Application Of Carbon Paste Electrode Research Articles

Characterization and Application of Carbon Paste Electrode Modified by Moringa Oleifera Seed Powder to the Electrochemical Detection of Mercury

Heavy metal pollution of surface waters from anthropogenic activities is constantly increasing. Monitoring techniques must therefore be more precise and more sensitive. One of the effective methods available is the development of sensitive electrochemical sensors, dedicated to the analysis of pollutants in aqueous solution. The carbon paste electrode (CPE) in this study was modified with Moringa Oleifera seed powder, a flocculant-adsorbent used to treat water. This chemically modified electrode presented improved electrochemical reactivity in cyclic votammetry towards the redox marker Ferri / Ferrocyanide compared to the bare carbon paste electrode. The 10 % modifier presented the most interest during the analysis. The Modified electrode was used to detect mercury (II) in anodic stripping voltammetry. The detection current of mercury (II) is seven times that of carbon paste electrode (CPE). The calibration curve is linear in the range from 0.002 μmol/L to 0.009 μmol/L (0.4 μg/L to 1.8 μg/L) with a detection limit of 0.4 ηmol/L (i.e.0.08 μg/L). This new technique can be used for routine monitoring of real aqueous matrices.

A modified carbon paste electrode based on Fe3O4@multi-walled carbon nanotubes@polyacrylonitrile nanofibers for determination of imatinib anticancer drug

The increasing application of carbon paste electrode (CPE) in the fabrication of electrochemical sensors has motivated researchers to develop new electrode materials. In the present work, Fe3O4 nanoparticles supported on the multi-walled carbon nanotubes and polyacrylonitrile nanofibers (Fe3O4@MWCNTs@PANNFs) was synthesized via the bulk modification approach to detect imatinib (IMA), as an important anticancer drug. The modified CPE materials were characterized by FESEM, FT-IR, Raman spectroscopy, EDX analysis, XRD, CV, and EIS techniques. The electrocatalytic behavior of IMA at the surface of the modified CPE was studied using a differential pulse voltammetry method. Taking advantages of the electrocatalytic behavior of Fe3O4 nanoparticles and MWCNTs, as well as the large surface area of PANNFs, an applicable-modified CPE was introduced for electrochemical determination of IMA with high sensitivity. The anodic peak currents of IMA increased linearly within the concentration ranges of 0.0017–0.8500 μM, along with detection limits of 0.4 nM. In addition, the oxidation mechanism of IMA was proved by electrochemical simulation. Finally, the Fe3O4@MWCNTs@PANNFs/CPE was employed to the electrochemical determination of IMA in urine samples.

Application of Carbon Paste Electrode Modified with Carbon Nanofibres/Polyaniline/Platinum Nanoparticles as an Electrochemical Sensor for the Determination of Bezafibrate

AbstractThe present study deals with the development of an electrochemical sensor for quantitative determination of Bezafibrate (BZF) based on carbon nanofibers/polyaniline/platinum nanoparticles modified carbon paste electrode (CNF/PANI/Pt/CPE). BZF is a fibric acid derivative and is used largely in the treatment of lipid disorders. The nanocomposite was synthesized by in situ polymerization of aniline using ammonium persulphate and platinum nanoparticles were uniformly decorated on the CNF/PANI surface by reducing hexachloroplatinic acid using sodium borohydride. The electrochemical response of BZF at CNF/PANI/Pt/CPE was studied using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The above study resulted into significant improvement of the electrochemical signal towards the oxidation of BZF, revealing that the oxidation process is highly favorable at the surface of modified electrode. The anodic peak current Ip (μA) is found to be linearly dependent on BZF concentration in the range of 0.025 μM to 100 μM with a detection limit of 2.46 nM. The practical analytical utilities of the sensor were investigated by performing the experiments on synthetic pharmaceutical formulations, human blood serum and urine samples which offered good recovery, suggesting the high efficacy and authenticity of CNF/PANI/Pt/CPE sensor for BZF determination.

Electrocatalytic determination of penicillamine using multiwall carbon nanotubes paste electrode and chlorpromazine as a mediator

In this study, we describe the application of carbon paste electrode modified with multiwall carbon nanotubes as a voltammetric sensor for determination of penicillamine (PA) in the presence of chlorpromazine as a mediator. This modified electrode showed very efficient electrocatalytic activity for the anodic oxidation of PA. The peak current of linear sweep voltammograms of PA increased linearly with it’s concentration in the range of 0.5–500 μM PA. The detection limit for PA was 0.2 μM. The RSDs for 1.0 and 10.0 μM PA were 1.1 and 1.7%, respectively. The proposed sensor was successfully applied for the determination of PA in human urine and tablet.

The mechanism of electrochemical dissolution of sphalerite in sulfuric acid media

The dissolution of sphalerite concentrate from Angouran mine was studied in 0.5M sulfuric acid solution by the application of carbon paste electrode at 22°C. Different electrochemical methods including cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) were applied to study the behavior of the sphalerite. Results showed that the oxidation of sphalerite proceeds in the anodic potential range of open circuit potential (OCP) to 900mV vs. Ag/AgCl. At low anodic potential of 400mV vs. Ag/AgCl a sulfur−rich passive layer forms on the mineral surface. The predominant reaction on the electrode surface at 400mV vs. Ag/AgCl is oxidative sphalerite dissolution, in which zinc ions and elemental sulfur layer, as a passive layer, form through the electrochemical reaction. By increasing the potential to 550mV vs. Ag/AgCl the passive layer was partially dissolved. Further increase of the potential to 900mV vs. Ag/AgCl results in the complete dissolution of the passive film and active dissolution of sphalerite. The electrochemical oxidation of sphalerite and the formation and dissolution of its passive film were also studied by EIS. Afterwards, the EIS spectra were modeled by equivalent electrochemical circuit. Together, the EIS data and Raman spectroscopy results strongly supported the proposed mechanisms for the oxidative sphalerite dissolution through the anodic potential range.

Porphyran-capped gold nanoparticles modified carbon paste electrode: a simple and efficient electrochemical sensor for the sensitive determination of 5-fluorouracil

The application of carbon paste electrodes modified with porphyran-capped gold nanoparticles (CPE/AuNps-PFR) to detect an important anticancer drug, 5-fluorouracil (5-FU), is described. Gold nanoparticles (AuNps) were synthesized through a green one-pot route, by using porphyran (PFR) (a sulfated polysaccharide extracted from red seaweed) as reducing and stabilizing agent. The reaction temperature and the concentrations of AuCl4− and PFR for AuNps-PFR synthesis were optimized by using a 23 full factorial design with central point assayed in triplicate. The smallest particle size (128.7 nm, obtained by DLS) was achieved by employing a temperature of 70 °C and AuCl4− and PFR concentrations equal to 2.5 mmol L−1 and 0.25 mg mL−1, respectively. The AuNps-PFR nanocomposite was characterized by UV–vis spectroscopy, FTIR, DLS, TEM, XRD and zeta potential, which proved that PFR was effective at reducing and capping the AuNps. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments showed that the nanocomposite could enhance the electrochemical performance of the electrodes, as a consequence of the high conductivity and large surface area presented by the AuNps. The CPE/AuNps-PFR was able to electrocatalyze the oxidation of 5-FU by CV and differential pulse voltammetry (DPV). A linear relationship between the DPV peak currents and 5-FU concentration was verified in the range from 29.9 to 234 μmol L−1 in 0.04 mol L−1 BR buffer solution pH 8.0. Detection and quantification limits were found to be 0.66 and 2.22 μmol L−1, respectively. Besides the good sensitivity, CPE/AuNps-PFR showed reproducibility and did not suffer significant interference from potentially electroative biological compounds. The good analytical performance of the modified electrode was confirmed for determining 5-FU in pharmaceutical formulations, with good percent recoveries (ranging from 96.6 to 101.4%) and an acceptable relative standard deviation (RSD = 2.80%).

Nano-Composite Carbon Paste Electrochemical Sensors for Monitoring of Lead Ions in Real Samples

Background: Determination of heavy and transition metal ions, like lead, especially with the aid of portable, user fiendly, and accurate and precise devices has long been an interesting area in analytical applications, especially in the case of environmental and biological samples. In this light, and given the facility, speed, accuracy, precision and also moderate costs of electrochemical monitoring techniques, these methods have been brought into the spotlight. Among the various areas of research used for such purposes, the preparation, modification and application of carbon paste electrodes (CPEs), as sensors which offer rather unique advantages of renewability of their surface, stable responses, low Ohmic resistance, and above all, the possibility of modifying and fine tuning their composition to meet the requirements of specific analytical applications, have given these devices a unique role among the other comparable techniques and hence this field has turned to a very attractive area of scientific endeavor. The composition of the carbon pastes usually consists of graphite powder dispersed in a binding solvent, but the characteristics of CPEs have been further improved through the addition of various modifiers. A rather recent step in the area of modification of CPEs, is the application of nano-materials to form nanocomposite carbon paste electrodes (NC-CPEs). Keywords: Nano-composite, carbon paste, electrochemical sensors, lead, glassy carbon electrodes, binding solvents.

Evaluation of antimony microparticles supported on biochar for application in the voltammetric determination of paraquat

This work describes the construction and application of carbon paste electrodes modified with biochar and antimony microparticles (SbBCPE) for voltammetric determination of paraquat using a simple and sensitive procedure based on voltammetric stripping analysis. Some parameters such as amount of biochar and antimony used in the composition of the carbon paste and instrumental parameters were examined in detail. Under optimized conditions, an analytical curve was obtained for paraquat determination employing SbBCPE, which showed a linear response ranging from 0.2 to 2.9μmolL−1, with limit of detection and quantification of 34nmolL−1 and 113nmolL−1, respectively, after paraquat pre-concentration of 120s. The repeatability study presented a RSD=2.0% for 10 consecutive measurements using the same electrode surface and the reproducibility study showed a RSD=2.7% for measurements with 10 different electrode surfaces. The proposed sensor was successfully applied for paraquat determination in tap water and citric fruit juice spiked samples and good recoveries were obtained without any sample pre-treatment, showing its promising analytical performance.

Electrochemical properties of α-tocopherol in aqueous electrolytes after its previous extraction into the glassy carbon paste from aqueous-acetonic mixture

Study on electrochemical behavior of lipophilic α-tocopherol, which is recognized as the most active form of vitamin E, was performed using extraction voltammetry in solely aqueous supporting electrolytes. In the first step, α-tocopherol was extracted into the silicone oil, acting as a binder of glassy carbon paste electrode, from aqueous-organic mixture. Generally, the extraction into the electrode material was carried out from solution containing 50 µmol dm−3 α-tocopherol and 60 % acetone for period of 240 s and corresponding stirring rate of 400 rpm. Electrochemical study was undertaken subsequently by cyclic voltammetry after placing the electrode in aqueous supporting electrolyte. Due to the accumulation effect of extraction, voltammetric records exhibited intensive current signals in acidic media when compared to those obtained at solid glassy carbon electrode. Investigations revealed a promising application of carbon paste electrodes for sensitive analysis of α-tocopherol or other electroactive lipophilic species after their extractive preconcentration.

Trace determination of cadmium in water using anodic stripping voltammetry at a carbon paste electrode modified with coconut shell powder

AbstractBackgroundIncreasing awareness on the environmental impact of heavy metals has increased a considerable interest in the determination of metals in natural water bodies. The present paper describes the development and electrochemical application of carbon paste electrode modified with fibrous part of coconut shell for the determination of cadmium in water samples.MethodsDetermination was carried out using anodic stripping voltammetry. It is a two-step process. First, the metal ions get accumulated at the electrode surface at open-circuit potential, followed by a potential scan for voltammetric determination of cadmium.ResultsDifferent parameters affecting the determination of Cd (II) were optimized and are as follows: HCl as stripping solvent, acetate buffer of pH 5 as accumulating solvent, and 15-min accumulation time. Triton X-100, cetyltrimethylammonium bromide, and sodium dodecyl sulfate were used as representative for neutral, cationic, and anionic surfactants, respectively, to see the effect of surface active macromolecules. Interference caused by other metal ions on the determination of cadmium was also studied.ConclusionsThe method shows the development of a sensor for the sensitive determination of cadmium with limit of detection at 105 μg L−1. This technique does not use mercury and, therefore, has a positive environmental benefit.

Nanocellulosic fiber-modified carbon paste electrode for ultra trace determination of Cd (II) and Pb (II) in aqueous solution

In recent years, increasing awareness of the environmental impact of heavy metals has prompted a demand for monitoring and decontaminating industrial wastes prior to discharging into natural water bodies. This paper describes the preparation and electrochemical application of carbon paste electrode modified with nanocellulosic fibers for the determination of cadmium and lead in water samples using anodic stripping voltammetry. First, cadmium and lead were adsorbed on the carbon paste electrode surface at open circuit potential, followed by anodic stripping voltammetric scan from -1 to 0 V. Different factors affecting sensitivity and precision of the electrode, including accumulating solvent, pH of the accumulating solvent, accumulation time, supporting electrolyte, and scan rate were investigated. The proposed method was also applied to the determination of Cd (II) and Pb (II) in the presence of other interfering metal ions and cetyl trimethyl ammonium bromide, sodium dodecyl sulfate, and Triton X-100 as a representative of cationic, anionic, and neutral surfactants. Linear calibration curves were obtained in the concentration ranges of 150-650 μg L(-1) and 80-300 μg L(-1), respectively, for cadmium and lead at an accumulated time of 10 min with limits of detection 88 and 33 μg L(-1). Optimized working conditions are defined as acetate buffer of pH 5 as accumulating solvent, hydrochloric acid as supporting electrolyte, and scan rate 50 mV/s. This technique does not use mercury and therefore has a positive environmental benefit. The method is reasonably sensitive and selective and has been successfully applied to the determination of trace amounts of Cd (II) and Pb (II) in water samples.

Application of carbon paste electrodes in highly methanolic solutions

In this paper, the application of carbon paste electrodes (constructed using silicone oil) in solutions containing 50% methanol (v/v) is demonstrated. The silicone oil-carbon paste electrode was shown to be more suitable in methanolic media compared to Nujol oil-carbon paste electrodes due to extraction of methanol into the Nujol paste. The silicone oil-carbon paste electrode has been shown to be a useful working electrode in methanolic media to investigate the voltammetric behaviour of some native and nitrated phenothiazine derivatives, namely phenothiazine, fluphenazine, and trifluoromethylphenothiazine.

Application of carbon paste electrodes to elucidate hydrometallurgical dissolution processes with special regard to chalcocite and covellite

Carbon paste electroactive electrodes offer possibilities for the investigation of hydrometallurgical dissolution processes. In this study the oxidation and reduction reactions of copper sulphides are examined by means of such a system. It was established that the anodic oxidation of Cu 2S proceeds in two steps. The first step of oxidation is the Cu 2S-CuS transition, which results in nonstoichiometric intermediate compounds and the reaction rate is controlled by solid state diffusion.