CN113563879A - Preparation method of graphene quantum dot fluorescent probe for paraquat detection - Google Patents

Preparation method of graphene quantum dot fluorescent probe for paraquat detection Download PDF

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CN113563879A
CN113563879A CN202110899639.8A CN202110899639A CN113563879A CN 113563879 A CN113563879 A CN 113563879A CN 202110899639 A CN202110899639 A CN 202110899639A CN 113563879 A CN113563879 A CN 113563879A
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paraquat
graphene quantum
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高大明
汪志辉
赵家东
倪才雨
张年玺
杨俊宇
程远
王竞
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Hefei University
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Abstract

A preparation method of a graphene quantum dot fluorescent probe for paraquat detection comprises the following steps: firstly, soaking cherry blossom leaves in absolute ethyl alcohol and stirring, centrifuging, taking supernatant, performing rotary evaporation to obtain chlorophyll, then re-dispersing the chlorophyll in water, then placing the chlorophyll in a microwave oven for heating, and finally dispersing the chlorophyll in the ethanol to obtain the graphene quantum dot fluorescent probe with a red emission spectral band, wherein the maximum emission wavelength of the graphene quantum dot fluorescent probe is 630nm, the maximum absorption peak position of a visible region of paraquat free radicals is also 630nm, energy levels of a fluorescent probe donor and a paraquat free radical acceptor are overlapped, and fluorescence resonance energy transfer occurs to cause fluorescence quenching of the probe. Probe for diquat and cypermethrinThe contrast detection of ester, chlorpyrifos and glyphosate isopropylamino has poor effect, however, the detection limit of the contrast detection on paraquat free radical is 10‑9mol·L‑1. The preparation method is simple and easy to implement, high in selectivity, high in sensitivity and low in detection limit.

Description

Preparation method of graphene quantum dot fluorescent probe for paraquat detection
Technical Field
The invention relates to the field of material science, in particular to a preparation method of graphene quantum dots with red emission spectral bands for detecting paraquat.
Background
Paraquat (PQ for short), also called Barara mown, has good weeding effect and can almost completely passivate in soil, but if the paraquat is taken orally by a person, the paraquat is absorbed by the digestive tract and enters the body to enable the lung of the person to be completely fiberized, and the process is irreversible. The wide use of paraquat pesticide brings yield increase to crops, meanwhile, residues of paraquat pesticide cause environmental pollution and harm to human health, and poisoning caused by paraquat has no specific antidote, so that a method for quickly and conveniently detecting the residues of paraquat is urgently needed.
The commonly used detection methods at present comprise a surface enhanced Raman method, an electrochemical method, a high performance liquid chromatography, a gas chromatography, an ultraviolet spectrophotometry, even a combined detection of ultraviolet and high performance liquid chromatography and the like. Zhu establishes a field direct detection method for paraquat in biological liquid based on an iodination-promoted pinhole shell separation nanoparticle enhanced Raman spectrum. The method can completely remove matrix interference on the surface of the nano-particles from a complex biological sample, and realizes selective adsorption of paraquat through strong electrostatic adsorption on the surface of the iodine-modified nano-particles, wherein the detection limit is 1mg ∙ L-1. Kalinke C first reported that castor oil cake biochar was used to modify carbon paste electrodes (CPME) at different temperatures (200-. Linear range of 3.0x10-8And 1.0x10-6mol∙L-1Detection limit of 7.5x10-9mol∙L-1. The method is successfully applied to the quantitative analysis of the paraquat in the marked samples of natural water and coconut water. Farahi A Carbon Paste Electrodes (CPEs) modified with silver particles are an effective tool for square wave voltammetry to determine Paraquat (PQ). PQ concentration at 1.0x10-7mol∙L-1To 1.0x10-3mol∙L-1Increase in range, detection limit 2.01X10-8mol∙L-1. Zou T establishes a method for measuring the herbicide paraquat in four edible vegetables (Chinese cabbage, lettuce, spinach and Chinese cabbage) by high performance liquid chromatography-tandem mass spectrometry-high performance liquid chromatography-mass spectrometry combined use (HPLC-MS-MS). The effectiveness of the method was evaluated by measuring the concentration of paraquat in 4 edible vegetables. The recovery rate is 43.6-73.5%. The detection limit is 0.94ng ∙ g-1. Yuexingjing et al selected plasma of 75 patients with paraquat acute poisoning, and high performance liquid chromatography was used to detect plasma paraquat concentration, indicating that the linear range of detection is 54.28-1.32 × 104ng∙mL-1Linear equation of y =0.0001x+0.0116，R2= 0.9983. The peri-cyclone uses an ultraviolet photometry to detect the paraquat in the urine, and the detection limit is 0.14ug ∙ L-1. Qu S et al established a simple method for determining paraquat in environmental samples. 1-ethyl-3-methylimidazole ammonium sulfate and anhydrous potassium hydrogen phosphate are used to form a two-aqueous phase system. Used for extracting paraquat and measuring by high performance liquid chromatography. Several experimental parameters were studied and optimized in order to obtain the best extraction performance. Under the best experimental conditions, 10-5-103ng∙mL-1The linearity within the range is good and the enrichment factor is 18. The phase behavior and the extraction mechanism of the aqueous two-phase system are researched by an ultraviolet-visible spectrophotometry. The method is successfully applied to the determination of paraquat in environmental samples, and the recovery rate is 92.3-95.1%. Rashidipour M combines a salt-assisted liquid-liquid extraction (SALLE) method and an inverse phase dispersion liquid-liquid microextraction (RP-DLLME) method as a novel paraquat content determination method. Paraquat is first extracted from the aqueous phase into acetonitrile and then preconcentrated into the aqueous phase by the RP-DLLME method. The influence of factors such as extraction solvent, volume of the extraction solvent, pH value of a sample, salt concentration and the like on the SALLE is optimized. Effective parameters of RP-DLLME were investigated, including insolubilityThe reagent and its volume, the volume of water as extraction solvent. Under optimized conditions, the recovery rate and the relative standard deviation are respectively between 80.0 and 96.0 and between 3.5 and 7.5. The detection limit is 0.02 mu g ∙ mL-1The limit of quantitation was 0.09. mu.g ∙ mL-1. The method is successfully applied to the determination of paraquat in food and environmental samples. Sha O establishes a simple and rapid clinical naked eye quantitative detection method for Paraquat (PQ) in human plasma and urine samples. A PQ quantitative spectrophotometry based on an indoor device is established. Various factors affecting the recovery rate of PQ have been studied and optimized in detail. Under the best condition, the whole analysis time of the naked eye method is less than 5min, and 0.2 mu g ∙ mL is provided for the determination of paraquat-1The detection range of the standard sample is 0.5-5.0 mu g ∙ mL-1. The method is applied to monitor the PQ level in the plasma and urine of PQ intoxication patients with different blood perfusion times in local hospitals. The detection result not only can immediately carry out medical intervention, but also is beneficial to the survival of the patient. Haibin Dong et al are novel Surface Plasmon Resonance (SPR) detection systems. The aromatic hydrocarbon sulfonate (pSC 4) is used as a recognition molecule of paraquat. PQ can mediate the aggregation of pSC4 end-capped nanogold (AuNPs) through host-guest recognition, and can be used as a signal for PQ detection to be amplified. This is due to several salient features of the detection system: first, local SPR and high refractive index AuNPs can significantly enhance the SPR signal; secondly, AuNPs are more stable and have stronger biocompatibility, and are widely applied to a colorimetric method; third, the network AuNPs structure has unique optical properties that can enhance SPR. Analyte-induced AuNPs aggregation amplification SPR analysis showed significant signal enhancement capability. The detection limit of PQ is 2.2pM, and a new idea is provided for developing a sensitive SPR sensor for high-selectivity small molecule detection.
The method has many advantages, but the preparation steps are complicated, the cost is high, and certain detection methods have strong dependence on large-scale instruments and are difficult to realize large-scale in-situ detection. The fluorescent probe technology can overcome the defects and has high selectivity and high sensitivity for detecting paraquat.
The fluorescent probe technology is characterized in that excited molecules are subjected to collision and emission excitation by using certain substances in an excited state of ultraviolet light, and the characteristics of fluorescent materials can be reflected by adopting a qualitative or quantitative analysis method. Fluorescent probes have attracted considerable attention from researchers. Researchers find that compared with the traditional detection method, the fluorescence analysis method has the advantages of high sensitivity, wide linear range, simple operation and low cost. Due to the characteristics of rapidness, sensitivity and simplicity, the method is rapidly developed into a detection and analysis method which is hot at present.
It was found that a fluorescent probe composed of triple-helix nucleic acid has multiple receptors, and the aptamer on the probe can specifically recognize a target by using a fluorescence resonance energy transfer mechanism. Gaoda has prepared the core-shell structure nanometer material with silicon dioxide as the substrate material, has added the fluorescent dye molecule on the material surface of imprinting and utilized the fluorescence emission energy transfer principle to detect TNT. Among the wavelet et al, the fluorescence resonance energy transfer effect between the carbon quantum dots and the gold nanoparticles is utilized to successfully realize the rapid detection of arginine.
Yang et al construct a sensor system of rhodamine B (RhB) auxiliary Graphene Quantum Dots (GQDs), adsorb rhodamine B on the surface of the graphene quantum dots, can prevent RhB-GQDs from contacting with interfering cations, and due to Hg2+Has strong affinity to amino and carboxyl on the surface of RhB-GQDs, so that Hg passes through2+The non-radiative electron transfer with the excited state of RhB-GQDs quenches the fluorescence of RhB-GQDs. Based on the fluorescence closing process, the synthesized RhB-GQDs can be used as Hg2+A fluorescent platform for sensitive selective detection. The Tiantian sweet constructs a microfluidic paper-based fluorescence sensing device for detecting miRNA and determining the expression of folate receptors on the cell surface. The visual signal output of the fluorescence analysis method is utilized to realize the detection purpose. Wangjiayu et al developed a fluorescence analysis method for detecting the content of apurinic/apyrimidinic endonuclease (APE 1) in human blood, synthesized DNA fluorescent probe containing abasic sites, hydrolyzed the DNA probe under a proper buffer solution and released fluorescent groups, and realized the quantitative detection of APE1 according to the rising rate of a fluorescent signal. One Carbon Quantum Dots (CQDs) was prepared by ome k. m. et al and used for detection of divalent chromium ions. The carbon quantum dots are prepared by a solvothermal methodThe results indicate that CQDs aqueous solution is opposite to Cr2+Has high selectivity and high fluorescence intensity via Cr2+Quenching to achieve the detection purpose.
In view of the above fluorescent probe technology, detection of different target analytes (target molecules) is realized, and the prepared fluorescent probes have defects and shortcomings, which are far less than those of graphene quantum dot fluorescent probes with red emission spectral bands, and are simple and convenient to prepare, low in cost and efficient in identification. Meanwhile, the detection of the graphene quantum dots on paraquat in the red emission spectral band is not reported. Therefore, the graphene quantum dot fluorescent probe with high selectivity and high sensitivity is synthesized, and the necessity of simply and conveniently realizing identification and detection of paraquat molecules is realized.
In the invention, the graphene quantum dots with red emission spectral bands prepared based on the fluorescence resonance energy transfer principle are reported to be used as fluorescent probes, so that the detection of trace paraquat is realized. The graphene quantum dots with red emission spectral bands are particularly suitable for being used as detection tools of trace paraquat. Experiments of detection limit of graphene quantum dots on paraquat show that only red emission spectral band graphene quantum dots increase with the concentration of paraquat, quenching effect is obvious, and the detection limit of the red emission spectral band quantum dots on paraquat can reach 1x10-9mol∙L-1Quenching constant 9758mol ∙ L-1Much higher than blue and green quantum dots. In order to evaluate whether the red graphene quantum dots have selective detection on paraquat as a fluorescent sensor, the red emission spectrum band graphene quantum dots are used for detecting other four pesticides as a comparison experiment. The probe is used for carrying out contrast detection on diquat, cypermethrin, chlorpyrifos and glyphosate isopropylamino, the effect is poor, the quenching constant is far smaller than that of paraquat on a red emission spectrum band graphene quantum dot, however, the high-selectivity identification and high-sensitivity detection on paraquat free radicals show that the probe has a high-efficiency selective detection effect on paraquat, and shows high selectivity, high sensitivity and trace detection on trace paraquat target molecules. Therefore, the graphene quantum dot for detecting the red emission spectral band of paraquat, which is prepared by the invention, has the advantages of simple preparation steps, high selectivity and high sensitivityStrong binding site, large binding capacity, fast binding kinetics, repeated use, low cost and the like.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the defects existing in the prior art, the red emission spectrum band graphene quantum dots with high selectivity, high sensitivity identification and trace detection effects on paraquat are prepared. Firstly, soaking cherry leaves in absolute ethyl alcohol and stirring, centrifuging, taking supernatant, performing rotary evaporation to obtain chlorophyll, then re-dispersing in water, subsequently placing in a microwave oven for heating, and finally dispersing in the ethanol to obtain the graphene quantum dot fluorescent probe with a red emission spectral band. Energy levels of the fluorescent probe donor and the free radical acceptor are overlapped, resonance energy transfer occurs, fluorescence quenching of the probe is caused, and high-selectivity recognition and high-sensitivity detection of paraquat free radicals are achieved.
The technical scheme of the invention is as follows: a preparation method of a graphene quantum dot fluorescent probe for paraquat detection is characterized by comprising the following steps: the graphene quantum dot fluorescent probe has a red emission spectral band with a maximum emission wavelength of 630nm, a visible spectrum characteristic absorption peak of paraquat with herbicidal activity is at 630nm, the fluorescence emission spectrum of the graphene quantum dot fluorescent probe and the maximum absorption wavelength of paraquat are mutually overlapped, according to a fluorescence resonance energy transfer principle, an energy donor in a fluorescent group of the graphene quantum dot fluorescent probe generates fluorescence emission, energy is radiationless transferred to an energy receptor paraquat molecule in a ground state nearby through dipole-dipole interaction, so that the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and paraquat molecule identification and detection are realized, and the preparation process of the graphene quantum dot fluorescent probe for paraquat detection comprises the following three steps:
1.1 preparation of graphene quantum dot fluorescent probe: cutting green plant leaves into 1-2cm, soaking in 40-60 mL of absolute ethyl alcohol, continuously stirring at 500 rpm for 20-40 min, standing for 10-20 min after stirring, centrifuging the obtained solution at 8000rpm for 10min, taking 40mL of supernatant, carrying out rotary evaporation on the supernatant to obtain a muddy solid, measuring 5mL of water, adding the muddy solid into the muddy solid, heating in a microwave oven for 5-10 min, and finally adding ethanol for dissolving to obtain the fluorescent probe of the red emission spectral band graphene quantum dot;
1.2, preparing a paraquat solution: weighing 2.572g of paraquat, placing the paraquat into a 100mL volumetric flask, and transferring 0.1mol ∙ L containing 1% of reducing agent by mass-1The sodium hydroxide solution reaches the constant volume scale of the volumetric flask to obtain the paraquat solution with the concentration of 0.1mol ∙ L-1Then 0.1mol of ∙ L with the concentration configured as above-1The paraquat solutions are respectively prepared into the concentration of 10 by a gradual dilution method-2、10-3、10-4、10-5、10-6And 10-7 mol∙L-1Sealing and storing the gradient paraquat solution for later use;
1.3 detection of paraquat by fluorescent probe of graphene quantum dots: respectively transferring 940 mu L of absolute ethyl alcohol by using a microsyringe, adding the absolute ethyl alcohol into seven quartz cuvettes with 5mL capacity and 10mm optical path, then respectively transferring 30 mu L of fluorescent probes of graphene quantum dots by using the microsyringe, dripping the fluorescent probes into the seven quartz cuvettes, finally sequentially adding the prepared paraquat solutions with different concentration gradients into the seven quartz cuvettes from low to high, measuring 30 mu L each time, and when the 10 mu L of paraquat solution is 30 mu L, adding 10mm of absolute ethyl alcohol into the seven quartz cuvettes-1、10-2、10-3、10-4、10-5、10-6、10-7mol∙L-1The paraquat solution is dripped into a cuvette containing 970 mu L of ethanol, and the solution concentration is respectively diluted to 10-3、10-4、10-5、10-6、10-7、10-8、10-9mol∙L-1After the target analyte paraquat is added, the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and the trace detection of paraquat is realized.
As a further improvement on the prior art, the green plant leaves adopted in the preparation of the graphene quantum dot fluorescent probe are cherry blossom leaves; the microwave power in the preparation of the graphene quantum dot fluorescent probe is 1000W; the microwave power in the preparation of the graphene quantum dot fluorescent probe is 1000W; the reducing agent in the preparation of the graphene quantum dot fluorescent probe is sodium hydrosulfite; during the preparation of the graphene quantum dot fluorescent probe, the mud-shaped solid is chlorophyll; paraquat with herbicidal activity in the preparation of the graphene quantum dot fluorescent probe is a paraquat free radical; the paraquat solution prepared in the graphene quantum dot fluorescent probe is a paraquat free radical solution.
Compared with the prior art, the method has the beneficial effects that:
in recent years, the technology for detecting trace paraquat is increasing. Zhu establishes a field direct detection method for paraquat in biological liquid based on an iodination-promoted pinhole shell separation nanoparticle enhanced Raman spectrum. The method can completely remove matrix interference on the surface of the nano-particles from a complex biological sample, and realizes selective adsorption of paraquat through strong electrostatic adsorption on the surface of the iodine-modified nano-particles, wherein the detection limit is 1mg ∙ L-1. Kalinke C first reported that castor oil cake biochar was used to modify carbon paste electrodes (CPME) at different temperatures (200-. Linear range of 3.0x10-8And 1.0x10-6mol∙L-1Detection limit of 7.5x10-9mol∙L-1. The method is successfully applied to the quantitative analysis of the paraquat in the marked samples of natural water and coconut water. Farahi A Carbon Paste Electrodes (CPEs) modified with silver particles are an effective tool for square wave voltammetry to determine Paraquat (PQ). PQ concentration at 1.0x10-7mol∙L-1To 1.0x10-3mol∙L-1Increase in range, detection limit 2.01X10-8mol∙L-1. Zou T establishes a method for measuring the herbicide paraquat in four edible vegetables (Chinese cabbage, lettuce, spinach and Chinese cabbage) by high performance liquid chromatography-tandem mass spectrometry-high performance liquid chromatography-mass spectrometry combined use (HPLC-MS-MS). The effectiveness of the method was evaluated by measuring the concentration of paraquat in 4 edible vegetables. The recovery rate is 43.6-73.5%. The detection limit is 0.94ng ∙ g-1. Selecting blood plasma of 75 patients with paraquat acute poisoning, and detecting blood by high performance liquid chromatographyThe concentration of paraquat indicates that the linear range of detection is 54.28-1.32 multiplied by 104ng∙mL-1Linear equation of y =0.0001x+0.0116，R2= 0.9983. The peri-cyclone uses an ultraviolet photometry to detect the paraquat in the urine, and the detection limit is 0.14ug ∙ L-1. Qu S et al established a simple method for determining paraquat in environmental samples. 1-ethyl-3-methylimidazole ammonium sulfate and anhydrous potassium hydrogen phosphate are used to form a two-aqueous phase system. Used for extracting paraquat and measuring by high performance liquid chromatography. Several experimental parameters were studied and optimized in order to obtain the best extraction performance. Under the best experimental conditions, 10-5-103ng∙mL-1The linearity within the range is good and the enrichment factor is 18. The phase behavior and the extraction mechanism of the aqueous two-phase system are researched by an ultraviolet-visible spectrophotometry. The method is successfully applied to the determination of paraquat in environmental samples, and the recovery rate is 92.3-95.1%. Rashidipour M combines a salt-assisted liquid-liquid extraction (SALLE) method and an inverse phase dispersion liquid-liquid microextraction (RP-DLLME) method as a novel paraquat content determination method. Paraquat is first extracted from the aqueous phase into acetonitrile and then preconcentrated into the aqueous phase by the RP-DLLME method. The influence of factors such as extraction solvent, volume of the extraction solvent, pH value of a sample, salt concentration and the like on the SALLE is optimized. Effective parameters of RP-DLLME were studied, including the insoluble solvent and its volume, the volume of water as the extraction solvent. Under optimized conditions, the recovery rate and the relative standard deviation are respectively between 80.0 and 96.0 and between 3.5 and 7.5. The detection limit is 0.02 mu g ∙ mL-1The limit of quantitation was 0.09. mu.g ∙ mL-1. The method is successfully applied to the determination of paraquat in food and environmental samples. Sha O establishes a simple and rapid clinical naked eye quantitative detection method for Paraquat (PQ) in human plasma and urine samples. A PQ quantitative spectrophotometry based on an indoor device is established. Various factors affecting the recovery rate of PQ have been studied and optimized in detail. Under the best condition, the whole analysis time of the naked eye method is less than 5min, and 0.2 mu g ∙ mL is provided for the determination of paraquat-1The detection range of the standard sample is 0.5-5.0 mu g ∙ mL-1. The method is applied to PQ poisoning patients with different blood perfusion times in local hospitalsMedium PQ levels were monitored. The detection result not only can immediately carry out medical intervention, but also is beneficial to the survival of the patient. Haibin Dong et al are novel Surface Plasmon Resonance (SPR) detection systems. The aromatic hydrocarbon sulfonate (pSC 4) is used as a recognition molecule of paraquat. PQ can mediate the aggregation of pSC4 end-capped nanogold (AuNPs) through host-guest recognition, and can be used as a signal for PQ detection to be amplified. This is due to several salient features of the detection system: first, local SPR and high refractive index AuNPs can significantly enhance the SPR signal; secondly, AuNPs are more stable and have stronger biocompatibility, and are widely applied to a colorimetric method; third, the network AuNPs structure has unique optical properties that can enhance SPR. Analyte-induced AuNPs aggregation amplification SPR analysis showed significant signal enhancement capability. The detection limit of PQ is 2.2pM, and a new idea is provided for developing a sensitive SPR sensor for high-selectivity small molecule detection.
The method has many advantages, but the preparation steps are complicated, the cost is high, and certain detection methods have strong dependence on large-scale instruments and are difficult to realize large-scale in-situ detection. The fluorescent probe technology can overcome the defects and has high selectivity and high sensitivity for detecting paraquat.
The fluorescent probe technology is characterized in that excited molecules are subjected to collision and emission excitation by using certain substances in an excited state of ultraviolet light, and the characteristics of fluorescent materials can be reflected by adopting a qualitative or quantitative analysis method. Fluorescent probes have attracted considerable attention from researchers. Researchers find that compared with the traditional detection method, the fluorescence analysis method has the advantages of high sensitivity, wide linear range, simple operation and low cost. Due to the characteristics of rapidness, sensitivity and simplicity, the method is rapidly developed into a detection and analysis method which is hot at present.
It was found that a fluorescent probe composed of triple-helix nucleic acid has multiple receptors, and the aptamer on the probe can specifically recognize a target by using a fluorescence resonance energy transfer mechanism. Gaoda has prepared the core-shell structure nanometer material with silicon dioxide as the substrate material, has added the fluorescent dye molecule on the material surface of imprinting and utilized the fluorescence emission energy transfer principle to detect TNT. Among the wavelet et al, the fluorescence resonance energy transfer effect between the carbon quantum dots and the gold nanoparticles is utilized to successfully realize the rapid detection of arginine.
Yang et al construct a sensor system of rhodamine B (RhB) auxiliary Graphene Quantum Dots (GQDs), adsorb rhodamine B on the surface of the graphene quantum dots, can prevent RhB-GQDs from contacting with interfering cations, and due to Hg2+Has strong affinity to amino and carboxyl on the surface of RhB-GQDs, so that Hg passes through2+The non-radiative electron transfer with the excited state of RhB-GQDs quenches the fluorescence of RhB-GQDs. Based on the fluorescence closing process, the synthesized RhB-GQDs can be used as Hg2+A fluorescent platform for sensitive selective detection. The Tiantian sweet constructs a microfluidic paper-based fluorescence sensing device for detecting miRNA and determining the expression of folate receptors on the cell surface. The visual signal output of the fluorescence analysis method is utilized to realize the detection purpose. Wangjiayu et al developed a fluorescence analysis method for detecting the content of apurinic/apyrimidinic endonuclease (APE 1) in human blood, synthesized DNA fluorescent probe containing abasic sites, hydrolyzed the DNA probe under a proper buffer solution and released fluorescent groups, and realized the quantitative detection of APE1 according to the rising rate of a fluorescent signal. One Carbon Quantum Dots (CQDs) was prepared by ome k. m. et al and used for detection of divalent chromium ions. The carbon quantum dots are prepared by a solvothermal method, and the characterization result shows that CQDs aqueous solution is used for Cr2+Has high selectivity and high fluorescence intensity via Cr2+Quenching to achieve the detection purpose.
Although the above inventions are more desirable, these methods are complicated to prepare, high in cost and low in sensitivity. Checking specificity. The method of fluorescent probes can overcome the above disadvantages. The graphene quantum dot with the red emission spectral band has the advantages of simple preparation steps, high selectivity, strong sensitivity, many binding sites, large binding capacity, high binding kinetics speed, reusability, low cost and the like. Meanwhile, the detection of the graphene quantum dots on paraquat in the red emission spectral band is not reported. Therefore, the graphene quantum dot fluorescent probe with high selectivity and high sensitivity is synthesized, and the necessity of simply and conveniently realizing identification and detection of paraquat molecules is realized.
The first step of the invention is the preparation of the graphene quantum dot fluorescent probe: cutting green plant leaves into 1-2cm, soaking in 40-60 mL of absolute ethyl alcohol, continuously stirring at 500 rpm for 20-40 min, standing for 10-20 min after stirring, centrifuging the obtained solution at 8000rpm for 10min, taking 40mL of supernatant, carrying out rotary evaporation on the supernatant to obtain a muddy solid, measuring 5mL of water, adding the muddy solid into the muddy solid, heating in a microwave oven for 5-10 min, and finally adding ethanol for dissolving to obtain the fluorescent probe of the red emission spectral band graphene quantum dot;
the second step is the preparation of paraquat solution: weighing 2.572g of paraquat, placing the paraquat into a 100mL volumetric flask, and transferring 0.1mol ∙ L containing 1% of reducing agent by mass-1The sodium hydroxide solution reaches the constant volume scale of the volumetric flask to obtain the paraquat solution with the concentration of 0.1mol ∙ L-1Then 0.1mol of ∙ L with the concentration configured as above-1The paraquat solutions are respectively prepared into the concentration of 10 by a gradual dilution method-2、10-3、10-4、10-5、10-6And 10-7 mol∙L-1Sealing and storing the gradient paraquat solution for later use;
the third step is that the fluorescence probe of the graphene quantum dots detects paraquat: respectively transferring 940 mu L of absolute ethyl alcohol by using a microsyringe, adding the absolute ethyl alcohol into seven quartz cuvettes with 5mL capacity and 10mm optical path, then respectively transferring 30 mu L of fluorescent probes of graphene quantum dots by using the microsyringe, dripping the fluorescent probes into the seven quartz cuvettes, finally sequentially adding the prepared paraquat solutions with different concentration gradients into the seven quartz cuvettes from low to high, measuring 30 mu L each time, and when the 10 mu L of paraquat solution is 30 mu L, adding 10mm of absolute ethyl alcohol into the seven quartz cuvettes-1、10-2、10-3、10-4、10-5、10-6、10-7mol∙L-1The paraquat solution is dripped into a cuvette containing 970 mu L of ethanol, and the solution concentration is respectively diluted to 10-3、10-4、10-5、10-6、10-7、10-8、10-9mol∙L-1And after target analyte paraquat is added, the graphene quantum dots fluoresceThe fluorescence intensity of the probe is reduced, and the trace detection of paraquat is realized.
In conclusion, the graphene quantum dot with the red emission spectral band, which is obtained by the invention, is a graphene quantum dot fluorescent probe for detecting paraquat.
One is as follows: in the method provided by the invention, the green plant leaves adopted in the preparation of the graphene quantum dot fluorescent probe are cherry blossom leaves.
The second step is as follows: the method provided by the invention comprises the following steps: the microwave power in the preparation of the graphene quantum dot fluorescent probe is 1000W.
And thirdly: in the method provided by the invention, the reducing agent in the preparation of the graphene quantum dot fluorescent probe is sodium hydrosulfite.
Fourthly, the method comprises the following steps: in the method provided by the invention, the mud-like solid is chlorophyll in the preparation of the graphene quantum dot fluorescent probe.
And fifthly: in the method provided by the invention, paraquat with herbicidal activity in the preparation of the graphene quantum dot fluorescent probe is a paraquat free radical.
And the sixth step: in the method provided by the invention, the paraquat solution prepared in the preparation of the graphene quantum dot fluorescent probe is a paraquat free radical solution.
Drawings
Fig. 1 is a uv-vis absorption spectrum of a red emission band graphene quantum dot prepared by the method.
Fig. 2 is a fluorescence spectrum of the graphene quantum dot with red emission band prepared by the invention.
Fig. 3 is a particle size distribution diagram of graphene quantum dots with red emission bands prepared by the method.
FIG. 4 is a Zeta potential diagram of a graphene quantum dot with a red emission band prepared by the method.
Fig. 5 is an infrared spectrum of the graphene quantum dots with red emission band prepared by the method.
Fig. 6 is a raman spectrum of the red emission band graphene quantum dot prepared by the method.
Fig. 7 is a comparison graph of a fluorescence emission spectrum of the red emission band graphene quantum dot prepared by the method and an ultraviolet-visible absorption spectrum of paraquat.
Fig. 8 shows the quenching effect (a) of the fluorescence intensity of the red graphene quantum dot probe prepared by the method of the invention along with the change of the concentration of paraquat, and the Stern-Volmer equation (B) of the fluorescence quenching of the red emission band graphene quantum dot probe by paraquat.
FIG. 9 shows the quenching effect (A) of the fluorescence intensity of the red graphene quantum dot probe prepared by the method along with the change of the concentration of the pesticide diquat, and the Stern-Volmer equation (B) of the fluorescence quenching of the diquat on the graphene quantum dot probe with the red emission spectral band.
FIG. 10 shows the quenching effect (A) of the fluorescence intensity of the red graphene quantum dot probe prepared by the method along with the change of the concentration of cypermethrin, and the Stern-Volmer equation (B) of the fluorescence quenching of the cypermethrin on the graphene quantum dot probe with the red emission spectral band.
FIG. 11 shows the quenching effect (A) of the fluorescence intensity of the red graphene quantum dot probe prepared by the method of the invention along with the change of the chlorpyrifos concentration, and the Stern-Volmer equation (B) of the fluorescence quenching of the graphene quantum dot probe with the red emission spectral band by the chlorpyrifos.
Fig. 12 shows the quenching effect (a) of the fluorescence intensity of the red graphene quantum dot probe prepared by the invention along with the change of the concentration of glyphosate isopropylamino, and the Stern-Volmer equation (B) of the fluorescence quenching of the red emission spectrum band graphene quantum dot probe by glyphosate isopropylamino.
The embodiments are further explained with reference to the drawings
Fig. 1 is a uv-vis absorption spectrum of a red emission band graphene quantum dot prepared by the method. As shown in fig. 1, the upper right corner is a photograph of the red graphene quantum dot under natural light. In the ultraviolet-visible spectrum, there are a plurality of absorption peaks. The characteristic absorption peaks of chlorophyll are at 670nm and 420nm, and the red emission spectrum band graphene quantum dots are obtained by microwave digestion of chlorophyll in oriental cherry leaves, so that the peaks of the chlorophyll are probably not completely digested. The synthesized graphene quantum dots with red emission spectral bands show absorption peaks at 280nm, which correspond to n-pi electron transitions in a carbon structure, and peaks at 320nm correspond to n-pi electron transitions of conjugated olefins.
Fig. 2 is a fluorescence spectrum of the graphene quantum dot with the red luminescence spectrum band prepared by the invention. As shown in fig. 2, the upper right corner is a photograph of red graphene quantum dots under an ultraviolet lamp. The fluorescence emission spectrum of the red graphene quantum dots with the emission wavelength of 630nm is obtained by taking 360nm as the excitation wavelength, the fluorescence emission wavelength range of the red light is just between 600 and 700nm, and the graphene quantum dots with the red emission spectrum band are observed under an ultraviolet lamp.
Fig. 3 is a particle size distribution diagram of graphene quantum dots with red emission bands prepared by the method. As shown in FIG. 3, the particle size of the red quantum dots prepared by the microwave-assisted method is mainly distributed between 2-8 nm.
FIG. 4 is a Zeta potential diagram of a graphene quantum dot with a red emission band prepared by the method. As shown in FIG. 4, the potential distribution of the red quantum dots is mainly distributed in the negative charge region, and the potential value is-3 mV, so that the red graphene quantum dots are negatively charged.
Fig. 5 is an infrared spectrum of the graphene quantum dots with red emission band prepared by the method. As shown in FIG. 5, the graphene quantum dots with red emission spectral bands are 3320cm-1And OH stretching vibration exists, and the solvent of the quantum dot is ethanol solution. 2960 and 2860cm-1Stretching vibration in the presence of C-C, 1370cm-1Corresponds to-CH3A bending vibration. 1080 and 1030cm-1Corresponding to the stretching and bending vibrations of hydroxyl (-OH) groups. Furthermore, at 875cm-1There is a C = C out-of-plane bending vibration.
Fig. 6 is a raman spectrum of the red emission band graphene quantum dot prepared by the method. As shown in FIG. 6, the red graphene quantum dots are prepared by taking chlorophyll as a carbon source, and are 560cm in length-1Bending vibration at 780cm where N-H bond is present-1Is a deformation vibration of COO, 1090cm-1Is NH2Symmetrical swing of 2438cm-1It is the characteristic peak of the quantum dot.
Fig. 7 is a graph comparing the fluorescence emission spectrum of the red emission band graphene quantum dot prepared by the method with the ultraviolet-visible absorption spectrum of paraquat. In the figure, a solid line refers to a fluorescence emission spectrum of a red graphene quantum dot, a dotted line refers to an ultraviolet-visible absorption spectrum of a paraquat solution, a dotted line refers to an ultraviolet-visible absorption spectrum of the paraquat solution after a reducing agent sodium hydrosulfite is added for color development, as can be seen from the figure, the maximum emission wavelength of the red emission spectrum of the graphene quantum dot fluorescence probe is 630nm, a visible spectrum absorption peak of the paraquat solution is 250nm, a characteristic absorption peak of the visible spectrum of the paraquat after the reducing agent is added is 630nm, the fluorescence emission spectrum of the graphene quantum dot fluorescence probe and the maximum absorption wavelength of the paraquat are mutually overlapped, according to a fluorescence resonance energy transfer principle, an energy donor in a fluorophore group of the graphene quantum dot fluorescence probe generates fluorescence emission, and energy is transferred to a nearby energy acceptor paraquat molecule in a ground state without radiation through interaction between dipoles, so that the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and paraquat molecule identification and detection are realized.
Fig. 8 shows the quenching effect (a) of the fluorescence intensity of the graphene quantum dot probe in the red emission band along with the change of the concentration of paraquat, and the Stern-Volmer equation (B) of the fluorescence quenching of the graphene quantum dot probe in the red emission band by paraquat. As can be seen from fig. 8 (a), when the concentration of paraquat increases in sequence, the quenching phenomenon of the graphene quantum dots in the red emission spectrum band becomes more and more obvious, and thus paraquat can effectively quench the red graphene quantum dots, and when the concentration of paraquat is 10-9mol∙L-1The phenomenon of fluorescence intensity reduction also occurs, thereby realizing the high-efficiency detection of paraquat. As can be seen from FIG. 8 (B), the quenching constant of the graphene quantum dot probe with the red emission band is 9758L ∙ mol -1. Therefore, the red graphene quantum dots can be used as fluorescent probes to realize sensitive and efficient detection of the trace amount of paraquat.
FIG. 9 shows the fluorescence intensity of a graphene quantum dot probe in a red emission band with the addition of 0, 2x10-6、4x10-6、6x10-6、8x10-6、1x10-5mol∙L-1The concentration change quenching effect (A) of the pesticide diquat and the Stern-Volmer equation (B) of the fluorescence quenching of the diquat on the graphene quantum dot probe with the red emission spectral band. As can be seen from fig. 9 (a), diquat has a poor quenching effect on red quantum dots, and fluorescence does not have a significant tendency to decrease. The Stern-Volmer fitting equation of diquat to the graphene quantum dots with the red emission band in FIG. 9 (B) is y =0.00446x +0.00231, R2=0.90249, and the quenching constant is 446L ∙ mol-1Is far less than the quenching constant 9758L ∙ mol of paraquat to red graphene quantum dots-1。
FIG. 10 shows the fluorescence intensity of a graphene quantum dot probe with red emission band added with 0, 2x10-6、4x10-6、6x10-6、8x10-6、1x10-5mol∙L-1The quenching effect (A) of the change of the concentration of the cypermethrin, and a Stern-Volmer equation (B) of the fluorescence quenching of the cypermethrin to the graphene quantum dot probe with the red emission spectral band. As can be seen from fig. 10 (a), cypermethrin has a poor quenching effect on the graphene quantum dots with the red emission spectrum band, and fluorescence does not have a significant downward trend. In FIG. 10 (B), the Stern-Volmer equation of the quenching of cypermethrin on the graphene quantum dots with the red emission spectral band isy=0.0071x+0.0022，R2=0.98623, quenching constant 710L ∙ mol-1Is far less than the quenching constant 9758L ∙ mol of paraquat to red graphene quantum dots-1。
FIG. 11 shows the fluorescence intensity of a graphene quantum dot probe with red emission band added with 0, 2x10-6、4x10-6、6x10-6、8x10-6、1x10-5mol∙L-1A chlorpyrifos concentration change quenching effect (A) and a Stern-Volmer equation (B) of chlorpyrifos to red emission spectral band graphene quantum dot probe fluorescence quenching. As can be seen from FIG. 11 (A), when 10 is added-9mol∙L-1When the fluorescence intensity is increased, the fluorescence intensity is reduced remarkably, and the subsequent quenching effect is not remarkable. As can be seen from FIG. 11 (B), the Stern-Volmer equation of chlorpyrifos for quenching of graphene quantum dots with red emission spectral band isy=0.00535x-0.00021，R2=0.86805, quenching constant 535L ∙ mol-1Is far less than the quenching constant 9758L ∙ mol of paraquat to quantum dots-1。
FIG. 12 shows the fluorescence intensity of a graphene quantum dot probe in a red emission band with the addition of 0, 2x10-6、4x10-6、6x10-6、8x10-6、1x10-5mol∙L-1The concentration change quenching effect of glyphosate isopropylamino (A) and a Stern-Volmer equation (B) of fluorescence quenching of glyphosate isopropylamino on a graphene quantum dot probe with a red emission spectrum band. As can be seen from fig. 12 (a), the glycerophosphine isopropylamino group had a poor quenching effect on the red quantum dots, and the fluorescence intensity did not decrease significantly. From fig. 12 (B), it can be seen that the Stern-Volmer equation of quenching of graphene quantum dots in red emission spectrum by glyphosate isopropylamino is as followsy=0.01007x+0.00674，R2=0.98009, quenching constant 1007L ∙ mol-1Is far less than the quenching constant 9758L ∙ mol of paraquat to quantum dots-1。
The specific implementation mode is as follows: a preparation method of a graphene quantum dot fluorescent probe for paraquat detection is characterized by comprising the following steps: the graphene quantum dot fluorescent probe has a red emission spectral band with a maximum emission wavelength of 630nm, a visible spectrum characteristic absorption peak of paraquat with herbicidal activity is at 630nm, the fluorescence emission spectrum of the graphene quantum dot fluorescent probe and the maximum absorption wavelength of paraquat are mutually overlapped, according to a fluorescence resonance energy transfer principle, an energy donor in a fluorescent group of the graphene quantum dot fluorescent probe generates fluorescence emission, energy is radiationless transferred to an energy receptor paraquat molecule in a ground state nearby through dipole-dipole interaction, so that the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and paraquat molecule identification and detection are realized, and the preparation process of the graphene quantum dot fluorescent probe for paraquat detection comprises the following three steps:
1.1 preparation of graphene quantum dot fluorescent probe: cutting green plant leaves into 1-2cm, soaking in 40-60 mL of absolute ethyl alcohol, continuously stirring at 500 rpm for 20-40 min, standing for 10-20 min after stirring, centrifuging the obtained solution at 8000rpm for 10min, taking 40mL of supernatant, carrying out rotary evaporation on the supernatant to obtain a muddy solid, measuring 5mL of water, adding the muddy solid into the muddy solid, heating in a microwave oven for 5-10 min, and finally adding ethanol for dissolving to obtain the fluorescent probe of the red emission spectral band graphene quantum dot;
1.2, preparing a paraquat solution: weighing 2.572g of paraquat, placing the paraquat into a 100mL volumetric flask, and transferring 0.1mol ∙ L containing 1% of reducing agent by mass-1The sodium hydroxide solution reaches the constant volume scale of the volumetric flask to obtain the paraquat solution with the concentration of 0.1mol ∙ L-1Then 0.1mol of ∙ L with the concentration configured as above-1The paraquat solutions are respectively prepared into the concentration of 10 by a gradual dilution method-2、10-3、10-4、10-5、10-6And 10-7 mol∙L-1Sealing and storing the gradient paraquat solution for later use;
1.3 detection of paraquat by fluorescent probe of graphene quantum dots: respectively transferring 940 mu L of absolute ethyl alcohol by using a microsyringe, adding the absolute ethyl alcohol into seven quartz cuvettes with 5mL capacity and 10mm optical path, then respectively transferring 30 mu L of fluorescent probes of graphene quantum dots by using the microsyringe, dripping the fluorescent probes into the seven quartz cuvettes, finally sequentially adding the prepared paraquat solutions with different concentration gradients into the seven quartz cuvettes from low to high, measuring 30 mu L each time, and when the 10 mu L of paraquat solution is 30 mu L, adding 10mm of absolute ethyl alcohol into the seven quartz cuvettes-1、10-2、10-3、10-4、10-5、10-6、10-7mol∙L-1The paraquat solution is dripped into a cuvette containing 970 mu L of ethanol, and the solution concentration is respectively diluted to 10-3、10-4、10-5、10-6、10-7、10-8、10-9mol∙L-1After the target analyte paraquat is added, the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and the trace detection of paraquat is realized.
The graphene quantum dot fluorescent probe has a maximum emission wavelength of a red emission band of 630nm, a visible spectrum characteristic absorption peak of paraquat with herbicidal activity is at 630nm, the fluorescence emission spectrum of the graphene quantum dot fluorescent probe and the maximum absorption wavelength of paraquat are mutually overlapped, according to a fluorescence resonance energy transfer principle, an energy donor in a fluorescent group of the graphene quantum dot fluorescent probe generates fluorescence emission, energy is radiationless transferred to an energy receptor paraquat molecule in a ground state nearby through interaction between dipoles and dipoles, so that the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and paraquat molecule identification and detection are realized.
Example (b): the oriental cherry leaves are used as raw materials, and the graphene quantum dot fluorescent probe with the red emission spectral band can be prepared after microwave digestion.
The first step is preparation of a graphene quantum dot fluorescent probe with a red emission spectral band: cutting green plant leaves into 1.5cm, soaking in 50 mL of absolute ethyl alcohol, continuously stirring at 500 rpm for 30min, standing for 15min after stirring, centrifuging the obtained solution at 8000rpm for 10min, taking 40mL of supernatant, carrying out rotary evaporation on the supernatant to obtain a muddy solid, measuring 5mL of water, adding the muddy solid into the muddy solid, heating in a 1000W microwave oven for 5min, and finally adding ethanol for dissolving to obtain the fluorescent probe for the red emission spectrum band graphene quantum dots;
the second step is the preparation of paraquat solution: weighing 2.572g of paraquat, placing the paraquat into a 100mL volumetric flask, and transferring 0.1mol ∙ L containing 1% of reducing agent by mass-1The sodium hydroxide solution reaches the constant volume scale of the volumetric flask to obtain the paraquat solution with the concentration of 0.1mol ∙ L-1Then 0.1mol of ∙ L with the concentration configured as above-1The paraquat solutions are respectively prepared into the concentration of 10 by a gradual dilution method-2、10-3、10-4、10-5、10-6And 10-7 mol∙L-1Sealing and storing the gradient paraquat solution for later use;
the third step is that the fluorescence probe of the graphene quantum dots detects paraquat: respectively transferring 940 mu L of absolute ethyl alcohol by using a microsyringe, adding the absolute ethyl alcohol into seven quartz cuvettes with the capacity of 5mL and the optical path length of 10mm, and then respectively transferring 30 mu L of graphene quantum dots by using the microsyringeDripping the fluorescent probe into the seven quartz cuvettes, and finally adding the prepared paraquat solutions with different concentration gradients into the seven quartz cuvettes from low to high in sequence, wherein each time the amount of the paraquat solution is 30 mu L, and when the amount of the paraquat solution is 10 mu L, the amount of the paraquat solution is 30 mu L-1、10-2、10-3、10-4、10-5、10-6、10-7mol∙L-1The paraquat solution is dripped into a cuvette containing 970 mu L of ethanol, and the solution concentration is respectively diluted to 10-3、10-4、10-5、10-6、10-7、10-8、10-9mol∙L-1After the target analyte paraquat is added, the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and the trace detection of paraquat is realized.

Claims (7)

1. A preparation method of a graphene quantum dot fluorescent probe for paraquat detection is characterized by comprising the following steps: the graphene quantum dot fluorescent probe has a red emission spectral band with a maximum emission wavelength of 630nm, a visible spectrum characteristic absorption peak of paraquat with herbicidal activity is at 630nm, the fluorescence emission spectrum of the graphene quantum dot fluorescent probe and the maximum absorption wavelength of paraquat are mutually overlapped, according to a fluorescence resonance energy transfer principle, an energy donor in a fluorescent group of the graphene quantum dot fluorescent probe generates fluorescence emission, energy is radiationless transferred to an energy receptor paraquat molecule in a ground state nearby through dipole-dipole interaction, so that the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and paraquat molecule identification and detection are realized, and the preparation process of the graphene quantum dot fluorescent probe for paraquat detection comprises the following three steps:
1.1 preparation of graphene quantum dot fluorescent probe: cutting green plant leaves into 1-2cm, soaking in 40-60 mL of absolute ethyl alcohol, continuously stirring at 500 rpm for 20-40 min, standing for 10-20 min after stirring, centrifuging the obtained solution at 8000rpm for 10min, taking 40mL of supernatant, carrying out rotary evaporation on the supernatant to obtain a muddy solid, measuring 5mL of water, adding the muddy solid into the muddy solid, heating in a microwave oven for 5-10 min, and finally adding ethanol for dissolving to obtain the fluorescent probe of the red emission spectral band graphene quantum dot;
1.2, preparing a paraquat solution: weighing 2.572g of paraquat, placing the paraquat into a 100mL volumetric flask, and transferring 0.1mol ∙ L containing 1% of reducing agent by mass-1The sodium hydroxide solution reaches the constant volume scale of the volumetric flask to obtain the paraquat solution with the concentration of 0.1mol ∙ L-1Then 0.1mol of ∙ L with the concentration configured as above-1The paraquat solutions are respectively prepared into the concentration of 10 by a gradual dilution method-2、10-3、10-4、10-5、10-6And 10-7 mol∙L-1Sealing and storing the gradient paraquat solution for later use;
1.3 detection of paraquat by fluorescent probe of graphene quantum dots: respectively transferring 940 mu L of absolute ethyl alcohol by using a microsyringe, adding the absolute ethyl alcohol into seven quartz cuvettes with 5mL capacity and 10mm optical path, then respectively transferring 30 mu L of fluorescent probes of graphene quantum dots by using the microsyringe, dripping the fluorescent probes into the seven quartz cuvettes, finally sequentially adding the prepared paraquat solutions with different concentration gradients into the seven quartz cuvettes from low to high, measuring 30 mu L each time, and when the 10 mu L of paraquat solution is 30 mu L, adding 10mm of absolute ethyl alcohol into the seven quartz cuvettes-1、10-2、10-3、10-4、10-5、10-6、10-7mol∙L-1The paraquat solution is dripped into a cuvette containing 970 mu L of ethanol, and the solution concentration is respectively diluted to 10-3、10-4、10-5、10-6、10-7、10-8、10-9mol∙L-1After the target analyte paraquat is added, the fluorescence intensity of the graphene quantum dot fluorescent probe is reduced, and the trace detection of paraquat is realized.
2. The method for preparing the graphene quantum dot fluorescent probe for paraquat detection as claimed in claim 1, wherein the method comprises the following steps: the green plant leaves adopted in the preparation of the graphene quantum dot fluorescent probe are cherry blossom leaves.
3. The method for preparing the graphene quantum dot fluorescent probe for paraquat detection as claimed in claim 1, wherein the method comprises the following steps: the microwave power in the preparation of the graphene quantum dot fluorescent probe is 1000W.
4. The method for preparing the graphene quantum dot fluorescent probe for paraquat detection as claimed in claim 1, wherein the method comprises the following steps: the reducing agent is sodium hydrosulfite.
5. The method for preparing the graphene quantum dot fluorescent probe for paraquat detection as claimed in claim 1, wherein the method comprises the following steps: during the preparation of the graphene quantum dot fluorescent probe, the mud-shaped solid is chlorophyll.
6. The method for preparing the graphene quantum dot fluorescent probe for paraquat detection as claimed in claim 1, wherein the method comprises the following steps: the herbicidally active paraquat is a paraquat free radical.
7. The method for preparing the graphene quantum dot fluorescent probe for paraquat detection as claimed in claim 1, wherein the method comprises the following steps: the paraquat solution is paraquat free radical solution.
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CN115418221A (en) * 2022-08-09 2022-12-02 甘肃中医药大学 Preparation and detection method of fluorescent sensor for detecting organophosphorus pesticide residues in angelica sinensis
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