فهرست مطالب

Analytical & Bioanalytical Electrochemistry
Volume:10 Issue: 5, May 2018

  • تاریخ انتشار: 1397/03/10
  • تعداد عناوین: 10
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  • Hadi Mahmoudi Moghaddam *, Mahsa Malakootian Pages 520-530
    A chemically modified electrode was prepared by incorporating NiO/graphene oxide nanocomposite into graphite screen printed electrode (NiO/GO/SPE) to determine levodopa. Cyclic voltammetry, differential pulse voltammetry and chronoamperometry were used to investigate the electrochemical behavior of levodopa at the chemically modified electrode. According to the results, NiO/GO/SPE showed high electrocatalytic activity for levodopa oxidation, producing a sharp oxidation peak current at about 240 mV vs Ag/AgCl reference electrode at pH 7.0. The peak current was linearly dependent on levodopa concentration over the range of 0.8–700.0 µM with the detection limit (3σ) of 0.2 µM. The proposed method was successfully applied as a rapid, highly selective, simple, and precise one to determine levodopa in biological fluids.
    Keywords: Levodopa, Graphene Oxide, NiO Nanoparticles, Drug Analysis
  • Natalia Zubenia, Zholt Kormosh *, Daria Semenyshyn, Victoria Kochubei, Andrii Kormosh Pages 531-540
    The interaction of organic cation gramine with methyl orange was investigated with the help of thermal studies. These slightly soluble associates were used as electrode active substances (EAS) in plasticized polyvinyl chloride (PVC) membranes of ion-selective electrodes (ISE), sensitive to organic cation gramine. The best response characteristics were obtained using the composition: ion pair 7%, 59% TCP 34% PVC. The electrochemical sensor shows a linear dynamic range 2.0×10-5–1.0×10-1 mol/L and a Nernstian slope of 45.0 mV/decade with a detection limit of 1.3×10-5 mol/L. it has a fast response time
    Keywords: Gramine, Membrane sensor, Potentiometry, Ion pair, Methyl orange
  • Deswati*, Hilfi Pardi, Hamzar Suyani, Yulizar Yusuf, Tri Widya Edelwis Pages 541-553
    In the present study, a selective method is presented for the simultaneous determination of lead and cadmium in sea water samples by adsorptive cathodic stripping voltammetry (AdCSV). In preliminary studies, it has been proven that the lead and cadmium react with Calcon, giving rise to the formation of these complexes. These complexes have adsorptive characteristics on hanging mercury drop electrode (HMDE) and can be reduced in a reduction step. In this study the optimum reaction parameters and conditions studies are investigated. The The optimum conditions of the AdCSV-calcon method are KCl concentration 1 mol/L pH 5, calcon concentration 0.1 mmol/L, accumulation potential -0.2 V, accumulation time 60 s. RSD for lead and cadmium are (4.2 and 0.36)%, performed 10 replicates (n=10), recovery for lead and cadmium (99.87, and 99.39)%. The calibration graphs were linear in the concentration range of (10–160, and 10–190) ng/ml for lead and cadmium, respectively. The limit of detection of the method was 10 ng/mL for lead and cadmium are (0.02, and 0.05) ng/mL. The interference of some common ions was studied and it was concluded that application of this method for the determination of lead and cadmium in sea water samples led to satisfactory results.
    Keywords: A selective method, (Pb, Cd), Sea water, Calcon, Adsorptive cathodic stripping voltammetry
  • Mustafa Aghazadeh* Pages 554-565
    Ni(OH)2 /mesoporous carbon composite was successfully deposited onto Ni foam by electrochemical deposition under ambient conditions. Using a simple electrochemical deposition (ECD) method, nickel hydroxide nanoparticles (NPs) was electrochemically formed onto mesoporous carbon structures (CMK). The surface morphology and crystallinity properties of the synthesized Ni(OH)2 NPs/CMK onto Ni foam are characterized by physicochemical techniques of XRD and FE-SEM. Furthermore, the deposited β-Ni(OH)2 NPs/CMK on Ni foam reveal superior energy storage ability in 1M KOH electrolyte as a binder-free electrode for pseudocapacitors. Compared to the Ni(OH)2@NF electrode, the composite sample (Ni(OH)2/CMK@ NF electrode) exhibit a relatively high electrochemical performance (Cs=1224 F g–1 at 2 A g–1) and stable Cs retention (94%) after 3000 GCD cycling, which was ascribed to the electronic and ionic synergisms between β-Ni(OH)2 NPs and mesoporous carbon material of Ni electrode. This cost-effective and in situ electrochemical growth of metal hydroxide nanostructures on carbonous structures may be useful for advanced energy storage device applications.
    Keywords: Ni(OH) 2, Mesoporous carbon, Electrochemical synthesis, Nanoparticles, Electrochemical properties
  • Rubin Gulaboski*, Sofija Petkovska Pages 566-575
    In this work we refer to a simple and time-independent cyclovoltammetric approach for evaluating kinetics of chemical step of a diffusional electrocatalytic regenerative (EC’) mechanism. The methodology relies on the dependence of the maximal catalytic (or limiting) current of the cyclic steady-state voltammograms on the catalyzing agent concentration. The magnitude of the limiting cyclovoltammetric current of an EC’ mechanism depends exclusively on the rate of the chemical regenerative reaction, while it is independent on all kinetic and thermodynamic parameters related to the electrode reaction. Theoretical results of a quasireversible EC’ mechanism reveal that the limiting current of calculated cyclic voltammograms is a linear function of the square-root of the dimensionless catalytic rate parameter. Because the rate of the catalytic reaction can experimentally be modified by altering the concentration of the regenerating agent (for constant scan rate), this scenario can be explored for the determination of the catalytic rate constant. The approach described in this work is important for the enzyme-substrate catalytic reactions, since the value of the catalytic rate constant allows estimation of the Michaelis-Menten constant.
    Keywords: EC mechanism, Catalytic rate constant, Cyclic voltammetry, Limiting currents, Quasi, reversible electrode reaction
  • Mohammad Hossein Hemmati *, Mehri-Saddat Ekrami-Kakhki Pages 576-586
    Fe3O4 nanoparticles were synthesized by solvothermal strategy using ethylene glycol (EG). Moreover, a graphite screen printed (SPE) was modified with this Fe3O4 nanoparticles by dropping method. The electrochemical behavior and the electrocatalytic activity of this Fe3O4/SPE electrode for the oxidation of sulfite were also investigated using cyclic voltammetry, chronoamperometry and differential pulse voltammetry. The results showed that this Fe3O4/SPE exhibited high electrochemical activity for the oxidation of sulfite under the synergistic action of Fe3O4 nanoparticles. In the differential pulse voltammetry analysis, under optimized experimental conditions, the oxidation peak increased with an increasing concentration of sulfite in the range of 0.5 to 100.0 μM. The calculated LOD value for sulfite was 0.1 μM. At last, the as-prepared modified electrode was successfully used for the determination of sulfite in real samples.
    Keywords: Sulfite, Fe3O4 nanoparticles, Voltammetric sensor, Screen printed electrode
  • Volodymyr V. Tkach, Iryna L. Kukovska, Svitlana M. Lukanova, Oleg M. Boychuk, Leonid P. Yurchuk, Vasyl´ I. Stefanchuk, Vasyl´ S. Khashchuks., Iacute, Lvio C. De Oliveira, Reza Ojani, Petro I. Yagodynets Pages 587-593
    The system with the sucralose electrochemical detection on the overoxidized polypyrrole has been described mathematically. The correspondent mathematical model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It was shown that the overoxidized polypyrrole may serve as a modifier for sucralose electrochemical detection in neutral solutions, participating in the electroanalytical process as a substrate. The electroanalytical process is diffusion-controlled. The possibility of oscillatory and monotonic instabilities has also been verified.
    Keywords: Sucralose, Electrochemical sensors, Conducting polymers, Overoxidized polypyrrole, Stable steady, state
  • Kamran Amini *, Farhad Gharavi Pages 594-611
    In this study, the weld nugget zone (WNZ) electrochemical behavior in copperbrass plates, welded using friction stir lap welding, in 0.015 M borate-buffered(Borax) (pH 9.3) and 1 M NaCl (pH 7.2) solutions are investigated. Therefore, dissimilar copper/ brass plates welded with welding conditions of welding speed of 25 mm/min and rotation speed of 710 rpm. Features of specimen welded nugget zone under open circuit potential; potentiodynamic polarizations are compered and then the morphology of the products corrosion formed in polarization experiment are analyzed using SEM. Electrochemical impedance spectroscopy (EIS) is used for the characterization of surface films formed on the welded specimens during 3600s immersion at Eocp in the two test solutions. Results showed that the welding process reduced the welded NZ corrosion resistance and offered lower corrosion resistance than copper and higher corrosion resistance than brass in 1 M NaCl (pH 7.2) solution. On the other hand, polarization plots showed that welding process results in current densities decreases from 0.512 for copper and 0.711 for brass to 0.213 µAcm−2 for the WNZ and significant shifts toward positive for corrosion potential in Borax solution. Indeed, the welded NZ corrosion rate in Borax solution was less than that in 1 M NaCl. The oxide film formed on the welded joints of NZ surface was more porous in borate buffer solution than in the NaCl solution. The hardness of welded joints was higher than copper and brass, and the highest hardness observed in the welded specimen nugget zone with low heat input during the welding process, because the grain refined most meaningfully in the welded joints NZ during welding process.
    Keywords: Friction Stir Welding, Copper, Brass Alloy, Electrochemical Behavior
  • Pattan Siddappa Ganesh, Bahaddurghatta Eshwaraswamy Kumara Swamy *, Amit Balasab Teradale Pages 612-630
    Niacinamide was electropolymerised on the surface of carbon paste electrode by cyclic voltammetric technique. The modified electrode showed an excellent electrocatalytic activity towards the oxidation of norepinephrine (NE) and ascorbic acid (AA). The response of the sensor was evaluated towards the different NE concentration in the range 40.98 to 244.3 µM, the oxidation peak current was linearly increased with varying NE concentration and the detection limit was calculated to be 0.21 µM. The modified electrode showed excellent selectivity in the determination of NE in presence of large excess of AA and UA. The voltammetric responses were stable and resistant to fouling. The proposed electrode can be used for the real sample analysis in medical, pharmaceutical and biotechnological sectors.
    Keywords: Norepinephrine, Ascorbic acid, Uric acid, Electroanalysis, Voltammetry
  • Isa Karimzadeh * Pages 631-641
    In this paper, Ni2 doped magnetite nanoparticles/graphene oxide composite are fabricated through an electrochemical synthesis procedure for the first time. The electrosynthesis procedure is based on the electrochemical growth of iron oxide nanoparticles onto the graphene oxide sheets electrophoretically deposited on the cathode electrode. An aqueous solution of iron nitrate nonahydrate (0.3 g), iron chloride tetrahydrate (0.1 g), nickel nitrate hexahydrate (0.1 g) and 0.03 g dispersed graphene oxide was used as the electrosynthesis bath. The X-ray diffraction pattern of the prepared composite revealed that it has magnetite crystal structure. The particle morphology, graphene oxide content and Ni2 cation doping were also confirmed through FE-SEM observations, EDS and FT-IR analyses. The superparamagnetic nature of the fabricated composite was determined from M-H curve and magnetic data obtained by vibrating sample magnetometer (VSM) analysis. The NiFe3O4/GO composite showed magnetic data of Ms=47.03 emug–1, Mr=0.14 emug–1 and Hci=3.76 G. In final, the cathodic electro-synthesis is proposed as a facile electrochemical technique for the fabrication of metal cations doped magnetite NPs/ graphene oxide nanocomposite.
    Keywords: Iron oxide, Metal ion doping, Graphene oxide, Electro, chemical synthesis, Nanocomposite