فهرست مطالب

Analytical & Bioanalytical Electrochemistry - Volume:9 Issue: 7, Nov 2017

Analytical & Bioanalytical Electrochemistry
Volume:9 Issue: 7, Nov 2017

  • تاریخ انتشار: 1396/09/25
  • تعداد عناوین: 10
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  • Hadi Beitollahi *, Somayeh Tajik, Shohreh Jahani, Hojatollah Khabazzadeh Pages 806-818
    A sensitive electrochemical sensor for determination of hydroxylamine has been introduced. This sensor profits by 2-(4-Oxo-3-phenyl-3,4-dihydroquinazolinyl)-N′-phenylhydrazinecarbothioamide (2PHC) as mediator and magnetic core–shell Fe3O4@TiO2/MWCNT nanocomposite and ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) to improve the working electrode behavior. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and differential pulse voltammetry (DPV) are used to study of the suitability of 2PHC, at the surface of modified electrode, as a mediator for the electrocatalytic oxidation of hydroxylamine in aqueous solutions. The electrocatalytic peak current of hydroxylamine oxidation shows a linear dependence on hydroxylamine concentration in the range of 0.1–500.0 μM, by DPV in optimized conditions at pH 7.0. The detection limit (3σ) was obtained 52.0 nM. Electrochemical parameters such as electron transfer coefficient, α and diffusion coefficient, D, are also determined. The proposed method was successfully applied as a highly sensitive, selective, simple, and precise method for hydroxylamine determination in the water samples.
    Keywords: Hydroxylamine, Fe3O4@TiO2, MWCNT nanocomposite, Ionic liquids, Modified electrodes
  • Rekha, Bahaddurghatta Eshwaraswamy Kumara Swamy*, Pattan Siddappa Ganesh Pages 819-833
    The poly (toluidine blue) modified carbon paste electrode (MCPE) was fabricated for the determination of catechol (CC) and hydroquinone (HQ) by cyclic voltammetric and differential pulse voltammetric techniques. The poly (toluidine blue) MCPE exhibited high sensitivity and selectivity towards the determination of CC and HQ in a binary mixture. The effect of scan rate reveals an adsorption controlled phenomenon at the modified electrode surface. In order to show the selectivity of the electrode, an interference study was performed by varying the concentration of one analyte while keeping other analyte constant which in turn gives a satisfactory result. Overall, a simple experimental procedure for fabricating the poly (toluidine blue) MCPE was reported with the merits of sensitivity, selectivity, reproducibility and anti-fouling property towards the determination of electroactive species.
    Keywords: Electropolymerisation, Catechol, Hydroquinone, Toluidine blue, Cyclic voltammetry
  • Zahra Karami, Iran Sheikhshoaie* Pages 834-840
    Tyrosine is an important amino acid with wide application in human body. So, we try for fabrication of a fast electrochemical tyrosine sensor based on carbon paste electrode modified with reduced graphene oxide/ZnO nanocomposite (rGO/ZnO-NC/CPE). In the first step, we synthesized rGO/ZnO by chemical precipitation method and characterized by SEM and EDAX methods. The rGO/ZnO-NC/CPE showed highly catalytic activity to tyrosine electro-oxidation in aqueous solution. The anodic peak current of tyrosine increased with concentration of this amino acid in the ranges of 0.1–400 μM with limit of detection ~0.07 μM. The performance of rGO/ZnO-NC/CPE was check for the analysis of tyrosine in water and pharmaceutical serum samples.
    Keywords: Tyrosine, Reduced graphene oxide, ZnO nanocomposite, Voltanetry, Senso
  • Manjunatha Puttaiah, Arthoba Nayaka Yanjerappa* Pages 841-861
    A novel electrochemical sensor based on the electrodeposition of gold nanoparticles on disposable pencil graphite electrode (GMPGE) has been developed and employed for the electrochemical investigation of acetaminophen. The developed GMPGE has been characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The modified electrode showed excellent electrocatalytic activities with respect to acetaminophen redox behavior, with good reproducibility. The electrochemical parameters such as, surface concentration (Γ), electron transfer coefficient (α) and the standard rate constant ( 0 k ) of acetaminophen at the GMPGE were calculated. Under the optimized experimental conditions, the proposed sensor exhibited a rapid response to acetaminophen in a linear range from 1.0×10-8 M to 0.9×10-6 M with a limit of detection (LOD) and limit of quantification (LOQ) was found to be 1.95×10-9 M and 6.47×10-9 M respectively. The analytical applicability of GMPGE was illustrated for the determination of acetaminophen present in pharmaceutical formulations, human serum and urine samples as real samples with good accuracy and precision. The UV-Vis spectroscopy has been adopted to confirm the presence of acetaminophen in pharmaceutical formulations, human serum and urine samples.
    Keywords: Gold Modified Pencil Graphite Electrode, Acetaminophen, Scanning Electron Microscope, Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, Differential Pulse Voltammetry
  • Arash Fattah-Alhosseini*, Sareh Sharifi Pages 862-873
    In order to evaluate the electrochemical properties of the passive film on pure Tantalum, various electrochemical methods including polarization, impedance spectroscopy and Mott–Schottky were applied in Ringer solution at 37 °C. Obtained results arisen from polarization and impedance spectroscopy measurements revealed that as the anodic passive potential increases, pure Tantalum samples passive response in Ringer solution was improved. Mott–Schottky measurements showed that the passive oxide films behaved as ntype semiconductors and passive potential cannot change the conductivity type of the passive oxide films. Moreover, Mott–Schottky measurements depicted that less donor densities in the passive film increased corrosion resistance of pure Tantalum in the test solution owing to higher anodic passive potential.
    Keywords: Tantalum, Ringer solution, Polarization, Impedance spectroscopy, Mott–Schottky
  • Vipparla Prabhakara Rao, Yenugu Veera Manohara Reddy, Kalluri Gangadhar Reddy, Chougoni Madhuri, Duddukuru Saritha, Gajulapalle Madhavi * Pages 874-887
    A Polymer film of cinnamic acid was formed on the surface of a bare carbon paste electrode (BCPE) by electropolymerisation of cinnamic acid in pH 7 Phosphate buffer solution (PBS) by using cyclic voltammetry (CV). This lead to the formation of polycinnamic acid modified carbon paste electrode (PCA/CPE). CV was used to study the electrochemical properties of the polymer film on the PCA/CPE. The modified electrode was used for the simultaneous electrochemical detection of dopamine (DA), ascorbic acid (AA) and uric acid (UA). The PCA/CPE showed a very good electrocatalytic activity for the oxidation of DA, AA and UA and exhibited an excellent ability to separate DA from AA by means of CV. The anodic peak potentials of DA and AA were separated by 0.259 V in pH 7 PBS containing 0.1 mM of DA and 2 mM of AA at the scan rate of 50 m V/S. The detection limit (LOD) and quantification limit (LOQ) of the present technique were found to be 3.52×10-6 M and 1.16×10-5 M respectively for DA. Compared to BCPE, the PCA/CPE exhibited the enhanced peak currents for DA, AA and UA. Also, the PCA/CPE showed good recoveries for DA in real sample analysis i.e. for both pharmaceutical formulations and blood serum. Hence, this modified electrode can be used for the selective determination of DA in the presence of higher concentrations of AA and UA in pharmaceuticals and medicine without any problem with greater sensitivity, selectivity and reproducibility.
    Keywords: Cinnamic acid modified carbon paste electrode, Dopamine, Ascorbic acid, Uric acid, Cyclic voltammetry, Differential pulse voltammetry
  • Ali Sharifi, Leila Hajiaghababaei *, Saeed Suzangarzadeh, Mohammad Reza Jalali Sarvestani Pages 888-903
    3-((6-methyl-5-oxo-3-thioxo-2,5-dihydro-1,2,4-triazin-4(3H)-yl)imino)indolin-2one was used as a neutral ion carrier in the PVC membrane to construction of a new zinc ion selective electrode. The sensor shows a good Nernstian response for Zn2 over a wide concentration range of 1.0×10-5 to 1.0×10-1 mol L-1 with a slope of 27.12 mV per decade. The limit of detection of the sensor is 8×10-6 mol L-1. The sensor has a relatively fast response time (~5 s) and a useful working pH range of 4.4-8.0 and it can be used without any divergence in Nernstian response for 60 days with high reproducibility. Interference of some cations was also evaluated and it exhibits an appropriate selectivity. Finally it was used as an indicator electrode in potentiometric titration of Zn2 with EDTA and in direct determination of Zn2 in rice and in zinc enriched soufflé cake samples. The results indicate that this electrode is sensitive for determination of Zn2 ion.
    Keywords: Potentiometry, Zinc, 3, ((6, methyl, 5, oxo, 3, thioxo, 2, 5, dihydro, 1, 2, 4, triazin4(3H), yl)imino)indolin, 2, one, Liquid membrane sensor
  • Mohamed Rbaa, Mouhsine Galai, Mohamed El Faydy, Younes El Kacimi, Mohamed Ebn Touhami, Abdelkader Zarrouk, Brahim Lakhrissi * Pages 904-928
    A new benzimidazoles derivatives of 8-hydroxyquinoline, namely 5-((4chlorophenyl)-benzimidazol-1-yl)-methyl)-quinolin-8-ol (Q-Cl) and 5-((2phenylbenzimidazol-1-yl)-methyl)-quinolin-8-ol (Q-H) have been synthesized and their chemical structure has been elucidated and confirmed using 1H and 13C NMR spectroscopy s 1H and 13C NMR spectroscopy. Their inhibitive action against the corrosion of mild steel in 1.0 M hydrochloric acid solution were investigated at different temperatures in the range from 298 to 328±2 K by a series of known techniques such as weight loss, polarization and electrochemical impedance spectroscopy (EIS). It was found that the studied compounds exhibit a very good performance as inhibitors for mild steel corrosion in 1.0 M HCl. Results show that the inhibition efficiency increases with decreasing temperature and increasing concentration of inhibitor’s. It has been determined that the adsorption for the studied inhibitors on mild steel complies with the Langmuir adsorption isotherm at all studied temperatures. Results show that the order of inhibition efficiency is Q-Cl > Q-H due to the presence of electron donating -Cl group in Q-Cl thereby enhances its ability to donate charges to the metal during the adsorption process. The kinetic and thermodynamic parameters for mild steel corrosion and inhibitor’s adsorption were determined and discussed. Scanning electron microscopy (SEM) confirmed both of the inhibitors played a significant protective effect in mild steel corrosion in 1.0 M HCl.
    Keywords: Organic synthesis, NMR spectropscopy, Benzimidazole, Quinolin, 8, ol, Mild steel, Corrosion, Inhibition, weight loss, EIS, SEM
  • Mahdieh Balooei, Jahan Bakhsh Raoof *, Fereshteh Chekin, Reza Ojani Pages 929-939
    This research discusses the preparation of an electrochemical sensor for cephalexin (Ceph) based on multi-walled carbon nanotubes (MWCNT) functionalized with
    3-mercaptopropyltrimethoxysilane (MPTS) molecule modified glassy carbon electrode (GCE). The MPTS functionalized MWCNT (MPTS-MWCNT) was structurally characterized by thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). In this area, glassy carbon electrode (GCE) modified with dispersed MPTS-MWCNT ethanol solution on the GCE, which MPTS-MWCNT was used as a new mediator for the voltammetric determination of cephalexin. Differential pulse voltammetry method was employed for determination of Ceph in phosphate buffer solution. Under the optimum conditions at pH 7.00, the oxidation of cephalexin at the surface of the modified electrode was occurred at 1.05 V vs. Ag|AgCl|KCl3M with higher oxidation current in compared to bare GCE. The MPTS-MWCNT/GCE showed an excellent electrocatalysis activity towards oxidation of Ceph. The oxidation peak current of cephalexin at the surface of MPTSMWCNT/GCE in the differential pulse voltammetry are found to be linear over the range of concentration 0.5 to 50 µM and the lower detection limit are found to be 0.12 µM for this drug. The proposed method showed good recovery results for voltammetric determination of Ceph in the Ceph tablet solution and spiked Ceph in human serum sample.
    Keywords: Cephalexin, Functionalized Multi, walled carbon nanotubes, Electrocatalysis, Electrochemical sensors, 3, mercaptopropyltrimethoxysilane
  • Pinjari Shaikshavali, Tukiakula Madhusudana Reddy *, Gujapaneni Venkataprasad, Palla Gopal Pages 940-955
    A sensitive electrochemical sensor was made by the electro polymerization of Lcystine (L-Cys) on the surface of a glassy carbon electrode (GCE) followed by drop casting of multi walled carbon nano tubes (MWCNTs). The sensor was characterized by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor showed good electrocatalytic activity towards the sensing of dopamine (DA) and simultaneously discriminated DA in presence of uric acid (UA) and folic acid (FA). The kinetic parameters, such as heterogeneous rate constant, number of electrons transfer and charge transfer coefficient values were evaluated. The effect of concentration on the DA was studied and a linear relationship was observed between the concentration verses peak currents, with a limit of detection (LOD) and limit of quantification (LOQ) values as 2.8×10-6 M and 9.6×10-6 M, respectively. The present method was successfully applied toward the recovery of DA in injection sample.
    Keywords: Dopamine (DA), L, Cystine (L, Cys), Multi, walled carbon nanotubes (MWCNTs), Voltammetry, Electrochemical impedance spectroscopy (EIS)