Analytical & Bioanalytical Electrochemistry
Volume:12 Issue: 4, Apr 2020

The aim of this work is to study the degradation and mineralization of antibiotic ofloxacin in aqueous medium using the Electro-Fenton method as advanced oxidation technology. In this context, Pt/carbon-felt cell was used to investigate the influence of various parameters including initial pH, different supporting electrolytes, different metal ions as a catalyst and antibiotic concentration over the mineralization rate and instantaneous current efficiency. The chemical oxygen demand (COD) measurements during the electrolysis allowed the evaluation of the kinetic of organic matter decay and the mineralization efficiency reaches 90% COD removal at only 200 mA for 300 min of electrolysis.

In the context of highly efficient, non-toxic and natural organic corrosion inhibitors, Phyllogorgia dilatata was studied as an anticorrosive for mild steel in acid medium. The marine octocoral crude extract (PDCE) was characterized and analyzed by LC-HRMS, revealing the presence of 16 different organic molecules. The corrosion inhibition was evaluated via weight loss study and electrochemical techniques. The obtained polarization curves showed that PDCE acts as a mixed-type inhibitor and gravimetric, Electrochemical Impedance Spectroscopy and Linear Polarization Resistance analyses reached an average maximum anticorrosive efficiency of 93.4% at 1 g L-1. The data crossing between gravimetric and electrochemical measurements indicated that the protection mechanism is due to adsorption, blocking electro-active sites. The adsorption data followed the Freundlich theory and SEM/EDX images confirmed the formation of a protective multilayer film.

Zolpidem is a drug that is easily attached to the GABA receptors in the brain. This property makes it very effective for tranquilizing as well as hypnagogia. According to the advantages of electrochemical analysis like high selectivity, high sensitivity, low concentration of analyte, cost-effective, portable and easy-to-use setup, they gained high amount of attention among scientists for determination of different compounds. So in the work, an electrochemical sensor was prepared by the modification of a carbon paste with sulfur-tin@tin oxide nanocomposite (SnS@SnO2NP/CPE) and was investigated for the determination of zolpidem in an aqueous solution. For this reason the electrochemical characteristic of SnS@SnO2NP /CPE including cyclic voltammetry and electrochemical impedance techniques were used. Cyclic voltammetry studies indicated that the process was irreversible. Determination of zolpidem was performed using differential pulse differential technique at the modified electrode surface and linear relationship of oxidation peak current with concentration of this drug show a LOD of 0.66 μM was in the range of 2-80 μM.

In this study, AuPdCu-rGO-MWCNTs nanocomposite was synthesised by a chemical reduction method which was applied to fabricate an electrochemical sensor for simultaneous determination Dopamine (DA), Acetaminophen (AC) and Tryptophan (Trp) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The formation of Au, Pd, and Cu nanoparticles on rGO-MWCNTs nanocomposite are characterized by XRD, FTIR, and SEM techniques. The relationship between the concentration of DA, AC, and Trp with the response of AuPdCu-rGO-MWCNTs/CPE was linear in the range of 10 nM to 8.3 μM, 20 nM to 12.5 μM and 10 nM to 9.4 μM by DPV technique, and 0.007-8.0, 0.011-11.6 and 0.008-8.8 μM by amperometric method, respectively. Also, the detection limits for DA, AC, and Trp were calculated to be 3, 7 and 4 nM, respectively by the voltammetric method and 2, 5 and 3 nM for DA, AC and Trp, by amperometric method. The investigations show that AuPdCu-rGO-MWCNTs/CPE has acceptable selectivity, stability, repeatability, and reproducibility. Finally, AuPdCu-rGO-MWCNTs/CPE was successfully applied to determine the analytes in the urine, blood plasma, and AC Tablet by desirable percentage of relative standard deviation and recovery.

In this study a novel method was developed to fabricate cadmium sulfide nanoparticles/multiwalled carbon nanotubes composite modified gold electrode (CdSNPs/MWCNTS/AuE) to measure trace amounts of norepinephrine(NE), indomethacin (IND), and uric acid (UA) simultaneously. Electrochemical investigations were carried out using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamprometery (CA) methods. Using DPV method under optimum condition, the NE anodic peak current represented a linear relationship in the two concentration ranges of 0.3 to 100.0 μM and 100.0 to 500.0 μM. For UA, the corresponding anodic peak current showed linear ranges from 0.5 to 100.0 μM and from 100.0 to 350.0 μM, and IND the corresponding linear range was between 2.0 to 80.0 μM, respectively. Detection limits have been calculated equal to 0.16 μM for NE, 0.09 μM for UA, and 0.46 μM for IND, respectively. The modified electrode has been applied for the determination of NE, UA and IND in human urine and blood serum with satisfactory results.

Direct drug determination without any pervious treatment steps is the most environmentally friendly method of analysis. Traditional analysis methods usually involve a pre-treatment step before analysis and this consumes time and organic solvents. This work describes direct potentiometric method by using ion selective electrode to determine Montelukast Sodium in its pure drug substance and in tablet formulation and for inline monitoring of its release from its tablet form without any sample pretreatment. A Sensor was fabricated using PVC based membrane containing tetradodecyl ammonium bromide (TDB) being as an anionic exchanger and 2-nitrophenyl-octyl-ether (2-NPOE) being a plasticizer. The validation of the proposed method was done according to International union of pure and applied chemistry recommendations, in which the proposed sensor show a linear dynamic range from 1.0×10-6 to 1.0×10-2 mol/L. The proposed sensor was applied to determine Montelukast sodium in bulk powder, tablets dosage form with no extraction. The sensor was also used as bench-top real-time analyser for in process tracking of Montelukast sodium concentration during monitoring of its dissolution behaviour, under U.S. Food and Drug Administration dissolution regulations, with clear discrimination from its common excipients. Results obtained by the proposed potentiometric method were compared with those obtained by the official HPLC method.

Recently, PEO process of tantalum has been developed as a method of producing corrosion-resistant, hard, wear-resistant, and biocompatible as well as having good adhesion coatings. In this review, we present the results of PEO process of tantalum in three main electrolytes. This review tries to measure the effect of electrolyte composition and voltage that were used within PEO procedure on the surface behavior of the produced oxide coatings on Ta. The results of the PEO treatment of Ta in H4SiW12O40 electrolyte revealed that the morphology of oxide coatings really depends on the PEO procedure time. Density of discharge channels declines as their diameter rises. This leads to an increase in the oxide coating roughness within the PEO procedure of tantalum. In electrolytes of β-glycerophosphate disodium and calcium acetate, the results indicated that the employed voltage significantly affected morphologies, the coatings bond strength and the phase components. However, it affected surface chemical species a little. Finally, in 0.5 M Ca (H2PO2)2 electrolytes, the results revealed that using a precise control on the procedure voltage, tuning the obtained coatings thickness is possible in addition to their roughness, adhesion strength and relative values of the electrolyte type inside the modified surfaces of tantalum.

Herein, gold nanoparticle had been successfully synthesized through a simple, inexpensive and clean electrochemical technique. Gold nanoparticles were directly deposited on the electrode surface using an electrochemical strategy. Then, the electrochemical deposition parameters (such as applied potential and deposition time) were optimized. 1.1 V and 250 s were applied as the optimal electrodeposition potential and time in the rest of the investigations. The fabricated electrode was morphologically characterized by field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy methods. Under the optimized condition, the proposed sensor demonstrated the lowest detection limit (7.04 nM) in the linear range of 0.01–1 μM obtained by differential pulse voltammetry. The electrochemical properties of fabricated modified electrode were investigated by a different techniques such as cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The constructed electrode also showed a negligible response from common interferences and the fabricated sensor was applied for Gabapentin analysis in pharmaceutical samples.

In the current work, a novel sensor was developed for the analysis of Vanillin (VN) by electrochemical polymerization of Niacin over the surface of carbon nanotube paste electrode. The features of electrode surface was studied using Field Emission Scanning Electron Microscopy (FE‒SEM) images. Sweep rate variation study was conducted in the optimum pH (pH 7.0) for the evaluation of number of electrons involved in the electrochemical reaction and to investigate the mode of mass transfer phenomena. This investigation reveals that the electrode undergoes adsorption controlled mass transfer process. Based on the data obtained from the measurements the oxidation mechanism of VN was proposed. The prepared sensor was also applied for the simultaneous detection of VN and Caffeine (CF). Quantitative determination of VN was accomplished by cyclic voltammetric (CV) method. The corresponding value of limit of detection (LOD) and limit of quantification (LOQ) of VN was found to be 10.1×10-7 M and 3.3×10-6 M, respectively. In addition, the applicability of the proposed method was checked with the detection of VN in real sample with good recovery data.

The Zn-Ni-TiO2 composite coatings were developed on mild steel by electrodeposition method. The bath constituents (ZnSO4.6H2O, NiSO4.6H2O, TiO2, thiamine hydrochloride) and operating conditions (temperature and pH) were optimized by Hull cell method, for peak performance of the coating against corrosion. The coatings were prepared by galvanostatic method at room temperature. The effect of current density (CD), on coating parameters, such as corrosion resistance, thickness and throwing power were studied. The micro hardness of the composite coating was investigated. Potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion resistance of Zn-Ni-TiO2 composite coatings at different current densities. Surface morphology and composition of the composite coatings was investigated using Scanning Electron Microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Atomic force microscopy (AFM) analysed the topographical surface of the coatings. A new and economical sulphate bath, for bright Zn-Ni-TiO2 composite coating on mild steel has been proposed, and results are discussed.