Electrochemical pre-activation detection method for identifying aromatic nitro compound isomeride

Abstract

The invention provides an electrochemical pre-activation detection method for identifying an aromatic nitro compound isomeride, and belongs to the field of electrochemical detection.The electrochemical pre-activation detection method is characterized in that when the aromatic nitro compound isomeride is subjected to differential pulse voltammetry (DPV) electrochemical detection, the aromatic nitro compound isomeride is firstly subjected to electrochemical pre-activation; according to the electrochemical pre-activation, a negative potential is applied firstly, an aromatic nitro compound isomeride is reduced into an aromatic nitroso isomeride, the aromatic nitroso isomeride is further subjected to a redox reaction to generate an aromatic hydroxylamine compound isomeride, and when DPV is used for electrochemically detecting the redox reaction, the aromatic hydroxylamine compound isomeride is obtained. The peak position interval of the isomeride is relatively large, so that the effective identification and detection of the aromatic nitro compound isomeride are realized.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical detection, and in particular 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 dyes, fungicides, and pesticides. However, these compounds pose a serious threat to the environment, contaminating water and soil, which in turn affects ecosystems. Their hazards to human health and aquatic life include blood disorders, spleen toxicity (associated with spleen sarcoma), and kidney toxicity. Therefore, it is important to monitor the concentration of aromatic nitro compounds in areas near chemical plants and wastewater treatment plants.

[0003] Among many detection technologies, 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 (GCE), many researchers have successfully achieved high-sensitivity 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 electrochemical detection of o-nitroaniline; Manavalan et al. used sensors constructed with porous carbon materials to achieve effective detection of m-nitroaniline and p-nitroaniline. These research results show the broad application prospects of electrochemical sensors in the detection of aromatic nitro compounds.

[0004] However, there is 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), among which the peak positions of o-nitroaniline and p-nitroaniline differ by only 3 mV, which makes them difficult to distinguish in electrochemical detection. Therefore, the existing traditional electrochemical detection methods are difficult to effectively distinguish these isomers.

[0005] In response to this problem, many researchers have devoted themselves to developing high-performance, low-detection-limit sensors that can identify isomers of aromatic nitro compounds in recent years. In this process, the design of high-performance sensitive materials is the key, and innovative electrochemical detection technology provides an important way to distinguish nitroaniline isomers. Summary of the invention

[0006] In order to solve the problems existing in the background technology, the present invention proposes an electrochemical pre-activation test method for identifying isomers of aromatic nitro compounds. Before using DPV to perform electrochemical detection on isomers of aromatic nitro compounds, a pre-activation process is added so that the isomers of aromatic nitro compounds have separate reduction peaks after DPV testing, thereby realizing the identification and detection of isomers of aromatic nitro compounds.

[0007] The present invention provides an electrochemical pre-activation detection method for identifying isomers of aromatic nitro compounds, comprising: when performing DPV electrochemical detection on the isomers of aromatic nitro compounds, firstly electrochemically pre-activating the isomers of aromatic nitro compounds.

[0008] Preferably, the aromatic nitro compound isomers are converted into aromatic nitroso compound isomers after electrochemical pre-activation; Preferably, the aromatic nitro compound isomers are nitroaniline isomers or nitrophenol isomers.

[0009] In the present invention, before performing DPV electrochemical detection, a negative potential is first applied through a pre-activation method to reduce the isomers of the aromatic nitro compound; during the pre-activation process, the isomers of the aromatic nitro compound are reduced to the isomers of the aromatic nitroso compound; when DPV electrochemical detection is subsequently performed, the isomers of the aromatic nitroso compound are further reduced to the isomers of the aromatic hydroxylamine compound; the peak potential interval of this reduction process is significantly increased compared to the case of detection without the pre-activation method, so that the isomers of the aromatic nitro compound can be effectively distinguished and identified through the difference in the peak positions.

[0010] Preferably, the electrochemical pre-activation potential ranges from 0 to -1.0 V, and the electrochemical pre-activation time ranges from 0 to 210 s; Preferably, the electrochemical pre-activation potential is -0.8 V, and the electrochemical pre-activation time is 90 s.

[0011] Preferably, the DPV electrochemical detection scanning potential is 0.3-0.1 V.

[0012] Preferably, the DPV electrochemical detection is performed in a three-electrode system comprising a working electrode, a reference electrode and a counter electrode; Preferably, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a Pt electrode.

[0013] Preferably, when the aromatic nitro compound isomer is a nitroaniline isomer, the working electrode is NiO / CSs / GCE; Preferably, the NiO / CSs / GCE is obtained by modifying GCE with NiO / CSs.

[0014] Preferably, the NiO / CSs is obtained by mixing carbonaceous balls with a Ni source and adsorbing them before calcining; In the present invention, the NiO / CSs is based on carbon ball CSs, and fine NiO particles are uniformly dispersed on the carbon ball. It has a high specific surface area. The carbon material has an adsorption effect on the analyte. When it is used to modify the glassy carbon electrode to form a working electrode, it can be used to analyze and detect nitroaniline isomers in a three-electrode system.

[0015] Preferably, the carbonaceous spheres are prepared by hydrothermal reaction of glucose and hexadecyltrimethylammonium bromide, and the Ni source is nickel phthalocyanine.

[0016] Preferably, when the aromatic nitro compound is nitrophenol, the working electrode is CoO / Co3O4 / CSs / GCE; Preferably, the CoO / Co3O4 / CSs / GCE is obtained by modifying GCE with CoO / Co3O4 / CSs.

[0017] In the present invention, the CoO / Co3O4 / CSs is also based on the carbon ball CSs, and the fine particles of CoO and Co3O4 are uniformly dispersed on the carbon ball CSs, which has a high specific surface area. The carbon material has an adsorption effect on the analyte. When it is used to modify the glassy carbon electrode to form a working electrode, it can be used to analyze and detect nitrophenol isomers in a three-electrode system.

[0018] Preferably, the CoO / Co3O4 / CSs is obtained by mixing carbonaceous balls with a Co source and adsorbing them before calcining; Preferably, the carbonaceous spheres are prepared by hydrothermal reaction of glucose and hexadecyltrimethylammonium bromide, and the Co source is cobalt nitrate.

[0019] Beneficial effects of the present invention: (1) The electrochemical pre-activation detection method of the present invention is essentially to first perform electrochemical pre-activation in a three-electrode system, and then detect the reduction peaks of the isomers of the aromatic nitro compound by the DPV testing technology, and identify the isomers of the aromatic nitro compound by the different positions of the redox peaks.

[0020] (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

[0021] Figure 1Schematic diagram of test condition optimization for electrochemical pre-activation detection of nitroaniline isomers described in Example 1: (a) is a DPV test current response diagram of o-nitroaniline at different pre-activation voltages described in Example 1; (c) is a DPV test current response diagram of m-nitroaniline at different pre-activation voltages described in Example 1; (e) is a DPV test current response diagram of p-nitroaniline at different pre-activation voltages described in Example 1; (b) is a DPV test current response diagram of o-nitroaniline at different pre-activation times described in Example 1; (d) is a DPV test current response diagram of m-nitroaniline at different pre-activation times described in Example 1; (f) is a DPV test current response diagram of p-nitroaniline at different pre-activation voltages described in Example 1; Figure 2 Schematic diagram of optimization of buffer test conditions for electrochemical pre-activation detection of nitroaniline isomers described in Example 1: (a) DPV test current response graph of o-nitroaniline in PBS buffers of different pH values ​​described in Example 1; (b) DPV test current response graph of m-nitroaniline in PBS buffers of different pH values ​​described in Example 1; (c) DPV test current response graph of p-nitroaniline in PBS buffers of different pH values ​​described in Example 1; Figure 3 The electrochemical pre-activation detection results of o-nitroaniline under the optimal pre-activation voltage, time and optimal pH buffer conditions described in Example 1 are shown in Figures: (a) is a DPV response curve; (b) is a calibration diagram of the response current changing with concentration; Figure 4 The electrochemical pre-activation detection results of m-nitroaniline under the optimal pre-activation voltage, time and optimal pH buffer conditions described in Example 1 are shown in Figures: (a) is a DPV response curve; (b) is a calibration diagram of the response current changing with concentration; Figure 5 The electrochemical pre-activation detection results of p-nitroaniline under the optimal pre-activation voltage, time and optimal pH buffer conditions described in Example 1 are shown in Figures: (a) is a DPV response curve; (b) is a calibration diagram of the response current changing with concentration; Figure 6 The electrochemical pre-activation detection results of o-nitrophenol under the optimal pre-activation voltage, time and optimal pH buffer conditions described in Example 2 are shown in Figures: (a) is a DPV response curve; (b) is a calibration diagram of the response current changing with concentration; Figure 7 The electrochemical pre-activation detection results of m-nitrophenol under the optimal pre-activation voltage, time and optimal pH buffer conditions described in Example 2 are shown in Figures: (a) is a DPV response curve; (b) is a calibration diagram of the response current changing with concentration; Figure 8The electrochemical pre-activation detection results of p-nitrophenol under the optimal pre-activation voltage, time and optimal pH buffer conditions described in Example 2 are shown in Figures: (a) is a DPV response curve; (b) is a calibration diagram of the response current changing with concentration; Fig. 9 This is a schematic diagram of the principle of the electrochemical pre-activation detection for identifying nitroaniline isomers described in Example 1; Fig.10 The DPV response curve comparison diagram of the electrochemical pre-activation detection for identifying nitroaniline isomers in Example 1 (under the optimal pre-activation voltage, pre-activation time and optimal pH buffer conditions) and Comparative Example 1 is as follows: (a) is o-nitroaniline; (b) is m-nitroaniline; (c) is p-nitroaniline; Fig.11 The test mechanism diagram of the electrochemical pre-activation detection for identifying nitroaniline isomers according to the present invention; Fig.12 This is a test mechanism diagram of the electrochemical pre-activation detection for identifying o-nitrophenol according to the present invention; Fig.13 This is a test mechanism diagram of the electrochemical pre-activation detection for identifying m-nitrophenol according to the present invention; Fig.14 This is a test mechanism diagram of the electrochemical pre-activation detection for identifying p-nitrophenol according to the present invention. DETAILED DESCRIPTION

[0022] Hereinafter, the present invention will describe the technical solution in detail through specific embodiments, but it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention. Example 1

[0023] This embodiment provides an electrochemical pre-activation detection method for identifying nitroaniline isomers, comprising: (1) Take 10 mL of PBS buffer with a pH of 7, use NiO / CSs / GCE (NiO / CSs nanomaterial modified GCE) as the working electrode, and slowly put it into the PBS buffer to form a three-electrode system with the reference electrode (Ag / AgCl electrode) and the counter electrode (Pt electrode). Test the baseline multiple times on the electrochemical workstation until the electrode is stable. The NiO / CSs nanomaterial modified GCE is prepared by the following method: Glucose (C6H 12O6·H2O), hexadecyltrimethylammonium bromide (CTAB) and deionized water were mixed in a mass ratio of 0.49:0.01:1.58, stirred at 50 °C for 1.5 h, transferred to a hydrothermal reactor containing a polytetrafluoroethylene liner, and hydrothermally reacted at 180 °C for 5 h, and then centrifuged and washed with ethanol and water in sequence to obtain carbonaceous balls; The carbonaceous balls and nickel phthalocyanine were dispersed in DMF at a mass ratio of 15:1, stirred at room temperature for 12 h, and then centrifuged and washed with DMF and ethanol in turn to obtain carbonaceous balls adsorbing nickel phthalocyanine; the carbonaceous balls adsorbing nickel phthalocyanine were dried, and then calcined at 700 °C for 0.5 h under nitrogen protection to obtain NiO / CSs nanomaterials; The NiO / CSs nanomaterials were added to deionized water and dispersed evenly by ultrasonication to obtain a dispersion with a concentration of 4 mg / mL, 7 μL of the dispersion was dropped on the GCE and dried naturally in the air to obtain the NiO / CSs nanomaterial modified GCE; (2) 10 μL of 100 mM ethanol solution of o-nitroaniline, m-nitroaniline, and p-nitroaniline was added dropwise to the above PBS buffer. After magnetic stirring for 2 min, stirring was turned off to start electrochemical preactivation, and then DPV electrochemical detection was immediately started.

[0024] In the above embodiment, electrochemical pre-activation and DPV electrochemical detection are completed by setting two windows on the electrochemical workstation, and the two windows correspond to the pre-activation window (window one) and the redox window (window two), respectively. Window one is a time-current program, and its activation potential is 0 V, -0.2 V, -0.4 V, -0.6 V, -0.7 V, -0.8 V, -0.9 V, and the activation time is 0 s, 5 s, 10 s, 20 s, 30 s, 90 s, 150 s, 210 s, respectively; Window two is a differential pulse voltammetry (DPV) window, and the voltage setting range is 0.4- -1.0 V, the operating frequency is 25 Hz, the amplitude is 25 mV, and the current limit of the two windows is 1×10 -4 A, save the test curve on the electrochemical workstation, the result is as follows Figure 1 shown.

[0025] 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, refer to Figure 1It can be seen that in the electrochemical pre-activation detection of nitroaniline isomers, the optimal pre-activation potential is -0.8 V and the pre-activation time is 90 s.

[0026] In the above embodiment, under the optimal pre-activation potential and pre-activation time conditions, the pH of the PBS buffer was changed to 5, 6, 7, 8, and 9, and the test curve on the electrochemical workstation was saved. The results are as follows: Figure 2 As shown; Figure 2 (a), (b), and (c) are the DPV test current responses of o-nitroaniline, m-nitroaniline, and p-nitroaniline in PBS buffers at different pH values, respectively. Figure 2 It can be seen that in the electrochemical detection of nitroaniline isomers, the optimal pH of PBS buffer is 7.

[0027] In the above embodiment, under the conditions of the optimal preactivation potential and preactivation time and pH=7 buffer solution, the concentrations of o-nitroaniline, m-nitroaniline and p-nitroaniline solutions were changed to 0.5 μM, 1 μM, 2 μM, 4 μM, 10 μM, 20 μM, 30 μM, 50 μM, 100 μM, 200 μM, 400 μM and 600 μM, respectively, and the test curve on the electrochemical workstation was saved. The results are as follows: Figure 3-5 As shown, refer to Figure 3-5 It can be seen that when nitroaniline isomers are detected by electrochemical pre-activation, not only can the content be quantitatively analyzed, but also the nitroaniline isomers can be identified according to the different peak positions. Example 2

[0028] This embodiment provides an electrochemical pre-activation detection method for identifying nitrophenol isomers, comprising: (1) Take 10 mL of PBS buffer with a pH of 7, use CoO / Co3O4 / CSs / GCE (CoO / Co3O4 / CSs nanomaterial modified GCE) as the working electrode, and slowly put it into the PBS buffer to form a three-electrode system with the reference electrode (Ag / AgCl electrode) and the counter electrode (Pt electrode). Test the baseline multiple times on the electrochemical workstation until the electrode is stable. The above-mentioned CoO / Co3O4 / CSs nanomaterial modified GCE is prepared by the following method: Glucose (C6H 12 O6·H2O), cetyltrimethylammonium bromide (CTAB) and deionized water were mixed in a mass ratio of 0.49:0.01:1.58, stirred at 50 °C for 1.5 h, transferred to a hydrothermal reactor containing a polytetrafluoroethylene liner, and hydrothermally reacted at 180 °C for 5 h. The resulting suspension was centrifugally washed with ethanol and water in turn to obtain carbonaceous balls. The carbonaceous balls and Co(NO3)2·6H2O were dispersed in anhydrous ethanol at a mass ratio of 100:0.58, stirred at room temperature for 12 h, and then washed by centrifugation with anhydrous ethanol to obtain the adsorbed Co 2+ The carbonaceous ball adsorbs Co 2+ After the carbonaceous balls were dried, they were calcined at 800 °C for 0.5 h under nitrogen protection to obtain CoO / Co3O4 / CSs nanomaterials. The CoO / Co3O4 / CSs nanomaterials were added to anhydrous ethanol and dispersed evenly by ultrasonication to obtain a dispersion with a concentration of 10 mg / mL. 6 μL of the dispersion was dropped on the GCE and dried naturally in the air to obtain the CoO / Co3O4 / CSs nanomaterial modified GCE. (2) A certain concentration of o-nitrophenol, m-nitrophenol or p-nitrophenol ethanol solution was added dropwise to the above PBS buffer. After magnetic stirring for 2 min, the stirring was turned off to start electrochemical pre-activation, and then DPV electrochemical detection was immediately started.

[0029] In the above embodiment, the electrochemical pre-activation and DPV electrochemical detection are completed by setting two windows on the electrochemical workstation, and the two windows correspond to the pre-activation window (window one) and the redox window (window two), respectively. Window one is a time-current program, and its activation potential is -0.6 V, and the activation time corresponds to 90 s; Window two is a differential pulse voltammetry (DPV) window, and the voltage setting range is 0.3 - -1.0 V, the operating frequency is 25 Hz, the amplitude is 25 mV, and the current limit of the two windows is 1×10 -4 A.

[0030] The concentrations of o-nitrophenol, m-nitrophenol, and p-nitrophenol solutions were changed to 0.5 μM, 2 μM, 6 μM, 10 μM, 20 μM, 40 μM, 70 μM, 100 μM, 200 μM, 300 μM, 400 μM, 600 μM, 800 μM, and 1000 μM, respectively. The test curves on the electrochemical workstation were saved. The results are shown in Figure 2. Figure 6-8 As shown, refer to Figure 6-8 It can be seen that nitrophenol isomers can also be quantitatively analyzed and identified through electrochemical pre-activation detection, indicating that the pre-activation electrochemical detection method is a universal and scalable method.

[0031] Comparative Example 1 This comparative example proposes an electrochemical detection method for identifying nitroaniline isomers, comprising: (1) Take 10 mL of PBS buffer with a pH of 7, use NiO / CSs / GCE (NiO / CSs nanomaterial modified GCE) as the working electrode, and slowly put it into the PBS buffer to form a three-electrode system with the reference electrode (Ag / AgCl electrode) and the counter electrode (Pt electrode). Test the baseline multiple times on the electrochemical workstation until the electrode is stable. The NiO / CSs nanomaterial modified GCE was prepared by referring to the method described in Example 1; (2) 10 μL of 100 mM ethanol solution of o-nitroaniline, m-nitroaniline, and p-nitroaniline was added dropwise to the above PBS buffer. After magnetic stirring for 2 min, the stirring was turned off and DPV electrochemical detection was started.

[0032] In the above comparative example, the DPV electrochemical test was completed by setting a window on the electrochemical workstation, namely the redox window, with a voltage setting range of 0.4 - -1.0 V, a frequency of 25 Hz, an amplitude of 25 mV, and a current limit of 1×10 -4 A, Test curve saved on the electrochemical workstation.

[0033] Fig. 9 Schematic diagram of the principle of electrochemical pre-activation detection for identifying nitroaniline isomers as described in Example 1, referring to Fig. 9 It can be seen that the nitroaniline isomers are first electrochemically preactivated, the nitroaniline isomers are reduced to nitrosoaniline isomers, and the nitrosoaniline isomers further undergo redox reactions to generate hydroxylaminoaniline isomers. Thereafter, when DPV electrochemical detection of the redox reaction is used, the peak positions of the isomers are spaced relatively wide, thereby achieving effective identification and detection of nitroaniline isomers.

[0034] The test curve obtained by comparing Example 1 under the conditions of the optimal pre-activation voltage, time and optimal pH buffer and the test curve obtained by Comparative Example 1 under the above conditions are as follows: Fig.10 See Fig.10 It can be seen that due to the pre-activation step, o-nitroaniline appears at -0.416 V in the electrochemical test. and appears at 0.012 V , m-nitroaniline appears at -0.024 V , p-nitroaniline appears at 0.204 V The positions of these reduction peaks are quite different, and nitroaniline isomers can be identified by them.

[0035] In the present invention, in order to explore the reaction mechanism of electrochemical detection of isomers of aromatic nitro compounds by cyclic voltammetry (CV), the operation method is as follows: (1) Take 10 mL of PBS buffer with a pH of 7, use the glassy carbon electrode modified with nanomaterials as the working electrode, and slowly place it into the buffer to form a three-electrode system with the reference electrode (Ag / AgCl electrode) and the counter electrode (Pt electrode); When the aromatic nitro compound isomer is nitroaniline isomer, the working electrode is NiO / CSs / GCE; When the aromatic nitro compound isomers are nitrophenol isomers, the working electrode is CoO / Co3O4 / CSs / GCE; (2) Scan CV multiple times in a blank buffer until the electrode is stable. Add 10 μL of 100 mM ethanol solution of o-nitroaniline, m-nitroaniline, and p-nitroaniline into the buffer and stir for 2 min before starting the CV test. Set the parameters of the CV test as follows: starting potential is -1.3 V, maximum potential is 0.6 V, minimum potential is -1.3 V, final potential is -1.3 V, sweep rate is 100 mV / s, and current limit is 1×10 -4 A, save the test curve on the electrochemical workstation; (3) Perform CV scans multiple times in a blank buffer until the electrode is stable. Add 10 μL of 300 mM ethanol solution of o-nitrophenol, m-nitrophenol, and p-nitrophenol to the buffer and stir for 2 min before starting the CV test. Set the parameters of the CV test as follows: starting potential is -1.5 V, maximum potential is 0.5 V, minimum potential is -1.5 V, final potential is -1.5 V, sweep rate is 100 mV / s, and current limit is 1×10 -4 A, Save the test curve on the electrochemical workstation.

[0036] Fig.11 The test mechanism diagram of the electrochemical pre-activation detection of nitroaniline isomers according to the present invention is shown in FIG. Fig.11 It can be seen that the CV curves of the blank buffer and the test after adding 10 μL of 100 mM analyte show that the nitroaniline isomers have a reduction peak and a pair of redox peaks in the electrochemical detection process. The test results confirm the detection mechanism.

[0037] Figure 12-14 The test mechanism diagram of the electrochemical pre-activation detection for identifying nitrophenol isomers according to the present invention is shown in FIG. Figure 12-14It can be seen that the CV curves of the blank buffer and the test after adding 10 μL of 300 mM analyte show that there is an oxidation peak, a reduction peak and a pair of redox peaks for o-nitrophenol in the electrochemical detection process, and there is a reduction peak and a pair of redox peaks for m-nitrophenol and p-nitrophenol in the electrochemical detection process. The test results confirm the detection mechanism.

[0038] 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. 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 firstly subjected to 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 converted into aromatic nitroso compound isomers after electrochemical pre-activation; 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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