An Electrochemical Pre-Activation Detection Method for Identifying Aromatic Nitro Compound Isomers

Abstract

The present invention provides an electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds, belonging to the field of electrochemical detection. Specifically, when performing differential pulse voltammetry (DPV) electrochemical detection on isomers of aromatic nitro compounds, the isomers of aromatic nitro compounds are first electrochemically pre-activated. Electrochemical pre-activation means applying a negative potential first, and the isomers of aromatic nitro compounds are reduced to isomers of aromatic nitroso compounds. The isomers of aromatic nitroso compounds further undergo redox reactions to generate isomers of aromatic hydroxylamine compounds. When using DPV electrochemical detection for redox reactions, the peak positions of the isomers are spaced relatively far apart, thereby achieving effective identification and detection of isomers of aromatic nitro compounds.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical detection, and particularly relates to an electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds. Background Art

[0002] Aromatic nitro compounds, such as nitroaniline, are widely used in fields such as dyes, fungicides, and pesticides. However, these compounds can cause serious harm to the environment, polluting water sources and soil, and thus affecting the ecosystem. Their harms to human health and aquatic organisms include causing blood diseases, splenotoxicity (associated with splenic sarcoma), and nephrotoxicity. Therefore, it is crucial to monitor the concentration of aromatic nitro compounds in the areas near chemical plants and sewage treatment plants.

[0003] Among many detection techniques, electrochemical detection is widely used in the monitoring of environmental pollutants due to its advantages such as simple operation, high precision, strong sensitivity, and low cost. With the development of nanomaterial-modified glassy carbon electrodes (GCEs), many researchers have successfully achieved the highly sensitive detection of aromatic nitro compounds (such as nitroaniline). For example, Nataraj et al. used Mn@LaZrO modified glassy carbon electrodes to achieve the detection of p-nitroaniline; Krishnapandi et al. used bismuth molybdate-functionalized carbon nanofibers as sensitive materials to successfully achieve the electrochemical detection of o-nitroaniline; Manavalan et al. used a sensor constructed with porous carbon materials to achieve the effective detection of m-nitroaniline and p-nitroaniline. These research results indicate the broad application prospects of electrochemical sensors in the detection of aromatic nitro compounds.

[0004] However, there has been no research that can simultaneously detect the isomers of aromatic nitro compounds such as nitroaniline, mainly because their electrochemical peak positions are very close. (For example, the peak potentials of o-nitroaniline, m-nitroaniline, and p-nitroaniline are -0.617 V, -0.528 V, and -0.620 V respectively), and the peak positions of o-nitroaniline and p-nitroaniline only differ by 3 mV, which makes it difficult to distinguish them in electrochemical detection. Therefore, the existing traditional electrochemical detection methods are difficult to effectively distinguish these isomers.

[0005] To address this problem, in recent years, many researchers have been committed to developing sensors with high performance, low detection limits, and the ability to identify the isomers of aromatic nitro compounds. In this process, designing high-performance sensitive materials is the key, and innovative electrochemical detection techniques provide an important way to distinguish nitroaniline isomers. Summary of the Invention

[0006] To solve the problems existing in the background art, the present invention proposes an electrochemical pre-activation test method for identifying isomers of aromatic nitro compounds. Before performing electrochemical detection of isomers of aromatic nitro compounds using DPV, a pre-activation process is added, so that the isomers of aromatic nitro compounds have separated reduction peaks after being tested by DPV, thereby realizing the identification and detection of isomers of aromatic nitro compounds.

[0007] An electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds proposed by the present invention includes: when performing DPV electrochemical detection on isomers of aromatic nitro compounds, first electrochemically pre-activate the isomers of aromatic nitro compounds.

[0008] Preferably, the isomers of aromatic nitro compounds are converted into isomers of aromatic nitroso compounds after electrochemical pre-activation;

[0009] Preferably, the isomers of aromatic nitro compounds are isomers of nitroaniline or isomers of nitrophenol.

[0010] In the present invention, before performing DPV electrochemical detection, first apply a negative potential through a pre-activation method to reduce the isomers of aromatic nitro compounds; during the pre-activation process, the isomers of aromatic nitro compounds are reduced to isomers of aromatic nitroso compounds; subsequently, when performing DPV electrochemical detection, the isomers of aromatic nitroso compounds will be further reduced to isomers of aromatic hydroxylamine compounds; the peak potential interval of this reduction process is significantly increased compared with the detection without the pre-activation method, so that the isomers of aromatic nitro compounds can be effectively distinguished and identified by the difference in peak positions.

[0011] Preferably, the range of the electrochemical pre-activation potential is 0 - -1.0 V, and the range of the electrochemical pre-activation time is 0 - 210 s;

[0012] Preferably, the electrochemical pre-activation potential is -0.8 V, and the electrochemical pre-activation time is 90 s.

[0013] Preferably, the scanning potential of the DPV electrochemical detection is 0.3 - -0.1 V.

[0014] Preferably, the DPV electrochemical detection is carried out in a three-electrode system including a working electrode, a reference electrode, and a counter electrode;

[0015] Preferably, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a Pt electrode.

[0016] Preferably, when the aromatic nitro compound isomer is a nitroaniline isomer, the working electrode is NiO / CSs / GCE;

[0017] Preferably, the NiO / CSs / GCE is obtained by modifying GCE with NiO / CSs.

[0018] Preferably, the NiO / CSs is obtained by mixing carbonaceous spheres with a Ni source, adsorbing them, and then calcining;

[0019] In the present invention, the NiO / CSs uses carbon spheres CSs as a substrate, and fine particles of NiO are uniformly dispersed on the carbon spheres. It has a high specific surface area. The carbon material has an adsorption effect on the analyte. When it is used to modify a glassy carbon electrode to form a working electrode, it can be used for the analysis and detection of nitroaniline isomers in a three-electrode system.

[0020] Preferably, the carbonaceous spheres are obtained by a hydrothermal reaction of glucose and cetyltrimethylammonium bromide, and the Ni source is nickel phthalocyanine.

[0021] Preferably, when the aromatic nitro compound is nitrophenol, the working electrode is CoO / Co3O4 / CSs / GCE;

[0022] Preferably, the CoO / Co3O4 / CSs / GCE is obtained by modifying GCE with CoO / Co3O4 / CSs.

[0023] In the present invention, the CoO / Co3O4 / CSs also uses carbon spheres CSs as a substrate, and fine particles of CoO and Co3O4 are uniformly dispersed on the carbon spheres CSs. It has a high specific surface area. The carbon material has an adsorption effect on the analyte. When it is used to modify a glassy carbon electrode to form a working electrode, it can be used for the analysis and detection of nitrophenol isomers in a three-electrode system.

[0024] Preferably, the CoO / Co3O4 / CSs is obtained by mixing carbonaceous spheres with a Co source, adsorbing them, and then calcining;

[0025] Preferably, the carbonaceous spheres are obtained by a hydrothermal reaction of glucose and cetyltrimethylammonium bromide, and the Co source is cobalt nitrate.

[0026] Advantages of the present invention:

[0027] (1) The electrochemical pre-activation detection method described in the present invention is essentially to first perform electrochemical pre-activation in a three-electrode system, and then detect the reduction peak of the aromatic nitro compound isomer through DPV testing technology. By the different positions of the oxidation-reduction peaks, the isomers of the aromatic nitro compound can be identified.

[0028] (2) The electrochemical pre-activation detection method of the present invention can not only identify the isomers of nitroaniline, etc., but also quantitatively analyze the isomers of nitroaniline, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram for optimizing the test conditions of the electrochemical pre-activation detection for identifying the isomers of nitroaniline in Example 1: (a) DPV test current response diagram of o-nitroaniline in Example 1 under different pre-activation voltages; (c) DPV test current response diagram of m-nitroaniline in Example 1 under different pre-activation voltages; (e) DPV test current response diagram of p-nitroaniline in Example 1 under different pre-activation voltages; (b) DPV test current response diagram of o-nitroaniline in Example 1 under different pre-activation times; (d) DPV test current response diagram of m-nitroaniline in Example 1 under different pre-activation times; (f) DPV test current response diagram of p-nitroaniline in Example 1 under different pre-activation voltages;

[0030] Figure 2 Schematic diagram for optimizing the buffer test conditions of the electrochemical pre-activation detection for identifying the isomers of nitroaniline in Example 1: (a) DPV test current response diagram of o-nitroaniline in Example 1 in PBS buffer solutions with different pH values; (b) DPV test current response diagram of m-nitroaniline in Example 1 in PBS buffer solutions with different pH values; (c) DPV test current response diagram of p-nitroaniline in Example 1 in PBS buffer solutions with different pH values;

[0031] Figure 3 Diagram of the electrochemical pre-activation detection results of o-nitroaniline in Example 1 under the optimal pre-activation voltage, time and optimal pH buffer conditions: (a) DPV response curve; (b) Calibration diagram of the response current varying with concentration;

[0032] Figure 4 Diagram of the electrochemical pre-activation detection results of m-nitroaniline in Example 1 under the optimal pre-activation voltage, time and optimal pH buffer conditions: (a) DPV response curve; (b) Calibration diagram of the response current varying with concentration;

[0033] Figure 5 Diagram of the electrochemical pre-activation detection results of p-nitroaniline in Example 1 under the optimal pre-activation voltage, time and optimal pH buffer conditions: (a) DPV response curve; (b) Calibration diagram of the response current varying with concentration;

[0034] Figure 6Electrochemical pre-activation detection result graph of o-nitrophenol under the optimal pre-activation voltage, time, and optimal pH buffer conditions described in Example 2: (a) is the DPV response curve; (b) is the calibration graph of the response current varying with concentration;

[0035] Figure 7 Electrochemical pre-activation detection result graph of m-nitrophenol under the optimal pre-activation voltage, time, and optimal pH buffer conditions described in Example 2: (a) is the DPV response curve; (b) is the calibration graph of the response current varying with concentration;

[0036] Figure 8 Electrochemical pre-activation detection result graph of p-nitrophenol under the optimal pre-activation voltage, time, and optimal pH buffer conditions described in Example 2: (a) is the DPV response curve; (b) is the calibration graph of the response current varying with concentration;

[0037] Figure 9 Schematic diagram of the principle of electrochemical pre-activation detection for identifying nitroaniline isomers described in Example 1;

[0038] Figure 10 Comparison graph of DPV response curves for electrochemical pre-activation detection of identifying nitroaniline isomers described in Example 1 (under the optimal pre-activation voltage, pre-activation time, and optimal pH buffer conditions) and Comparative Example 1: (a) is o-nitroaniline; (b) is m-nitroaniline; (c) is p-nitroaniline;

[0039] Figure 11 Test mechanism diagram of electrochemical pre-activation detection for identifying nitroaniline isomers described in the present invention;

[0040] Figure 12 Test mechanism diagram of electrochemical pre-activation detection for identifying o-nitrophenol described in the present invention;

[0041] Figure 13 Test mechanism diagram of electrochemical pre-activation detection for identifying m-nitrophenol described in the present invention;

[0042] Figure 14 Test mechanism diagram of electrochemical pre-activation detection for identifying p-nitrophenol described in the present invention. Detailed implementation mode

[0043] Next, the present invention details the technical solution through specific examples, but it should be clearly stated that these examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention. Example 1

[0044] This example proposes an electrochemical pre-activation detection method for identifying nitroaniline isomers, including:

[0045] (1) Measure 10 mL of PBS buffer with a pH of 7. Use NiO / CSs / GCE (GCE modified with NiO / CSs nanomaterials) as the working electrode, and form a three-electrode system with a reference electrode (Ag / AgCl electrode) and a counter electrode (Pt electrode). Slowly place it into the PBS buffer and test the baseline multiple times on an electrochemical workstation until the electrode is stable;

[0046] The above-mentioned NiO / CSs nanomaterial-modified GCE is prepared by the following method:

[0047] Mix glucose (C6H 12 O6·H2O), cetyltrimethylammonium bromide (CTAB), and deionized water in a mass ratio of 0.49:0.01:1.58. Stir at 50 °C for 1.5 h, transfer to a hydrothermal reaction kettle with a polytetrafluoroethylene lining, and perform a hydrothermal reaction at 180 °C for 5 h. Then, centrifuge and wash successively with ethanol and water to obtain carbonaceous spheres;

[0048] Disperse the above carbonaceous spheres and nickel phthalocyanine in DMF in a mass ratio of 15:1, stir at room temperature for 12 h, then centrifuge and wash successively with DMF and ethanol to obtain carbonaceous spheres adsorbed with nickel phthalocyanine. After drying the carbonaceous spheres adsorbed with nickel phthalocyanine, calcine them at 700 °C for 0.5 h under nitrogen protection to obtain NiO / CSs nanomaterials;

[0049] Add the above NiO / CSs nanomaterials to deionized water and disperse them evenly by ultrasonic treatment to obtain a dispersion with a concentration of 4 mg / mL. Drop 7 μL of this dispersion onto GCE and let it dry naturally in the air to obtain the NiO / CSs nanomaterial-modified GCE;

[0050] (2) Drop 10 μL of an ethanol solution of 100 mM o-nitroaniline, m-nitroaniline, and p-nitroaniline into the above PBS buffer, stir magnetically for 2 min, then turn off the stirring and start electrochemical pre-activation, and immediately start DPV electrochemical detection.

[0051] In the above embodiments, the electrochemical pre-activation and DPV electrochemical detection are completed by setting two windows on an electrochemical workstation. The two windows respectively correspond to the pre-activation window (Window 1) and the redox window (Window 2). Window 1 is a time-current program, and its activation potentials are 0 V, -0.2 V, -0.4 V, -0.6 V, -0.7 V, -0.8 V, -0.9 V respectively, and the corresponding activation times are 0 s, 5 s, 10 s, 20 s, 30 s, 90 s, 150 s, 210 s; Window 2 is a differential pulse voltammetry (DPV) window, the voltage setting range is 0.4 - -1.0 V, the frequency used is 25 Hz, and the amplitude is 25 mV. The current limit for both windows is 1×10 -4 A, save the test curves on the electrochemical workstation, and the results are as Figure 1 shown.

[0052] Figure 1 (a) and (b) are the DPV test current response diagrams of o-nitroaniline at different pre-activation voltages and times, Figure 1 (c) and (d) are the DPV test current response diagrams of m-nitroaniline at different pre-activation voltages and times, Figure 1 (e) and (f) are the DPV test current response diagrams of p-nitroaniline at different pre-activation voltages and times. Referring to Figure 1 it can be seen that in the electrochemical pre-activation detection for identifying nitroaniline isomers, the optimal pre-activation potential is -0.8 V and the pre-activation time is 90 s.

[0053] In the above embodiments, under the conditions of the optimal pre-activation potential and pre-activation time, change the pH of the PBS buffer to 5, 6, 7, 8, 9 respectively, save the test curves on the electrochemical workstation, and the results are as Figure 2 shown; Figure 2 (a), (b), and (c) are the DPV test current response diagrams of o-nitroaniline, m-nitroaniline, and p-nitroaniline in PBS buffer with different pH values respectively. Referring to Figure 2 it can be seen that in the electrochemical detection for identifying nitroaniline isomers, the optimal pH of the PBS buffer is 7.

[0054] In the above embodiments, under the conditions of the optimal pre-activation potential, pre-activation time, and pH = 7 buffer, change the concentrations of o-nitroaniline, m-nitroaniline, and p-nitroaniline solutions to 0.5 μM, 1 μM, 2 μM, 4 μM, 10 μM, 20 μM, 30 μM, 50 μM, 100 μM, 200 μM, 400 μM, 600 μM respectively, save the test curves on the electrochemical workstation, and the results are as Figures 3 - 5 shown, referring to Figures 3 - 5It can be seen that when detecting nitroaniline isomers by electrochemical pre-activation, not only can the content be quantitatively analyzed, but also nitroaniline isomers can be identified according to the different peak positions. Example 2

[0055] This example presents an electrochemical pre-activation detection method for identifying nitro-phenol isomers, including:

[0056] (1) Measure 10 mL of PBS buffer with a pH of 7. Use CoO / Co3O4 / CSs / GCE (GCE modified with CoO / Co3O4 / CSs nanomaterials) as the working electrode, and form a three-electrode system with a reference electrode (Ag / AgCl electrode) and a counter electrode (Pt electrode). Slowly place it into the PBS buffer and test the baseline multiple times on an electrochemical workstation until the electrode is stable.

[0057] The above-mentioned GCE modified with CoO / Co3O4 / CSs nanomaterials is prepared by the following method:

[0058] Mix glucose (C6H 12 O6·H2O), cetyltrimethylammonium bromide (CTAB), and deionized water in a mass ratio of 0.49:0.01:1.58, stir at 50 °C for 1.5 h, transfer to a hydrothermal reaction kettle with a polytetrafluoroethylene liner, and carry out hydrothermal reaction at 180 °C for 5 h. The obtained suspension is centrifugally washed with ethanol and water in sequence to obtain carbonaceous spheres.

[0059] Disperse the above carbonaceous spheres and Co(NO3)2·6H2O in absolute ethanol in a mass ratio of 100:0.58, stir at room temperature for 12 h, and then centrifugally wash with absolute ethanol to obtain carbonaceous spheres adsorbed with Co 2+ ; Dry the carbonaceous spheres adsorbed with Co 2+ and calcine them at 800 °C for 0.5 h under nitrogen protection to obtain CoO / Co3O4 / CSs nanomaterials.

[0060] Add the above CoO / Co3O4 / CSs nanomaterials to absolute ethanol, ultrasonically disperse them evenly to obtain a dispersion with a concentration of 10 mg / mL. Drop 6 μL of this dispersion onto GCE and let it dry naturally in the air to obtain the GCE modified with CoO / Co3O4 / CSs nanomaterials.

[0061] (2) Drop an ethanol solution of a certain concentration of o-nitrophenol, m-nitrophenol, or p-nitrophenol into the above PBS buffer, magnetically stir for 2 min, then turn off the stirring and start electrochemical pre-activation, and then immediately start DPV electrochemical detection.

[0062] In the above embodiments, electrochemical pre-activation and DPV electrochemical detection are completed by setting two windows on an electrochemical workstation. The two windows respectively correspond to the pre-activation window (Window 1) and the redox window (Window 2). Window 1 is a time-current program with an activation potential of -0.6 V and an activation time corresponding to 90 s. Window 2 is a differential pulse voltammetry (DPV) window with a voltage setting range of 0.3 - -1.0 V, a frequency of 25 Hz, and an amplitude of 25 mV. The current limit for both windows is 1×10 -4 A.

[0063] Change the concentrations of o-nitrophenol, m-nitrophenol, and p-nitrophenol solutions to 0.5 μ, 2 μM, 6 μM, 10 μM, 20 μM, 40 μM, 70 μM, 100 μM, 200 μM, 300 μM, 400 μM, 600 μM, 800 μM, 1000 μM respectively, and save the test curves on the electrochemical workstation. The results are as Figures 6 - 8 shown, referring to Figures 6 - 8 it can be seen that nitro-phenol isomers can also be quantitatively analyzed and identified through electrochemical pre-activation detection, indicating that the pre-activation electrochemical detection method is a general and expandable method.

[0064] Comparative Example 1

[0065] This comparative example proposes an electrochemical detection method for identifying nitroaniline isomers, including:

[0066] (1) Measure 10 mL of PBS buffer with a pH of 7. Use NiO / CSs / GCE (GCE modified with NiO / CSs nanomaterials) as the working electrode, and form a three-electrode system with a reference electrode (Ag / AgCl electrode) and a counter electrode (Pt electrode). Slowly place it into the PBS buffer and test the baseline multiple times on the electrochemical workstation until the electrode is stable;

[0067] The above NiO / CSs nanomaterials modified GCE are prepared according to the method described in Example 1;

[0068] (2) Drop 10 µL of 100 mM ethanol solutions of o-nitroaniline, m-nitroaniline, and p-nitroaniline into the above PBS buffer. After magnetic stirring for 2 min, turn off the stirring and start DPV electrochemical detection.

[0069] In the above comparative example, DPV electrochemical testing is completed by setting one window on the electrochemical workstation, that is, the redox window, with a voltage setting range of 0.4 - -1.0 V, a frequency of 25 Hz, and an amplitude of 25 mV. The current limit for both windows is 1×10 -4A, the test curves saved on the electrochemical workstation.

[0070] Figure 9 It is a schematic diagram of the principle of electrochemical pre-activation detection for identifying nitroaniline isomers described in Example 1. Referring to Figure 9 As can be seen, first, the nitroaniline isomers are electrochemically pre-activated. The nitroaniline isomers are reduced to nitrosoaniline isomers, and the nitrosoaniline isomers further undergo redox reactions to form hydroxylaminoaniline isomers. Thereafter, when using differential pulse voltammetry (DPV) for electrochemical detection of the redox reaction, the peak positions of the isomers are relatively far apart, thereby realizing the effective identification and detection of nitroaniline isomers.

[0071] Comparing the test curves obtained in Example 1 under the optimal pre-activation voltage, time, and optimal pH buffer conditions with the test curves obtained in Comparative Example 1 under the above conditions, the results are as Figure 10 shown. Referring to Figure 10 As can be seen, due to the pre-activation step, in the electrochemical test, o-nitroaniline appears at -0.416 V and appears at 0.012 V , m-nitroaniline appears at -0.024 V , p-nitroaniline appears at 0.204 V , and the positions of these reduction peaks are quite different, and the nitroaniline isomers can be identified through them.

[0072] In the present invention, in order to explore the reaction mechanism of electrochemical detection of aromatic nitro compound isomers by cyclic voltammetry (CV), the operation method is as follows:

[0073] (1) Measure 10 mL of PBS buffer with a pH of 7. Use the glassy carbon electrode modified with nanomaterials as the working electrode, and form a three-electrode system with a reference electrode (Ag / AgCl electrode) and a counter electrode (Pt electrode), and slowly place it into the buffer;

[0074] When the aromatic nitro compound isomer is a nitroaniline isomer, the working electrode is NiO / CSs / GCE;

[0075] When the aromatic nitro compound isomer is a nitrophenol isomer, the working electrode is CoO / Co3O4 / CSs / GCE;

[0076] (2) Scan the CV multiple times in the blank buffer until the electrode is stable. Add 10 μL of an ethanol solution of 100 mM o-nitroaniline, m-nitroaniline, and p-nitroaniline to the buffer. After stirring for 2 min, start the CV test. Set the parameters for the CV test: the initial potential is -1.3 V, the highest potential is 0.6 V, the lowest potential is -1.3 V, the final potential is -1.3 V, the sweep rate is 100 mV / s, and the current limit is 1×10 -4 A, and save the test curve on the electrochemical workstation;

[0077] (3) Scan the CV multiple times in the blank buffer until the electrode is stable. Add 10 μL of an ethanol solution of 300 mM o-nitrophenol, m-nitrophenol, and p-nitrophenol to the buffer. After stirring for 2 min, start the CV test. Set the parameters for the CV test: the initial potential is -1.5 V, the highest potential is 0.5 V, the lowest potential is -1.5 V, the final potential is -1.5 V, the sweep rate is 100 mV / s, and the current limit is 1×10 -4 A, and save the test curve on the electrochemical workstation.

[0078] Figure 11 This is the test mechanism diagram of the electrochemical pre-activation detection for identifying nitroaniline isomers. Referring to Figure 11 It can be seen that for the CV curves tested in the blank buffer and after adding 10 μL of 100 mM analyte, there is a reduction peak and a pair of oxidation-reduction peaks for nitroaniline isomers during the electrochemical detection process. The test results confirm the detection mechanism.

[0079] Figures 12 - 14 This is the test mechanism diagram of the electrochemical pre-activation detection for identifying nitrophenol isomers. Referring to Figures 12 - 14 It can be seen that for the CV curves tested in the blank buffer and after adding 10 μL of 300 mM analyte, there is an oxidation peak, a reduction peak, and a pair of oxidation-reduction peaks for o-nitrophenol during the electrochemical detection process, and there is a reduction peak and a pair of oxidation-reduction peaks for m-nitrophenol and p-nitrophenol during the electrochemical detection process. The test results confirm the detection mechanism.

[0080] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered by the protection scope of the present invention.

Claims

1. An electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds, characterized in that: include: When the isomers of aromatic nitro compounds are subjected to DPV electrochemical detection, the isomers of aromatic nitro compounds are first electrochemically preactivated; The aromatic nitro compound isomers are converted into aromatic nitroso compound isomers after electrochemical pre-activation.

2. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 1, characterized in that: The aromatic nitro compound isomers are nitroaniline isomers or nitrophenol isomers.

3. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 1 or 2, characterized in that: The electrochemical pre-activation potential ranges from 0 to -1.0 V, and the electrochemical pre-activation time ranges from 0 to 210 s.

4. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 1 or 2, characterized in that: The electrochemical pre-activation potential is -0.8 V, and the electrochemical pre-activation time is 90 s.

5. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 1 or 2, characterized in that: The DPV electrochemical detection scanning potential is 0.3-0.1 V.

6. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 1 or 2, characterized in that: The DPV electrochemical detection is carried out in a three-electrode system including a working electrode, a reference electrode and a counter electrode; The reference electrode is an Ag / AgCl electrode, and the counter electrode is a Pt electrode.

7. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 6, characterized in that: When the aromatic nitro compound isomers are nitroaniline isomers, the working electrode is a nickel oxide composite carbon sphere nanomaterial modified glassy carbon electrode NiO / CSs / GCE; The NiO / CSs / GCE is obtained by modifying the glassy carbon electrode GCE with nickel oxide composite carbon ball nanomaterial NiO / CSs.

8. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 7, characterized in that: The NiO / CSs is obtained by mixing carbonaceous balls with Ni source for adsorption and then calcining; The carbonaceous ball is prepared by hydrothermal reaction of glucose and hexadecyltrimethylammonium bromide, and the Ni source is nickel phthalocyanine.

9. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 6, characterized in that: When the aromatic nitro compound is nitrophenol, the working electrode is a cobalt oxide / cobalt tetroxide composite carbon sphere nanomaterial modified glassy carbon electrode CoO / Co3O4 / CSs / GCE; The CoO / Co3O4 / CSs / GCE is obtained by modifying the glassy carbon electrode GCE with the cobalt oxide / cobalt tetroxide nanomaterial CoO / Co3O4 / CSs.

10. The electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds according to claim 9, characterized in that: The CoO / Co3O4 / CSs is obtained by mixing carbonaceous balls with a Co source for adsorption and then calcining; The carbonaceous ball is prepared by hydrothermal reaction of glucose and hexadecyltrimethylammonium bromide, and the Co source is cobalt nitrate.

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