KR102075700B1 - Reduced graphene oxide sensor coated with polydiaminobenzene thin film and electrochemical determination of nitrite using the same - Google Patents

Abstract

The present invention relates to a reduced graphene oxide sensor coated with a polydiaminobenzene thin film and an electrochemical detection method of nitrite using the same, and more particularly, a reduced oxidation coated with a polydiaminobenzene (p-DAB) thin film. Graphene sensors exhibit higher reactivity to nitrite by forming p-DAB films on reduced graphene oxide (ERGO) -modified glassy carbon electrodes, and are particularly sensitive and nitrite sensitive to other interference ions due to their high sensitivity and selectivity. As the detection limit is 30 nM and shows excellent nitrite detection performance, it is possible to more effectively detect nitrite ions in water samples such as drinking water or tap water.

Description

Reduced graphene oxide sensor coated with polydiaminobenzene thin film and electrochemical determination of nitrite using the same}

The present invention relates to a reduced graphene oxide sensor coated with a polydiaminobenzene thin film and an electrochemical detection method of nitrite in a water sample using the same.

Nitrite ions are of interest because they play an important role in important environmental conservation and anthropogenic activities, and are mainly found in detergents, corrosion inhibitors, fertilizers and industrial wastewater. Nitrite ions oxidize hemoglobin to methemoglobin, reducing the oxygen-carrying capacity of the blood. Low levels of oxygen in the human body cause blue child syndrome, leading to death. Nitrite also reacts with secondary amines and amides to form N-nitrosamine derivatives, causing gastric cancer.

The World Health Organization (WHO) defines a maximum allowable amount of nitrite ions in drinking water of 50 mg / L. Contamination of nitrites in drinking water causes many medical problems, leading to problems such as intrauterine growth limitations, natural heritage and birth defects in the central nervous system. Therefore, accurate detection of nitrite is very important.

Various methods for the analysis of nitrite concentrations are known, for example, chromatography, capillary electrophoresis, spectroscopic analysis, cyclic voltammetry and the like. Among these methods, electrochemical methods have advantages over other methods because they can be cheaper, faster, more accurate and simpler to prepare.

Electrochemical detection of nitrite is carried out by reduction or oxidation, and oxidative detection of nitrite is preferred because it can be performed without interference such as nitrate and molecular oxygen. The measurement of nitrite concentrations on pure electrodes has the disadvantage that the electrodes are poisoned by species formed during high overpotential or oxidation, which can reduce the sensitivity and accuracy of the electrodes. Therefore, it is very important to modify the electrode with a suitable material capable of oxidizing nitrite ions at low overpotentials.

For oxidation of nitrite, electrode modified with graphene oxide / multi-walled carbon nanotube composite functionalized with cetyltrimethylammonium bromide (CTAB), Ag catalytic modified electrode supported on graphene nanosheet functionalized with TiO ₂ , Ag nano Electrode modified with multi-walled carbon nanotubes coated with particles, Electrode modified with ferrocene-dendrimer film coated with gold nanoparticles, Glassy carbon electrode modified with graphene / polypyrrole / chitosan nanocomposites, Cytochrome c immobilized Electrodes modified with poly-3-methylthiophene / multi-walled carbon nanotube hybrids and the like are used.

On the other hand, these electrodes have disadvantages such as the use of expensive materials, higher operating potential, narrow range of measurement, etc., and therefore, there is still a need for the development of more sensitive and selective nitrite detection electrodes and detection methods in the presence of general obstacles. It is true.

Republic of Korea Patent No. 10-0461921 (2004.12.06)

An object of the present invention is to provide a sensor capable of detecting sensitive nitrite ions present in a water sample with high sensitivity and a nitrite ion detection method using the same.

In order to achieve the above object, the present invention is an electrode modified with reduced graphene oxide; And a polydiaminobenzene thin film coated on the reduced graphene oxide.

In addition, the present invention comprises the steps of drop-casting the graphene oxide (GO) on the electrode (first step); Electrochemically reducing the electrode modified with graphene oxide (second step); Preparation of a nitrite detection sensor comprising the step of adding diaminobenzene on the electrode modified with reduced graphene oxide and performing a potential scan to form polydiaminobenzene on the electrode (third step) Provide a method.

The present invention also provides a nitrite detection method using the nitrite detection sensor.

The reduced graphene oxide sensor coated with a polydiaminobenzene (p-DAB) thin film according to the present invention has a higher nitrite by forming a p-DAB film on a reduced graphene oxide (ERGO) modified glassy carbon electrode. Nitrite ions in water samples, such as drinking water or tap water, can be detected as the sensitivity and selectivity are particularly excellent, so that nitrite can be detected sensitively even if there are other interfering ions, and the detection limit is 30 nM. Can be detected more effectively.

1 is a conceptual diagram of a reduced graphene oxide sensor coated with a polydiaminobenzene (p-DAB) thin film according to the present invention,
Figure 2 shows the CV results for the electrochemical reduction of GO on the glassy carbon electrode (GCE),
FIG. 3A shows the potentiodynamic formation of a pDAB film (15 cycles) on a pure electrode GC electrode (red line: 1-4th cycle, green line: 5-14th cycle, black line: 15th cycle), FIG. 3B shows the potentiodynamic formation of the pDAB film (15 cycles) on the ERGO-modified electrode,
4 shows SEM images of GO, ERGO, p-DABDAGC and p-DAB ＠ ERGO / GC film-modified plates (A: GO / GC, B: ERGO / GC, C: p-DAB ＠ GC) , D: high magnification p-DAB ＠ GC, E: p-DAB ＠ ERGO / GC, F: high magnification p-DAB ＠ ERGO / GC plate),
5A shows the XPS spectra of GO / GC (a), ERGO / GC (b) and p-DAB ＠ ERGO / GC (c) plates,
5B is an extended spectral result for N 1s of the p-DAB ＠ ERGO / GC plate,
6 shows Raman analysis results of GO / GC and ERGO / GC plates,
FIG. 7 shows EIS analysis results of pure GC (a), p-DAB ＠ GC (b) and p-DAB ＠ ERGO / GC (c) film-modified electrodes,
8 shows the CVs of pure GC (a), p-DABDAGC (b), and p-DAB ＠ ERGO / GC (c) film-modified electrodes for nitrite analysis,
9 shows differential pulse voltammetry (DPV) using p-DABDAERGO / GC (c) film-modified electrode at 7 μM nitrite concentration in 0.2 M phosphate buffer (PB) (pH 7.2) solution. To represent
Figure 10A shows the addition of nitrite at regular intervals of 60 seconds in a 0.2 M PB (pH 7.2) electrolyte solution at +0.76 V application potential to analyze nitrite on p-DAB®ERGO / GC film-modified electrodes (each time 7 Increasing concentration of μM) shows the amperometric it curve obtained, FIG. 10B in 0.2 M PB (pH 7.2) electrolyte solution under application potential of +0.76 V for nitrite analysis on p-DAB ＠ ERGO / GC film-modified electrode Various concentrations of nitrite are added at regular intervals of 60 seconds (increasing concentrations (a) 7, (b) 10, (c) 20, (d) 30, (e) 40, (f) 50, (g) 60, (h) 70, (i) 80, (j) 90, (k) 100, (l) 200, (m) 500, (n) 1000, (o) 2000, (p) 3000, (q) 4000, (r) 5000, (s) 7000, (t) 10,000, and (u) 20,000 μM) obtained amperometric it curves,
FIG. 11 shows a current measurement it curve for confirming the interference effect of nitrite detection of p-DABDAERGO / GC film-modified electrode in a 0.2 M PB pH 7.2 solution (a: nitrite 10 μM, and b: nitrite + NO ₃ ^-, c: nitrite + HCO ₃ ^{2 -,} d: nitrite + SO ₄ ^2-, e: nitrite + NaOH, f: nitrite + SO ₃ ^2-, g: nitrite + CO ₃ ^2- Is 1 mM each),
FIG. 12 shows spikes with (a) water samples and commercial nitrite ((b) 10 μM, (c) 30 μM NO _{2 at} p-DAB®ERGO / GC film-modified electrode in 0.2 M PB pH 7.2 electrolyte solution. ^- ) Shows DPV obtained after

Hereinafter, the present invention will be described in more detail.

The inventors of the present invention showed higher reactivity to nitrite by forming a polydiaminobenzene thin film on the electrode modified with reduced graphene oxide while researching and developing an electrochemical detection sensor which is more useful for nitrite detection. In particular, the present invention has been found to be able to detect nitrite sensitively even with other interfering ions because of its excellent sensitivity and selectivity, and has a detection limit of 30 nM, which shows excellent nitrite detection performance.

The present invention is an electrode modified with reduced graphene oxide; And a polydiaminobenzene thin film coated on the reduced graphene oxide.

The electrode may be a glassy carbon electrode, but is not limited thereto.

In addition, the present invention comprises the steps of drop-casting the graphene oxide on the electrode (first step); Electrochemically reducing the electrode modified with graphene oxide (second step); It provides a method for manufacturing a nitrite detection sensor comprising the step (third step) of forming a polydiaminobenzene on the electrode by adding diamino benzene on the electrode modified with reduced graphene oxide and performing a potential scan do.

In the second step, it is preferable to reduce the electrochemically modified electrode with graphene oxide for 5 to 50 cycles at a scan rate of 20 to 100 mV / s and a potential of 0 to -2.0 V. The reduction may not be sufficient or the reduction may proceed too much, which may cause a problem that the diaminobenzene is not well attached.

In the third step, diaminobenzene is added on the electrode modified with reduced graphene oxide, and potential scanning is performed for 5 to 50 cycles at a scan rate of 20 to 100 mV / s and a potential of -0.5 to 2.0 V. It is preferable to form polydiaminobenzene on the electrode, and beyond this range, problems may occur that the diaminobenzene does not adhere well or the polydiaminobenzene does not form well.

The electrode may be a glassy carbon electrode, but is not limited thereto.

In the present invention, before the first step, the step of cleaning the electrode; Alternatively, the method may further include one or more of the steps of preparing a homogeneous suspension by mixing graphene oxide with ethanol containing Nafion solution and sonicating.

More preferably, the present invention comprises the steps of cleaning the electrode; Or mixing graphene oxide with ethanol containing a Nafion solution and sonicating to prepare a homogeneous suspension; Dropcasting graphene oxide onto the electrode; Electrochemically reducing the electrode modified with graphene oxide; It provides a method for producing a nitrite detection sensor comprising the step of adding diaminobenzene on the electrode modified with reduced graphene oxide and performing a potential scan to form a polydiaminobenzene on the electrode.

In addition, the present invention comprises the steps of adjusting the pH of the water sample to 7.0 to 7.4; It provides a nitrite detection method comprising the step of analyzing the pH adjusted water sample in the nitrite detection sensor according to claim 1.

The pH of the water sample is more preferably 7.2.

The water sample may be selected from beverages, tap water or lake water, but is not limited thereto.

The analysis is preferably performed by differential pulse voltammetry (DPV), but is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by these examples.

< Example  1> Polydiaminobenzene  Electrochemically reduced thin film (p-DAB) Graphene oxide (ERGO) sensor production

Graphene oxide (GO) was synthesized from graphite powder using a conventionally known improved Hummers method. 1 shows a conceptual diagram of a method for forming p-DAB on an ERGO-modified glassy carbon (GC) electrode.

That is, the glassy carbon electrode (GCE) was wiped with emery paper and then with 0.5 and 0.05 μm alumina slurries and thoroughly washed with water. GO was mixed with ethanol (1 mg / mL) containing 5 μL of 5% Nafion solution and this mixture was sonicated to prepare a homogeneous suspension. 10 μL of this drop of liquid was dropped onto the GCE surface (named GO / GC electrode). GO attached to the surface was electrochemically reduced (named ERGO / GC electrode) to a potential cycle of 0 to -1.5 V (in 0.2 M PB, pH 7.2) for 15 cycles at a scan rate of 50 mV / s. 15 consecutive potential injections of -0.20 to +1.6 V at a scan rate of 50 mV / s using 1 mM p-diaminobenzene dissolved in 0.1 M sulfuric acid solution for the polymerization of diaminobenzene on ERGO / GC electrodes (potential sweep) was performed (named p-DAB®ERGO / GC film-modified electrode). For SEM, Raman analysis and XPS, GO / GC, ERGO / GC, p-DAB ＠ GC and p-DAB ＠ ERGO / GC film-modified plates were prepared and used in the same manner in the present invention.

< Example  2> real sample analysis

Bottled drinking water was purchased at the market, and tap and well water was collected nearby. The pH of the water was adjusted to pH 7.2 (PB) and transferred to the electrochemical cell according to Example 1 for analysis without pretreatment.

Experimental Example 1 Characterization of p-DAB®ERGO / GC Film

In order to analyze the characteristics of the p-DAB ＠ ERGO / GC film prepared in Example 1 was performed as follows.

1. Method of Analysis

Shape analysis was performed using FE-SEM (Hitachi S4800), Raman analysis using an XploRA PLUS Raman microscope (Horiba) at an emission wavelength of 532 nm, and XPS using K-Alfa system (Thermo Scientific). The C 1s peak (284.6 eV) of the carbon sample was corrected and analyzed using XPSPEAK41 software. After removing the Shirley background, all spectra were fitted with convolution of the Gaussian function. All electrochemical experiments were performed at the Autolab PGSTAT302N electrochemical workstation (Metrohm-Autolab BV, Netherlands), and a typical three-electrode electrochemical cell was used. 3 mm glassy carbon electrodes (GCE), Pt wires and saturated caramel electrodes (SCE) were used as working electrodes, counter electrodes and standard electrodes, respectively. All electrochemical measurements were performed at room temperature under a nitrogen atmosphere.

2. Analysis Results

1) Confirmation of pDAB Formation

FIG. 2 is a CV result for electrochemical reduction of GO on a glassy carbon electrode (GCE), in which a reduction peak appeared at −1.3 V in the first cycle, indicating reduction of an oxygen functional group present on the surface of GO. The reduction peak decreased from the second cycle and then disappeared after the third cycle.

FIG. 3A shows the potential kinetics of pDAB film (15 cycles) on pure electrode GC electrode (red line: 1-4 cycles, green line: 5-14 cycles, black line: 15 cycles), FIG. 3B shows ERGO -Potential dynamic formation of the pDAB film (15 cycles) on the modified electrode (red lines: 1-4 cycles, green lines: 5-14 cycles, black lines: 15 cycles), resulting from the ERGO surface It was confirmed that pDAB was adsorbed on the phase.

2) Shape analysis through SEM image

Figure 4 shows SEM images of GO, ERGO, p-DAB ＠ GC and p-DAB ＠ ERGO / GC film-modified plates (A: GO / GC, B: ERGO / GC, C: p-DAB ＠ GC) , D: high magnification p-DAB ＠ GC, E: p-DAB ＠ ERGO / GC, F: high magnification p-DAB ＠ ERGO / GC plate), GO attached on the GC plate is a laminated structure (Fig. 4A) electrochemical After reduction, it was changed to a corrugated structure (FIG. 4B), in which an increase in pi-pie bonds between graphene layers caused aggregation of GO.

Meanwhile, the p-DAB modified GC plate exhibited a thick plate-like structure (FIGS. 4C and 4D), and the p-DAB®ERGO / GC film-modified plate exhibited a disordered aggregation structure of p-DAB on the ERGO surface (FIG. 4E and 4F). This can be explained by defects on the ERGO surface with non-reducing oxygen functional groups of ERGO interacting with amines of diaminobenzene, and from these results, it was confirmed that p-DAB film and ERGO were formed on the electrode surface.

3) XPS

FIG. 5A shows the XPS spectra of GO / GC (a), ERGO / GC (b) and p-DABGOERGO / GC (c) plates, with XPS peaks at 531 eV and 285 eV showing O 1s and C, respectively. For 1s. GO after reduction on the GC plate (ERGO) showed a higher C / O ratio than GO on the GC plate. Table 1 shows the C / O ratio and the specified peak names. These results confirm that more oxygen atoms were removed due to the reduction of electrochemical GO. This also confirms the successful attachment of GO on the GC plate and the electrochemical reduction of oxygen functional groups. The peak at 400 eV (FIG. 5A, curve c) confirms the increase of nitrogen functional groups on the ERGO surface due to p-DAB film formation.

5B is an extended spectrum result for N 1s of the p-DABDAERGO / GC plate, and FIG. 5C is an extended spectrum result for C 1s of the p-DAB 의 ERGO / GC plate. Table 2 shows the peak correction results and the designated peaks.

From these XPS results, the electrochemical reduction of GO on the surface of ERGO and DAB film formation were confirmed.

4) Raman analysis

6 shows Raman analysis results of GO / GC and ERGO / GC plates, and the GO modified electrode showed two peaks at 1348 cm ⁻¹ and 1595 cm ⁻¹ , which means D peak and G peak of GO, respectively. (Curve a). After electrochemical reduction, the ERGO modified electrode showed D and G peaks at 1340 cm ⁻¹ and 1587 cm ⁻¹ , respectively (curve b). From these results, successful adhesion and electrochemical reduction of GO were confirmed. The ERGO-modified electrode increased the intensity of the D-band and shifted to a lower wavelength than the G-band, indicating an increase in defects in the carbon base plane and regeneration of the aromatic skeleton of graphene.

5) Electrochemical Behavior

FIG. 7 shows EIS measurements of pure GC (a), p-DAB ＠ GC (b), and p-DAB ＠ ERGO / GC (c) film-modified electrodes, with 5 mM dissolved in 0.1 M KCl [ Fe (CN) ₆ ] measured in the frequency range of ^{3- / 4-} to 100 kHz-0.01 Hz.

The Nyquist spectrum shows the semicircle in the high frequency region representing the electron transport process and the linear portion in the low frequency region representing the diffusion process. The semicircle diameter in the high frequency region represents the electron transfer resistance (R _ct ), where the R _ct values of pure GC, p-DAB ＠ GC and p-DAB ＠ ERGO / GC film-modified electrodes are 175 Ω, 1120 Ω, and 732, respectively. Ω.

The increased electron transfer resistance after the formation of the DAB film on the GC electrode means that the DAB film has a larger charge transfer resistance (R _ct ) which reduces the conductivity (curve b). On the other hand, p-DAB ＠ ERGO / GC film-modified electrodes have lower R _ct due to the electrical conductivity of Values are shown (curve c).

6) Electrochemical Activity on Nitrite

FIG. 8 shows the CVs of pure GC (a), p-DAB ＠ GC (b), and p-DAB®ERGO / GC (c) film-modified electrodes for nitrite analysis, pure GC and p-DAB® Oxidation of nitrite at GC was observed at 0.91 V and 0.87 V, respectively (curve a, curve b). On the other hand, the p-DAB ＠ ERGO / GC film-modified electrode exhibited nitrite oxide peaks with 1.3 and 1.2 times higher currents than pure GC and p-DAB ＠ GC electrodes, respectively, at 0.87 V (curve c). The p-DAB®ERGO / GC film-modified electrode showed a reduced peak with smaller peak current in the potential region of +0.17 to +0.05 V without nitrite at 0.2 M PB (pH 7.2) (curve d). This redox reaction is caused by protons and electron addition / removal reactions at the —NH— site of the p-DAB ＠ ERGO / GC film and shows excellent activity against nitrite due to the high electrical conductivity of ERGO. In addition, the positive (+) backbone of the p-DAB film attracts negatively charged (-) nitrites.

7) Nitrite Analysis by Differential Pulse Voltammetry (DPV)

9 shows DPV results using a p-DABDAERGO / GC (c) film-modified electrode at 7 μM nitrite concentration in 0.2 M PB (pH 7.2) solution, with peak oxide observed at 0.76 V by nitrite addition. It became. This means that the oxidation potential of nitrite did not shift during the concentration increase. For each nitrite addition, the current increased linearly in the range of 7.0 × 10 ⁻⁶ to 1.05 × 10 ⁻⁴ M (correlation coefficient: 0.997).

8) Nitrite Amperometric Analysis

FIG. 10A shows the amperometric it curve for nitrite analysis by p-DABGOERGO / GC film-modified electrode in an application potential of +0.76 V and 0.2 M PB (pH 7.2) electrolyte solution, p-DAB ＠ The ERGO / GC film-modified electrode exhibited an initial current response due to 7 μM nitrite. The current response increased due to the addition of 7 μM nitrite at each step at 60 second intervals, and steady-state current response was reached within 3 seconds. The dependence of the current response on nitrite concentration was linear with a correlation coefficient of 0.999 at 7 μM to 161 μM.

10B shows (a) 7, (b) 10, (c) 20, (d) 30, (e) 40, (f) 50, (g) 60, (h) 70, (i) 80, (j ) 90, (k) 100, (l) 200, (m) 500, (n) 1000, (o) 2000, (p) 3000, (q) 4000, (r) 5000, (s) 7000, (t ) For the nitrite analysis by p-DAB ＠ ERGO / GC film-modified electrode in 0.2 M PB (pH 7.2) electrolyte with an application potential of +0.76 V when various concentrations of 10,000 and (u) 20,000 μM nitrite were added. As the current measurement it curve, the current response increased linearly in the range of 7.0 x 10 ^-6 to 2.0 x 10 ^-2 M with increasing nitrite concentration (correlation coefficient: 0.994) and the detection limit was 30 nM. .

From these results, it was confirmed that the p-DAB ＠ ERGO / GC film-modified electrode had excellent activity for nitrite analysis.

9) Interference, Stability and Reproducibility Analysis

Various interfering ion in modified electrodes (a - Current measurement p-DAB @ ERGO / GC film ^{_{using: NO 3 -, b: HCO}} 3 2 -, SO 4 2-, NaOH, SO 3 2-, CO 3 2- Nitrite ion analysis was carried out in the presence of the present invention, and as shown in FIG. 11, 10 μM nitrite could be analyzed even in the presence of 1 mM of all interfering ions, indicating very high selectivity for nitrite. From these results, it can be seen that the p-DAB®ERGO / GC film-modified electrode can analyze 10 μM nitrite ions even with 100-fold excess of other interference ions.

To confirm the storage stability of the p-DABDAERGO / GC film-modified electrode, current measurements were made on 10 μM nitrite at 0.2 M PB (pH 7.2), followed by 5.2% relative measurements with 5 sets of replicates after 30 days. Standard deviation (RSD) is shown. Reproducibility tests were performed using five sets of p-DAB®ERGO / GC film-modified electrodes and the reduced peak current remained similar (4.2% RSD). These results confirmed that the p-DAB®ERGO / GC film-modified electrode was a stable and reproducible nitrite detection electrode.

10) Detection of nitrites in drinking water and tap water samples

FIG. 12 shows DPV for water samples after spikes with commercial nitrites, and the DPV for water samples at PB (pH 7.2) did not show any response (curve a), indicating no nitrite. On the other hand, when nitrite was added to the same solution, the peak of oxidation was observed at 0.79 V with increased current (curve b). Therefore, it was confirmed that nitrite detection was possible even in real samples using p-DAB®ERGO / GC film-modified electrode.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this and is given by the person of ordinary skill in the art to which this invention belongs, Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

Claims (11)

And a polydiaminobenzene thin film coated on the reduced graphene oxide and an electrode modified with reduced graphene oxide, and having a detection limit of 30 nM. The nitrite detection sensor according to claim 1, wherein the electrode is a glassy carbon electrode. Dropcasting graphene oxide onto the electrode (first step);
Electrochemically reducing the electrode modified with graphene oxide (second step);
Adding diaminobenzene on the electrode modified with reduced graphene oxide and performing potential scanning to form polydiaminobenzene on the electrode (third step)
Method for producing a nitrite detection sensor comprising a. The method of claim 3, wherein the second step is characterized in that the electrochemically reduced the electrode modified with graphene oxide for 5 to 50 cycles at a scan rate of 20 ~ 100 mV / s and a potential of 0 ~ -2.0 V Manufacturing method of sensor for nitrite detection. The method of claim 3, wherein the third step is to add diaminobenzene on the electrode modified with reduced graphene oxide and for 5 to 50 cycles at a scan rate of 20 to 100 mV / s and a potential of -0.5 to 2.0 V A method for producing a nitrite detection sensor, characterized in that a potential scan is performed to form polydiaminobenzene on an electrode. The method of claim 3, wherein the electrode is a glassy carbon electrode. The method according to claim 3, Before the first step,
Cleaning the electrode; Or mixing graphene oxide with ethanol containing a Nafion solution and sonicating to prepare a homogeneous suspension. The method of claim 7, wherein the manufacturing method comprises: cleaning an electrode; Mixing graphene oxide with ethanol containing a Nafion solution and sonicating to prepare a homogeneous suspension; Dropcasting graphene oxide onto the electrode; Electrochemically reducing the electrode modified with graphene oxide; A method for manufacturing a nitrite detection sensor comprising adding diaminobenzene on an electrode modified with reduced graphene oxide and performing potential scanning to form polydiaminobenzene on the electrode. Adjusting the pH of the water sample to 7.0 to 7.4;
Nitrite detection method comprising the step of analyzing the pH-adjusted water sample in the nitrite detection sensor according to claim 1. The method of claim 9, wherein the water sample is nitrite detection method, characterized in that selected from drinking water, tap water or lake water. The nitrite detection method according to claim 9, wherein the analysis is performed by differential pulse voltammetry (DPV).

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