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Analytical & Bioanalytical Electrochemistry - Volume:8 Issue: 5, Aug 2016

Analytical & Bioanalytical Electrochemistry
Volume:8 Issue: 5, Aug 2016

  • تاریخ انتشار: 1395/06/30
  • تعداد عناوین: 11
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  • Arash Fattah, Alhosseini, Behnaz Hamrahi* Pages 535-546
    In this study, the effect of Thyme leaves hydroalcoholic extract (as a green corrosion inhibitor) on corrosion behavior of API 5L carbon steel in 0.5 M H2SO4 solution was investigated by Tafel polarization and electrochemical impedance spectroscopy (EIS). Tafel polarization plots showed that Thyme is a mixed inhibitor. Also, Tafel polarization and EIS results indicated that the inhibition efficiency increases with increasing Thyme leaves hydroalcoholic extract concentration to attain 89% at 12 g/L. Impedance parameters change with increasing concentration of extract shows that the adsorption of this extract on the steel surface will form a protective layer on the steel surface. Moreover, Temkin isotherm revealed that Thyme physically is absorbed on API 5L carbon steel surface in 0.5 M H2SO4 solution. The adsorption isotherm was obtained -17.86 kJ mol-1.
    Keywords: API 5L carbon steel, Thyme Extract, Polarization, EIS, Temkin isotherm
  • Sakineh Esfandiari Baghbamidi, Hadi Beitollahi *, Somayeh Tajik, Hojatollah Khabazzadeh Pages 547-556
    2-(4-Oxo-3-phenyl-3,4-dihydroquinazolinyl)-N′-phenyl-hydrazinecarbothio amide was synthesized and used to construct a modified-graphene oxide nano sheets paste electrode. The electrocatalytic oxidation of dopamine at the surface of this electrode was studied using cyclic voltammetry (CV), chronoamperometry (CHA), and square wave voltammetry (SWV). Under the optimized conditions, the square wave voltammetric peak current of dopamine increased linearly with dopamine concentration in the ranges of 5.0×10-7 to 4.0×10−4 M. The detection limit of 9.5×10-8 M was obtained for dopamine. Finally this modified electrode was used for determination of dopamine in some real samples.
    Keywords: Dopamine, Graphene oxide nano sheets, Chemically modified electrodes, Electrocatalysis
  • Volodymyr V. Tkach*S., Iacute, Lvio C. De Oliveira, Fauze J. Anaissi, Reza Ojani, Virg, Iacute, Nia S. Neves, Michel O. Galeano Esp, Iacute, Nola, Petro I. Yagodynets Pages 557-565
    The possibility of the use of cobalt(III) oxyhydroxyde as an electrode modifier for hydrazine detection has been investigated. The mechanism for the electrochemical oxidation of hydrazine over CoO(OH) has been suggested, and the correspondent mathematical model was developed and analyzed. The optimal pH for electroanalytical efficiency of the system is between 7 and 12. Strongly alkaline media promote the direct hydrazine oxidation and may destroy the modifying material. The oscillatory and monotonic instabilities´ possibility has been also investigated. These instabilities may be caused by surface and electrochemical factors.
    Keywords: Hydrazine, Electroanalysis, Cobalt(III) oxyhydroxide, Electrooxydation, Stable steady, state
  • Omid Fazlolahzadeh, Ahmad Rouhollahi*, Mojtaba Hadi Pages 566-577
    An electrochemical sensor employing edge-plane pyrolytic graphite electrode (EPPGE), without any need for surface pretreatment or surface chemical modification, for the sensitive detection of atorvastatin (AT) are reported using voltammetric techniques. The results indicated that EPPGE remarkably enhanced the electro-oxidation of AT, which led to enhanced peak currents and decrease in peak potentials to less positive values. Compared with basal-plane pyrolytic graphite electrode (BPPGE) and glassy carbon electrode (GCE), EPPGE showed better electrochemical responses both in terms of sensitivity and detection limit. The repeatability of the responses was found good and the method was applied successfully for sensing of AT in pharmaceutical formulations with good recoveries.
    Keywords: Atorvastatin electro, oxidation, Basal, plane pyrolytic graphite, Edge, plane pyrolytic graphite
  • Mehdi Shabani, Nooshabadi *, Maryam Roostaee Pages 578-588
    A NiO nanoparticle (NiO/NPs) ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) modified carbon paste electrode (NiO/NPs/HMIHP/CPE) was developed for the analysis of tryptophan. The electrochemical behavior of tryptophan was investigated using cyclic voltammetry, chronoamperometry and square wave voltammetry (SWV). NiO nanoparticles synthesized by direct chemical precipitation method and characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. These studies revealed that the oxidation of tryptophan is facilitated at NiO/NPs/HMIHP/CPE. Using SWV, the method allowed determination of tryptophan in the linear working range of 0.08-350 μM with detection limit of 0.04 μM (S/N=3). The NiO/NPs/HMIHP/CPE was used for the determination of tryptophan in urine and water samples.
    Keywords: Tryptophan analysis, NiO nanoparticle, Ionic liquid, Modified electrode
  • Arehalli Sathisha, Bahaddurghatta E. Kumaraswamy* Pages 589-603
    A carbon paste electrode modified by torasemide was used for determination of dopamine (DA). The modified electrode exhibited strong promoting effect and stability towards the electrochemical oxidation of dopamine at pH 7.0.in phosphate buffer solution (PBS). The parameters which influence the electrode response like paste composition; effects of scan rate, concentration, pH, surfactants and interferences have been studied. The linear range of DA 0.9990 and the detection limit for DA was found to be 2.4×10−6 M. Anionic surfactant Sodium Dodecyl Sulphate (SDS) showed very good electrocatalytic effect on the modified carbon paste electrode. The preparation of the modified electrode was easy and renewed by simple polishing gives very good reproducibility, high stability in its voltammetric response and low detection limit for DA.
    Keywords: Dopamine, Serotonin, Folic acid, Torasemide Modified electrode, Surfactants, Cyclic voltammetry, Simultaneous
  • Isa Karimzadeh, Mustafa Aghazadeh *, Taher Doroudi Pages 604-614
    Superparamagnetic Fe3O4 nanoparticles double coated with poly(vinylpyrrolidone)/polyvinyl chloride polymers were successfully fabricated by a facile cathodic electrochemical deposition (CED) method. In this method, in situ polymer coating ofthe surface of Fe3O4 nanoparticles was achieved through electrodeposition process. The evaluation by XRD analysis confirmed that the electrodeposited nanoparticles are composed of pure phase of iron oxide i.e. magnetite (Fe3O4). The structure and composition of the prepared nanoparticles were characterized by SEM, TEM, DLS, XRD, FTIR, and TG analysis. The DLS analysis revealed that the bare and prepared polymer coated Fe3O4 nanoparticles have size of 20nm and 62nm, respectively. The polymer coated nanoparticles with having 15nm in size, suitable magnetization value (Ms=22 emu/g), and negligible coercivity (Ce=0.42 emu/g) and remanence (Mr=1.1 Oe) are proper candidate for biomedical applications. This electrochemical strategy is proposed as facile and efficient for preparation and double coating of Fe3O4 nanoparticles.
    Keywords: Nanoparticles, Cathodic electrochemical deposition, Polymer coating, Biomedical Applications
  • Pattan Siddappa Ganesh, Bahaddurghatta Eshwaraswamy Kumara Swamy* Pages 615-628
    A non-ionic surfactant triton X-100 (TX-100) modified carbon paste electrode (TX-100/CPE) was fabricated for the electrocatalytic oxidation of catechol (CC) and hydroquinone (HQ) by cyclic voltammetric (CV) technique. The study of concentration variation for both CC and HQ was conducted; the lower limit of detection was calculated to be 0.59 µM and 0.56 µM for CC and HQ by CV technique. The fabricated TX-100/CPE was achieved the voltammetric separation of CC and HQ in a mixture by CV and differential pulse voltammetric (DPV) techniques. The effect of scan rate on the binary mixture of CC and HQ was examined; results suggest the electrode process was controlled by the adsorption phenomenon. The elimination of the fouling effect by the oxidised product was achieved by the TX-100/CPE.
    Keywords: Catechol, Hydroquinone, Triton X, 100, Electrocatalytic effect, Carbon paste electrode
  • Liju Elias, Amper. Chitharanjan Hegde* Pages 629-643
    A new alkaline citrate bath has been formulated for electrodeposition of Ni-P alloy coatings through conventional Hull cell method, using glycerol as an additive. Electrodeposition following induced type of codeposition was carried out on mild steel (MS) substrate at different current densities (c.d.’s), using the basic bath. The influences of bath constituents and operating parameters on the appearance, hardness, thickness and composition of the deposits have been studied. Corrosion behavior of alloy coatings, having hard-adherent mirror bright appearance developed at different c.d.’s were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods in 5 wt.% NaCl solution. Experimental results revealed that corrosion protection efficacy of NiP coatings increased with deposition c.d., in proportion of its P content up to an optimal limit, and then decreased. The coating developed at 4.0 A dm-2 was found to exhibit the least corrosion rate (14.2×10-2 mm y-1), compared to those at other c.d.’s. The process and products of electrodeposition have been studied using different methods, such as cyclic voltammetry (CV), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. Experimental results were analyzed in the light of principles of induced codeposition and role of additives, and results are discussed.
    Keywords: Ni, P alkaline bath, Glycerol, CV study, Corrosion study, SEM, XRD study
  • Parviz Mohamadian Samim*, Arash Fattah, Alhosseini Pages 644-657
    In this work, the effect of cyclic potentiodynamic passivation (CPP) on the passive and electrochemical behavior of a mild carbon reinforcing steel in an alkaline media simulating the concrete pore (0.1 M NaOH.1 M KOH) solution was studied by electrochemical impedance spectroscopy (EIS) and Mott–Schottky analysis. Nyquist and Bode plots revealed that the passive film resistance of mild carbon reinforcing steel was increased by applying further CPP cycles. Mott–Schottky analysis showed that the passive films behave as both n-type and p-type semiconductors depending on the potential. Moreover, this analysis revealed that the semiconducting character of the passive films was not altered by CPP method. Also, it was found that both donor densities reduced by increasing the number of CPP cycles. More noble free potentials, smaller cyclic voltammogram loops, larger imperfect semicircles in the Nyquist plots, and less donor densities within the passive film were all indications of the positive effects of CPP. All electrochemical measurements revealed that the electrochemical behavior of mild carbon reinforcing steel was enhanced under the effect of CPP method, mainly attributed to the formation of thicker yet less defective passive films.
    Keywords: Mild carbon reinforcing steel, Cyclic potentiodynamic passivation, EIS, Mott– Schottky analysis
  • Nadia M. Mostafa, Yasmin M. Fayez, Joliana F. Farid*, Abd El, Aziz B. Abd El, Alim Pages 658-660
    According to the authors request there is a correction on the figures. Figures (2-5) were not incorporated in the published article. The authors regret that an error occurred in the article. The errors are now corrected as follow. The authors apologize for any inconvenience occurred for the readers.