فهرست مطالب

Analytical & Bioanalytical Electrochemistry - Volume:8 Issue: 2, Mar 2016

Analytical & Bioanalytical Electrochemistry
Volume:8 Issue: 2, Mar 2016

  • تاریخ انتشار: 1395/02/03
  • تعداد عناوین: 10
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  • Kashif R. Ansari*, Mumtaz A. Quraishi Pages 136-144
    The inhibition property of 2,6-diaminopyridine for aluminum in 3.5% NaCl was carried out by using Tafel polarization, Scanning electron microscopy (SEM), Atomic force microscopy (AFM) and quantum chemical methods. Tafel polarization study reveals that inhibitor is of mixed type but predominantly anodic. The maximum inhibition is 98.5% at 100 mg/L. Surface analysis (SEM and AFM) supports the formation of a protective inhibitor film on the aluminum surface. Quantum chemical calculation has performed for both neutral and protonated molecules in order to study the effect of molecular structure on inhibition efficiency.
    Keywords: Aluminum alloy, Tafel polarization, SEM, AFM
  • Arash Fattah, Alhosseini*, Mahdis Noori Pages 145-157
    Corrosion inhibition of carbon steel in solutions containing H2S and HCl by using the Salvia officinalis extract was studied by the Tafel polarization and electrochemical impedance spectroscopy (EIS) methods. Tafel polarization and EIS results revealed that the protection efficiency increases with increasing inhibitor concentration to attain 93% at 7.5 g/l inhibitor. Also, the Tafel polarization plots showed that current inhibitor acts as a mixed type inhibitor. It was found that inhibition occurs due to the physical absorption of inhibitor on the metal surface that follows from longmuir isotherm.
    Keywords: Corrosion inhibition, Carbon steel, Salvia officinalis extract, Electrochemical impedance spectroscopy, Tafel polarization
  • Shohreh Jahani *, Hadi Beitollahi Pages 158-168

    A carbon paste electrode modified with TiO2/Fe3O4/MWCNT nanocomposite and ionic liquids (TFMWCNT/IL/CPE) was employed for the simultaneous determination of ascorbic acid (AA) and tryptophan (TRP). The TFMWCNT/IL/CPE displayed excellent electrochemical catalytic activities toward AA and TRP oxidation compared with bare CPE. In the differential pulse voltammetry technique, both AA and TRP gave sensitive oxidation peaks at 270 and 700 mV respectively. Under the optimized experimental conditions, AA gave linear responses over range of 2.5 to 100.0 μM. The lower detection limit was found to be 1.13 μM for AA. The investigated method showed good stability, reproducibility, and repeatability for determination of AA and TRP in pharmaceutical samples.

    Keywords: Ascorbic acid, Tryptophan, TiO2, Fe3O4, MWCNT nanocomposite, Ionic liquids
  • Ghasem Karim, Nezhad*, Sara Pashazadeh Pages 169-183
    In the present study, a new carbon paste electrode chemically modified with copper sulfide nanostructures is constructed and used for the catalytic oxidation of cisapride. The voltammetric behavior and electrochemical reaction mechanism of cisapride have been investigated at modified electrode using cyclic voltammetry (CV), steady state polarization and differential pulse voltammetry. In CV studies, no oxidation response of cisapride can be seen at the unmodified electrode, but at the copper sulfide nanostructures modified carbon paste electrode (CSN-MCPE), a large anodic peak appears, indicating that the anodic oxidation of cisapride could be catalyzed at CSN-MCPE. This proves that the copper sulfide nanostructures bear the main role in electrocatalytic oxidation of cisapride. The kinetic parameter such as the electron transfer coefficient (α) and exchange current density (j0) for the modified electrode were calculated. The differential pulse peak current varied linearly with the concentration of cisapride in range of 9×10−8 to 15×10−6 mol L-1. The modified electrode can be prepared very easy and renewed in its surface by simple polishing. The reproducibility of the electrode response, based on six measurements during two month, was 3.23% for the slope of the calibration curve.
    Keywords: Cisapride, Modified carbon paste electrode, Copper sulfide nanostructures, Electrocatalytic oxidation, Kinetic study
  • Rekha, Bahaddurghatta Eshwaraswamy Kumara Swamy*, Pattan Siddappa Ganesh Pages 184-192
    The carbon paste electrode (CPE) was modified by electropolymerisation of amoxicillin in 0.2 M acetate buffer solution (ABS) of pH 5.0 by using cyclic voltammetric (CV) technique. The modified electrode was used for the electrochemical determination of dopamine (DA). The poly(amoxicillin) modified CPE showed excellent electrocatalytic activity towards the oxidation of DA. The study of variation in concentration and scan rate shows that the electrode process was diffusion-controlled. Further the modified electrode was used for the simultaneous determination of DA and ascorbic acid (AA) by CV technique.
    Keywords: Dopamine, Electropolymerisation, Carbon paste electrode, Cyclic voltammetry
  • Ramincheraghali *, Mustafa Aghazadeh Pages 193-206
    Porous nanostructured Mn3O4 was deposited from 0.005 M manganese nitrate bath using a one-pot cathodic electrodeposition route. The deposition experiments were performed under the direct current mode with applying a current density of 10 mA cm-2. The structural analyses by XRD and FTIR, revealed that the product is composed of pure tetragonal Mn3O4. Morphological observation by SEM and TEM disclosed that the prepared Mn3O4 product is made up of porous plates at nanoscale. BET analysis further revealed that the prepared sample has high surface are of 125 m2/g with mesoporous structure. Electrochemical evaluations by cyclic voltammetry and charge-discharge tests also showed the prepared Mn3O4 to be capable of delivering high specific capacitance values of 328 F g−1, in addition to exhibiting excellent long-term cycling stability (95.9% of initial capacity after discharging 1000 cycles).
    Keywords: Mn3O4, Pulse electrodeposition, Porous structure, Supercapacitors
  • Nadia M. Mostafa, Yasmin M. Fayez, Joliana F. Farid*, Abd El, Aziz B. Abd El, Alim Pages 207-218
    Four different polyvinyl chloride (PVC) membrane sensors were investigated for the determination of ivabradine HCl in pure drug substance, pharmaceutical formulations and plasma. These sensors were fabricated using sodium tetraphenyl borate (TPB) [sensor 1a,1b,1c] or ammonium reineckate (RNC) [sensor 2a,2b] or sodium phosphotungestate (PTA) [sensor 3a,3b] or tetrakis(4-chlorophenyl)borate (TpClPB) [sensor 4a,4b] as ion exchanger. The proposed sensors showed fast and stable nernstian response range from 55.159.8 mV/decade across a concentration range 10-5-10-2 M in pH range 4.5-7.5. These electrodes exhibit good selectivity for ivabradine HCl with respect to a large number of inorganic, organic cations, sugars and amino acids. The results were statistically compared with a reported method. The comparison showed no significant difference between the proposed methods and the reported method regarding both accuracy and precision.
    Keywords: Ivabradine, Sodium tetraphenyl borate, Ammonium reineckate, Sodium phosphotungestate, Tetrakis(4, chlorophenyl)borate
  • Ebrahim Tavakolian, Javad Tashkhourian* Pages 219-233
    An electrochemical sensor based on modification of carbon paste electrode by reduced graphene oxide-silver nanocomposite (RGO-Ag/CPE) was prepared for voltammetric determination of acetaminophen. The morphology and structure of the resulting products were characterized by transmission electron micrograph, X-ray diffraction and infrared spectroscopy. The electrochemical behaviours of acetaminophen on resulting modified electrode were investigated by cyclic voltammetry and differential pulse voltammetry. Differential pulse voltammetry shows that peak current increase linearly by increasing in acetaminophen concentration. Acetaminophen was determined in the range of 5.0–480.0, and the limit of detection was determined as 0.18 µM using differential pulse voltammetry under optimization conditions. This electrode obtains good and satisfactory results in the determination of acetaminophen in a commercial tablet.
    Keywords: Reduced graphene oxide, Silver nanoparticles, Modified carbon paste electrode, Acetaminophen
  • Hassan A. Hindawe, Hoda M. Elqudaby, * Gehad G. Mohamed, Eglal R. Souaya, Ghada M. G. Eldin Pages 234-255
    Electrochemical oxidation behavior of ritodrine hydrochloride (RT.HCl) was studied in Britton Robinson buffer at different pH range from 2 to 10 using carbon paste (CPE), modified zirconium oxide carbon paste (ZrO2-MCPE), graphite pencil (GPE) and glassy carbon electrodes (GCE). Cyclic voltammetry (CV) was showed one well-defined, irreversible, diffusion-controlled anodic peak at pH 9 by using CPE and GPE electrodes and pH 8 and 7 at ZrO2-MCPE and GCE electrodes, respectively. The linear response was obtained in the concentration range of 3.33×10-6-4.33×10-5, 6.67×10-8-7.33×10-7, 4.0×10-66×10-5 and 5.0×10-6-4×10-5 M with detection limit (LOD) of 1.57×10-6, 6.18×10-8, 1.71×10-6 and 3.32×10-6 mol L-1 by using differential pulse voltammetric method (DPV) at CPE, ZrO2MCPE, GPE and GCE, respectively. The linear concentration response was obtained in the concentration range of 1.33×10-6-1.47×10-5, 3.33×10-8-3.67×10-7, 4.0×10-6-5.5×10-5 and 5.00×10-6-4.5×10-5 M with detection limit (LOD) 5.78×10-7, 1.11×10-8, 1.74×10-6 and 1.84×10-6 mol L-1 by using square wave voltammetric method (SWV) at CPE, ZrO2-MCPE, GPE and GCE, respectively. The repeatability and reproducibility of the method were 0.411.27, 0.25-1.11, 0.49-1.86 and 0.73-2.13% relative standard deviations (RSD) for anodic peak current by using square wave voltammetric method (SWV) at CPE, ZrO2-MCPE, GPE and GCE electrodes. The mechanism successfully confirmed by molecular orbital calculation (MOC). These calculations give the bond order, bond length and charge distribution. This helps the successful choice of the weakest bond which changed during oxidation or reduction. Therefore, the best pathway for the oxidation of this drug is correctly selected for proposed mechanism.
    Keywords: Carbon paste electrode, Zirconium oxide nanoparticles, Graphite pencil electrode, Glassy carbon electrode, Differential pulse, Square wave voltammetry, Ritodrine hydrochloride
  • Mohammad Reza Ganjali, * Nazila Davarkhah Pages 256-267
    A novel all-solid-state ion selective electrode (ASS-ISE) has been constructed for the determination of Pb(II) ions in complex aqueous media. The ASS-ISE is constructed of a layer of a conductive graphite-epoxy resin composite on a copper wire, further coated with a Pb(II) selective PVC membrane. The optimal PVC membrane is composed of 31% PVC, 62% nitrobenzen (NB), 2% of sodium tetraphenyl borate, and 5% of N,N՛-dimethylcyanodiaza-18crown-6 as a selectophore (L). The studies proved the device to have a Nernstian response (i.e. 29.4±0.3 mV per decade) in a concentration range from 1.0×10-8 mol L-1 to 1.0×10-3 mol L-1, with a lower detection limit of 4.0×10-9 mol L-1. The proposed ASS-ISE was also found to possess a good Pb(II)-selectivity as opposed to various interfering cations. The device was further practically tested in the analysis of lead content of some water samples with complex matrices.
    Keywords: Lead, Sensor, All solid state, Potentiometry, Water