Fabrication of ZnWO4/Carbon Black Nanocomposites Modified Glassy Carbon Electrode for Enhanced Electrochemical Determination of Ciprofloxacin in Environmental Water Samples

The major problem facing humanity in the world right now is the sustainable provision of water and electricity. Therefore, it is essential to advance methods for the long-term elimination or removal of organic contaminants in the biosphere. Ciprofloxacin (CIP) is one of the most harmful pollutants affecting human health through improper industrial usage. In this study, a zinc tungsten oxide (ZnWO4) nanomaterial was prepared with a simple hydrothermal synthesis. The ZnWO4/Carbon black nanocomposites were fabricated for the determination of CIP. The nanocomposites were characterized by field emission scanning electron microscopy, energy dispersion X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. Electrochemical studies were done using cyclic voltammetry and differential pulse voltammetry methods. Based on the electrode preparation, the electrochemical detection of CIP was carried out, producing exceptional electrocatalytic performance with a limit of detection of 0.02 μM and an excellent sensitivity of (1.71 μA μM−1 cm−2). In addition, the modified electrode displayed great selectivity and acceptable recoveries in an environmental water sample analysis for CIP detection of 97.6% to 99.2%. The technique demonstrated high sensitivity, selectivity, outstanding consistency, and promise for use in ciprofloxacin detection. Ciprofloxacin was discovered using this brand-new voltammetry technique in a water sample analysis.


Introduction
The second-generation fluoroquinolone ciprofloxacin (CIP), also known as 1-cycloprop yl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid is used to treat various bacterial infections [1]. CIP is one of the most often prescribed fluoroquinolones and is widely used in people and cattle for its broad-spectrum antibacterial action. Unlike other antibiotics, CIP can be induced either parenterally or orally [2]. This medication is used to treat a variety of infectious disorders, including urinary tract, respiratory tract, and gastrointestinal tract infections, as well as skin and soft tissue infections. Furthermore, ingesting foods of animal origin in humans might result in allergic or carcinogenic responses owing to antibiotic residues [3]. However, the most severe of all the negative effects of antibiotic residues in the environment is the rise of microbial drug resistance. Additionally, it is used to treat those who have contracted anthrax following inhalation exposure [4,5]. Agranulocytosis, thrombocytopenia, myelosuppression, toxic epidermal electrochemical sensors with low cost and outstanding electroanalytical capabilities since it is less expensive than other carbon compounds such as carbon nanotubes and graphene [27]. Typically, some research teams have employed CB to create electrodes, thin films, and composite materials. Moreover, this nanomaterial may be easily changed with other materials, such as metallic nanoparticles and polymers [28,29]. CB is analogous to other carbon nanomaterials such as graphene, carbon nanotubes (both single-walled and multiwalled), and fullerene [30][31][32]. Hence, ZnWO 4 /CB has been emphasized as an excellent modifier that takes place in the electrochemical detection of the CIP [33]. Recently, GCE has been widely used due to its low residual current in aqueous media, is widely used in aqueous micellar solutions and is frequently used as an indicator. Several papers on glassy carbon electrodes have emphasized the extraordinary sensitivity of the apparent rates of redox reactions to the quality of the electrode surface, and this is the reason that we have chosen CB/ZnWO 4 /GCE for the detection of CIP [34].
Electrochemical sensors have improved the performance of conventional analytical equipment and generated low-cost substitutes by obviating the requirement for expensive reagents and delayed preparation. Since electrochemical sensors are inexpensive, portable, and simple to use, they have significant advantages over conventional analytical equipment. Electrochemical detection has advantages, such as high sensitivity, simple operation, great selectivity, short reaction time, low cost, and speedy detection. On the other hand, electrochemically active interferences in the sample, poor long-term stability, and difficult electron-transfer routes are the disadvantages of electrochemical sensors. These detection technologies also have several limitations, such as expensive electrode raw materials, environmental pollution, and lengthy electrode preparation times during the electrode material synthesis. However, electrochemical sensors, have a wide range of applications in food analysis, environmental monitoring, and clinical diagnostics. Therefore, we preferred the electrochemical method for detecting CIP by CB/ZnWO 4 /GCE [35]. The resulting nanocomposites exhibited extremely high catalytic activity and have a broad linear range, a low detection limit, good selectivity, stability, and repeatability. As a result, it is also used in the examination of practical applications using CB/ZnWO 4 /GCE towards CIP in diverse biological and environmental materials.

Preparation of ZnWO 4 /CB
The ZnWO 4 /CB composite was prepared by the simple hydrothermal method. In the common preparation process, Zinc nitrate hexahydrate (0.37 g) and sodium tungstate dihydrate (0.58 g) were dissolved with 40 mL of deionized water and the mixture was stirred continuously for 25 min. Then, 10 mL of NaOH (0.5 M) solution was mixed with the solution and it was stirred by magnetic stirring for another 20 min at room temperature. Finally, the precipitate was transferred into the Teflon-coated autoclave and kept for hydrothermal synthesis for 12 hrs with a temperature of 180 • C, after completing the reaction solution was centrifuged with C 2 H 5 OH/H 2 O. The synthesized ZnWO 4 sample was calcinated at 400 • C for 3 h and the fine powder was collected. The prepared ZnWO 4 was prepared with the combination of CB as ZnWO 4 /CB for the experimental procedures to obtain effective electrochemical results (Scheme 1).

Characterizations
The prepared samples were characterized by X-ray diffraction (XRD) w ducted on an XPERT-PRO, PAN analytical B.V., (Netherlands) with Cu Kα 1.54 Å ) in a range from 10° to 90° with a scan rate of 5.0° per minute. The s phology, and elemental results were characterized by high-resolution tran tron microscopy (HRTEM, JEOL JEM-2100F) and field emission scanning e copy (FESEM; JEOLJSM-6500F) including energy-dispersive X-ray (EDX) photoelectron spectroscopy (XPS) images were analyzed by a Thermo scie 2000. Electrochemical impedance spectroscopy (EIS) was recorded by the ektrik. The electrochemical methods were conducted by the CHI 1205B and trochemical workstations used in the CV and DPV techniques. A glassy ca (GCE) (0.0729 cm 2 ), Ag/AgCl saturated KCl, and Pt wire corresponds to the trode, reference electrode, and counter electrode, respectively.

Modification of the GCE/ZnWO4/CB Electrode
The GCE was cleaned with water and ethanol before being polished slurries for the sensor studies. The substance was then combined with 0.5 m water and 2.0 mg of the ZnWO4/CB material to create a composite while b To fabricate ZnWO4/CB modified GCE, 8.0μL of ZnWO4/CB composite was the precleaned GCE surface and dried for 15 min at 40 °C in an air oven. electrochemical experiments were performed using the constructed workin the detection of CIP described in Scheme 2.

Characterizations
The prepared samples were characterized by X-ray diffraction (XRD) which was conducted on an XPERT-PRO, PAN analytical B.V., (Netherlands) with Cu Kα radiation (k = 1.54 Å) in a range from 10 • to 90 • with a scan rate of 5.0 • per minute. The structure, morphology, and elemental results were characterized by high-resolution transmission electron microscopy (HRTEM, JEOL JEM-2100F) and field emission scanning electron microscopy (FESEM; JEOLJSM-6500F) including energy-dispersive X-ray (EDX) studies, X-ray photoelectron spectroscopy (XPS) images were analyzed by a Thermo scientific multilab 2000. Electrochemical impedance spectroscopy (EIS) was recorded by the ZAHNER-Elektrik. The electrochemical methods were conducted by the CHI 1205B and CHI 900 electrochemical workstations used in the CV and DPV techniques. A glassy carbon electrode (GCE) (0.0729 cm 2 ), Ag/AgCl saturated KCl, and Pt wire corresponds to the working electrode, reference electrode, and counter electrode, respectively.

Modification of the GCE/ZnWO 4 /CB Electrode
The GCE was cleaned with water and ethanol before being polished with alumina slurries for the sensor studies. The substance was then combined with 0.5 mL of deionized water and 2.0 mg of the ZnWO 4 /CB material to create a composite while being sonicated.

Characterization
FE-SEM, EDAX, and TEM analysis were used to examine the surface morphology of pure CB, ZnWO4, and ZnWO4/CB composites. Figure 1A shows the SEM image of CB has elemental carbon organized into tiny particles to create the CB primary particle, which has an amorphous and quasi-graphitic structure. However, the characteristics of CB are nanostructured aggregates exhibiting semispherical groups. Additionally, these aggregate groupings have a defined long dimension. The range of CB particle sizes is 3.0 to 100 nm. The ZnWO4 nanoparticles were uniformly sized at 100 nm, and show a monoclinic crystal system in Figure 1B. Figure 1C,D exhibits the FE-SEM pictures of the ZnWO4/CB composite, the ZnWO4 nanoparticles were adorned on CB to form the ZnWO4/CB composite. In addition, energy dispersive X-ray spectra and elemental mapping analysis studies were used to study the chemical composition and distribution of the ZnWO4/CB composite ( Figure 2A). Figure 2B shows the EDS spectrum found in Zinc (Zn), tungsten (W), carbon (C), and oxygen (O) components, without any other contaminants. Additionally, Figure 2C-F demonstrates the elemental mapping results which show that the Zn, W, C, and O in the scanning area were distributed uniformly throughout the ZnWO4/CB composite. Figure 1C shows that the elemental mapping exhibiting the ZnWO4 particles was uniformly distributed on the surface of CB. The EDAX studies depict the element weight with the percentages of Zn as 21.6%, Was 62.8%, O as 15.6%, and C as 100%, respectively [36]. Figure 3A,B shows the prepared nanocomposites further studied with TEM analysis, which shows that the ZnWO4 particles coated on the CB surface and a well-formed ZnWO4/CB composite.

Characterization
FE-SEM, EDAX, and TEM analysis were used to examine the surface morphology of pure CB, ZnWO 4, and ZnWO 4 /CB composites. Figure 1A shows the SEM image of CB has elemental carbon organized into tiny particles to create the CB primary particle, which has an amorphous and quasi-graphitic structure. However, the characteristics of CB are nanostructured aggregates exhibiting semispherical groups. Additionally, these aggregate groupings have a defined long dimension. The range of CB particle sizes is 3.0 to 100 nm. The ZnWO 4 nanoparticles were uniformly sized at 100 nm, and show a monoclinic crystal system in Figure 1B. Figure 1C,D exhibits the FE-SEM pictures of the ZnWO 4 /CB composite, the ZnWO 4 nanoparticles were adorned on CB to form the ZnWO 4 /CB composite. In addition, energy dispersive X-ray spectra and elemental mapping analysis studies were used to study the chemical composition and distribution of the ZnWO4/CB composite ( Figure 2A). Figure 2B shows the EDS spectrum found in Zinc (Zn), tungsten (W), carbon (C), and oxygen (O) components, without any other contaminants. Additionally, Figure 2C-F demonstrates the elemental mapping results which show that the Zn, W, C, and O in the scanning area were distributed uniformly throughout the ZnWO4/CB composite. Figure 1C shows that the elemental mapping exhibiting the ZnWO 4 particles was uniformly distributed on the surface of CB. The EDAX studies depict the element weight with the percentages of Zn as 21.6%, Was 62.8%, O as 15.6%, and C as 100%, respectively [36]. Figure 3A,B shows the prepared nanocomposites further studied with TEM analysis, which shows that the ZnWO 4 particles coated on the CB surface and a well-formed ZnWO 4 /CB composite. Figure 4A shows the XPS studies done on the ZnWO 4 /CB composite, which indicate the survey scan of elements such as Zn 2p, W 4f, O 1s, and C 1s. The absorption of air atmosphere in the prepared sample shows the C element peak. The spectra of Zn 2p 1/2 and Zn 2p 3/2 are displayed in Figure 4B with binding energies of 1046.5 eV and 1045.6 eV. Figure 4C shows that W4f 1/2 and W4f 3/2 are ascribed to the corresponding peaks at 40.5 eV and 46.6 eV, respectively. Figure 4D shows that the O1s peaks at 534 eV are attributed to the metal-oxygen bond and the hydroxyl group that was absorbed from the moisture. Figure 4E shows that the binding energies C 1s peaks at 288 eV [36]. XPS studies confirmed the successful formation of the ZnWO 4 /CB composite. Materials 2023, 16, x FOR PEER REVIEW 6 of 16      Figure 4A shows the XPS studies done on the ZnWO4/CB composite, which indicate the survey scan of elements such as Zn 2p, W 4f, O 1s, and C 1s. The absorption of air atmosphere in the prepared sample shows the C element peak. The spectra of Zn 2p 1/2 and Zn 2p 3/2 are displayed in Figure 4B with binding energies of 1046.5 eV and 1045.6 eV. Figure 4C shows that W4f 1/2 and W4f 3/2 are ascribed to the corresponding peaks at 40.5 eV and 46.6 eV, respectively. Figure 4D shows that the O1s peaks at 534 eV are attributed to the atmosphere in the prepared sample shows the C element peak. The spectra of Zn 2p and Zn 2p 3/2 are displayed in Figure 4B with binding energies of 1046.5 eV and 1045.6 eV. Figure 4C shows that W4f 1/2 and W4f 3/2 are ascribed to the corresponding peaks at 40.5 eV and 46.6 eV, respectively. Figure 4D shows that the O1s peaks at 534 eV are attributed to the metal-oxygen bond and the hydroxyl group that was absorbed from the moisture. Figure  4E shows that the binding energies C 1s peaks at 288 eV [36]. XPS studies confirmed the successful formation of the ZnWO4/CB composite.

Electrochemical Performance of Different Modified Electrodes
The interfacial resistance of the GCE, CB/GCE, ZnWO 4 /GCE, and ZnWO 4 /CB/GCE was investigated using electrochemical impedance spectra (EIS) utilizing a solution of 0.1 M KCl and 5.0 mM [Fe(CN) 6 ] 3−/4− at the detected potential of 10 mV and a frequency range of 0.1 Hz to 100 kHz. Figure 5A shows the EIS plot in two sections that are consistent with each other. The high-frequency semicircle region, which is associated with charge transfer resistance (R ct ), and the low-frequency linear zone are related to diffusion kinetics. CB diffraction peaks successfully appeared in the ZnWO4/CB composite composition without impurities, which confirms the formation of the ZnWO4/CB composite [37].

Electrochemical Performance of Different Modified Electrodes
The interfacial resistance of the GCE, CB/GCE, ZnWO4/GCE, and ZnWO4/CB/GCE was investigated using electrochemical impedance spectra (EIS) utilizing a solution of 0.1 M KCl and 5.0 mM [Fe(CN)6] 3−/4− at the detected potential of 10 mV and a frequency range of 0.1 Hz to 100 kHz. Figure 5A shows the EIS plot in two sections that are consistent with each other. The high-frequency semicircle region, which is associated with charge transfer resistance (Rct), and the low-frequency linear zone are related to diffusion kinetics. The bare GCE, CB/GCE, ZnWO4/GCE, and ZnWO4/CB/GCE have identified the Rct values of 745.7 Ω, 586.9 Ω,149.21 Ω, and 44.43 Ω, respectively. . Hence, the lower E p and higher redox peak currents indicate that the GCE/ZnWO 4 /CB has a greater electroactive surface area and transfers electrons more quickly than the other bare GCE, CB/GCE, and ZnWO 4 /GCE electrodes. Additionally, the GCE/ZnWO 4 /CB composite display a significantly increased redox peak current as compared to bare GCE, GCE/CB, and GCE/ZnWO 4 . As shown by these results, the enhanced GCE/ZnWO 4 /CB electrode exhibits strong conductive properties that promote higher charge transfer efficiency.  Figure 6A,B. On this electrode, a substantial oxidation peak current was determined. As can be seen, there is no oxidation peak current seen for the GCE/ZnWO 4 /CB when CIP is not present. The lowest oxidation peak current on the addition of CIP was observed at I pa = 5.2 µA with an oxidation peak potential of (∆E p ) 1.02 V (bare GCE). After CB was coated on the GCE surface, oxidation peaks current of I pa = 8.51 µA along a peak potential of E pa = 1.05 V was obtained. Additionally, the ZnWO 4 / GCE electrode compared to the bare GCE and CB/GCE exhibits a moderately improved oxidation peak current and a positively transferred oxidation potential of (E pa = 1.48 V) and has I pa = 30.53 µA with a peak potential of E pa = 0.85 V. As a result, GCE/ ZnWO 4 /CB has exceptional electrical conductivity and excellent catalytic function for detecting CIP. When compared to the bare GCE, CB/GCE, and ZnWO 4 /GCE, the fabricated GCE/ZnWO 4 / CB showed the highest oxidation peak current response at I pa = 60.9 µA, and the oxidation peak potential shifted to the more positive side (E pa = 0.93 V). In contrast to the other electrodes, the modified GCE/ZnWO 4 /CB exhibits exceptional electrochemical activity and a rapid electron shifting process during CIP detection (Scheme 3). By the different pH ranging from 3.0 to 11.0, the impact of pH on the electrocatalytic behavior of CIP in 0.05 M PBS at 0.05 Vs −1 was determined by GCE/ZnWO4/CB electrode and shown in Figure 6C,D. An anodic peak current appeared from pH 3.0 to 11.0 upon the addition of 100 µ M of CIP. As can be seen, as the pH rises from 3.0 to 7.0, the amplification of CIP steadily increases because there are more protons freely circulating. The electrolyte solution of GCE/ZnWO4/CB has Ipa = 60.13 μA with a peak potential of Epa = 0.83 V. Hence, the oxidation peaks current increases with pH above 7.0, probably as a result of the hydrogen ions interfering with CIP detection. Finally, the very quick decrease in peak currents in the pH range of 7.0-11.0. The pH of the CIP was then influenced, and Scheme 3. Electrochemical oxidation of CIP by GCE/ZnWO 4 /CB electrode. electrode compared to the bare GCE and CB/GCE exhibits a moderately improved oxidation peak current and a positively transferred oxidation potential of (Epa = 1.48 V) and has Ipa = 30.53 μA with a peak potential of Epa = 0.85 V. As a result, GCE/ ZnWO4/CB has exceptional electrical conductivity and excellent catalytic function for detecting CIP. When compared to the bare GCE, CB/GCE, and ZnWO4/GCE, the fabricated GCE/ZnWO4/ CB showed the highest oxidation peak current response at Ipa = 60.9 μA, and the oxidation peak potential shifted to the more positive side (Epa = 0.93 V). In contrast to the other electrodes, the modified GCE/ZnWO4/CB exhibits exceptional electrochemical activity and a rapid electron shifting process during CIP detection (Scheme 3).  By the different pH ranging from 3.0 to 11.0, the impact of pH on the electrocatalytic behavior of CIP in 0.05 M PBS at 0.05 Vs −1 was determined by GCE/ZnWO 4 /CB electrode and shown in Figure 6C,D. An anodic peak current appeared from pH 3.0 to 11.0 upon the addition of 100 µM of CIP. As can be seen, as the pH rises from 3.0 to 7.0, the amplification of CIP steadily increases because there are more protons freely circulating. The electrolyte solution of GCE/ZnWO 4 /CB has I pa = 60.13 µA with a peak potential of E pa = 0.83 V. Hence, the oxidation peaks current increases with pH above 7.0, probably as a result of the hydrogen ions interfering with CIP detection. Finally, the very quick decrease in peak currents in the pH range of 7.0-11.0. The pH of the CIP was then influenced, and the peak current shift was obtained. Thus, we have chosen pH 7.0 for further electrochemical studies. The CIP oxidized to the formation of cationic radical and the single electron transfer kinetics on the GCE/ZnWO 4 /CB electrode has occurred.

Effect of Different Concentrations and the Scan Rates
The CV response at a scan rate of 50 mV s −1 for CIP concentrations ranging from 0-100 µM at GCE/ZnWO 4 /CB in pH 7.0 (50 mM PBS). From 0 to 100 µM, the oxidation peaks current (I pa ) gradually increased concerning the various concentrations in Figure 7A and the mechanism of oxidation of CIP is shown in Scheme 3. The calibration curve between the oxidation peak current and various concentrations is shown in Figure 7B, I pa (µA) = 0.1953X [µM] + 7.222, (R 2 = 0.9952) is the corresponding regression equation and correlation coefficient which is represented in Figure 7B. However, the findings show that the GCE/ZnWO 4 /CB has excellent electrocatalytic activity towards CIP detection as well as it has quick electron transfer. The CV was carried out with GCE/ZnWO 4 /CB in various scan rate ranges of 20-200 mVs −1 and reached pH 7.0, as shown in Figure 7C, to test the various scan rates of CIP. As the sweeping scan rate is increased, the anodic peak current of CIP progressively rises. The relation between anodic peak current and scan rate is presented in Figure 7C. Figure 7D shows the linear regression equation is I pa (µA) = 0.1479 × (mVs −1 ) + 18.361 and the coefficient of (R 2 = 0.9935). This finding implies that diffusion controls the electrocatalytic oxidation of CIP detected on the GCE/ZnWO 4 /CB surface [37].

Differential Pulse Voltammetry (DPV), Interference Studies, and Repeatability of CIP
DPV has higher sensitivity, greater resolution, and better selectivity when compared to other voltammetry methods. In order to ascertain the reduced concentration of CIP on GCE/ZnWO4/CB in 0.05 M PBS (pH 7) containment, we chose the DPV approach, which is shown in Figure 8A. As the CIP concentration is increased from 0.01 µ M to 120 µ M, the oxidation peaks current rises linearly, as seen in the linear plot of the maximum current during oxidation vs. various CIP concentrations. We obtained three linear ranges. The linear calibration equation observed for the first linear range from 0.01 µ M to 120 µ M has Ipa (µ A) = 0.3273 C (µ M) + 11.127 (R 2 = 9985) and is shown in Figure 8B. The analytical parameters from the first linear range were computed, with the calculated limit of detection being 0.02 µ M and sensitivity being 1.71 µ A µ M −1 cm −2 . The following equation was used for the calculation [38] = 3σ/S Here S denotes the linear plot's slope value and denotes the relative standard deviation (RSD). The acquired analytical properties were compared to those of previously reported sensors and included a wide linear range, good sensitivity, and a lower detection limit of CIP on GCE/ZnWO4/CB, which was calculated by Equation (1) [39]. GCE/ZnWO4/CB has received a lot of attention lately, due to their distinct optical, physical, and electrochemical applications as well as their prospective advantages in terms of higher surface area, improved chemical stability, equal particle size distribution, and high porosity. For electrochemically detecting CIP, we have created a ZnWO4 nanomaterial that exhibits a broad range of potential and has an outstanding catalytic activity. However, the detection response of the CIP at the CB/ZnWO4/GCE is lower than that of the

Differential Pulse Voltammetry (DPV), Interference Studies, and Repeatability of CIP
DPV has higher sensitivity, greater resolution, and better selectivity when compared to other voltammetry methods. In order to ascertain the reduced concentration of CIP on GCE/ZnWO 4 /CB in 0.05 M PBS (pH 7) containment, we chose the DPV approach, which is shown in Figure 8A. As the CIP concentration is increased from 0.01 µM to 120 µM, the oxidation peaks current rises linearly, as seen in the linear plot of the maximum current during oxidation vs. various CIP concentrations. We obtained three linear ranges. The linear calibration equation observed for the first linear range from 0.01 µM to 120 µM has I pa (µA) = 0.3273 C (µM) + 11.127 (R 2 = 9985) and is shown in Figure 8B. The analytical parameters from the first linear range were computed, with the calculated limit of detection being 0.02 µM and sensitivity being 1.71 µA µM −1 cm −2 . The following equation was used for the calculation [38] LOD = 3σ/S Here S denotes the linear plot's slope value and denotes the relative standard deviation (RSD). The acquired analytical properties were compared to those of previously reported sensors and included a wide linear range, good sensitivity, and a lower detection limit of CIP on GCE/ZnWO 4 /CB, which was calculated by Equation (1) [39]. GCE/ZnWO 4 /CB has received a lot of attention lately, due to their distinct optical, physical, and electrochemical applications as well as their prospective advantages in terms of higher surface area, improved chemical stability, equal particle size distribution, and high porosity. For electrochemically detecting CIP, we have created a ZnWO 4 nanomaterial that exhibits a broad range of potential and has an outstanding catalytic activity. However, the detection response of the CIP at the CB/ZnWO4/GCE is lower than that of the other electrochemical sensor mentioned in Table 1 such as, TiO 2 /AuNPs/Nafion/CMK-3 electrode (LOD = 0.108 µM) [7], AuNP/CHI/SPCE electrode (LOD = 0.001 µM) [8], CNT-V 2 O 5 CS/SPCE electrode (LOD = 3.0 µM) [10], PBE electrode (LOD 4.96 µM) [40], TiO 2 /PVA-GCE electrode (LOD = 0.04 µM) [41], GR-ZnO/GCE electrode (LOD = 0.4 µM) [42], GO/ZnO/ GCE electrode (LOD = 0.01 µM) [43], and OLA-Fe 3 O 4 /MWCNTs/GCE electrode (LOD = 0.06 M) [44]. Moreover, the CB/ZnWO 4 /GCE electrode exhibited CIP detection at a low detection limit and long linear range than another electrode due to the high activity and active surface area of the CB/ZnWO 4 /GCE. Therefore, this result demonstrates that the CB/ZnWO 4 /GCE can be used as an excellent electrode for the sensing of CIP.
DPV was conducted to determine the impact of varying possible anti-interference investigations in 0.05 PBS (pH 7) with 20 µ M CIP at GCE/ZnWO4/CB. As can be shown in Figure 8C, CIP was selectively detected at the same time, with the oxidation peak potential being 1.26 V. The initial oxidation peak current and peak potential of the original CIP were unaffected by other interfering compounds. Furthermore, CIP with the presence of various interferents such as sulfadiazine, carbofuran, sulfamethazine, mefenamic acid, K + , Cl − , and Na + were studied and shown in Figure 8C. The experiments were conducted in N2immersed conditions with a pH of 7.0 (0.05 M PBS) and 0.05 V s −1 . CIP's independence from outside meddling has thus been demonstrated in Figure 8C. Additionally, the CV examination of the manufactured electrodes in the assessment of repeatability for the CIP sensor was successful and are shown in Figure 8D. With a critical current difference between the oxidation peak current of 100 µ M CIP in 0.05 M PBS (pH 7), it can be concluded that the GCE/ZnWO4/CB had better sensor repeatability.  DPV was conducted to determine the impact of varying possible anti-interference investigations in 0.05 PBS (pH 7) with 20 µM CIP at GCE/ZnWO 4 /CB. As can be shown in Figure 8C, CIP was selectively detected at the same time, with the oxidation peak potential being 1.26 V. The initial oxidation peak current and peak potential of the original CIP were unaffected by other interfering compounds. Furthermore, CIP with the presence of various interferents such as sulfadiazine, carbofuran, sulfamethazine, mefenamic acid, K + , Cl − , and Na + were studied and shown in Figure 8C. The experiments were conducted in N 2 -immersed conditions with a pH of 7.0 (0.05 M PBS) and 0.05 V s −1 . CIP's independence from outside meddling has thus been demonstrated in Figure 8C. Additionally, the CV examination of the manufactured electrodes in the assessment of repeatability for the CIP sensor was successful and are shown in Figure 8D. With a critical current difference between the oxidation peak current of 100 µM CIP in 0.05 M PBS (pH 7), it can be concluded that the GCE/ZnWO 4 /CB had better sensor repeatability.

Reproducibility, Stability, and Real Sample Analysis
The reproducibility of GCE/ZnWO 4 /CB was tested in four separate tests using a different electrode in 100 µM CIP containing 0.05 M PBS (pH 7) and the results are shown in Figure 9A. We suggest that the manufactured sensor GCE/ZnWO 4 /CB has an outstanding level of reproducibility. Furthermore, the stability of storage was studied by the CV in N 2 immersed in 0.05 M PBS (pH 7) containing 100 µM CIP at the extensive scan rate of 0.05 Vs −1 by the optimal circumstances shown in Figure 9B. The altered electrode current response shows very good stability as well as the electrocatalytic oxidizing property of CIP.
The presence of CIP in real samples taken from various rivers and tap water was detected by the GCE/ZnWO 4 /CB electrode ( Figure 9C,D). As a result, real samples of the undefined concentration were spiked with the known concentration of CIP mentioned in Table 2. The recovery values exhibit the relative standard deviation (RSD) approach. These results represent the experimental applications of the GCE/ZnWO 4 /CB altered electrode for the determination of CIP in real samples of water with excellent recoveries. The recoveries values of river water and tap water samples were obtained as 98.5% and 99.6%, with average RSD values of 4.2% and 3.6%, respectively. The results of real sample analysis demonstrated the outstanding capability of GCE/ZnWO 4 /CB electrodes for the detection of the CIP. Therefore, the values found are very reasonable for use in practical applications. The reproducibility of GCE/ZnWO4/CB was tested in four separate tests using a different electrode in 100 µ M CIP containing 0.05 M PBS (pH 7) and the results are shown in Figure 9A. We suggest that the manufactured sensor GCE/ZnWO4/CB has an outstanding level of reproducibility. Furthermore, the stability of storage was studied by the CV in N2 immersed in 0.05 M PBS (pH 7) containing 100 µ M CIP at the extensive scan rate of 0.05 Vs −1 by the optimal circumstances shown in Figure (9B). The altered electrode current response shows very good stability as well as the electrocatalytic oxidizing property of CIP.

Conclusions
In this study, we effectively prepared a reliable, simple, and affordable GCE/ZnWO 4 /CB electrode for the electrochemical detection of CIP. The crystalline structure and shape of the prepared materials were confirmed by the analytical spectroscopic characterizations of XRD, FTIR, FESEM, and EDX-elemental mapping. The GCE/ZnWO 4 / CB electrode shows high sensitivity (1.71 µA µM −1 cm −2 ) with a lower detection limit of 0.02 µM, and the electrochemical performance of the modified GCE showed a long linear range from 0.02 to 120 µM, with effective electrocatalytic responsiveness of CIP detection. Furthermore, the suggested electrode has higher selectivity, stability, repeatability, and reproducibility. The GCE/ZnWO 4 /CB exhibited an excellent result for the electrochemical measurement of CIP in real water samples. Therefore, the GCE/ZnWO 4 /CB electrode is also a promising option for the electrochemical detection of hazardous chemicals in biological and environmental samples.