Preparation method of an adsorbent for efficiently enriching multiple mycotoxins in cereals

Abstract

The present invention provides a method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals. The method adopts polydopamine and 1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles as a novel adsorbent to enrich multiple types of mycotoxins in cereals, such as aflatoxins, ochratoxins, fumonisins, zearalenone toxins, penicillin toxins, sterigmatocystin, and Class A and Class B trichothecenes toxins. The method reduces the co-adsorption of matrix components in the cereals, and provides a sample to be tested in which the target is enriched and interference is purified for subsequent analysis and detection.

Description

Technical Field

[0001] The invention provides a preparation method of an adsorbent for efficiently enriching multiple mycotoxins in cereals, and belongs to the technical field of sample pretreatment. Background Art

[0002] Agricultural products such as rice, wheat, and corn, and their products, are commonly contaminated with multiple mycotoxins during production, processing, and storage, posing additive or synergistic risks to consumer health. Monitoring mycotoxin contamination in agricultural products is crucial. Consequently, safety supervision departments and agencies at all levels shoulder the arduous task of monitoring a vast number of diverse samples. Improving efficiency remains a key challenge.

[0003] Mycotoxins often remain at low concentrations in various complex sample matrices, requiring pretreatment to remove interference and enrich the target compounds before subsequent detection. Therefore, sample pretreatment is an essential and crucial step in sample testing. Existing sample pretreatment processes often take tens of minutes or even hours, and this time and cost contribute to as much as 60-70% of the total monitoring effort, becoming the rate-limiting step in practical work. New and efficient sample pretreatment technologies are urgently needed to ensure the feasibility and efficiency of the entire monitoring process.

[0004] There are two core problems that sample pretreatment technology needs to solve: one is to enrich trace or trace amounts of target substances to meet the requirements of sensitive detection; the other is to purify the sample matrix, remove or reduce interference, and achieve accurate detection of the target substances. Summary of the Invention

[0005] Technical problem: The present invention is a method for preparing an adsorbent that can efficiently enrich multiple fungal toxins in cereals. The adsorbent can be prepared to efficiently enrich multiple fungal toxins in cereals and effectively purify matrix interference in cereals, providing samples to be tested for subsequent analysis and detection.

[0006] Technical solution: The present invention provides a method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals, comprising the following steps:

[0007] Step 1. Preparation of magnetic ferroferric oxide nanoparticles by solvothermal method;

[0008] Step 2. Using the magnetic ferroferric oxide nanoparticles as a template, polydopamine-modified magnetic nanoparticles were obtained by in situ polymerization;

[0009] Step 3. The polydopamine-modified magnetic nanoparticles are further modified to obtain polydopamine and 1-carboxyethyl-3-butylimidazolium bromide double-modified magnetic nanoparticles, which are used as adsorbents for efficiently enriching various fungal toxins in grains.

[0010] The process of preparing magnetic ferroferric oxide nanoparticles by the solvothermal method is as follows:

[0011] FeCl3·6H2O was placed in a round-bottom flask, and ethylene glycol was added and stirred to dissolve. After ultrasonic mixing, sodium acetate solution was added and stirred until a uniform viscous solution was formed. The solution was transferred to a polytetrafluoroethylene reactor and reacted at high temperature to produce magnetic ferrosoferric oxide nanoparticles. After the reactor was naturally cooled to room temperature, the particles were washed with deionized water and anhydrous ethanol several times and then dried in a vacuum drying oven.

[0012] The preparation process of the polydopamine modified magnetic nanoparticles is as follows:

[0013] The ferroferric oxide nanoparticles prepared as above were added to a Tris solution, ultrasonically dispersed, and dopamine hydrochloride was added. The mixture was shaken at room temperature to prepare polydopamine-modified magnetic nanoparticles. The polydopamine-modified magnetic nanoparticles were repeatedly washed with water and anhydrous ethanol until the washing solution became colorless, and then dried in a vacuum drying oven.

[0014] The pH value of the Tris solution is 8.5.

[0015] The preparation process of the polydopamine and 1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles is as follows:

[0016] 1-carboxyethyl-3-butylimidazolium bromide is dissolved in dichloromethane to prepare a 1-carboxyethyl-3-butylimidazolium bromide solution; the polydopamine-modified magnetic nanoparticles prepared above are immersed in the solution, 4-dimethylaminopyridine and ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride are added as catalysts, and the mixture is fully reacted under shaking or stirring to prepare magnetic nanoparticles dual-modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide; the magnetic nanoparticles dual-modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide are washed alternately with water and anhydrous ethanol, respectively, and dried in a vacuum drying oven.

[0017] The mycotoxins include one or more of aflatoxins, ochratoxins, fumonisins, zearalenone toxins, penicillin toxins, sterigmatocystin, and class A and class B trichothecenes toxins.

[0018] The cereals include rice, wheat and corn.

[0019] Beneficial effects: The present invention provides a method for preparing an adsorbent for efficiently enriching a variety of fungal toxins in cereals. The method uses magnetic nanoparticles double-modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide as a new adsorbent, which can efficiently and simultaneously adsorb and remove aflatoxin, ochratoxin, fumonisin, zearalenone toxins, penicillin toxins, sterigmatocystin, Class A and Class B trichothecenes toxins, and other types of fungal toxins in cereals such as rice, wheat, and corn. Compared with existing adsorbents, more types of fungal toxins can be adsorbed and enriched at the same time. In addition, in the solid-liquid separation process, only an external magnetic field is needed to achieve rapid separation, avoiding the centrifugation, filtration, sample loading and other operating steps in the traditional solid-phase extraction process, and the operation is simple and time-saving.

[0020] The novel adsorbent provided by the present invention—magnetic nanoparticles dually modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide—uses the benzene rings on polydopamine to generate π-π interactions with target substances, while its abundant amino and hydroxyl groups can form hydrogen bonds with the target substances. The introduction of 1-carboxyethyl-3-butylimidazolium bromide further enriches the interactions between the magnetic nanoparticles and mycotoxins: the imidazole rings on 1-carboxyethyl-3-butylimidazolium bromide can form hydrogen bonds with hydroxyl, amino, and carboxyl groups on the mycotoxins, or π-π interactions with benzene rings and heterocycles on the mycotoxins. Its long carbon chain also forms hydrophobic interactions with the target substances. These interactions among the various functional groups enrich the retention mechanism of the magnetic nanoparticles dually modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide for the target substances, improving the adsorption efficiency of the target substances while reducing the co-adsorption of matrix-interfering components in grain samples, achieving excellent sample pretreatment results. DETAILED DESCRIPTION

[0021] Example 1

[0022] 1.0 g of FeCl3·6H2O was weighed and placed in a round-bottom flask. 35 mL of ethylene glycol was added and stirred to dissolve. After 30 minutes of ultrasonic mixing, 30 mmol of sodium acetate was added and stirred for 1 hour to form a uniform viscous liquid. The above solution was transferred to a polytetrafluoroethylene reactor and reacted at 200°C for 15 hours to obtain magnetic ferrosoferric oxide nanoparticles. After the reactor was naturally cooled to room temperature, it was washed with deionized water and anhydrous ethanol several times and then dried in a vacuum at 60°C.

[0023] 0.4 g of magnetic Fe3O4 nanoparticles was added to 200 mL of 10 mmol L -1The obtained polydopamine-modified magnetic nanoparticles were prepared by ultrasonically dispersing the obtained magnetic nanoparticles in a tris (hydroxymethyl)aminomethane (Tris) solution (pH = 8.5) for 30 minutes to obtain a magnetic nanoparticle solution; 0.4 g of dopamine hydrochloride was added to the magnetic nanoparticle solution and the mixture was shaken and reacted at room temperature for 10 hours to obtain polydopamine-modified magnetic nanoparticles; the obtained polydopamine-modified magnetic nanoparticles were repeatedly washed with water and anhydrous ethanol until the washing liquid became colorless, and then dried in a vacuum drying oven at 60°C.

[0024] 1-Carboxyethyl-3-butylimidazolium bromide was dissolved in dichloromethane to prepare a 5% (mass fraction) 1-carboxyethyl-3-butylimidazolium bromide solution. 200 mg of polydopamine-modified magnetic nanoparticles were immersed in the 1-carboxyethyl-3-butylimidazolium bromide solution. 0.6 mmol of 4-dimethylaminopyridine and 1.5 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added as catalysts. The mixture was shaken and stirred for 24 hours and then removed to prepare polydopamine-1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles. The polydopamine-1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles were then washed alternately with water and anhydrous ethanol, respectively, and dried in a vacuum drying oven at 60°C.

[0025] 50 g each of wheat, corn, and rice were ground into powder using a grinder and passed through a 500 μm sieve. A 0.2 g homogenized sample was weighed and placed in a 2 mL centrifuge tube. After moistening with water, 0.1 ng each of aflatoxins (AFB1, AFB2, AFG1, AFG2), ochratoxins (OTA, OTB), zearalenones (ZEN, ZAN, α-ZEL, β-ZEL, α-ZAL, β-ZAL), penicillin (CIT), sterigmatocystin (ST), class A trichothecenes (T2), and class B trichothecenes (NIV) were added. The mixture was then added with 0.5 mL of 84% acetonitrile-water (v / v) containing 1% acetic acid. The mixture was vortexed for 10 min and then centrifuged at 10,000 rpm for 10 min at -4°C. 0.5 mL of the supernatant was diluted to 2.0 mL with ultrapure water to obtain the sample solution.

[0026] 25 mg of magnetic nanoparticles dually modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide were weighed and ultrasonically activated with 0.1 mL of acetonitrile and 0.1 mL of deionized water for 1 minute. The sample solution was then added and vortexed for 1 minute. The adsorbent and sample solution were separated using an external magnet, and the supernatant was collected for analysis by high-performance liquid chromatography-tandem mass spectrometry. The recoveries of the various targets ranged from 85.3% to 98.7%, and the matrix effects of the three samples (wheat, corn, and rice) were all less than -9.2%. These results demonstrate that the polydopamine and 1-carboxyethyl-3-butylimidazolium bromide dually modified magnetic nanoparticles exhibit high adsorption efficiency for the target compounds and excellent purification of the sample matrix.

[0027] Example 2

[0028] 2.0 g of FeCl3·6H2O was weighed and placed in a round-bottom flask. 50 mL of ethylene glycol was added and stirred to dissolve. After 30 minutes of ultrasonic mixing, 35 mmol of sodium acetate was added and stirred for 1 hour to form a uniform viscous liquid. The above solution was transferred to a polytetrafluoroethylene reactor and reacted at 200°C for 15 hours to obtain magnetic ferrosoferric oxide nanoparticles. After the reactor was naturally cooled to room temperature, it was washed with deionized water and anhydrous ethanol several times and then dried in a vacuum at 60°C.

[0029] 0.5 g of magnetic Fe3O4 nanoparticles was added into 200 mL of 10 mmol L -1 The obtained polydopamine-modified magnetic nanoparticles were prepared by ultrasonically dispersing the obtained magnetic nanoparticles in a tris (hydroxymethyl)aminomethane (Tris) solution (pH = 8.5) for 30 minutes to obtain a magnetic nanoparticle solution; 0.8 g of dopamine hydrochloride was added to the magnetic nanoparticle solution and the mixture was shaken and reacted at room temperature for 10 hours to obtain polydopamine-modified magnetic nanoparticles; the obtained polydopamine-modified magnetic nanoparticles were repeatedly washed with water and anhydrous ethanol until the washing liquid became colorless, and then dried in a vacuum drying oven at 60°C.

[0030] 1-Carboxyethyl-3-butylimidazolium bromide was dissolved in dichloromethane to prepare a 10% (mass fraction) 1-carboxyethyl-3-butylimidazolium bromide solution. 200 mg of polydopamine-modified magnetic nanoparticles were immersed in the 1-carboxyethyl-3-butylimidazolium bromide solution. 1.2 mmol of 4-dimethylaminopyridine and 2.5 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added as catalysts. The mixture was shaken and stirred for 24 hours and then removed to prepare polydopamine-1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles. The polydopamine-1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles were then washed alternately with water and anhydrous ethanol, respectively, and dried in a vacuum drying oven at 60°C.

[0031] Grind 50 g of corn into powder using a grinder and pass through a 500 μm pore size mesh. Weigh 0.5 g of a homogenized sample into a 5 mL centrifuge tube and moisten with water. Add 0.5 ng each of aflatoxins (AFB1, AFB2, AFG1, AFG2), zearalenones (ZEN, ZAN, α-ZEL, β-ZEL, α-ZAL, β-ZAL), and fumonisins (FB1, FB2). Add 1.0 mL of 84% acetonitrile-water (v / v) containing 1% acetic acid, vortex for 10 minutes, and centrifuge at 10,000 rpm for 10 minutes at -4°C. The supernatant is diluted to 5.0 mL with ultrapure water to obtain the sample solution.

[0032] 30 mg of magnetic nanoparticles double-modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide were weighed and ultrasonically activated with 0.1 mL of acetonitrile and 0.1 mL of deionized water for 1 min, then the sample solution was added and vortexed for 1 min. The adsorbent and sample solution were separated by an external magnet, and the supernatant was collected for high-performance liquid chromatography-tandem mass spectrometry detection.

[0033] The recoveries of the various targets were measured to be 82.8-100.7%, and the matrix effects of the various targets in the corn samples were all below -8.6%. The results demonstrate that the polydopamine- and 1-carboxyethyl-3-butylimidazolium bromide-modified magnetic nanoparticles exhibit high adsorption efficiency for the target compounds and excellent purification of the sample matrix.

Claims

1. A method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals, characterized in that: The method comprises the following steps: Step 1. Preparation of magnetic ferroferric oxide nanoparticles by solvothermal method; Step 2. Using the magnetic ferroferric oxide nanoparticles as a template, polydopamine-modified magnetic nanoparticles were obtained by in situ polymerization; Step 3. The polydopamine-modified magnetic nanoparticles are further modified to obtain polydopamine and 1-carboxyethyl-3-butylimidazolium bromide double-modified magnetic nanoparticles, which are used as adsorbents for efficiently enriching various fungal toxins in grains.

2. The method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals according to claim 1, characterized in that: The process of preparing magnetic ferroferric oxide nanoparticles by the solvothermal method is as follows: FeCl3·6H2O was placed in a round-bottom flask, and ethylene glycol was added and stirred to dissolve. After ultrasonic mixing, sodium acetate solution was added and stirred until a uniform viscous solution was formed. The solution was transferred to a polytetrafluoroethylene reactor and reacted at high temperature to produce magnetic ferrosoferric oxide nanoparticles. After the reactor was naturally cooled to room temperature, the particles were washed with deionized water and anhydrous ethanol several times and then dried in a vacuum drying oven.

3. The method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals according to claim 1, characterized in that: The preparation process of the polydopamine modified magnetic nanoparticles is as follows: The ferroferric oxide nanoparticles prepared as above were added to a Tris solution, ultrasonically dispersed, and dopamine hydrochloride was added. The mixture was shaken at room temperature to prepare polydopamine-modified magnetic nanoparticles. The polydopamine-modified magnetic nanoparticles were repeatedly washed with water and anhydrous ethanol until the washing solution became colorless, and then dried in a vacuum drying oven.

4. The method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals according to claim 3, characterized in that: The pH value of the Tris solution is 8.

5.

5. The method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals according to claim 1, characterized in that: The preparation process of the polydopamine and 1-carboxyethyl-3-butylimidazolium bromide dual-modified magnetic nanoparticles is as follows: 1-carboxyethyl-3-butylimidazolium bromide is dissolved in dichloromethane to prepare a 1-carboxyethyl-3-butylimidazolium bromide solution; the polydopamine-modified magnetic nanoparticles prepared above are immersed in the solution, 4-dimethylaminopyridine and ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride are added as catalysts, and the mixture is fully reacted under shaking or stirring to prepare magnetic nanoparticles dual-modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide; the magnetic nanoparticles dual-modified with polydopamine and 1-carboxyethyl-3-butylimidazolium bromide are washed alternately with water and anhydrous ethanol, respectively, and dried in a vacuum drying oven.

6. The method for preparing an adsorbent for efficiently enriching multiple mycotoxins in cereals according to claim 1, characterized in that: The mycotoxins include one or more of aflatoxins, ochratoxins, fumonisins, zearalenone toxins, penicillin toxins, sterigmatocystin, and class A and class B trichothecenes toxins.

7. The method for preparing the adsorbent for efficiently enriching multiple mycotoxins in cereals according to claim 1, characterized in that: The cereals include rice, wheat and corn.