ZIF-8 (at) MB / AuNPs ratio type electrochemical sensor, preparation method thereof and parathion-methyl detection method

Abstract

The invention relates to the technical field of electrochemical sensing, in particular to a ZIF-8 (at) MB / AuNPs ratio type electrochemical sensor, a preparation method of the ZIF-8 (at) MB / AuNPs ratio type electrochemical sensor and a detection method of parathion-methyl. The ratio-type electrochemical sensor constructed by the method can realize the detection effects of high sensitivity, high speed and high precision on parathion-methyl, is good in anti-interference performance and repeatability, and has potential application prospects in the field of quality detection of agricultural products.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical sensing, and in particular to a ZIF-8@MB / AuNPs ratio electrochemical sensor and a preparation method thereof, and a method for detecting methyl parathion. Background Art

[0002] Methyl parathion (MP) is a typical nitroaromatic organophosphorus pesticide, which is widely used because it can effectively prevent insect invasion and reduce agricultural losses. Although the widespread use of MP has increased food production, MP has contact and stomach toxicity, and its residues in agricultural products may have long-term potential impacts on humans and the environment. Therefore, it is necessary to develop effective detection technology to achieve efficient detection and analysis of MP in agricultural products.

[0003] At present, the main detection technologies for MP include gas chromatography, high performance liquid chromatography-mass spectrometry, surface enhanced Raman scattering, etc. However, these detection technologies have disadvantages such as expensive instruments, long time consumption, and complex operation. They cannot meet the requirements of rapid on-site detection and bring inconvenience to the detection of agricultural and sideline products. Therefore, it is necessary to develop a simple, fast and efficient detection method. Compared with the above methods, electrochemical sensing technology has attracted the attention of more and more researchers due to its advantages of low cost, fast response and simple operation.

[0004] Existing electrochemical sensors only detect methyl parathion through changes in a single signal, which may be affected by many external factors, such as different electrode modification methods, instrument efficiency, and changes in environmental conditions. These factors will lead to slight differences in the peak currents of different electrodes, thereby reducing the reliability of methyl parathion detection. Unlike traditional single-signal sensing, ratiometric electrochemical sensors have a dual-signal response to the target. Since the disturbance caused by external factors will be applied to the dual signals at the same time, the ratio strategy of quantifying the concentration of methyl parathion by measuring the ratio of the dual signals can effectively improve the detection accuracy of the sensor. Therefore, the development of a high-performance ratiometric electrochemical sensor that can achieve dual signals is of great research significance for efficient and high-precision detection of MP. Summary of the invention

[0005] In order to solve the above technical problems, a ZIF-8@MB / AuNPs ratio electrochemical sensor and a preparation method thereof, and a method for detecting methyl parathion are provided. The present invention modifies a zeolite imidazole framework-8@methylene blue / gold nanoparticle composite material (ZIF-8@MB / AuNPs composite material) on a glassy carbon electrode, and the ratio electrochemical sensor constructed by the above is used to detect methyl parathion, which has the advantages of high sensitivity, fast speed, high accuracy, etc.

[0006] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0007] The first aspect of the present invention provides a method for preparing a ZIF-8@MB / AuNPs ratiometric electrochemical sensor, comprising the following steps:

[0008] (1) adding methylene blue to an aqueous solution containing ZIF-8, stirring the reaction at room temperature, and performing solid-liquid separation and washing to obtain a ZIF-8@MB precipitate;

[0009] The ZIF-8@MB precipitate was dispersed in water to form a ZIF-8@MB solution, to which the AuNPs solution was added and stirred to obtain a ZIF-8@MB / AuNPs composite material solution;

[0010] (2) The ZIF-8@MB / AuNPs composite material solution is coated on the surface of the pretreated glassy carbon electrode and dried at room temperature to obtain a ZIF-8@MB / AuNPs ratiometric electrochemical sensor.

[0011] Furthermore, the concentration of the ZIF-8@MB / AuNPs composite material solution is 0.5-1.5 mg / mL, and the amount of the ZIF-8@MB / AuNPs composite material solution coated on the pretreated glassy carbon electrode is 4-8 μL.

[0012] Furthermore, in the aqueous solution containing ZIF-8, the ratio of ZIF-8 to water is 10-30 mg: 5-20 mL, and the ratio of the ZIF-8 to the methylene blue is 10-30 mg: 1-10 mg;

[0013] The concentration of the ZIF-8@MB solution is 0.3-0.8 mg / mL;

[0014] The dosage ratio of the ZIF-8@MB solution to the AuNPs solution is in the range of 1 mL:5-20 μL.

[0015] Furthermore, the method for obtaining the AuNPs solution is: mixing a tetrachloroauric acid trihydrate solution with water and heating to complete boiling, then adding a sodium citrate solution, and continuing heating and stirring for 10-30 minutes to obtain an AuNPs solution;

[0016] Wherein, the tetrachloroauric acid trihydrate solution is 0.05-0.3M, and the volume ratio of the tetrachloroauric acid trihydrate solution to water is 100-400:15-30; the concentration of the sodium citrate solution is 50-200 mg / mL;

[0017] The volume ratio of the tetrachloroauric acid trihydrate solution to the sodium citrate solution is 100-400:0.05-1.

[0018] Furthermore, the particle size of the ZIF-8 is less than 2 μm; the stirring reaction time at room temperature is 10-48 hours; the diameter of the glassy carbon electrode is 3 mm, and the glassy carbon electrode is polished with alumina powder to obtain a pretreated glassy carbon electrode, which is polished with alumina powder with a particle size of 0.3 μm and 0.05 μm respectively.

[0019] The second aspect of the present invention provides a ZIF-8@MB / AuNPs ratiometric electrochemical sensor prepared by the above preparation method.

[0020] The last aspect of the present invention provides a method for detecting methyl parathion, comprising the steps of:

[0021] S1. Prepare a series of concentrations of methyl parathion standard solutions, place the ZIF-8@MB / AuNPs ratiometric electrochemical sensor prepared by the above method as the working electrode, reference electrode and counter electrode in a series of concentrations of methyl parathion standard solutions, perform differential pulse voltammetry (DPV) detection of the three-electrode system, and obtain the DPV response curves corresponding to a series of concentrations of methyl parathion standard solutions. The DPV response curve shows a double peak, and the current peak value that appears in the voltage range of -0.3V to -0.1V is recorded as I MB The current peak value that appears when the voltage is in the range of -0.1V to 1V is recorded as I MP ;

[0022] A series of concentrations of methyl parathion standard solution C MP The horizontal axis is the ratio of the peak current I MP / I MB As the ordinate, draw the standard curve and obtain the standard equation by linear fitting;

[0023] S2, placing the ZIF-8@MB / AuNPs ratio electrochemical sensor prepared by the above preparation method in the test solution, detecting and recording the measured results by differential pulse voltammetry DPV in a three-electrode system according to step S1, and calculating the ratio of the obtained current peak value I MP / I MB Substituting the value of into the standard equation, the actual concentration of methyl parathion in the test solution is obtained.

[0024] Furthermore, a series of concentrations of methyl parathion standard solutions ranged from 5 × 10 -8 ~3×10 -5 g / mL; when testing the solution to be tested, adjusting the pH value of the solution to be tested to 4.5-7;

[0025] The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum wire.

[0026] Further, the standard equation is MP / I MB =0.0541+0.313C MP , R 2 =0.997, the linear range is 50 ng / mL to 30000 ng / mL, and the detection limit concentration of methyl parathion by the ZIF-8@MB / AuNPs ratiometric electrochemical sensor is 16.67 ng / mL.

[0027] Beneficial technical effects:

[0028] The present invention obtains a ratiometric electrochemical sensor by modifying a zeolite imidazole framework-8@methylene blue / gold nanoparticle (ZIF-8@MB / AuNPs) composite material on a glassy carbon electrode. A stable internal standard output signal can be provided by MB, and during detection, the signal of methyl parathion appears simultaneously without interfering with each other, thereby forming a stable ratiometric electrochemical sensor, thereby achieving high-sensitivity and high-precision detection of methyl parathion. The linear range of the ratiometric electrochemical sensor of the present invention is 50 ng / mL-30 μg / mL, and the detection limit is 16.67 ng / mL. The ratiometric electrochemical sensor of the present invention has the advantages of fast detection speed, high sensitivity, high precision, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the construction principle of ZIF-8@MB / AuNPs / GCE in Example 1 of the present invention;

[0030] Figure 2 The DPV response curves of a series of MP standard solutions, where the concentrations of the MP standard solutions are 5×10 -8 g / mL, 1×10 -7 g / mL, 1×10 -6 g / mL, 5×10 -6 g / mL, 1×10 -5 g / mL, 1.5×10 -5 g / mL, 2×10 - 5 g / mL, 2.5×10 -5 g / mL, 3×10 -5 g / mL;

[0031] Figure 3 is the ratio of the current peak value calculated from the DPV response curve I MP / I MB Linear relationship diagram of the standard curve plotted against MP concentration, with the abscissa being MP concentration;

[0032] Figure 4GCE, ZIF-8 / GCE, ZIF-8@MB / GCE and ZIF-8@MB / AuNPs / GCE were prepared in the presence of 5.0 μg mL - 1 Comparison of DPV response curves of MP in 0.1 M PBS (pH 5.5), with the abscissa being voltage and the ordinate being current;

[0033] Figure 5 I is the ratio of the current peak value in the DPV response curve of MP detection with different volume ratios of ZIF-8@MB solution and AuNPs solution MP / I MB relationship diagram. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0035] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. The technology and method known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and method should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0036] The experimental methods in the following examples without specifying specific conditions are usually measured in accordance with national standards; if there is no corresponding national standard, the method is carried out in accordance with the general standard requirements or general methods.

[0037] Preparation Example 1

[0038] Preparation of ZIF-8: First, dissolve 1.756 g of zinc acetate dihydrate in 40 mL of methanol and ultrasonically treat it for 5 minutes to obtain solution A; dissolve 2.627 g of 2-methylimidazole in 160 mL of methanol and ultrasonically treat it for 5 minutes to obtain solution B; slowly add solution A to solution B, stir at room temperature for 24 hours, centrifuge, wash, and dry to obtain ZIF-8 powder, and the particle size of ZIF-8 is 1 μm.

[0039] Preparation Example 2

[0040] Preparation of AuNPs solution: Add 200 mL of 0.1 M tetrachloroauric acid trihydrate solution to 25 mL of water and heat to complete boiling, then quickly add 0.25 mL of 100 mg / mL trisodium citrate solution, continue heating and stirring for 15 minutes to obtain the AuNPs solution.

[0041] Example 1

[0042] The preparation method of the ZIF-8@MB / AuNPs ratiometric electrochemical sensor comprises the following steps:

[0043] (1) Preparation of ZIF-8@MB / AuNPs solution:

[0044] 24 mg of ZIF-8 powder prepared in Preparation Example 1 was dispersed in 12 mL of water and ultrasonicated for 30 minutes. 1.5 mg of MB powder was added thereto and ultrasonicated for 30 minutes. After stirring at room temperature for 24 hours, the mixture was centrifuged, washed and dried to obtain ZIF-8@MB precipitate.

[0045] 24 mg of ZIF-8@MB precipitate was redispersed in 35 mL of water to form a ZIF-8@MB solution, to which 0.35 mL of the AuNPs solution prepared in Preparation Example 2 was added, and stirred evenly to obtain a ZIF-8@MB / AuNPs composite material solution with a concentration of 0.7 mg / mL;

[0046] (2) Preparation of ZIF-8@MB / AuNPs ratiometric electrochemical sensor:

[0047] A glassy carbon electrode (GCE) with a diameter of 3 mm was polished with 0.3 μm and 0.05 μm aluminum oxide powders, and then ultrasonicated in ethanol and water to remove surface residues, and then dried at room temperature to obtain a pretreated GCE.

[0048] 6 μL of the aforementioned 0.7 mg / mL ZIF-8@MB / AuNPs composite material solution was added dropwise to the pretreated GCE and dried at room temperature to obtain ZIF-8@MB / AuNPs / GCE, which is the ZIF-8@MB / AuNPs ratio electrochemical sensor. This is used as a ratio electrochemical sensor for detecting methyl parathion MP. The construction principle of ZIF-8@MB / AuNPs / GCE is as follows Figure 1 shown.

[0049] Comparative Example 1

[0050] This case is the preparation of ZIF-8 / GCE: 5.1 mg of ZIF-8 powder prepared in Preparation Example 1 was dispersed in 7 mL of water to obtain a ZIF-8 solution with a concentration of 0.7 mg / mL, 6 μL of the ZIF-8 solution of this concentration was dripped onto the pretreated GCE (treated in the same manner as in Example 1), and dried at room temperature to obtain ZIF-8 / GCE, which was used as a ratiometric electrochemical sensor for methyl parathion MP.

[0051] Comparative Example 2

[0052] This case is the preparation of ZIF-8@MB / GCE: 5.1 mg of ZIF-8@MB precipitate (same as step 1 in Example 1) was dispersed in 7 mL of pure water to obtain a ZIF-8@MB solution with a concentration of 0.7 mg / mL, 6 μL of this concentration of ZIF-8@MB solution was added dropwise to the pretreated GCE (treated in the same manner as in Example 1), and dried at room temperature to obtain ZIF-8@MB / GCE, which was used as a ratiometric electrochemical sensor for methyl parathion MP.

[0053] Example 2

[0054] The detection method of methyl parathion comprises the following steps:

[0055] S1. Prepare a series of concentrations of methyl parathion (MP) standard solutions: dilute MP with PBS buffer to prepare standard solutions of different concentrations. The concentrations are as follows: 5×10 -8 g / mL, 1×10 -7 g / mL, 1×10 -6 g / mL, 5×10 -6 g / mL, 1×10 -5 g / mL, 1.5×10 -5 g / mL, 2×10 -5 g / mL, 2.5×10 -5 g / mL, 3×10 -5 g / mL;

[0056] The ZIF-8@MB / AuNPs / GCE prepared in Example 1 was used as the working electrode, the Ag / AgCl (saturated KCl) electrode was used as the reference electrode, and the platinum wire was used as the counter electrode. They were placed in the above series of MP standard solutions, and the differential pulse voltammetry (DPV) detection of the three-electrode system was performed. The DPV response curves corresponding to the series of MP standard solutions were obtained. The results are shown in FIG. Figure 2 As shown in the figure, the DPV response curve shows a double peak, and the current peak value that appears in the voltage range of -0.3V to -0.1V is recorded as I MB The current peak value that appears when the voltage is in the range of -0.1V to 1V is recorded as I MP ;Depend on Figure 2 It can be seen that as the MP concentration increases, the peak current of MP gradually increases, while the peak current of MB remains unchanged;

[0057] A series of concentrations of MP standard solution C MP The horizontal axis is the ratio of the peak current I MP / I MB As the ordinate, draw the standard curve, and obtain the standard equation by linear fitting. The standard curve is as follows: Figure 3 As shown by Figure 3 It can be seen that the ratio of the current peak value I MP / I MB With C MP The standard equation for the linear fit of the standard curve between MP / I MB =0.0541+0.313C MP , R 2 =0.997, linear range is 50ng / mL~30μg / mL, detection limit is 16.67ng / mL;

[0058] S2. Actual detection:

[0059] The ZIF-8@MB / AuNPs ratiometric electrochemical sensor prepared by the preparation method of Example 1 was placed in the solution to be tested, and the differential pulse voltammetry DPV was used in a three-electrode system according to step S1 to detect and record the measured results. The ratio of the obtained current peak value I MP / I MB Substituting the value into the standard equation I MP / I MB =0.0541+0.313C MP The actual MP concentration in the test solution can be obtained.

[0060] Example 3

[0061] The ZIF-8@MB / AuNPs ratiometric electrochemical sensor (ie, ZIF-8@MB / AuNPs / GCE) prepared in Example 1 was applied to the spiked detection of different concentrations of MP in actual lettuce samples.

[0062] The test process is as follows: First, the lettuce purchased from the local market was chopped and filtered through a 0.2 μm nylon membrane. After centrifugation, it was diluted 100 times with a 0.1 M PBS solution, and 5 mL was taken as the actual test solution for testing;

[0063] The ZIF-8@MB / AuNPs / GCE prepared in Example 1 was used as the working electrode, the Ag / AgCl (saturated KCl) electrode was used as the reference electrode, and the platinum wire was used as the counter electrode. The three electrodes were placed in the actual test solution, and differential pulse voltammetry (DPV) detection was performed to obtain the current peak values ​​I of MP and MB. MP and I MB , will I MP and I MB Substituting the ratio into the standard equation I MP / I MB =0.0541+0.313C MP , and thus the actual MP concentration information in lettuce is calculated. See Table 1 for details.

[0064] Table 1 Detection results of MP in lettuce samples by ratiometric electrochemical sensor of Example 1

[0065]

[0066]

[0067] As shown in Table 1, the ZIF-8@MB / AuNPs / GCE prepared in Example 1 of the present invention can achieve high-sensitivity and high-precision detection of methyl parathion, and the relative standard deviation can be controlled within 5%.

[0068] GCE, ZIF-8 / GCE, ZIF-8@MB / GCE and ZIF-8@MB / AuNPs / GCE were respectively prepared in the presence of 5.0 μg mL -1 The DPV current response curves were compared in 0.1 M PBS (pH 5.5) of MP. Figure 4 As shown in the figure, GCE, ZIF-8 / GCE, ZIF-8@MB / GCE and ZIF-8@MB / AuNPs / GCE respectively represent glassy carbon electrode, ZIF-8 modified glassy carbon electrode, ZIF-8@MB material modified glassy carbon electrode, and ZIF-8@MB / AuNPs composite material modified glassy carbon electrode, which are used as ratiometric electrochemical sensors. Figure 4 It can be seen that after ZIF-8 and MB are combined, the DPV current response of MP is significantly reduced, but it provides an internal standard output signal for the sensor. After ZIF-8@MB and AuNPs are combined, the DPV current response of MP is much higher than the current response detected by ZIF-8 and ZIF-8@MB. The ZIF-8@MB / AuNPs / GCE prepared by the present invention can significantly improve the detection effect of MP.

[0069] Example 4

[0070] The preparation of the ratio sensor in this case is the same as that in Example 1, except that the volume of the AuNPs solution is changed so that the volume ratio of the ZIF-8@MB solution to the AuNPs solution is 1 mL:0.0025 mL, 1 mL:0.005 mL, 1 mL:0.01 mL (this is the ratio in Example 1), 1 mL:0.015 mL, 1 mL:0.02 mL. The ZIF-8@MB / AuNPs ratio electrochemical sensor is prepared in the manner of Example 1 and used to detect MP (MP concentration is 10 μg / mL), respectively. The results are shown in FIG. Figure 5 As shown by Figure 5 It can be seen that when the volume ratio of ZIF-8@MB solution to AuNPs solution is 1mL:10μL, the DPV response is the highest and the detection effect is the best; when the volume ratio of ZIF-8@MB solution to AuNPs solution is greater than 1mL:10μL, the detection effect is poor.

[0071] The working principle of the ZIF-8@MB / AuNPs electrochemical sensor of the present invention is: ZIF-8 has a large specific surface area, high porosity and adsorption capacity for MP, which is of great significance for improving the detection ability of MP. With ZIF-8 as a substrate, methylene blue (MB) and gold nanoparticles (AuNPs) are covered on the surface of ZIF-8 and a composite material is formed through physical adsorption, chemical bonding, electron transfer and other interactions. MB is combined with ZIF-8 to provide a stable internal standard output signal, which appears simultaneously with the signal of methyl parathion during detection and does not interfere with each other. The reliability of the sensor will not be reduced due to disturbances of external factors, thereby forming a stable ratio sensor, which makes up for the problem of low accuracy of traditional single signal electrodes. The AuNPs in the ZIF-8@MB / AuNPs electrochemical sensor are covered on the surface of ZIF-8 to further increase the specific surface area, have excellent conductivity and abundant active sites; the synergistic effect of MB, ZIF-8 and AuNPs greatly improves the accuracy, conductivity and electrochemical active surface area of ​​the entire electrochemical sensor. When methyl parathion undergoes redox reaction, with the help of the excellent performance of the modified electrode, obvious redox peaks of methyl parathion and MB will appear during the electrochemical detection process, realizing the qualitative detection of methyl parathion. As the concentration of methyl parathion increases, the peak current intensity of methyl parathion also increases significantly, while the peak current of MB remains stable. Therefore, the ratio of the current peak value corresponding to the concentration of methyl parathion can be compared. MP / I MB The concentration of methyl parathion in the sample to be tested was obtained using a standard curve.

[0072] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a ZIF-8@MB / AuNPs ratiometric electrochemical sensor, characterized in that: The steps include: (1) adding methylene blue to an aqueous solution containing ZIF-8, stirring the reaction at room temperature, and performing solid-liquid separation and washing to obtain a ZIF-8@MB precipitate; The ZIF-8@MB precipitate was dispersed in water to form a ZIF-8@MB solution, to which the AuNPs solution was added and stirred to obtain a ZIF-8@MB / AuNPs composite material solution; (2) The ZIF-8@MB / AuNPs composite material solution is coated on the surface of the pretreated glassy carbon electrode and dried at room temperature to obtain a ZIF-8@MB / AuNPs ratiometric electrochemical sensor.

2. The method for preparing the ZIF-8@MB / AuNPs ratiometric electrochemical sensor according to claim 1, characterized in that: The concentration of the ZIF-8@MB / AuNPs composite material solution is 0.5-1.5 mg / mL, and the amount of the ZIF-8@MB / AuNPs composite material solution coated on the pretreated glassy carbon electrode is 4-8 μL.

3. The method for preparing the ZIF-8@MB / AuNPs ratiometric electrochemical sensor according to claim 1, characterized in that: The ratio of ZIF-8 to water in the aqueous solution containing ZIF-8 is 10-30 mg: 5-20 mL, and the ratio of ZIF-8 to methylene blue is 10-30 mg: 1-10 mg; The concentration of the ZIF-8@MB solution is 0.3-0.8 mg / mL; The dosage ratio of the ZIF-8@MB solution to the AuNPs solution is in the range of 1 mL:5-20 μL.

4. The method for preparing the ZIF-8@MB / AuNPs ratiometric electrochemical sensor according to claim 3, characterized in that: The AuNPs solution is obtained by mixing a tetrachloroauric acid trihydrate solution with water and heating the mixture to complete boiling, then adding a sodium citrate solution, and continuing to heat and stir for 10-30 minutes to obtain an AuNPs solution; Wherein, the tetrachloroauric acid trihydrate solution is 0.05-0.3M, and the volume ratio of the tetrachloroauric acid trihydrate solution to water is 100-400:15-30; the concentration of the sodium citrate solution is 50-200 mg / mL; The volume ratio of the tetrachloroauric acid trihydrate solution to the sodium citrate solution is 100-400:0.05-1.

5. The method for preparing the ZIF-8@MB / AuNPs ratiometric electrochemical sensor according to claim 1, characterized in that: The particle size of the ZIF-8 is less than 2 μm; the stirring reaction time at room temperature is 10-48 hours; the diameter of the glassy carbon electrode is 3 mm, and the glassy carbon electrode is polished with aluminum oxide powder to obtain a pretreated glassy carbon electrode, which is polished with aluminum oxide powders with particle sizes of 0.3 μm and 0.05 μm, respectively.

6. A ZIF-8@MB / AuNPs ratiometric electrochemical sensor prepared by the preparation method according to any one of claims 1 to 5.

7. A method for detecting methyl parathion, characterized in that: The steps include: S1. Prepare a series of concentrations of methyl parathion standard solutions, place the ZIF-8@MB / AuNPs ratio electrochemical sensor prepared by the preparation method according to any one of claims 1 to 5 as a working electrode, a reference electrode and a counter electrode in a series of concentrations of methyl parathion standard solutions, perform differential pulse voltammetry (DPV) detection of a three-electrode system, and obtain DPV response curves corresponding to a series of concentrations of methyl parathion standard solutions. The DPV response curve presents a double peak, and the current peak value that appears in the voltage range of -0.3V to -0.1V is recorded as I MB The current peak value that appears when the voltage is in the range of -0.1V to 1V is recorded as I MP ; A series of concentrations of methyl parathion standard solution C MP As the horizontal axis, the ratio of the current peak value I MP / I MB As the ordinate, draw the standard curve and obtain the standard equation by linear fitting; S2, placing the ZIF-8@MB / AuNPs ratio electrochemical sensor prepared by the above preparation method in the test solution, detecting and recording the measured results by differential pulse voltammetry DPV in a three-electrode system according to step S1, and calculating the ratio of the obtained current peak value I MP / I MB Substituting the value of into the standard equation, the actual concentration of methyl parathion in the test solution is obtained.

8. The method for detecting methyl parathion according to claim 7, characterized in that: A series of concentrations of methyl parathion standard solutions ranged from 5 × 10 -8 ~3×10 -5 g / mL; when testing the solution to be tested, adjusting the pH value of the solution to be tested to 4.5-7; The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum wire.

9. The method for detecting methyl parathion according to claim 8, characterized in that: The standard equation is MP / I MB =0.0541+0.313C MP , R 2 =0.997, the linear range is 50 ng / mL to 30000 ng / mL, and the detection limit concentration of methyl parathion by the ZIF-8@MB / AuNPs ratiometric electrochemical sensor is 16.67 ng / mL.

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