Carbon Paste Electrode Research Articles

Determination of the total phenolic content in Hardaliye by amperometric laccase-based biosensor and comparison of the LC-MS/MS

In this study, a laccase-based amperometric biosensor was fabricated for the quantitative analysis of total phenolic content in Hardaliye. The biosensor was constructed using a carbon paste electrode with simple modifications. The laccase obtained from Trametes versicolor was immobilized into a carbon paste electrode modified with a gelatin matrix. The immobilization parameters for biosensor fabrication, as well as its working conditions were optimized with gallic acid as the phenolic standard. Additionally, molecular docking simulation was used to examine the interaction between Trametes versicolor laccase and gallic acid. The biosensor's analytical parameters were determined under optimal conditions including linearity, repeatability, stability and selectivity. The linear range of gallic acid was calculated as 0.5–100 μM, with the detection limit of 0.1323 ± 0.1 μM. With good selectivity and stability, the biosensor successfully determined the total phenolic contents in Hardaliye, and red-wine samples. Comparison studies showed that the biosensor results agreed with those obtained from the Liquid Chromatography-Tandem Mass Spectrometry method. This work indicates that the proposed biosensor is a promising analytic tool for total phenolic analyses of beverages.

Mesoporous pineapple crown-derived activated carbon modified matrix for the detection of carbendazim in the presence of anionic surfactant

Carbon paste electrodes (CPEs) are commonly employed in electroanalysis because of their chemical stability, broad electrochemical window, low capacitive current, ease of fabrication, and surface renewability. Electrocatalysts can easily be embedded into CPEs to make them suitable for a variety of applications. Poor biowaste management presents a significant challenge in the agro-industry and agriculture due to the rapid decomposition of biowaste, driven by its high water content and limited biological stability, which leads to pest attraction and greenhouse gas emissions. Consequently, this green waste can be utilized for the development of electrocatalysts. Activated carbon (AC) has been utilized in progressive electrochemical applications as it exhibits high conductivity and porosity that help to enhance electrocatalytic activity. Herein, pineapple fruit crown (PC) peel-derived AC (PCAC) is utilized as the sensing material for the determination of fungicide, carbendazim (CBM). The synthesized material was characterized using SEM, FT-IR, XRD, EDX, AFM, CV and EIS. Besides, to enhance the surface properties, Sodium dodecyl sulfate (SDS) surfactant is used as a mediator in detecting CBM. The CV and SWV approaches were employed to assess the electrochemical response of the developed electrodes for the CBM determination. Under optimum experimental conditions, the SDS/PCAC/CPE exhibits low DLim and QLim values of 32.0 nM and 128.0 nM with considerable selectivity. Furthermore, the SDS/PCAC/CPE was employed in real-time analysis of CBM in spiked environmental samples, which showed satisfying recovery results. Moreover, the electrode showed good stability over multiple measurements, and these results demonstrate that SDS/PCAC/CPE is a promising sensor for CBM detection.

Shungite Paste Electrodes: Basic Characterization and Initial Examples of Applicability in Electroanalysis

This article introduces a new type of carbon paste electrode prepared from black raw shungite. In powdered form, this carbonaceous material was mixed with several nonpolar binders. The resulting shungite pastes were microscopically and electrochemically characterized. Mixtures of several pasting liquids with different contents of shungite powder were tested to select the optimal composition and compared with other types of carbon paste-based electrodes made of graphite and glassy carbon powder. In terms of physical and mechanical properties, shungite paste electrodes (ShPEs) formed a composite mass being like dense pastes from glassy carbon microspheres, having harder consistency than that of traditional graphitic carbon pastes. The respective electrochemical measurements with ShPEs were based on cyclic voltammetry of ferri-/ferro-cyanide redox pairs, allowing us to evaluate some typical parameters such as electrochemically active surface area, double-layer capacitance, potential range in the working media given, heterogeneous rate constant, charge-transfer coefficient, exchange current density, and open-circuit potential. The whole study with ShPEs was then completed with three different examples of possible electroanalytical applications, confirming that the carbon paste-like configuration with powdered shungite represents an environmentally friendly (green) and low-cost electrode material with good stability in mixed aqueous-organic mixtures, and hence with interesting prospects in electroanalysis of biologically active organic compounds. It seems that similar analytical parameters of the already established variants of carbon paste electrodes can also be expected for their shungite analogues.

α-Fe2O3/, Co3O4/, and CoFe2O4/MWCNTs/Ionic Liquid Nanocomposites as High-Performance Electrocatalysts for the Electrocatalytic Hydrogen Evolution Reaction in a Neutral Medium.

Transition metal oxides are a great alternative to less expensive hydrogen evolution reaction (HER) catalysts. However, the lack of conductivity of these materials requires a conductor material to support them and improve the activity toward HER. On the other hand, carbon paste electrodes result in a versatile and cheap electrode with good activity and conductivity in electrocatalytic hydrogen production, especially when the carbonaceous material is agglomerated with ionic liquids. In the present work, an electrode composed of multi-walled carbon nanotubes (MWCNTs) and cobalt ferrite oxide (CoFe2O4) was prepared. These compounds were included on an electrode agglomerated with the ionic liquid N-octylpyridinium hexafluorophosphate (IL) to obtain the modified CoFe2O4/MWCNTs/IL nanocomposite electrode. To evaluate the behavior of each metal of the bimetallic oxide, this compound was compared to the behavior of MWCNTs/IL where a single monometallic iron or cobalt oxides were included (i.e., α-Fe2O3/MWCNTs/IL and Co3O4/MWCNTs/IL). The synthesis of the oxides has been characterized by X-ray diffraction (XRD), RAMAN spectroscopy, and field emission scanning electronic microscopy (FE-SEM), corroborating the nanometric character and the structure of the compounds. The CoFe2O4/MWCNTs/IL nanocomposite system presents excellent electrocatalytic activity toward HER with an onset potential of -270 mV vs. RHE, evidencing an increase in activity compared to monometallic oxides and exhibiting onset potentials of -530 mV and -540 mV for α-Fe2O3/MWCNTs/IL and Co3O4/MWCNTs/IL, respectively. Finally, the system studied presents excellent stability during the 5 h of electrolysis, producing 132 μmol cm-2 h-1 of hydrogen gas.

Silica graphite as an ink additive for stencil printed electrodes: A novel approach for electroanalytical determination of sulfanilamide

Silica-graphite composites present a high surface area, mechanical and chemical stability, and high functionality to be applied in electrochemical sensing. Indeed, those materials have been successfully employed to build composite electrodes such as carbon paste electrodes for a wide range of applications. Despite excellent performance, this kind of electrodes have been replaced by stencil printed electrodes (SPEs), emerging as a scalable alternative for manufacture offering sensors disposables, low-cost, customizable, and miniaturized. Based on this, herein a novel silica-graphite (SiG) composite is described as an ink additive aiming scalable production of SPEs with high functionality and surface area. The SPE as well as SiG were characterized by electrochemical impedance spectroscopy, scanning electron microscopy, thermogravimetric analysis, and contact angle. After an accumulation step, SiG-SPE pretreated has shown a significant improvement on oxidation of sulfanilamide compared with unmodified SPE. Electrochemical surface activation and pre-concentration conditions were investigated to enhance sensitivity and selectivity. Under optimized conditions, silica-graphite stencil printed electrode (SiG-SPE) was employed for the electrochemical determination of sulfanilamide by using square wave-adsorptive stripping voltammetry (SWAdSV). It was possible to achieve a linear dynamic range (LDR) from 2 to 20 mmol L−1 with a limit of detection (LOD) and quantification (LOQ) of 0.34 and 1.13 mmol L−1, respectively. The stability of the sensors was evaluated over five weeks, and a decrease of around 5.5 % in response was observed compared to fresh electrodes. SiG-SPE also presented high selectivity and low matrix interference for sulfanilamide determination with a recovery range of 96.2–100.1 % for urine and 98.2–106.1 % for commercial fat milk. Those results suggest that SiG is a promising ink additive for the production of low-cost and high-performance sensors, showing enhanced analytical properties, mechanical resistance, and chemical stability.

Development of Molecularly Imprinted Magnetic Amino Acid-Based Nanoparticles for Voltammetric Analysis of Lead Ions in Honey.

Lead (Pb) is a hazardous metal that poses a significant threat to both the environment and human health. The presence of Pb in food products such as honey can pose a significant risk to human health and is therefore important to detect and monitor. In this study, we propose a voltammetric detection method using molecularly imprinted polymer (MIP) electrodes to detect Pb (II) ions in honey. Pb (II) ion-imprinted amino acid-based nanoparticles with magnetic properties on a carbon paste electrode (MIP-CPE) were designed to have high sensitivity and selectivity towards Pb (II) ions in the honey sample. Zetasizer measurements, electron spin resonance, and scanning electron microscopy were used to characterize magnetic polymeric nanoparticles. The results showed that the voltammetric detection method using MIP-CPE was able to accurately detect Pb (II) ions in honey samples with a low detection limit. The proposed method offers a simple, rapid, cost-effective solution for detecting Pb (II) ions in honey. It could potentially be applied to other food products to ensure their safety for human consumption. The MIP-CPE sensor was designed to have high sensitivity and selectivity towards Pb (II) ions in the honey sample. The results showed that the technique was able to deliver highly sensitive results since seven different concentrations were prepared and detected to obtain an R2 of 0.9954, in addition to a low detection limit (LOD) of 0.0912 µM and a low quantification limit (LOQ) of 0.276 µM. Importantly, the analysis revealed no trace of Pb (II) ions in the honey samples obtained from Cyprus.

One‐pot hydrothermal biochar obtained from malt bagasse waste as an electrode‐modifying material towards the stripping voltammetric sensing of lead

AbstractPb2+ ions are highly toxic to living beings because they tend to bioaccumulate in the body. For this reason, the development of simpler, low‐cost, and easy‐to‐operate techniques that can detect and quantify low concentrations of metal ions would help to identify contaminating media and improve public health. This work proposes a Pb2+ voltammetric sensor based on a carbon paste electrode modified with hydrothermal biochar (hydrochar, HC) obtained from malt bagasse waste (HC/CPE). The obtained hydrochar was characterized by zero‐charge point, FT‐IR, XRD and thermogravimetry. The differential pulse adsorptive anodic stripping voltammetry (DPAdASV) technique was used to perform the Pb2+ determination. After optimizing important parameters for detecting Pb2+ ions and the parameters of the voltammetric technique employed, a linear response range of 0.50 to 7.06 μmol L−1 with a limit of detection (LOD) and limit of quantification (LOQ) of 55.0 and 181.5 nmol L−1 were achieved, respectively. The developed voltammetric procedure was applied towards the Pb2+ determination at tap water and river water samples, with excellent recoveries (ranging of 91.19 to 109.22 %), proving that the HC‐based electrode has great potential for detecting Pb2+ ions. Hydrothermal carbonization allowed the biomass to be converted into functionalized hydrochar, eliminating the need for subsequent functionalization/activation steps for use as a Pb2+ adsorbing material on the electrodic surface. The proposed sensor also proved to be easy to assemble and environmentally friendly by using biomass waste as the carbon material. Thus, the proposed sensor adds to the literature the possibility of simple and easy detection of metal ions with a waste reuse bias.

Amino‐Montmorillonite Crystalline Clay as Electrode Modifier for Electrochemical Detection of Ciprofloxacin in Presence of Cetyltrimethylammonium Bromide

AbstractThis research focused on harnessing amino‐functionalized montmorillonite (Mt) clay, achieved through the grafting of [3(2‐aminoethyl)amino]propyltrimethoxysilane (AEP‐TMS), as carbon paste electrode (CPE) modifier for the electroanalysis of ciprofloxacin (CF). The characterization of both Mt and the amino‐functionalized (Mt‐NH2) materials was carried out using various techniques including Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray diffraction (XRD). Afterwards, various CPEs modified using Mt and Mt‐NH2 were prepared and characterized employing SEM‐energy dispersive X‐ray (EDX), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). By EIS, Mt‐NH2‐CPE exhibited significantly faster electron transfer with lower charge‐transfer resistance (438.5 Ω) compared to Mt‐CPE (3572.1 Ω) and to the bare CPE (2066.1 Ω). Additionally, CV experiments performed by using redox probes demonstrated the excellent accumulation capability of [Fe(CN)6]3− ions on Mt‐NH2‐CPE surface. The Mt‐NH2‐CPE was subsequently applied using square wave voltammetry to determine CF in the presence of cetyltrimethylammonium bromide (CTAB), yielding an impressive linear range from 30 to 240 μM (R=0.999) and a low detection limit of 0.07 μM (23.2 μg L−1). The method exhibited stable and reproducible responses (RSD=3.25 %; n= 6) under optimized conditions. Following interference studies, the optimized method was effectively applied to quantify CF concentrations in pharmaceutical and water samples.

Comprehensive analysis of Alpelisib detection: Uniting molecular docking, dynamics, and precision electrochemistry at the PEDOT:PSS-carbon paste interface

The increasing utilization of carbon paste electrodes (CPE) in developing electrochemical sensors has led to a heightened search for innovative electrode materials. In the present study, incorporating poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) emerges as a pivotal modification technique for the electrochemical determination of Alpelisib (ALP), a paramount anticancer agent. The electrochemical behavior of ALP at the interface of the PEDOT:PSS-modified CPE was thoroughly investigated using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. By capitalizing on the intrinsic electrocatalytic properties of PEDOT:PSS, a refined design of a CPE was developed, enabling the electrochemical detection of ALP with enhanced sensitivity. The oxidation peak currents attributed to ALP exhibited a linear increase within the concentration range of 0.01–5 μM, and the detection limits were determined to be 4.8 nM. Significantly, this study highlights the effective utilization of the PEDOT:PSS-modified CPE for the electrochemical analysis of ALP in various matrices, including urine, human plasma, and pharmaceutical samples. Crucially, molecular docking and dynamics simulations substantiate the binding efficacy of ALP and its metabolites to the target protein, further corroborating the sensor’s precision in diverse biological and pharmaceutical mediums. The achieved recovery rates demonstrate the strength and effectiveness of the applied system. In addition to expanding the field of electrochemical sensor development, this study presents a robust framework for accurately measuring ALP, which has important implications in both clinical and pharmaceutical contexts.

Modification of carbon paste electrodes for the selective determination of adenosine in the presence of phosphate adenylic derivatives

Modification of carbon paste electrodes for the selective determination of adenosine in the presence of phosphate adenylic derivatives

Development of a Diethylcarbamazine Citrate‐Based Electrochemical Sensor for Quick and Affordable Detection of Sulfadiazine and Uric Acid in Environmental Monitoring

AbstractThe widespread use of antibiotics like sulfadiazine (SDZ) in various industries has raised environmental and health concerns due to their potential for bioaccumulation and the subsequent effects on human health and the environment. Diethylcarbamazine citrate (DCZ), a well‐established antifilarial drug, has yet to be explored as a sensing agent despite its extensive use. This study proposes a cost‐effective and efficient method for detecting SDZ and Uric acid (UA) using a DCZ‐modified carbon paste electrode (poly‐DCZ/MCPE). The poly‐DCZ film is synthesized via cyclic voltammetry (CV) on the carbon paste electrode surface, demonstrating excellent electrocatalytic activity for SDZ and UA detection at pH 7.4. The diffusion‐controlled electrode process is observed with a lower limit of detection (LOD) and limit of quantification (LOQ) for SDZ as 3.8×10−9 M and 12.94×10−9 M respectively. For UA, LOD and LOQ were found to be 6.291×10−9 M and 20.97×10−9 M respectively at the poly‐DCZ/MCPE. Notably, the sensor exhibits simultaneous detection capabilities for SDZ and UA by CV and differential pulse voltammetry (DPV) methods, addressing the need to monitor antibiotic residues in aquatic ecosystems and animal‐derived products.

Electrochemical oxidation of edoxaban and its determination in pharmaceutical samples and human serum

Edoxaban (EDX) electrooxidation was investigated at a carbon paste electrode using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). Several experimental conditions were evaluated, including buffer solution, pH, concentration, and scan rate. The results indicated that the redox process was irreversible over the pH and scan range studied and exhibited a diffusion-controlled behaviour. Furthermore, the drug was subjected to bulk electrolysis followed by UHPLC-QTOF/MS to elucidate the mechanism behind its electrooxidation. The present study also demonstrated the electroanalytical method’s ability to successfully determine EDX in pharmaceutical formulations and human serum without interference from the leading excipients and biological constituents. The obtained analytical curves exhibited two linear ranges, from 1.2 × 10−6 to 1.2 × 10−5 mol/L and from 1.4 × 10−5 to 7.4 × 10−5 mol/L, with a sensitivity of 0.068 μA (μmol/L)−1 and a limit of detection (LOD) of 2.6 × 10−7 mol/L, at a relative standard deviation (RSD) of 2.96 %.

Ferulic acid detection in honey using carbon paste electrode modified by C-C3N4/Li2CoMn3O8 nanocomposite

Honey is regarded as a valuable food commodity which has many and varied components, including phenolic compounds. Ferulic acid (FA) is one of these compounds, which possesses activities such as antioxidant, anti-inflammatory, anti-diabetic, haemolytic, antiviral, anti-cancer, etc. In view of these unique characteristics, a quick, sensitive, simple and inexpensive method for FA identification is required. This research developed a novel electrochemical sensor for measuring FA in honey samples. The sensor utilizes a C-C3N4/Li2CoMn3O8 nanocomposite modified carbon paste electrode (C-C3N4/LCMO/CPE) to enhance the sensitivity and detection. The synthesized nanocomposite exhibits remarkable properties, featuring an abundance of electrochemically active sites and enhanced electron transfer rates, making it ideal for developing advanced electrochemical sensors. The XRD, SEM and EDX analysis were used to examine and look like the synthesised nanocomposite structure. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods were used to evaluate the electrochemical behavior of C-C3N4/LCMO/CPE sensor for FA detection and optimized by adjusting pH, and potential scan rate. FA was measured in a phosphate buffered saline (PBS; 0.1 M, pH 4.0) by DPV with the detection limit of 3.6 nM and quantitative limit of 0.009 µM in the linear response ranges of 0.009–3.000 and 5.00–100 µM. Chronoamperometry was utilized to calculate the diffusion coefficient of FA (D = 3.45 (±0.11) × 10−6 cm2.s−1) on the surface of the C-C3N4/LCMO/CPE, as well as the electron transfer coefficient (α = 0.68). The sensor’s high sensitivity for accurately assessing FA in real samples was demonstrated by recovery values ranging from 96.96 to 102.36 %.

A new sensing platform based on poly(valine)-modified carbon paste electrode for the determination of hydroquinone and resorcinol

A new sensing platform based on poly(valine)-modified carbon paste electrode for the determination of hydroquinone and resorcinol

Voltammetric determination of hydrogen peroxide at decorated palladium nanoparticles/poly 1,5-diaminonaphthalene modified carbon-paste electrode.

In this work, palladium nanoparticles (PdNPs)/p1,5-DAN/ carbon paste electrode (CPE) and p1,5-DAN/CPE sensors have been developed for determination of hydrogen peroxide. Both sensors showed a highly sensitive and selective electrochemical behaviour, which were derived from a large specific area of poly 1,5 DAN and super excellent electroconductibility of PdNPs. PdNPs/p1,5-DAN/CPE exhibited excellent performance over p1,5-DAN/CPE. Thus, it was used for detecting hydrogen peroxide (H2O2) with linear ranges of 0.1 to 250 µM and 0.2 to 300 µM as well as detection limits (S/N = 3) of 1.0 and 5.0 nM for square wave voltammetry (SWV) and cyclic voltammetry (C.V) techniques, respectively. The modified CPE has good reproducibility, adequate catalytic activity, simple synthesis and stability of peak response during H2O2 oxidation on long run that exceeds many probes. Both reproducibility and stability for H2O2 detection are attributable to the PdNPs immobilized on the surface of p1,5-DAN/CPE. The modified CPE was used for determining H2O2 in real specimens with good stability, sensitivity, and reproducibility.

Green voltammetric method for determination of diclofenac sodium in environmental and biological samples using aluminium tungstate nanoparticles modified carbon paste electrode

ABSTRACT Based upon aluminium tungstate (Al2(WO4)3 NPs), a new modified sensor was created in order to monitor diclofenac sodium (DCF) electrochemically in environmental samples. The electrode composition, electrolyte effect, selectivity, scan rate, and pH parameters that affect the assay’s performance were optimised and the pH study revealed that pH 3.6 was found to be suitable to improve the electrochemical behaviour of diclofenac. The electrochemical characteristics of the built-in electrode were assessed using cyclic voltammetry technique (CV).The electrode composition, electrolyte effect, selectivity, scan rate, and pH parameters were optimised. The limit of detection was found to be 0.076 µM and the limit of quantification (LOQ) value was 0.25 µM for the concentration range (0.2–25 µM) of DCF. It has demonstrated good selectivity for (DCF) in presence of the interfering species and its electrochemical sensing’s repeatability, reproducibility and stability were evaluated and found typical. Some environmental samples like tap water, waste water, Nile-river water and biological ones like urine and plasma, have been effectively applied using the proposed electrochemical sensor. Green chemistry metrics, viz. Analytical GREEnness Preparation (AGREEprep), Analytical Eco-Scale Assessments (ESA) and The AMVI for the proposed method were calculated and have assured that the method has limited negative impact on both human health and the environment.

Voltammetric sensor based on a Ni-Co-layered double hydroxide/multi-walled carbon nanotubes nanocomposite for 4-aminophenol determination

In this work, we developed a simple technique to produce an effective electrode material consisting of nickel-cobalt-layered double hydroxide/multi-walled carbon nanotubes nanocomposite (Ni-Co-LDH/MWCNTs). This nanocomposite was prepared and characterization techniques such as field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FT-IR) and x-ray powder diffraction (XRD) were used to characterize its morphology and structure. The electrochemical studies and measurements were carried out by using various techniques including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA). The Ni-Co-LDH/MWCNTs nanocomposite-modified carbon paste electrode (Ni-Co-LDH/MWCNTs/CPE) exhibited enhanced electrocatalytic performance for the determination of 4-aminophenol. Detection of 4-aminophenol was done by using DPV. According to the results of DPV, the Ni-Co-LDH/MWCNTs/CPE sensor demonstrated a linear response to 4-aminophenol in the linear range of 0.02–700.0 µM, with a limit of detection (LOD) of 0.01 µM, and a sensitivity of 0.076 µA/µM. Also, the modified CPE presented reproducible and repeatable responses to determine 4-AP. The prepared sensor was also applied for determination of 4-aminophenol in the presence of possible interfering species and good results were obtained. In addition, the sensor successfully detected 4-aminophenol in real water samples with recoveries ranging from 98.0 % to 104.0 %, and with relative standard deviation (RSD) below 3.3 %. Therefore, the obtained results indicate that the prepared sensor can be an effective tool for the simple, fast, and sensitive detection of 4-aminophenol in water samples.

A novel electrochemical sensor for determination of 2, 4-dichlorophenol as an environmental pollutant based on a carbon paste electrode modified with NixMn3-xO4 nanoparticles

A novel electrochemical sensor for determination of 2, 4-dichlorophenol as an environmental pollutant based on a carbon paste electrode modified with NixMn3-xO4 nanoparticles

A novel L-Cysteine voltammetric sensor based on a dual-nucleation copper (II) complex

A novel platform of simple and cost-effective carbon paste electrode (CPE)-modified with a binuclear copper (II)-8-hydroxyquinoline complex was used for catalytic electroxidation of L-Cysteine. The modified electrode described was observed to significantly reduce the electrooxidation potential of L-Cysteine. Electrochemical impedance spectroscopy confirmed a significant decrease in the charge transfer resistance at the electrode surface by introducing the binuclear copper complex in the CPE. It was proposed that the two molecules of cysteine, adsorbed to the modified electrode surface, are oxidized to a cystine molecule via copper (II) centers of the complex which are consequently reduced to copper (I) species, responsible for the voltammetric peak observed when the potential was scanned toward the positive direction. To improve the electrode signal for cysteine, the electrode composition was also optimized. Two electrochemical techniques of cyclic voltammetry and amperometry were applied for the establishment of the calibration curve for cysteine determination by this electrode. The linear ranges of the calibration curves are obtained utilizing two electrochemical techniques of cyclic voltammetry and amperometry were 286–5000 μM and 11.6–500 μM, respectively. Also, the detection limits of cysteine assay by the above-cited techniques were calculated and equal to 86.7 μM and 3.5 μM, respectively. The electrode described was applied for cysteine determination in some vegetable samples which showed satisfactory results. Also, the selectivity of the sensor was checked against some biomolecules and amino acids such as Glycine, Alanine, Arginine, Methionine, Glucose, Urea, BrO3- and Citric acid. The introduced sensor exhibited excellent selectivity for cysteine determination in food samples.

Synthesis of graphitic carbon nitride (g-C3N4) by high-temperature condensation for electrochemical evaluation of dichlorophen and thymol in environmental trials

The work deals with synthesizing carbon-based nanomaterial, i.e., graphitic carbon nitride, which was carried out using the high-temperature condensation method. Graphitic carbon nitride is characterized by cost efficiency, increased thermal resilience, a two-dimensional molecular layer structure, biocompatibility and stability. These properties can be used in the electrochemical investigations of fungicides such as dichlorophen and thymol. The synthesized nanomaterial was first characterized using XRD, SEM, UV-DRS, BET, FTIR, CV and EIS investigations. The cyclic voltammetry behavior of dichlorophen and thymol shows the proton-coupled irreversible electron transfer process at a modified carbon paste electrode with the participation of same number of protons and electrons. The developed sensor exhibited good detection limits for the dichlorophen and thymol as low as 15.3 nM and 12.0 nM with the sensitivity of 126.8 µA·µM−1·cm−2 and 59.2 µA·µM−1·cm−2, respectively. The applicability of the developed sensor was tested in spiked soil and water samples, and good recoveries were achieved with a% RSD of 1.67 and 1.30, respectively. The anti-interference responses to metal ions demonstrate the selectivity (qualitative) of the developed sensor in the electrochemical detection of dichlorophen and thymol. In the future, the sensor developed would offer the potential to sensitively and selectively detect other pesticide molecules in environmental samples.