in the center of the three-necked flask 5 and the chloramphenicol molecular imprint solid phase microextraction fiber coating is immersed in the mixed solution. The condenser tube 3 is installed on the top of the three-necked flask 5.

[0120] The device was placed on a magnetic stirrer, heated to 80°C, and stirred under reflux for 24 hours. After the reaction was completed, it was cooled to room temperature. The chloramphenicol molecularly imprinted solid-phase microextraction fiber was then removed and washed with methanol to obtain the chloramphenicol molecularly imprinted solid-phase microextraction fiber modified with the imprint.

[0121] Example 7

[0122] Place a stir bar 7 into a three-necked flask 5, and seal both sides of the flask 5 with glass stoppers 4; then add 1.08g of succinic anhydride, 0.8784g of 4-dimethylaminopyridine and 45mL of N,N-dimethylformamide to the three-necked flask 5 to obtain a mixed solution.

[0123] Ten fibers 6, after the template molecules were washed away in Example 1, are fixed at one end of cotton thread 1. The other end of the cotton thread is passed through the condenser tube 3. Then, the other end of the cotton thread is fixed to the opening of the condenser tube 3 with rubber band 2. At this time, the fibers 6 after the template molecules were washed away in Example 1 are located in the center of the three-necked flask 5 and the chloramphenicol molecular imprint solid phase microextraction fiber coating is immersed in the mixed solution. The condenser tube 3 is installed on the top of the three-necked flask 5.

[0124] After purging with nitrogen, the device was placed on a magnetic stirrer and stirred under reflux at 25°C for 48 hours. After the reaction was completed, the device was cooled to room temperature, and the chloramphenicol molecularly imprinted solid-phase microextraction fiber was removed and washed with ethanol to obtain the chloramphenicol molecularly imprinted solid-phase microextraction fiber modified by imprinting.

[0125] Performance testing

[0126] High-performance liquid chromatography (HPLC) was used to analyze chloramphenicol standard solutions with concentrations of 0.01 mg / L, 0.05 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, 10 mg / L, 25 mg / L, and 50 mg / L. A standard curve was established, and the equation for the chloramphenicol standard curve was y = 0.56895C - 0.0276, R0. 2 =0.99996.

[0127] 1. The chloramphenicol molecularly imprinted solid-phase microextraction fibers prepared in Examples 2 to 7 were used to extract 50 mL and 100 μg / L chloramphenicol aqueous solutions, respectively, for 120 min. Then, the solutions were ultrasonically desorbed in 240 μL of chromatographic methanol for 5 min.

[0128] The desorbed liquid was analyzed using a high-performance liquid chromatography (HPLC) analyzer. The HPLC analysis conditions were as follows: C18 column, mobile phase acetonitrile:water = 35:65 (v / v), flow rate 1 mL / min, column temperature 30℃, injection volume 20 μL, and detection wavelength 273 nm.

[0129] The results showed that the amount of chloramphenicol extracted by the post-imprinted chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 2 was 1.55 μg.

[0130] The amount of chloramphenicol extracted by the imprinted and modified chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 3 was 1.14 μg.

[0131] The amount of chloramphenicol extracted by the imprinted and modified chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 4 was 0.9539 μg.

[0132] The amount of chloramphenicol extracted by the imprinted and modified chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 5 was 0.88 μg; indicating that the affinity of the sulfonamide group introduced by the derivatization reagent aminosulfonic acid for chloramphenicol is not as strong as that of the original hydroxyl group.

[0133] The amount of chloramphenicol extracted by the imprinted and modified chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 6 was 1.31 μg.

[0134] The amount of chloramphenicol extracted by the imprinted and modified chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 7 was 1.25 μg.

[0135] 2. The chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 2 was used to extract 50 mL of 100 μg / L chloramphenicol aqueous solution. The pH of the chloramphenicol aqueous solution was 6, the mass concentration of NaCl in the chloramphenicol aqueous solution was 20%, the extraction time was 120 min, and then ultrasonic desorption was performed in 240 μL of chromatographic methanol for 5 min.

[0136] The desorbed liquid was analyzed using a high-performance liquid chromatography (HPLC) analyzer. The HPLC analysis conditions were as follows: C18 column, mobile phase acetonitrile:water = 35:65 (v / v), flow rate 1 mL / min, column temperature 30℃, injection volume 20 μL, and detection wavelength 273 nm.

[0137] The results showed that the chloramphenicol molecularly imprinted solid-phase microextraction fiber prepared in Example 2 extracted 4.02 μg of chloramphenicol under the extraction conditions (pH 6, NaCl concentration 20%, extraction time 120 min), which was 6.28 times that of the chloramphenicol extracted by the non-molecularly imprinted solid-phase microextraction fiber in Example 1 and 4.22 times that of the chloramphenicol extracted by the molecularly imprinted solid-phase microextraction fiber in Example 1.

[0138] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification, characterized in that, Includes the following steps: Molecularly imprinted solid-phase microextraction fibers and a first derivatization reagent are mixed and subjected to a first reaction to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting. or, Molecularly imprinted solid-phase microextraction fibers, a second derivatization reagent, and a first solvent are mixed and a second reaction is carried out to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting. or, Molecularly imprinted solid-phase microextraction fibers, a third derivatization reagent, a second solvent, and a catalyst are mixed and subjected to a third reaction to obtain molecularly imprinted solid-phase microextraction fibers modified after imprinting. The molecularly imprinted solid-phase microextraction fiber is a chloramphenicol molecularly imprinted solid-phase microextraction fiber. The method for preparing the chloramphenicol molecularly imprinted solid-phase microextraction fiber includes the following steps: (1) The template molecule chloramphenicol, β-cyclodextrin derived from the functional monomer and dimethyl sulfoxide were mixed and subjected to a prepolymerization reaction to obtain a prepolymer; (2) Mix the prepolymer, crosslinking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile, and then pass nitrogen gas to remove oxygen to obtain a mixed solution; (3) Inject the mixed solution into a glass capillary with one end sealed, and then insert a silanized glass capillary with one end sealed into the glass capillary with one end sealed. Use raw rubber tape to seal the gap between the glass capillary with one end sealed and the silanized glass capillary with one end sealed to isolate the air and carry out the polymerization reaction. After the polymerization reaction is completed, remove the glass capillary with one end sealed to obtain the fiber. Cut the coating on the fiber to 1.8 cm, and then wash away the template molecules in a mixed solution of methanol and acetic acid by magnetic stirring to obtain chloramphenicol molecular imprinted solid phase microextraction fiber. The method for preparing the derivatized β-cyclodextrin described in step (1) includes the following steps: Mono(6-ethylenediamine-6-deoxy)-β-cyclodextrin, sodium bicarbonate solution, and 1,2-hydroxy-7-octene were mixed and reacted. After the reaction was completed, the pH of the resulting solution was adjusted to 7 with HCl solution, and then the crude product was obtained by vacuum drying. The crude product was dissolved in N,N-dimethylformamide, and the solution was filtered to remove sodium chloride. Then, diethyl ether was added to the filtered solution to collect DMF, and acetone was added to collect the precipitate. The precipitate was dissolved in water at 70°C, diethyl ether was added to collect the aqueous phase, and acetone was added to collect the precipitate. This purification process was repeated twice. The obtained precipitate was dissolved in methanol and placed in a water bath at 70°C. Finally, acetone was added at room temperature to collect the precipitate. This purification process was repeated twice again. The obtained product was dried to obtain derivatized β-cyclodextrin. The first derivatizing reagent includes trifluoroacetic anhydride; The second derivatizing agent includes benzoyl chloride, tert-butyl isocyanate, or 3,5-dimethylphenyl isocyanate; The third derivatizing reagent includes succinic anhydride; The catalyst is 4-dimethylaminopyridine; The temperature of the first reaction is 20~25℃, and the reaction time is 1 hour; When the second derivatizing reagent is benzoyl chloride, the temperature of the second reaction is 80℃, and the reaction time is 23~25h; When the second derivatizing reagent is tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the temperature of the second reaction is 80°C and the time of the second reaction is 9~11h. The temperature of the third reaction is 20~25℃, and the time of the third reaction is 47~49h.

2. The method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification according to claim 1, characterized in that, The ratio of the second derivatizing reagent to the first solvent is 2.95~22.77g: 28.2~45mL; The ratio of the third derivatizing reagent, the second solvent, and the catalyst is 1.00~1.10g: 42~45mL: 0.8~0.9g.

3. The method for preparing molecularly imprinted solid-phase microextraction fibers with post-imprinting modification according to claim 2, characterized in that, When the second derivatizing agent is benzoyl chloride, the first solvent is pyridine; When the second derivatizing agent is tert-butyl isocyanate or 3,5-dimethylphenyl isocyanate, the first solvent is N,N-dimethylformamide; The second solvent is N,N-dimethylformamide.

4. The molecularly imprinted solid-phase microextraction fiber prepared by the method of any one of claims 1 to 3.

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