Behavior Of Carbon Paste Electrode Research Articles

Development and Detailed Performance Study of a Carbon Paste Electrode for the Electrochemical Detection of Malachite Green

The present investigation aims to lighten a quick electrochemical detection technique of malachite green (MG) content using an easy and affordable carbon paste electrode (CPE). MG finds a wide area of application for controlling external fungi plus parasites on the fish egg for its antifungal and antiparasitic features. However, MG is noticed to be dreadfully poisonous and unsafe. Hence, the determination of MG in aquaculture is very much necessary. In this current report, the electrochemical behavior of CPE has been studied using a three-electrode system containing a silver-silver chloride (Ag/AgCl) reference electrode and a platinum counter electrode to record the corresponding cyclic voltammetry (CV) and differential pulse voltammetry (DPV) responses. CV plots in the applied potential range from 0.3 V to 1.5 V described a strong indication of MG existence, while DPV results successfully illustrated the quantification of several MG concentrations. The linear range of operation was from 10[Formula: see text][Formula: see text]M to 1000[Formula: see text][Formula: see text]M with the lowest limit of detection (LOD) as 0.78 [Formula: see text]M. Various concentrations like 50, 300, 600, 800, and 1000[Formula: see text][Formula: see text]M were assessed via principal component analysis (PCA) with effective data clustering (separability index (SI) found as 131.08). The prediction estimations of MG content using PLSR (partial least square regression) along with PCR (principal component regression) algorithms were also carried out, resulting in 95.39% and 93.02% prediction accuracies, respectively. Moreover, applying this CPE over natural aqueous sample extracts exhibited a reasonable recovery rate of 94.85–97.3%.

Co-precipitation synthesis of cobalt doped ZnO nanoparticles: Characterization and their applications for biosensing and antibacterial studies

A new modified sensor based on carbon paste electrode (CPE) was developed using cobalt doped ZnO (Co-ZnO) nanoparticles (NPs). In this work, we demonstrated the analytical behavior and applications of CPE modified with Co-ZnO/MCPE for the simultaneous determination of uric acid (UA) and adrenaline (AD) with highly selective and sensitive using voltammetric techniques. The synthesized Co-ZnO NPs were characterized by utilizing XRD, FTIR, FESEM with EDX, TEM, UV–Vis and photoluminescence spectroscopy. XRD suggests that the average size of these NPs was between 21 and 35 nm with a hexagonal wurtzite structure. Tauc plot exhibited that the optical energy bandgap of ZnO NPs gradually decreases with Co doping. Compared with undoped ZnO, Co-ZnO modified carbon paste electrode (Co-ZnO/MCPE) exhibits excellent electrochemical performance towards the oxidation of UA. Influencing factors, including scan rate, concentration, and pH values were optimized. Under the optimal condition, the Co-ZnO/MCPE responded to UA linearly with a detection limit of 3.37 µM and the fabricated sensor exposes diffusion-controlled electrode process. The developed Co-ZnO/MCPC has capable of determination of both UA and AD simultaneously with two different oxidation peaks. The sensitivity, long-term stability and reproducibility of the developed sensor were estimated. The bacterial efficiency of undoped and Co-ZnO NPs was inspected against gram-negative (Escherichia coli) and gram-positive (Enterococcus faecalis) bacteria.

Electrical and Electrochemical Behavior of Carbon Paste Electrodes Modified with Ionic Liquids Based in N-Octylpyridinium Bis(Trifluoromethylsulfonyl)Imide. A Theoretical and Experimental Study.

In this work, we studied carbon paste electrodes (CPEs) with two kinds of binders: mineral oil or ionic liquids (IL) derived from N-substituted octyl pyridinium bis(trifluoromethylsulfonyl)imide with the substituents H-, CH3-, CN- and CF3-. The work aims to study this series of IL and determine a possible effect of the substituent of the cation in the behavior of the IL as a binder of graphite for obtaining IL-CPEs. The electrochemical response and the electrical behavior were measured by cyclic voltammetry and electrochemical impedance spectroscopy, respectively. Surprisingly, the substituent does not affect the cyclic voltammetry response because in all the cases, high resistance and high capacitive currents were obtained. The best response in terms of conductivity is obtained by CPE. In the case of impedance measurements, the substituent does not cause differences, and in all the cases, the IL-CPEs show nearly the same responses. CPE shows lower capacitance and higher resistance for diffusion compared to the IL-CPEs due to his lower porosity. The high resistance showed by the IL-CPEs by cyclic voltammetry can be attributed to poorly intermolecular forces among graphite, water, electrolyte, and ILs as demonstrated by theoretical calculations.

An ultrasensitive and selective electrochemical sensor for determination of estrone 3-sulfate sodium salt based on molecularly imprinted polymer modified carbon paste electrode.

A highly sensitive and selective electrochemical sensor based on carbon paste electrode (CPE) modified with molecularly imprinted polymers (MIPs) has been developed for the determination of estrone 3-sulfate sodium salt (ESS). MIPs were prepared in polar medium via bulk polymerization and characterized by scanning electron microscopy and infrared spectroscopy. Cyclic voltammetry was performed to the study preparation process and binding behavior of the MIP-modified CPE (MIP/CPE) toward ESS. The conditions for preparing MIPs and MIP/CPE as well as ESS detection were optimized. Under the optimal experimental conditions, the detection linear range for ESS is 4×10-12 to 6×10-9M with a limit of detection of 1.18×10-12M (S/N=3). In addition, the sensor exhibits high binding affinity toward ESS over its structural analogues with excellent repeatability and stability. The fabricated MIP/CPE was then successfully employed to detect ESS in pregnant mare urine (PMU) without any pretreatment, and the average recoveries were from 99.6 to 104.9% with relative standard deviation less than 3.0%. High-performance liquid chromatography was adopted as a reference to validate the established approach in detecting ESS and their results showed good agreement. The as-prepared sensor has high potential to be a decent tool for on-site determination of ESS in PMU in a fast and convenient manner. Graphical Abstract ᅟ.

An electrochemical sensor for clozapine at ruthenium doped TiO2 nanoparticles modified electrode

A new modified sensor based on carbon paste electrode (CPE) was developed using ruthenium doped titanium dioxide nanoparticles (Ru-TiO2). In this work, we demonstrated the analytical behavior and applications of CPE modified with Ru-TiO2 (Ru-TiO2/CPE) for the determination of Clozapine by employing different voltammetric techniques. The characterization of synthesized ruthenium doped titanium dioxide nanoparticles was accomplished by utilizing X-ray diffraction (XRD), scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscope (TEM). The morphology of the sensing surface was analyzed by atomic force microscope (AFM). Modification of working electrode increases the electro-oxidation of clozapine with increased current intensity. The influence of parameters like scan rate, pH, accumulation time, amount of the modifier and concentration on the peak current of the drug were studied. A probable electro-oxidation mechanism was proposed based on the obtained experimental results. The effect of CLZ concentration variation was studied using square wave voltammetric (SWV) technique in the range of 9.0×10−7M to 4.0×10−5M with the detection limit of 0.43nM. The prepared Ru-TiO2 modified sensor was employed for the determination of clozapine in pharmaceutical formulations and human urine.

Controllable Synthesis and Electrochemical Behavior of Micro/Nano Octahedron Ceria

Octahedron ceria crystals were fabricated by one-step hydrothermal synthesis without using any hard-template, with Ce(NO3)3·6H2O being raw materials and polyvinylpyrrolidone (PVP) being surfactant. The content of ethanol plays an important role in the morphology evolution of as-obtained CeO2. At 200°C, with the addition of ethanol into the water and by adjusting the ratio between ethanol and water from 1:3 to 3:1, the morphology of the as-obtained CeO2 changed from solid octahedron to hollow irregular particles. When the ratio between ethanol and water is 1:1, prolonging the reaction time from initial 6 h to 12 h and ultimate 48 h, the morphology of the as-obtained CeO2 growing from solid quasi-octahedron to regular octahedron, and then to hollow irregular particles. The electrochemical behavior of carbon paste electrode (CPE) modified by graphene/CeO2/CHIT nanocomposite membrane in 2.0 × 10–5 mol/L methylene blue (MB) containing 0.02 mol/L NaCl, and glassy carbon electrode (GCE) modified by MWNTs/CeO2/CHIT nanocomposite membrane in 1.0 mmol/L K3Fe(CN)6/K4Fe(CN)6 (1:1) containing 0.5 mol/L KCl as the supporting electrolyte were measured respectively. The electrochemical measurements were carried out by cyclic voltammetric (CV) and differential pulse voltammetry (DPV). The synergistic effects of as-synthesized micro/nano CeO2 and new carbon materials (MWNTs, graphene) on enhancing electrochemical signal were demonstrated, and a bright prospect of micro/nano octahedron CeO2 on electrochemical application can be seen from this paper.

Effect of solvent on the construction of Co(II) coordination polymers containing a semi-rigid bis(benzimidazole) derivative: syntheses, structures, and properties

Two Co(II) coordination polymers, [CoL(npa)]·2H2O (1) and [CoL(Hnpa)2] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H2npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound 1 was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting a μ2-bridging mode and connecting two Co2+ cations to generate a 26-membered Co2L2 loop. The npa2− link adjacent Co2L2 loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound 2 was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa− adopt a μ1-η0 : η1 coordination to connect adjacent Co2+ cations into a 2-D polymeric layer. The μ2-bridging L ligands connect adjacent 2-D [Co(Hnpa)]n polymeric layers into a 3-D NaCl-like framework. The Co2+ cations and the L ligands in compounds 1 and 2 exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing 1 and 2 and the thermal stabilities of 1 and 2 were investigated.

Voltammetry Behavior of Carbon Paste Electrodes with Native and Chemical Modified Porphyrans

Porphyra species are important edible red algae abundantly cultivated; they are commonly known as ‘nori’ and used to prepare sushi. P. tenera and P. yezoensis are the species cultured and processed into this sheet type dried food. Porphyran is a linear sulfated water soluble polysaccharide that can be obtained from Porphyra species1,2. It is constituted by units of (6-O-methyl)-β-D-galactose, 3,6-anhydro-α-L-galactose and α-L-galactose 6-sulfate1,2. Carbon paste electrodes (CPE) containing natural ionic polysaccharides (pectic and alginic acid and heparin) have been studied3 and biosensors like these are generally developed for the detection of analytes particularly in aqueous phase4. The present work describes the voltammetric behavior of porphyran-modified CPE obtained before and after chemical desulfation of the polysaccharides. Porphyran was obtained from dried milled nori by water extraction (1.5 %w/v, for 16 h, at room temperature) and precipitation with ethanol (three volumes). The native fraction (PN) was purified by redissolution in water, dialysis and lyophilization. The desulfated porphyrans fractions were obtained by solvolysis5 (PD) and alkaline treatment6 (PA) from the native fraction. The polysaccharides structures were confirmed by 13C NMR analysis. The carbon paste was prepared by hand-mixing the porphyran with graphite powder (100 mg) and mineral oil (30 µL). Electrodes containing 10, 20, 40, 60, 80 and 100 µg of the native (EN) and chemically modified porphyran (ED and EA) were studied. The carbon paste was packed into the hole of the electrode body (working electrode) and an Ag/AgCl (reference electrode) and a platinum wire (auxiliary electrode) completed the three-electrode system in the measurement cell. Cyclic voltammograms (CV) were recorded in the potential range of -0.6 – 1.0 V (PBS buffer 0.15 mol L-1, pH 6.5) with a scan rate of 50 mV s-1 using K3Fe(CN) 6 /K4Fe(CN) 6 0.1 mol L-1 as redox reference solution. The measurements were performed using a PalmSens potentiostat (Palm Instruments BV). The NMR spectra obtained for PN, PD and PA confirmed the porphyran structural pattern as they also showed that the chemical treatments produced desulfated polysaccharides. Especially for PA fraction, the NMR spectrum indicated an increase in the 3,6-anhydrogalactose content as a result of cyclization of the galactose-6-sulfate, as expected by the alkaline treatment7. The CVs was used to characterize the porphyran-modified CPEs and the voltammograms indicated an increase in the cathodic and anodic current peaks in the same potential range for all electrodes as compared to unmodified CPE. Despite this, the increase in current values did not correlate directly with the porphyran concentration used to modify the electrodes, so the CPEs with 10, 20 and 40 µg showed the most intense anodic peaks for EN (3,648.81 µA), EA (3,838.67 µA) and ED (4,452.00 µA), respectively (Figure 1). The higher values of redox current peaks were found for the electrode ED at all porphyrans concentrations studied. This behavior can be attributed to electrostatic repulsion between the K3Fe(CN) 6 /K4Fe(CN) 6 and the ionic polysaccharide. As the porphyran PD has a lower number of sulfate groups, the electrode ED may have a better electrochemical response. In addition, the peak currents increased and the cathodic and anodic peak potential exhibited a small shift along with the increase of scan rate for EN (10ug), EA (20ug) and ED (40ug). At the same time, the anodic peak current increased linearly with the square root of the scan rate (correlation coefficient of 0.9711, 0.9975 and 0.9943 for EN, EA and ED respectively). This phenomenon suggested that the redox process was diffusion-controlled. In conclusion, the CVs demonstrated that the electron transfer on the porphyran-modified CPEs surface, especially on ED, are more efficient, conducting higher current and offering lower resistivity.1- JIANG, Z.; HAMA, Y.; YAMAGUCHI, K.; ODA, T. J. Biochem., v. 151, p. 65, 2012.2- ISHIHARA, K.; OYAMADA, C.; MATSUSHIMA, R., et al. Biosci. Biotechnol. Biochem., v. 69, p. 1824, 2005.3- WANG, J.; TAHA, Z.; NASER, N. Talanta, v. 38, p. 81, 1991. 4- MOHSENI, G.; NEGAHDARY, M.; FARAMARZI, H.; et al. Int. J. Electrochem. Sci., v. 7, p. 12098, 2012. 5- CIANCIA, M.; NOSEDA, M.D.; MATULEWICZ, M.C.; CEREZO, A.S. Carbohydrate Polymers, v. 20, p. 95, 1993.6- NAGASAWA, K.; INOUE, Y.; TOKUYASU, T. Journal of Biological Chemistry, v. 86, p. 1323, 1979.Figure 1: Cyclic voltammogram of EN (10 µg), EA (20 µg) and ED (40 µg), in PBS buffer 0.15 mol L-1, pH 6.5, potential range of -0.6 – 1.0 V, using K3Fe(CN) 6 /K4Fe(CN) 6 0.1 mol L-1 as redox reference solution.

Evaluation of the Electrochemical Behavior of Carbon Paste Electrode (CPE) with Chalcopyrite (CuFeS2) in the Presence of Ferrous Ions

In this work we present an electrochemical study using carbon paste electrode (CPE) with CuFeS2in solutions with different concentrations of Fe2+ions in order to evaluate the possible interaction between these ions and mineral sulfide in the absence and presence of the bacteriaAcidithiobacillus ferroxidans.

Electrochemical Behavior of Carbon Paste Electrode with Gold-Bearing Pyrite in Bioleaching

The dissolution of gold-bearing pyrite plays an important role in bioleaching of gold. This paper describes a fundamental study on the electrochemical behavior and reaction mechanisms of gold-bearing pyrite leaching in the form of Carbon Paste Electrode (CPE) with and without microorganisms using Cyclic Voltammetry (CV) and polarization curve. A two step process was suggested from Cyclic voltammetry. Electrode passivation by elemental sulphur was observed below 700mV (vs. SCE), elemental sulphur was then oxidized to sulphate when the electrode potential further increased from 700mV. The polarization current density of CPE and the oxidation rate of pyrite are further enhanced by the presence of microorganisms. Analyses of EDS and XPS confirmed the formation of elemental sulphur and sulphate. This electrochemical method successfully showed its simplicity and reliability to measure oxidation rate of gold bearing pyrite.

Maghemite-Nanoparticles Enhanced Effects in Electrochemical Determination of Dipyridamole Utilizing Simultaneous Statistical Based Experimental Design Optimization

Significant effects of maghemite (γ-Fe2O3) nanoparticles on the voltammetric behavior of carbon paste electrode for bio determination of dipyridamole (DIP) were studied. The electrochemical performance of maghemite NPs modified carbon paste electrode (MMCPE) was investigated (compared to unmodified and the other manufactured modified electrodes) and the mechanism was studied by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. Herein we utilized statistical based experimental design for simple optimization of effective parameters on the response of the electrode. Results indicate that MMCPE can remarkably enhance electrocatalytic activity toward the oxidation of dipyridamole (DIP) in Britton−Robinson buffer at pH 2.0. Under optimal conditions a detection limit of 5.0 × 10−9 mol L−1 (2.5 ng mL−1) was obtained by DPV. The advantageous method was then tested for the simple, rapid and sensitive electrochemical determination of DIP in pharmaceutical formulations and human plasma as real samples.

Electrocatalytic behavior of carbon paste electrode modified with metal phthalocyanines nanoparticles toward the hydrogen evolution

This paper describes the construction of a carbon paste electrode (CPE) impregnated with nanoparticles of Zn and Ni phthalocyanine (nano ZnPc and nano NiPc). These new electrodes (nano ZnPc-CPE and nano NiPc-CPE) reveal interesting electrocatalytic behavior toward hydrogen evolution reaction (HER). Voltammetric characteristics indicated that the proposed electrodes display better electrocatalytic activity compared to their corresponding bulky modified metal phthalocyanines (MPcs) in minimizing overpotential and increasing the reduction current of HER. Electrocatalytic activities irregularly change with the pH of the solution. However by increasing the pH while nano MPcs are still active, bulky MPcs are almost inactive, and their corresponding ΔE increase by increasing the pH.

Synthesis of ZSM-5 zeolite: Electrochemical behavior of carbon paste electrode modified with Ni (II)–zeolite and its application for electrocatalytic oxidation of methanol

In this research, we reported a novel method for synthesis of ZSM-5 zeolite. The synthesized zeolite was characterized using X-ray diffraction, scanning electronic microscopy and FT-IR techniques. The modified carbon paste electrode was prepared by incorporation of Ni (II)–zeolite in the carbon paste matrix. The electrochemical oxidation of methanol was investigated at the surface of this modified electrode in alkaline solution using cyclic voltammetry and chronoamperometry methods. It was found that methanol was oxidized by NiOOH generated with further electrochemical oxidation of nickel hydroxide on the surface of this modified electrode during the anodic potential sweep. The effect of some parameters such as scan rate of potential, concentration of methanol, amount of Ni (II)–zeolite was investigated on the oxidation of methanol at this electrode. Also, the rate constant for the catalytic reaction ( k) of methanol was obtained.

Influence of the Electrode Material on the Electrochemical Behavior of Carbon Paste Electrodes Modified with Meldola Blue and Methylene Green Adsorbed on a Synthetic Zeolite

AbstractCarbon paste electrodes modified with a phenoxazine derivative, Meldola blue, and a phenothiazine derivative, methylene green, both strongly adsorbed on a synthetic zeolite were investigated using either glassy carbon powder (Sigradur K, SK) or single‐walled carbon nanotubes (SWCNT) as conductive electrode material. In the case of SWCNT based electrodes, the formal potential of both mediators was pH dependent, as expected for a redox process involving proton transfer. In contrast, the formal potential of both mediators of SK based modified electrodes was practically insensitive to pH. This behavior is discussed in terms of interactions existing in the heterogeneous system mediator‐zeolite‐electrode material.

Electrochemical behavior of carbon paste electrodes modified with methylene green immobilized on two different X type zeolites

Two new modified carbon paste electrodes (CPEs) based on two different X type zeolites, a natural zeolitic volcanic tuff (NZ) and a NaX type synthetic zeolite (SZ), modified with methylene green (MG) were developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer rate and a good stability for both investigated electrodes. The observed differences between the electrochemical behavior of MG-NZ-CPEs and MG-SZ-CPEs (the effect of pH on the formal standard potential, the magnitude of the rate constants for heterogeneous electron transfer and electrode response decay) were explained in terms of zeolites structure. The modified electrodes showed moderate electrocatalytic effect towards H2O2 reduction and a relatively low limit of detection (0.5 mM for MG-NZ-CPEs).

Chronoamperometric and cyclic voltammetric study of carbon paste electrodes using ferricyanide and ferrocenemonocarboxylic acid

The electrochemical behavior of carbon paste electrodes (CPEs) was studied by chronoamperometry and cyclic voltammetry in solutions containing either potassium ferricyanide or ferrocenemonocarboxylic acid. An evaluation of the experimental results leads to the conclusion that the electron transfer reaction at CPE for ferricyanide is more consistent with the “pinhole model”, whereas for ferrocenemonocarboxylic acid it may take place through the uniform phase (“membrane”) of the pasting liquid. The electrochemical behavior of ferricyanide at glucose- oxidase-containing CPEs is discussed in terms of the electrostatic interaction of the negatively charged electroactive species with the positively charged protein domain.

Chemical species produced in the reaction between ethanedial (glyoxal) and 5-amino-1,10-phenanthroline and their iron(II) complexes: electrochemical studies and analytical applications

The cyclic voltammetric behavior of carbon paste electrodes modified by direct admixing with the products of the reactions between ethanedial (glyoxal) and 5-amino-1,10-phenanthroline at 100°C and that of their iron(II) complexes is reported. The ligand(s) produced in absence of iron(II) are able to complex iron(II) and copper(II) ions reversibly, but other ions such as nickel(II), cobalt(II), cadmium(II) and manganese(II), if complexed, show no electrochemical activity. Admixing with the products of the reaction in the presence of excess of iron(II) ion, because of high insolubility and fast electron exchange, produces surfaces useful for amperometric detection in continuous-flow systems. The voltammetric and amperometric behavior in the presence of HSO − 3 ions is reported in order to illustrate this application.