Surface Of Carbon Paste Electrode Research Articles

Electropolymerized Congo Red Film based Sensor for Dopamine: A Voltammetric Study

The polymerization film of Congo red was prepared on the surface of carbon paste electrode by electropolymerization using cyclic voltammetric method. The higher catalytic activity was obtained for electrocatalytic oxidation of Dopamine, with drastic enhancement of the reversibility and peak current in 0.2 phosphate buffer solution of pH 7.0 at the sweep rate 100 mV/s. The variation of sweep rate and pH were investigated. The limit of detection of Dopamine was found to be 0.06 μM. The effect of interference studies was done by differential pulse voltammetric technique. In the simultaneous look at, Dopamine and Uric acid were well separated by cyclic voltammetric technique. The proposed method showed good sensitivity, selectivity, and reproducibility.

Adsorptive Stripping Voltammetric Determination of Oxolinic Acid in Water Sample

One new methodology for analysis of the antimicrobial oxolinic acid (OXA) based on adsorptive stripping voltammetry (AdSV) in carbon paste electrode (CPE) was developed and applied in untreated pond water sample. Cyclic voltammetry (CV) indicated that an irreversible anodic process occurs in KOH solution as supporting electrolyte. Quantification of the antimicrobial was carried out by differential pulse adsorptive stripping voltammetry (DPAdSV) at potential of deposition (ED) +1.05 V for 45 s to examine OXA adsorption on the surface of CPE. The limits of detection (LOD) and quantification (LOQ) of the method for OXA analysis were determined. The values of LOD were 0.0570 and 0.512 mg L-1 in absence of matrix and in the water sample, respectively, and the corresponding values of LOQ were 0.192 and 1.707 mg L-1, respectively. The apparent recovery percentage for different concentrations of OXA in natural waters ranged between 98.4 and 109%.

Electrochemical Chelation and Reduction of Nitrate Ion on EDTA Modified Carbon Paste Electrode

The aim of this work is to combine two methods for removing nitrate ions from concentrated aqueous solutions. This involves chelating and then reducing NO3- by EDTE modified carbon paste electrode (EDTA-CPE). We find that in the absence of EDTA on the carbon paste electrode surface, the nitrate reduction is almost impossible. The reduction of nitrate ions was invested on the surface of the EDTA-CPE, the cyclic voltammograms recorded in electrolytic medium 0.1 M KCl, shows two reduction peaks, the first at -0.2 V, attributed to the reduction of nitrite ions (NO2-) and the second one at 0.8 V which corresponds to the reduction of nitrate to nitrite ions.

Design of an electrochemical DNA-based biosensor for selective determination of cadmium ions using a DNA hybridization indicator

A simple electrochemical DNA- based biosensor was designed for determination of Cd2+ using ethyl green (EG) as a DNA hybridization indicator on the surface of carbon paste electrode (CPE). The interaction of Cd2+ with double strand DNA (dsDNA) led to the destabilizing of dsDNA and the increase in the reduction peak currents of EG. The difference in the values of electrochemical responses of EG before and after DNA helix destabilization in the presence of Cd2+ (ΔI) was used for Cd2+ determination and was linearly related to the concentration of Cd2+ over the ranges of 1.0pM–1.0nM and 10.0nM–1.0μM. Detection limit was achieved as low as 0.3pM using simple and low cost working electrode and without applying any materials for modification of electrode or DNA. The proposed biosensor was utilized successfully to real sample analysis of Cd2+.

Modification of carbon paste electrode by electrochemical polymerization of neutral red and its catalytic capability towards the simultaneous determination of catechol and hydroquinone: A voltammetric study

In this study, a new electrochemical sensor was developed and fabricated based upon the electrochemical polymerization of neutral red (NR) on the surface of carbon paste electrode (CPE). The newly developed sensor shows electrocatalytic capability towards the simultaneous determination of catechol (CC) and hydroquinone (HQ) in presence of 0.2M phosphate buffer solution (PBS) at pH7.4 with the scan rate of 50mVs−1. Electrochemical measurements were performed using both cyclic voltammetry (CV) and differential pulse voltammetric (DPV) methods at poly (neutral red) modified carbon paste electrode (PNR/MCPE). The effects of scan rate, concentration and pH variation for CC and HQ was investigated at PNR/MCPE. The proposed sensor exhibits adsorption-controlled type of electrode process, moreover it show good detection limit (LOD) (CC=6.46μM and HQ=4.97μM) and limit of quantification (LOQ) (CC=21.5μM and HQ=16.5μM). Hence, the proposed sensor was successfully applied in the simultaneous determination of CC and HQ with satisfied results.

Electrooxidation Study of Amoxicilline Using Nano ZSM-5 Modified Carbon Paste Electrode

Introduction: This study investigated the electrocatalytic oxidation of amoxicillin on the surface of carbon paste electrode modified with synthesized nano zeolite which was doped with nickel ion in the basic solution. This electrode functions as a sensor to determine amoxicillin. Materials & methods: At first, the percentage of nano zeolite via carbon paste and the flotation of the modified electrode in the nickel chloride solution (1.0 M) for determination of drug were optimized. Then, the determination of amoxicillin in the 0.1 NaOH was conducted using cyclic voltammetry and chronoamprometry techniques. Findings: Obtained results show that the produced NiOOH on the surface of modified electrode acts as an electrocatalyst for the oxidation of amoxicillin. The linear dynamic range and the limit of detection for amoxicillin determination via the proposed electrode were 8.2* 10-5 M - 2.46* 10-4 M and 2.3*10-5 M. The catalytic rate constant for the electro-oxidation of amoxicillin was obtained 4.2*105 cm3s-1mol-1. Discussion & conclusions: Finally obtained results reveal that introduced procedure was simple, fast, available, repeatable, and sensetive.

Molecular Dynamics Simulation and Density Functional Theory Study of Chemisorption of Propranolol Optical Isomers on a Uracil‐modified Carbon Paste Electrode

To reveal the nature of the interaction of the optical isomers of propranolol with the surface of carbon paste electrodes modified by uracil, we performed a combined computational and experimental study. Our study comprised the different modes of complexation between propranolol and uracil molecules covering the carbon paste electrode within two approaches: molecular dynamics simulation (MD) and quantum mechanics (QM) modeling. A graphene layer was used as a model of the carbon paste electrode. The computations showed that uracil modification of the carbon paste electrode surface enhanced the selectivity toward the D‐isomer of propranolol as compared to the unmodified case. These theoretical results agree with our voltammetric measurements.

Magnetite Nanospheres As Modifier of Carbon Paste Electrode for Determination of Inhibition Kinetics of Syzygiumpolyanthum extract Toward Xanthine Oxidase

Magnetite nanospheres was prepared and used to fabricate a modified carbon paste electrode as xanthine biosensor and applied to determine inhibition kinetics of Syzygium polyanthum extract toward xanthine oxidase (XO). The magnetite nanospheres was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Electrochemical behavior of xanthine was investigated by immobilizing the XO on the surface of carbon paste electrode (CPE), modified magnetite nanospheres-CPE (MCPE), and modified 2,3-dimethoxy-5-metil-1,4-benzoquinone (Q0)-CPE (QCPE) employing cyclic voltammetry (CV) technique. The result showed that the MCPE was the best electrode to determine the analytical performance under optimum condition, based on lower limit of detection (0.005 mM), wider linearity range (0.01-1 mM with R2= 99.24%), and higher sensitivity (5.16 µM-1) than the two oter electrodes (CPE and QCPE). The MCPE successfully improve the analytical performance on xanthine biosensor and to be applied for determining inhibition kinetics of S. polyanthum extract. Inhibition kinetics of the extract has caused increase of KM and VMAX (IMAX) constant. Based on the result, the type of inhibition kinetics was a competitive inhibition.

Magnetic silver(I) ion-imprinted polymeric nanoparticles on a carbon paste electrode for voltammetric determination of silver(I)

Magnetic silver ion imprinted polymer nanoparticles (mag-IIP-NPs) were prepared and used as a recognition element in electrochemical detection of silver(I). The procedure involves two steps: (a) the extraction of the Ag(I) by the mag-IIP-NPs, and (b) determination of the preconcentrated Ag(I) ions on the surface of the magneto carbon paste electrode (MCPE) using differential pulse voltammetry. The amount of sorbent, pH value of the sample solution, extraction time, supporting electrolyte, reduction potential and reduction time were optimized. Under optimal conditions and at a working voltage of +0.02 V (vs. Ag/AgCl), the method displays a linear response in the 0.05 to 150 μg⋅L−1 Ag(I) concentration range. Other features include a low detection limit (15 ng⋅L−1), a remarkable selectivity and good reproducibility (with an RSD of 4.7%). The results obtained with this analytical assay when analyzing different water samples were compared with the data obtained by GF-AAS, and the results agreed satisfactorily. In our perception, this approach also may be extended to electrochemical detection for other ions, and this makes it a widely applicable strategy for heavy metal ion analysis.

Electrocatalytic Oxidation of Ethanol and Ethylene Glycol onto Poly (o-Anisidine)-Nickel Composite Electrode

In this work, poly (o-Anisidine) (POA) was prepared by consecutive potential cycling in an acidic monomer solution at the surface of Carbon Paste Electrode (CPE). Nickel ions were dispersed into the polymer by immersing the electrode in NiSO4 solution. The prepared Ni/POA/CPE was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Atomic Force Microscopy (AFM) and electrochemical methods. The electrochemical oxidation of ethanol and ethylene glycol was investigated at the Ni/POA/CPE by cyclic voltammetry and chronoamperometry techniques. The results indicated that the Ni/POA/CPE in comparison with Ni/CPE exhibited excellent electrocatalytic activity towards oxidation. Then, using a chronoamperometry method, the catalytic rate constant, k, for ethanol and ethylene glycol oxidation were found to be 2.6×106 and 1.07×107 cm3/mol s, respectively. Furthermore, the effect of several parameters such as OA concentration, POA thickness, and NiSO4 concentration and accumulation times towards the ethanol oxidation as well as the long-term stability of the modified electrode has been investigated.

Palladium nanoparticles in electrochemical sensing of trace terazosin in human serum and pharmaceutical preparations

In this approach, palladium nanoparticle film was simply fabricated on the surface of carbon paste electrode by electrochemical deposition method. The film was characterized using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The prepared electrode exhibited an excellent electrocatalytic activity toward detection of trace amounts of terazosin, which is an antihypertensive drug. Under the optimum experimental conditions, a linear range of 1.0×10−8–1.0×10−3molL−1 with a detection limit of 1.9×10−9molL−1 was obtained for determination of terazosin using differential pulse voltammetry as a sensitive method. The efficiency of palladium nanoparticle film on the surface of carbon paste electrode successfully proved for determination of terazosin in pharmaceutical sample and human serum sample with promising recovery results. The effect of some foreign species has been studied.

Electrocatalytic Oxidation of Formaldehyde onto Carbon Paste Electrode Modified with Hydrogen Titanate Nanotubes, Including Nickel Hydroxide

In this study, the hydrogen titanate nanotubes (HTNs) with a high specific surface area were applied for modification of carbon paste electrode (CPE). Then, a novel, cheap and efficient catalyst for formaldehyde electrocatalytic oxidation was developed by decorating Ni2+ ions on the surface of the modified electrode. A sensitive oxidation peak was observed at 0.62 V vs. Ag|AgCl|KCl (3 M) in 0.1 M NaOH solution for electrocatalytic oxidation of formaldehyde. It has been observed that HTNs at the surface of CPE can improve catalytic efficiency of the dispersed Ni2+ ions toward oxidation of formaldehyde. The values of electron-transfer coefficient, the mean value of catalytic rate constant, and diffusion coefficient for formaldehyde and redox sites were obtained to be 0.545, 2.65 × 104 cm3 mol−1 s−1, and 3.97 × 10−6 cm2 s−1, respectively. The good catalytic activity, high sensitivity, and easy in preparation rendered the Ni-HTN/CPE to be a capable electrode for electrocatalytic oxidation of formaldehyde.

Electrochemical Determination of Dopamine Using a Carboxyl-functionalized Carbon Nanotube-Modified Carbon Paste Electrode Doped with Polymeric Ferric Sulfate

ABSTRACTA novel electrochemical device for the sensitive determination of dopamine was developed based on a carbon paste electrode with polymeric ferric sulfate doped in the carbon paste and a carboxyl-functionalized carbon nanotube thin film on the surface. The modified electrode was characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The conditions for the preparation of electrode were optimized. The carbon nanotubes were shown to be stable on the surface of carbon paste electrode. The novel electrochemical device provided excellent activity toward dopamine. Amperometry and differential pulse voltammetry were used for the determination of dopamine in pH 7.0 phosphate buffer with a long linear range from 0.8 to 261 µM and a detection limit of 0.2 µM. The modified electrode showed excellent repeatability, good stability, and satisfactory reproducibility, thus demonstrating potential for practical applications.

Trace Determination of Duloxetine HCl in Formulation and Spiked Human Serum at a Carbon Paste Electrode

The electrochemical behavior of duloxetine HCl (DXT.HCl) at a carbon paste electrode (CPE) was achieved by cyclic voltammetry and a mechanism of its oxidation was reported and illustrated. A sensitive linear sweep and square-wave adsorptive anodic stripping voltammetry methods were described for trace determination of DXT.HCl. Introduction: DXT.HCl, N-methyl-3-(nap-thalen-1- yloxy)-3-(thiophene-2-yl) propan-1-amine hydrochloride is a selective serotonin-norepinephrine reuptake inhibitor (SNRI) originally developed as an antidepressant and is currently recommended for maintenance treatment of major depressive disorder. Methods: Electrochemical behavior was studied using cyclic voltammetric method, and the analytical application was studied using linear sweep and square wave voltammetric methods. Solution pH has been measured by pH meter. Results: The process on the surface of carbon paste electrode was found to be irreversible and diffusion-controlled. The number of proton and electron transferred were calculated. Possible reaction mechanism taking place on the surface of electrode was proposed. Calibration plot constructed using square wave voltammetric technique was used for quantitative analysis in pharmaceutical and human serum samples. Limit of detection (LOD) and limit of quantification (LOQ) were calculated. Conclusions: In the present work, we described the electrochemical behavior of DXT.HCl drug. Two precise linear sweep and square wave adsorptive anodic stripping voltammetry methods have been described for its trace quantitation in pharmaceutical formulation and human serum. The method shows the development of a sensor for selective and sensitive determination of DXT.HCl.

Development of Graphite-DNA Polymer Composites as Electrode for Methanol Fuel Cells

DNA aggregates were electro less deposited onto carbon paste electrode, firstly and electrode surface was coated by polymer film to protect the DNA film. Prepared electrode has shown great activity towards the oxidation of methanol, and no effect of empoisoning is observed. The effect of various parameters such as scan rate and methanol concentration, on the electro catalytical oxidation of methanol has also been investigated. The morphological study of electrode surface was investigated by Atomic Force Microscopy (AFM) and optical microscopy.

Electrochemical Detection and Removal of Mercury (II) at DNA Modified Carbon Paste Electrode

Herein, we report a simple and inexpensive way for the fabrication of a microelectrode, DNA modified carbon paste electrode (DNA-CPE). DNA is deposited onto carbon paste electrode surface by self-assembled monolayers. The electrochemical behaviour of DNA-CPE’s was studied by cyclic voltammetry (SWV) tests. The recorded CV’s showed two redox peacks simultaneously at E oxidation=0.3 V and E reduction=0.2 V. The recorded SWV curves at DNA-CPE have shown great efficiency in the analysis of mercury (II) at different concentrations.

Mercury Nanodroplets Immobilized on the Surface of a Chitosan-Modified Carbon Paste Electrode as a New Thallium Sensor in Aqueous Samples

In the present work chitosan (CT) was used to construct a chitosan-modified carbon paste electrode (CT/CPE). The amine groups in the chitosan bind mercury ions from an aqueous KCl solution (PH 5.0). Then the electrode was held at a negative potential (−1.3 V) to reduce the Hg2+ bound to the CT/CPE to forming mercury nanodroplets. The proposed electrode was evaluated for preconcentration and determination of Tl+1 ions by differential pulse anodic stripping voltammetry (DPASV). The electrochemical procedure was based on the accumulation of thallium ions at the surface of the modified carbon paste electrode with mercury nanodroplets and chitosan biopolymer. Parameters involved in the binding of Hg+2 ions to the CT/MCPE, preconcentration of thallium ions and voltammetric stripping step were studied and the best set of experimental conditions were chosen. Under the optimized conditions, the voltammetric peak current of Tl+1 increased linearly with Tl+1 concentrations in the range of 1.0–400 ng mL−1 and a detection limit of 0.20 ng mL−1 was obtained for Tl+1. The practical application of the suggested modified electrode was evaluated by the determination of trace amount of Tl in the environmental and biological samples.

Electrocatalytic Determination of Cysteamine Uses a Nanostructure Based Electrochemical Sensor in Pharmaceutical Samples

The electrochemical bahaviour of cysteamine (CA) has been investigated by synergic effect of acetylferrocene (AF) and NiO/CNT nanocomposite at a surface of carbon paste electrode (AF/NiO/CNTs/CPE). Voltammetric techniques were used to investigate the suitability of AF/NiO/CNTs/CPE for the electrocatalytic oxidation of CA in pH=7.0 as a suitable condition in voltammetric analysis. AF/NiO/CNTs/CPE shows a dynamic range to electrocatalytic analysis of CA in the range of 0.1-600 µM with a detection limit of 0.07 µM by square wave voltammetric method (SWV). The ability of AF/NiO/CNTs/CPE as a sensor checked analysis of CA in real samples. Keywords: Cysteamine, NiO/CNTs nanocomposite, modified electrode, voltammetry.

High catalytic activity of Fe(II)-clinoptilolite nanoparticales for indirect voltammetric determination of dichromate: Experimental design by response surface methodology (RSM)

A novel, simple, cheap and very sensitive modified carbon paste electrode (CPE) was used for indirect determination of dichromate in aqueous solution. Peak current of Fe(II) redox system exited form Fe(II)-exchanged clinoptilolite nanoparticles modifier (Fe(II)-NClin) at the surface of CPE was decreased in the presence of dichromate. Hence, this decrease in peak current was used for indirect determination of dichromate. Raw and modified zeolite and CPE were characterized by XRD, FT-IR, SEM-EDX, BET, X-ray map, electrochemical impedance spectroscopy (EIS) and TEM techniques. EIS results confirm that the Fe(II)-NClin/CPE has the best charge transfer efficiency with respect to raw CPE and NClin/CPE. To study the effects of more influencing experimental variables (such as modifier% and loaded of Fe(II), solution pH and scan rate) and reducing numbers of experiments experimental design was applied by response surface methodology (RSM). Under optimum conditions, the current response of Fe(II)-NClin/CPE was inversely proportional to Cr2O72− in the concentration range from 2.0×10−9–4.0×10−3molL−1 with a DL of 1.1×10−11molL−1.

Electroactive polyamide modified carbon paste electrode for the determination of ascorbic acid

ABSTRACTSConstruction electroactive polyamide (EPA) with aniline-pentamer-based in the main chain has been modified on the surface of carbon paste electrode (CPE) for detecting ascorbic acid (AA). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy studies confirm the well-defined molecular structure of the oligoaniline and EPA. Further, the in situ chemical oxidation of EPA was monitored by UV-Visible absorption spectrum. The electroactivity of the EPA was evaluated by performing electrochemical cyclic voltammetry study. The sensing response studies have revealed that this EPA-modified CPE electrode can detect AA in the range of 0.05–0.7 mM with detection limit of 0.005 mM and sensitivity of 1.5 × 10–5 AmM–1. Besides, this EPA-modified CPE electrode shows a minimal relative standard deviation of 1.73%.