Analytical & Bioanalytical Electrochemistry
Volume:11 Issue: 9, Sep 2019

Polyamines have a pivotal role in many biological functions. The goal of this study was to assess the validity of a voltammetric technique for the evaluation of the behavior of some biogenic amines. A square wave voltammetric (SWV) method was applied for direct assessment of Spermine (SPM) and Spermidine (SPD). Then, the voltammetric peak of SPM was used to find the Polyamine oxidase (PAO) activity in some animals’ milk and to determine the SPD concentration. Only SPM and SPD generated an adsorption peak at -0.446 V and -0.576 V vs Ag/AgCl, respectively. The proposed method was specific and sensitive. The LOD was found at 0.7×10-8 M and LOQ was computed as 2.1×10-8 M. The standard deviation (SD) and the relative standard deviation (RSD) for SPM and SPD sensitivity (n=6) was ±1.5 (3.4%) and ±0.5 (4.5%), respectively. The suggested method showed a good reproducibility, the relative standard deviation RSD (n =6) was 4.1% and 4.3%; whereas, the accuracy was between 86-92% and 108–111% for SPM and SPD, respectively. The proposed method was valid for determination of polyamine oxidase (PAO) activity in sheep and cow milk. Furthermore, SPD concentration can be assessed in the same sources, using this method.

Bilirubin is predominantly formed in the liver as a result of breakdown of hemoglobin. Knowing the concentration of bilirubin in serum is important in evaluating the health of the liver, and for the diagnosis of hyperbilirubinemia (a condition that afflicts approximately 60% of full term and 80% of pre-term newborns). In this work, a carbon paste electrode (CPE) has been used to study the electrochemical oxidation of bilirubin (BR) and its feasibility to be performed at unmodified or untreated carbon paste in an effort to propose a simple voltammetric method for detection of bilirubin. Irreversible oxidation of BR at CPE had occurred at about +0.32 V vs. Ag/AgCl as a diffusion-controlled process, when suitable pH for this redox transformation was either a mild alkaline solution (of Phosphate buffer, pH 8) or a neutral supporting medium. After having chosen the DPV mode and optimizing the electroanalytical parameters, the oxidation responses of the analyte has been justly proportional to concentration in the range of 3.5–25 μmol. L-1 with LOD of 1.2 μmol. L-1 in phosphate buffer.

An electrochemical sensor was developed for the electroanalysis of catechol (CC) and hydroquinone (HQ) using poly-nile blue (NB) modified glassy carbon electrode (MGCE) i.e., poly-NB/MGCE. The fabricated electrode showed an excellent electrocatalytic activity towards the electrooxidation of CC and HQ in 0.2 M phosphate buffer solution (PBS) of pH 7.4 by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The effect of scan rate suggests the adsorption and diffusion controlled electrode process for CC and HQ respectively. The limit of detection of CC and HQ was found to be 53.2 nM and 31.5 nM by CV techniques. Overall, the sensitivity, selectivity, stability, linearity and reproducibility were obtained at the poly-NB/MGCE

An electrochemical sensor was developed for the electroanalysis of catechol (CC) and hydroquinone (HQ) using poly-nile blue (NB) modified glassy carbon electrode (MGCE) i.e., poly-NB/MGCE. The fabricated electrode showed an excellent electrocatalytic activity towards the electrooxidation of CC and HQ in 0.2 M phosphate buffer solution (PBS) of pH 7.4 by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The effect of scan rate suggests the adsorption and diffusion controlled electrode process for CC and HQ respectively. The limit of detection of CC and HQ was found to be 53.2 nM and 31.5 nM by CV techniques. Overall, the sensitivity, selectivity, stability, linearity and reproducibility were obtained at the poly-NB/MGCE

A novel bio electrode containing bacteria immobilized on clay mixed carbon paste electrode (Bactria-clay-CPE) is developed for detection and degradation of the phenolic solutions based on electrochemical techniques such cyclic voltammetry, square wave voltammetry, electroctrochemical impedence spectroscopy. The results obtained showed that bacteria-clay-CPE exhibited excellent electro-catalytic activity towards phenol. The recorded cyclic voltammogram shows that the oxidation of phenol is manifested by the appearance of four oxidation peaks

The aim of this paper was to determine the effects of different immersion times on electrochemical behaviour of pure molybdenum in NaCl solution (0.1 M). Immersion tests were conducted in different time span. Scanning electron microscope (SEM) indicated that there was not any pitting formation of corrosion products after immersion. The most significant consideration which obtained from Molybdenum EDS maps before and after immersion in solution of 0.1 M NaCl shows increases in combination of oxygen. Pure molybdenum is indicated to have a passive behavior in the given solution by using potentiodynamic polarization (PDP) plots. In addition, electrochemical impedance spectroscopy (EIS) reveals that molybdenum total resistance increases considerably while rising the immersion time.

The interaction of organic cation Amprolium with methyl orange was investigated with the help of thermal studies. The thermolysis of IA Amprolium with methyl orange begins at 20 °C and is characterized by the fact that the molecule of ammonia is released at the first stage at a temperature of 50 °C. In the process of thermolysis no sulfur is released, and we observe a slight exoeffect at 220 °C. Then we observe a small endoeffect at 260 °C. The mass loss at this stage is 34%, which may correspond to the allocation of NH3, SO2, CO and N2, which were identified by qualitative reactions. At the last stage, within the limits of 440-680 °C, combustion of IA occurs, which is accompanied by an exothermic effect at a temperature of 485, 610 °C and endothermic at 520 °C with a significant loss in mass. These slightly soluble associates were used as electrode active substances (EAS) in plasticized polyvinyl chloride (PVC) membranes of ion-selective electrodes (ISE), sensitive to organic cation Amprolium. The influence of the nature of plasticizer on the basic electroanalytical
characteristics in the system is investigated. The following organic solvents with corresponding dielectric constant (ε) and Rorschneider polarity (PR) were investigated as membrane plasticizers: diethyl phtalate (8.15; 40), dibutyl phtalate (6.1-6.4; 38), dibutyl sebacate, dioctyl phtalate (5.1; 30), dinonyl phtalate (4.47; 26), tricresyl phosphate (6.7-7; 25). The results of the study of the electroanalytical properties of the sensors developed by the nature of the plasticizer indicate that the best plasticizer for the system is TFC or DNP. For these solvents work of size of the dielectric constant and the Rorschneider polarity are 123.5 and 175, respectively. For plasticizers which appeared less more effective (DBP and DEP) these sizes are 235.6 and 326, accordingly. For membranes with identical content of plasticizer of one homological row (DEP, DBP, DOP, DNF), the Nernstian slope diminishes with growth of dielectric constant of solvent-plasticizer The pH working range of the sensors based on ion associates with methyl orange are 5.5-10.0 respectively. The linearity ranges of the electrode are in the range 6.3×10-5–1×10-1 mol/L, and the function slope is 28-35 mV/decade. The efficiency of the use of sensor for determination of Amprolium in pharmaceuticals was shown

The sorbitol film coated pencil graphite electrode was developed for the determination of Dopamine (DA) by using cyclic voltammetric method. Compared to bare pencil graphite electrode (BPGE) the poly (sorbitol) modified pencil graphite electrode (MPGE) exhibited a high sensitivity and better electrocatalytic performance towards the oxidation of DA in phosphate buffer solution (PBS) of pH 7.4. A well-defined redox peaks were observed with good enhancement signals at poly (sorbitol) MPGE. From the study of scan rate variation the electrode process was found to be diffusion controlled. A complete investigation of electrochemical parameters such as the heterogeneous rate constant (ks), and detection limit were measured for DA at poly (sorbitol) MPGE. The pH studies confirm that an equal number of protons and electrons were involved in the electrochemical detection of DA. The simultaneous determination of DA and Uric acid (UA) in their sample mixture was analysed by using cyclic voltammetric and differential pulse voltammetric techniques.

Nowadays electrochemiluminescence (ECL) has shown considerable growth as a stage for analytical procedures in numerous areas such as pharmaceutical analysis, immunoassay, DNA analysis as well as clinical analysis. Herein, a novel ECL sensor was fabricated for ultrasensitive detection of Dextromethorphan HBr (DXM HBr) based on Ru(bpy)32+/Eu2(CO3)3 nanoparticle/chitosan composite. The electrochemical and ECL performance of the suggested sensor were examined. Under the optimal conditions, the constructed DXM HBr sensor showed a wide linear range from 1.0×10-12 to 1.0×10-8 mol.L-1 with a detection limit of 7.4×10-13 mol.L-1 (at signal-to-noise ratio of 3) and relative standard deviation of 3.7%. Furthermore, the demonstrated ideal stability and sensitivity was found for the ECL sensor which might be contributed to the high surface area and the good electrical conductivity of Eu2(CO3)3 NPs. In addition, the ECL sensor was used to detect DXM HBr in human serum samples and displayed desirable results.

The impact of effective parameters on the electrochemical deposition rate optimization of Au-Cu alloy at high thicknesses on the silver substrate was investigated in the present study. To have co-deposition of gold-copper alloy with the cartage of 18 K (750 ppt) and appropriate deposition rates values of 6mAcm2,6grlit , 55grlit , 24grlit, 66 ˚C, 12.3, 100 rpm and 1mllit, the specified parameters in this method, including current density, ions concentrations of gold, copper and cyanide, temperature, pH, agitation and additive concentration were effectively optimized by the "one factor at a time" method. Scanning electron microscopy (SEM) and surface chemical analysis system (EDS) were used to study the effect of deposition on the cross-sections of the formed layers. The results showed that under the optimum conditions obtained at about 18K, the average current density (Iavg=0.6mAcm2) and a duty cycle (30%) at the same time, the deposition rate was 0.841μmmin and in this method, that was significantly higher than the commercial methods. It should be noted that in a pulsed electrodeposition, with increasing percentages in duty cycle, the deposition rate of the layers was reduced, which can be explained by the reduction of the double layer thickness due to shortening of the pulse off-time.