Analytical & Bioanalytical Electrochemistry
Volume:14 Issue: 4, Apr 2022

The object of this work is to evaluate the inhibitory efficiency of the essential oil of leaves of Pistacia lentiscus (EOPL) on the corrosion of commercially pure titanium (CP-Ti) in a simulated marine environment (3.0 wt. % NaCl). The inhibition effectiveness of this green corrosion inhibitor was investigated using weight loss measurement and potentiodynamic polarization in the presence of different concentrations of EOPL ranging from 0.1 to 2.0 g/L. A complementary vision of this study is obtained by means of surface characterization by scanning electron microscopy (SEM). Adsorption of the inhibitor on the titanium surface obeyed Langmuir’s isotherm. The thermodynamic parameters were determined and discussed. It is found that the activation energy increases with an increase in inhibitor concentration, suggesting physisorption. With increasing EOPL concentration, inhibition increased to 84.58% at 2.0 g/L. Thus, the results obtained from the different techniques used in this work are in very good agreement and revealed that EOPL of Pistacia lentiscus could be used as a source of green corrosion inhibitors on CP-Ti in 3.0 wt. % NaCl solution.

In this work, we have synthesized the surfactant compounds derived from 2-(N-Alkyl-3-methyl-1,2,4-triazolthioyl) acetic acid (MTSACCn; n=10, n=11 and n=12). These compounds have been purified and identified using several spectroscopic methods such as 1H NMR; 13C NMR spectroscopy. The molecular aggregation of MTSACCn has been foxed using tensiometer apparatus. The electrochemical study was carried out using a coupling of potentiodynamic and electrochemical impedance methods. The polarization curves indicate that the MTSACCn act as mixed-type inhibitors of carbon steel in 1M HCl solution. The electrochemical impedance spectroscopy measurements showed that all synthesized compounds act by establishing a barrier layer on the steel surface. Therefore, we noted that the inhibition efficiency increases with increasing of concentrations inhibitors. Also, the MTSACC12 is the best inhibitor, its inhibition efficiency reached a maximum value of 95% at 510-4 M. The adsorption of all surfactants studied follows the Langmuir isotherm.

A high urea compound in human blood is indicated for kidney disease, urinary tract stones, and even bladder tumors. It is necessary to take several preventive measures, starting with detecting the urea compound. This study presents the preparation of a working electrode based on graphite-TiO2 (G/TiO2) composites immobilized into a glass tube for sensing urea compound under an electrochemical system. The G/TiO2 composites were successfully synthesized through a physical mixing method and then immobilized into a glass tube for fabricating a working electrode to sense the urea compound under the cyclic voltammetry (CV) technique. The material characterization results show that the nano-TiO2 powder is composed of irregular polycrystalline and amorphous, revealing a broad pattern with low intensity. However, the effect of amorphous materials on the expansion of the nano-sized XRD TiO2 pattern is negligible. In addition, the morphological analysis of graphite has a very tight layer of flakes with a smooth and uniform surface. At the same time, the G/TiO2 composites are also granule-shaped that attached to the graphite surface, identified to cover part of the graphite surface. Under the electrochemical performance test, the excellent composition of TiO2 modifier is 0.5 g mixed into graphite to sense urea compound by using CV technique under a scan rate of 0.5 V.s-1 with 0.1M K3[Fe(CN)6] (+0.1M NaNO3) electrolyte solution. We obtain a standard deviation of 0.361403514 and a detection limit of 0.005976905 mg.L-1 with RSDr and PRSDr values of 5.51% and 3.13%, respectively. The performance of the electrodes over 25 days showed a significant effect on stability over 10 days.

In this research project, a sensitive electrochemical sensor was developed for simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA) based on a gold electrode modified with functionalized multi-wall carbon nanotubes/graphene oxide (f-MWCNTs/GO) nanocomposite capped with gold nanoparticles (AuNPs). The modified electrode showed excellent electrocatalytic activity for the oxidation of DA and PA molecules in aqueous solutions with well-separated oxidation peaks for each species. The fabrication process of the proposed sensor was evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Cyclic voltammetry (CV) and also electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of f-MWCNTs/GO/AuNPs/AuE. Under the optimized experimental conditions, the calibration curves were linear over the concentration ranges of 1-400 µM with a detection limit of 0.5 and 0.3 µM for DA and PA, respectively. Finally, the constructed electrode was successfully applied for the quantitative measurement of dopamine and paracetamol in pharmaceutical and urine samples.

In this study, the quantitative amount of 5-hydroxyindoleacetic acid (5-HIAA) was determined at poly (p-amino benzene sulfonic acid) (p-ABSA) modified glassy carbon electrode. The redox property of 5-HIAA was investigated by cyclic voltammetry. The cyclic voltammograms showed that the redox reaction of 5-HIAA was irreversible. Scan rate study showed that the redox reaction of 5-HIAA was controlled by both diffusion and adsorption on the poly (p-ABSA) modified sensor. Differential pulse voltammetry technique was used for the quantitative analysis of 5-HIAA in phosphate buffer solution at pH 7.00. The linear working range of the calibration graphs was determined as 1×10-5–9×10-5 M (R2, 0.9912), and the detection limit was determined as 5.3×10-7 M. Recovery values ​​in the analysis of urine samples were between 99.4% and 103.0%. The results showed that the modified sensor can be applied to the determination of 5-HIAA in the presence of ascorbic acid. The proposed sensor is promising for routine analysis due to its high selectivity, reproducibility, long-term stability, and high recovery values in biological samples.

High and low-level concentrations of uric acid (UA) lead to several diseases and physiological disorders. A simple method or sensor is required for the detection of UA. In this work, we have prepared a NiO nanoparticles/ carbon paste electrode (NiONPs/CPE) as an electrochemical sensor and applied it for the detection of UA. Electrochemical parameters such as the effect of pH, scan rate, and concentration were studied. The obtained results represent the excellent electrocatalytic activity of NiONPs/CPE with a diffusion-controlled electrode process. The electrocatalytic process was pH-dependent with a slope of 59 mV/pH. Peak current increased linearly with the increases in UA concentrations. The detection limit was found to be 0.1 mm for the linear range from 0.19 mM to 49 mM. The NiONPs/CPE electrodes exhibited good sensitivity for the detection of UA. As a result, this work is expected to be used for the development of a sensor for the detection of UA.

According to the authors’ request, there is a correction on the authorship of the previously published article: “A Novel Potentiometric Sensor for Determination of Tramadol Hydrochloride in Biological Samples” (Vol. 14, No. 2, 191-200). The name of the co-author “Hossein Tavallali” was missed by the authors in the previous version. This name is now added to the authors’ names. The authors regret that an error occurred in the previous version of their article.