Electrochemical luminescence sensor based on rare earth metal Eu as luminescent material

Abstract

The invention discloses an electrochemical test performed by preparing a novel electrochemical luminescence material and application of the electrochemical luminescence material to an electrochemical luminescence sensor. The invention designs an electrochemical luminescence sensor for detecting carbaryl based on a rare earth metal Eu co-reaction-free promoter complex illuminant. Specifically, the electrochemical luminescence sensor is prepared by taking a complex of rare earth metal europium as a luminescent material and potassium persulfate as a co-reactant. The sensor shows an excellent development prospect in the aspect of carbaryl detection.

Description

Technical Field

[0001] The present invention relates to a design of an electrochemiluminescent sensor for detecting carbaryl based on a rare earth metal Eu non-co-reaction promoter complex luminescent body, specifically based on Eu~L 1 H complex is a sensor for luminescent materials. Background Art

[0002] In the late 1970s, with the ban on organochlorine pesticides, the use of organophosphorus and carbamate pesticides gradually increased. As an early developed carbamate pesticide, carbaryl was widely used during this period. However, the large-scale use of carbaryl may pose a threat to human health because it can enter poultry, livestock and even the human body through the respiratory tract, skin contact or digestive system, and as an acetylcholinesterase inhibitor, it has harmful effects on the nervous system, muscles, liver, pancreas and brain. The maximum allowable residue limit of carbaryl in edible oil in my country is less than or equal to 0.5 mg / kg. Considering the potential harm that carbaryl may cause to the human body, it is crucial to establish an accurate and reliable detection method to monitor and control carbaryl residues in edible oil.

[0003] As an analytical method combining electrochemistry and photochemistry, ECL has attracted widespread attention due to its advantages of high sensitivity, fast response speed and strong controllability. Based on this, we synthesized new functional materials as ECL luminophores, and built biosensors by modifying the functional materials differently with the goal of adjusting the ECL luminescence intensity of the functional materials. In ECL detection technology, luminescent substances play a core role, and lanthanide metal ions have become a hot topic of research due to their unique optical properties. However, the 4f-4f electron transitions of these metal ions in their trivalent state are affected by the spin-forbidden effect, resulting in their relatively low molar absorption coefficients, which limits their efficiency in luminescence applications. We selected a ligand L containing a nitrogen atom. 1 H, it can form lone pairs of electrons of six nitrogen atoms with europium (Eu) to construct a conjugated macrocyclic structure, which can effectively capture and transfer energy to lanthanide metal ions, thereby promoting more efficient photon emission. Although the inherent electronic transitions of lanthanide metal ions limit their ability to directly emit light, their luminescence intensity can be greatly improved by coordinating them with carefully designed organic ligands, making them a potential luminescent source in ECL detection and other optical sensing applications.

[0004] In this study, we constructed a simple and sensitive electrochemiluminescent sensing platform for the detection of the pesticide carbaryl. Using a new rare earth metal complex as the luminescent material and potassium persulfate as a co-reactant, the prepared electrochemiluminescent sensor showed high sensitivity when the carbaryl concentration was 1 pg / mL~1000 ng / mL, and the detection limit was as low as 8.8fg / ml. Summary of the invention

[0005] One of the purposes of the present invention is to prepare an electrochemiluminescent sensor using a rare earth metal Eu complex as a luminescent material and potassium persulfate as a co-reactant.

[0006] The second purpose of the present invention is to use the sensor to detect the pesticide carbaryl with high sensitivity and specificity.

[0007] The technical solution of the present invention is as follows: An electrochemiluminescent sensor based on rare earth metal Eu as luminescent material is as follows: (1) A glassy carbon electrode with a diameter of 4 mm was polished with alumina powder and then ultrasonically rinsed with ultrapure water and ethanol; (2) Take 6 μL of Eu~L1H with a concentration of 1~10 mg / ml and drop it on the electrode surface and let it dry at room temperature; (3) 8 μL of a series of concentration gradient solutions of the pesticide carbaryl ranging from 1 pg / mL to 1000 ng / mL was added dropwise onto the glassy carbon electrode and the electrode was placed in a 4°C refrigerator for storage and incubation; thus, an electrochemiluminescent sensor for detecting carbaryl was prepared.

[0008] The beneficial effects of the present invention are: (1) Introduction of ligand L 1 H can form a hexacoordinated planar complex with Eu so that the complex can exhibit excellent optical properties and enable the rare earth metal Eu to be effectively excited to produce high luminescence intensity.

[0009] (2) For the first time, Eu~L 1 H was used as the luminescent material in electrochemiluminescence sensors.

[0010] (3) The present invention uses rare earth metal Eu and ligand L 1 The sensitive electrochemiluminescence sensor constructed by H can be applied to the detection of the pesticide carbaryl, and has the advantages of simple operation, rapid detection, wide linear range (1 pg / mL~1000 ng / mL) and low detection limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Diagram of the construction process of the electrochemiluminescence sensor Figure 2 The Eu~L obtained by the present invention1 Electron micrograph of H Figure 3 Ligand L 1 H NMR Figure 4 To establish the standard curve for the experiment DETAILED DESCRIPTION

[0012] Example 1 An electrochemiluminescence sensor based on rare earth metal Eu as luminescent material (1) A glassy carbon electrode with a diameter of 4 mm was polished with alumina powder and then ultrasonically rinsed with ultrapure water and ethanol; (2) Take 6 μL of Eu~L with a concentration of 1~10 mg / ml 1 H was dropped on the electrode surface and allowed to dry at room temperature; (3) 8 μL of a series of concentration gradient solutions of the pesticide carbaryl ranging from 1 pg / mL to 1000 ng / mL was added dropwise onto the glassy carbon electrode and the electrode was placed in a 4°C refrigerator for storage and incubation. Thus, an electrochemiluminescent sensor for detecting carbaryl was prepared.

[0013] Example 2 An electrochemiluminescence sensor based on rare earth metal Eu as luminescent material (1) A glassy carbon electrode with a diameter of 4 mm was polished with alumina powder and then ultrasonically rinsed with ultrapure water and ethanol; (2) Take 6 μL of Eu~L with a concentration of 5 mg / ml 1 H was dropped on the electrode surface and allowed to dry at room temperature; (3) 8 μL of a series of concentration gradient solutions of the pesticide carbaryl ranging from 1 pg / mL to 1000 ng / mL was added dropwise onto the glassy carbon electrode and the electrode was placed in a 4°C refrigerator for storage and incubation. Thus, an electrochemiluminescent sensor for detecting carbaryl was prepared.

[0014] Example 3 Preparation of L 1 H and Eu~L 1 H luminous body 14.7mmol pyrazole was dissolved in N,N-dimethylformamide (DMF, 20 mL), and the solution was slowly injected into a double-necked flask containing a small amount of NaH (65%) under N2 atmosphere with a syringe. After stirring for 45 minutes, 14.7mmol 2-bromo-6-cyanopyridine was dissolved in 25 mL DMF and injected into the flask, heated to 130℃, and refluxed for 2 hours. After cooling, the liquid in the flask was added to ice water and stirred, filtered, and the crude product was placed in a fume hood to dry. The crude product was further purified using silica gel petroleum ether: ethyl acetate (5:1, v / v) as the eluent to obtain a white solid 1.

[0015] 9.8 mmol of white solid 1, 24.2 mmol of sodium azide and 24.3 mmol of ammonium chloride were dissolved in 36 mL of anhydrous DMF, refluxed at 130 °C for 20 h under N2 atmosphere, cooled, added into about 100 mL of ice water, adjusted the pH to 2 with 1 M HCl, stirred, filtered and dried to obtain a white product L1H.

[0016] 0.38mmol of ligand L1H was dissolved in a mixture of 14mL of dichloromethane (CH2CI2) and 6mL of methanol (MeOH), and then 0.4mmol of triethylamine was added and stirred at room temperature for 15min. 0.1mmol of Eu(NO3)3·H2O was added and stirred for 2h. The mixture was filtered and allowed to stand at room temperature to obtain the expected material Eu~L 1 H.

[0017] Example 4 Detection of Carbaryl (1) The Ag / AgCl electrode is used as a reference electrode, the platinum wire electrode is used as a counter electrode, and the prepared electrochemiluminescence sensor is used as a working electrode, which are connected to a dark box of a chemiluminescence detector, and the electrochemical workstation and the chemiluminescence detector are connected together; (2) The parameters of the chemiluminescence detector were set as follows: the high voltage of the photomultiplier tube was set to 700 V, and the scanning rate was set to 0.1 V / s; (3) The parameters of the electrochemical workstation were set as follows: the cyclic voltammetry scanning potential range was -2 V to -3 V, and the scanning rate was set to 0.1 V / s; (4) using a PBS buffer solution containing 0.1 M KCl and 90 mM K2S2O8, the electrochemiluminescence signal intensity generated by different concentrations of carbaryl was detected by electrochemiluminescence; the PBS buffer solution, whose pH = 7.0-11.0, was prepared with 0.1 MNa2HPO4 and 0.1 M KH2PO4; (5) Determine the magnitude of the electroluminescent signal corresponding to a series of different concentrations of carbaryl and establish a linear relationship between the electroluminescent signal and the carbaryl concentration. Figure 3 ; Based on this quantitative relationship, the concentration of carbaryl in unknown edible oil samples can be determined.

[0018] Example 6 The sensors constructed using Examples 1, 2, 3, and 4 were used to detect carbaryl according to the detection method of Example 5, and the linear detection range of the sensor was found to be 1 pg / mL to 1000 ng / mL, and the detection limit was 8.8 fg / ml.

Claims

1. A method for preparing an electrochemiluminescence sensor based on rare earth metal Eu as a luminescent material, characterized in that: It involves several steps: (1) A glassy carbon electrode with a diameter of 4 mm was polished with alumina powder and then ultrasonically rinsed with ultrapure water and ethanol; (2) Take 6 μL of Eu(L)3 with a concentration of 1-10 mg / mL and drop it on the electrode surface and let it dry at room temperature; (3) 8 μL of a series of carbaryl solutions with a concentration gradient of 1 pg / mL to 1000 ng / mL were dropped onto the glassy carbon electrode, and the electrode was placed in a 4°C refrigerator for storage and incubation; thus, an electrochemiluminescent sensor for detecting carbaryl was prepared.

2. A method for preparing an electrochemiluminescence sensor based on rare earth metal Eu as a luminescent material according to claim 1, wherein the ligand LH and the luminescent body Eu(L)3 are characterized in that: The preparation steps are as follows: 14.7mmol pyrazole was dissolved in N,N-dimethylformamide (DMF, 20mL), and the solution was slowly injected into a double-necked flask containing a small amount of NaH (65%) with a syringe under N2 atmosphere, and stirred for 45 minutes; 14.7mmol 2-bromo-6-cyanopyridine was dissolved in 25mL DMF and injected into the flask, heated to 130°C, and refluxed for 2h; after cooling, the liquid in the flask was added to ice water and stirred, filtered, and the crude product was placed in a fume hood to dry. The crude product was further purified using silica gel petroleum ether: ethyl acetate (5:1, v / v) as eluent to obtain a white solid 1.

3. 9.8 mmol of white solid 1, 24.2 mmol of sodium azide and 24.3 mmol of ammonium chloride were dissolved in 36 mL of anhydrous DMF, refluxed at 130 °C for 20 h under N2 atmosphere, cooled, added with about 100 mL of ice water, adjusted the pH to 2 with 1 M HCl, stirred, filtered and dried to obtain a white product LH.

4. Dissolve 0.38 mmol of ligand LH in a solvent mixture of 14 mL of dichloromethane (CH2CI2) and 6 mL of methanol (MeOH), then add 0.4 mmol of triethylamine and stir at room temperature for 15 min; add 0.1 mmol of Eu(NO3)3·H2O, continue stirring for 2 h, filter and let stand at room temperature to obtain the expected material Eu(L)3.

5. The method for preparing an electrochemiluminescence sensor based on rare earth metal Eu as a luminescent material according to claim 1 is characterized in that: The test buffer solution has a formula composition of 70-130 mM K2S2O8 PBS buffer solution, wherein the pH of the PBS buffer solution is 7.0-11.0 and the solution is prepared with 0.1 M Na2HPO4 and 0.1 M KH2PO4.

6. The detection of carbaryl according to claim 1, characterized in that: The detection steps are as follows: (1) An Ag / AgCl electrode is used as a reference electrode, a platinum wire electrode is used as a counter electrode, and the prepared electrochemiluminescence sensor is used as a working electrode, which are connected to a dark box of a chemiluminescence detector, and an electrochemical workstation and the chemiluminescence detector are connected together; (2) Parameters of the chemiluminescence detector: The high voltage of the photomultiplier tube was set to 700 V and the scanning rate was set to 0.1 V / s; (3) The electrochemical workstation parameters were set as follows: the cyclic voltammetry scanning potential range was -2 V to -3 V, and the scanning rate was set to 0.1 V / s; (4) Determine the magnitude of the electroluminescent signal corresponding to a series of different concentrations of carbaryl, and establish a linear relationship between the electroluminescent signal and the carbaryl concentration; based on this quantitative relationship, the concentration of carbaryl in the unknown edible oil sample can be determined.

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