Analytical and Bioanalytical ElectroChemistry
Year:2017 | Volume:9 | Issue:3|Papers Count:10

In this work, a highly dispersed Multi-walled carbon nanotube (MWCNT) was successfully functionalized with 3-mercaptopropyltrimethoxysilane (MPTS) molecule by silanization method. The MPTS functionalized MWCNT (MPTS-MWCNT) were structurally characterized by scanning electron microscope (SEM) and energy dispersive X-ray (EDAX) techniques. Moreover, glassy carbon electrode modified with MPTS-CNT (MPTS-MWCNT/GCE) was prepared by casting of the MPTS-MWCNT solution on GCE. The MPTS-MWCNT/GCE showed an excellent electrocatalytic activity towards cefixime (CEF). Bare GCE shows an ill-defined oxidation wave around 0. 95 V for CEF, whereas MPTS-MWCNT/GCE shows a well-defined oxidation peak at 0. 7 V vs. Agǀ AgClǀ KCl (3 M). Differential pulse voltammetry method was used to determine CEF in the concentration range of 0. 6-20 μ M with a detection limit of 0. 07 μ M (S/N=3). The present modified electrode shows good recovery results for CEF tablet and spiked CEF in human blood plasma sample. Possible interferences, such as: glycine, alanine, ascorbic acid, cephalexine, L-cysteine, glutathione and lysine for the detection of CEF at the MPTS-MWCNT/GCE were investigated. The results showed that L-cysteine and glutathione showed interference, whereas another mentioned compounds did not show interference.

A graphite screen printed electrode modified with ZrO2 nanoparticles (ZrO2/SPE) was investigated for its ability to serve as a sensor towards propranolol. The ZrO2/SPE was found to exhibit an electro-catalytic activity for the electrochemical oxidation of propranolol in 0. 1 M phosphate buffer solution (pH 7. 0). Cyclic voltammetry and differential pulse voltammetry were employed to study the electrochemical properties of the modified electrode. The electrochemical oxidation of propranolol occurs at +0. 95 V with a limit of detection (3σ ) found to be 1. 5 μ M and with linear range of 10. 0 μ M to 200. 0 μ M. The present study widens the scope of applications of ZrO2 nanoparticles for on-site monitoring of propranolol.

The possibility of the electrochemical detection of propoxur pesticide over a conducting polymer, saturated by radical sites, was described from theoretical mechanistic point of view. The correspondent mathematical model was developed and analyzed by means of linear stability theory and bifurcation analysis. It was shown that, despite of the effects of radical coupling, the radical sites saturated conducting polymers may serve as an efficient electrode modifier for propoxur electrochemical detection. The reaction is expected to be diffusion controlled. The oscillatory behavior in this system is possible and may be caused by surface and electrochemical reaction factors.

A polymeric film of Dianix Blue was formed electrochemically on a glassy carbon electrode and used for electrochemical detection of levodopa (LD), ascorbic acid (AA) and uric acid (UA). Electrode modification and characterization, conditions optimization and electrochemical detection were performed by using cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. The sensor represented electrocatalytic activity for their oxidations. The resultant differential pulse voltammograms display well defined and fully resolved anodic oxidation peaks for determination of the LD in the presence of AA and UA. Anodic oxidation currents of LD, AA and UA showed linearity with good correlation coefficient (>0. 998), high sensitivity, and low detection limits (0. 005, 0. 028 and 0. 005 μ M respectively). The sensor was used successfully for recovery of the analytes in human plasma samples

Li-rich Mn-based layered oxides, which are considered as solid solutions of xLi2MnO3. (1-x)LiMn0. 33Ni0. 33Co0. 33)O2 have attracted much attention for their high theoretical capacity (>250 mAh g-1) and operating voltage (>3. 5 V vs. Li/Li+). In this research work, synthesis, electrochemical investigation of Li1. 2Mn0. 54Ni0. 13Co0. 13O2 and influence of the doping Pr3+ ion on its structure and properties has been investigated. These Li-rich cathode materials with the general formula of Li1. 2Mn0. 54-xNi0. 13Co0. 13PrxO2 (x=0, 0. 01, 0. 03, 0. 05) have been synthesized by a hydrothermal method. The synthesis of samples and increase of cell volume was confirmed by X-ray diffraction. The stoichiometric ratios for x=0. 03 according to experimental formula of Li1. 2Mn0. 50Ni0. 12Co0. 13Pr0. 02O2 were determined by inductively coupled plasma (ICP) method. In order to better understand the morphology of the synthesized samples, SEM analysis was applied and in order to specify particles distribution, EDS images were prepared. The purpose of this study is achieving better electrochemical properties such as cycle performance. The ability of these materials as a cathode in Li-ion batteries was studied with cyclic voltammetry, Electrochemical Impedance Spectroscopy (EIS) and galvanostatic charge/discharge methods. The doped compound with x=0. 03 exhibited the higher columbic efficiency and cycle performance, which delivering an initial discharge capacity of 247 mAh g-1 at 0. 05 C and 195 mAh g-1 after 10 cycles with capacity retention of 79%, compared to pristine sample with capacity retention of 62% retention. The columbic efficiency of the pristine sample was promoted from 79% to 83% for the doped sample. The results of EIS demonstrated that doping with Pr3+ ions reduces the charge transfer resistance from 696 μ Ω to 252 μ Ω and facilitates the Li ion diffusion.

A sensitive and quick responsive analytical method was developed for the electrochemical oxidation of masalazine (MSZ) using poly (glutamic acid) modified glassy carbon electrode (MGCE). The modified electrode shows electrocatalytic activity towards the oxidation of MSZ drug in 0. 2 M phosphate buffer solution (PBS) of pH 7. 4 by cyclic voltammetric (CV) technique. The limit of detection was calculated to be 23. 94 nM at modified electrode. The effect of scan rate study reveals an adsorption controlled electrode phenomenon. The modified electrode can be used as an analytical tool for the determination MSZ in pharmaceutical formulations.

A Cu(II) nanocomplex, [CuCl2(salophen)]. H2O [salophen=o-phenylenediaminebis(salicylidenaminato)], was synthesized. The electrochemical properties of the as-prepared Cu(II) nanocomplex modified graphite screen printed electrode (Cu/SPE) were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Moreover, as a nanosensor for the determination of epinephrine the Cu/SPE exhibited excellent electrocatalytic activity for the oxidation of epinephrine with a faster electron-transfer rate. The DPV technique was used for the trace determination of epinephrine. The dependence of current vs. concentration was linear from 10. 0 to 600. 0 μ M with a regression coefficient of 0. 9975, and the detection limit of epinephrine was 2. 5± 0. 05 μ M. Finally, the method was applied to the selective and precise analysis of epinephrine in epinephrine injection.

The development of a new modified glassy carbon electrode with ZnO nanoparticales and a polymer film of 1, 2-napthaquinone-4-sulphonic acid have been reported. The electrochemical behaviour of paracetamol in pharmaceutical form at ZnONPs-Nq/GC modified electrode using cyclic and linear sweep voltammetry was investigated. The modified electrode exhibited excellent electrocatalytic activity for the behaviour of PA. The anodic and cathodic peak currents of PA at ZnONPs-Nq/GCME increased significantly when compared with that at a bare glassy carbon electrode and ZnONPs/GCE, also its potential shifted to more negative value. The effect of pH, concentration and scan rate were also investigated. The anodic peak current was linearly proportional to the concentration of PA in the range from 0. 088 to 1. 1 mM with detection and quantification limits of 30. 03×10-6 and 10. 01×10-5 M respectively. The pH 7. 6 is the gives value for studying the behaviour of PA at the modified electrode. Some parameters such as the diffusion coefficient (D), the electron transfer rate constant (ks) and the electron transfer coefficient (α ) were calculated and found for the PA oxidation to be 5. 998×10-6 cm2 s– 1, 11. 279 s-1 and 0. 721 respectively. The modified electrode shows high selectivity, satisfied stability and good reproducibility for the detection of PA. This modified electrode was successfully applied to PA determination in pharmaceuticals tablets samples.

In this research we describe application of Ficus carica sub sp. rupestris for biosynthesis of Ag nanoparticle in the first step. The synthesized nanoparticle was characterized by TEM and UV-Vis spectroscopy methods. In the continuous a carbon paste electrode modified with Ag nanoparticle (CPE/M/Ag/NPs) was fabricated as a highly sensitive sensor for ascorbic acid analysis. The CPE/M/Ag/NPs showed good catalytic activity for electrochemical analysis of ascorbic acid using voltammetric methods. The anodic peak current was linearly proportional to the concentration of ascorbic acid in the range from 0. 09 to 600. 0 μ M with detection limit of 0. 02 μ M. The CPE/M/Ag/NPs was successfully applied to ascorbic acid determination in food and pharmaceuticals samples.

Copper oxide and nickel oxide-copper oxide (NiO-CuO) metal oxide nanoparticles were prepared by co-precipitation method in aqueous solution using sodium hydroxide as precipitating agent and Cetyl Trimethyl Ammonium Bromide (CTAB) as a surfactant. The particles were characterized by XRD, SEM, EDS and FTIR analysis. The crystallite sizes of both metal oxide particles were in the nano range calculated by Debye-Scherrer equation. The prepared metal oxide nanoparticles were employed for the fabrication of zinc-composite coating on mild steel by electroplating and their corrosion behaviour was investigated by Tafel and Electrochemical impedance spectroscopy in corrosive media of 3. 5% NaCl solution. The surface morphology of coated steel articles and also their corrosion morphology have been characterized by scanning electron microscopic (SEM) images.