Ajwain is one of the medicinal plants, which the highest composition is thymol, as a strong antioxidant respect to the obtained chromatograms of GC/MS. The antioxidant activity of the Ajwain is measured by Square wave voltammetry method and cyclic voltammetry method and 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) method in at the specific concentrations of 1%, 1. 5%, 2% and 2. 5% and constant pH. The results of the present study indicated that the antioxidant activity of Ajwain obtained from cyclic voltammetry and Square wave is almost equal to the results of the DPPH method, which can be used to measure the antioxidant activity. Compared to DPPH method, electrochemical method involves a number of advantages such as simplicity, cheap operating costs, fastness, low amount of solvent, and no need for chemical reagents. Furthermore, based on the results obtained, the Square wave method includes a higher sensitivity and accuracy than cyclic voltammetry method and DPPH method.

In this theoretical work, we present for the first time voltammetric results of a surface multistep electron transfer mechanism that is associated with a preceding chemical reaction that is linked to the first electron transfer step. The mathematical model of this so-called “ surface CEE mechanism” is solved under conditions of Square-wave voltammetry. We present relevant set of results portraying the influence of kinetics and thermodynamics of chemical step to the features of simulated voltammograms. In respect to the potential difference at which both electrode processes occur, we consider two different situations. In the first scenario, both peaks are separated for at least |150 mV|, while in the second case both peaks occur at same potential. Under conditions when both peaks are separated for at least |150 mV|, the first process can be described with the voltammetric features of a surface CE mechanism, while the second peak gets attributes of a simple surface electrode reaction. When both peaks take place at same potential, we elaborate an elegant methodology to achieve separation of both overlapped peaks. This can be done by modifying the concentration of the substrate “ Y” in electrochemical cell that is involved in the preceding chemical reaction. The results of this work can be of big assistance to experimentalists working in the field of voltammetry of metal complexes and drug-drug interactions.

In this study, cytosine (CT) modified glassy carbon (GC) electrode was used to investigate the detectability of caffeine (CAF) found in foods such as tea, coffee and soft drinks. Using the cyclic voltammetry (CV) technique, 1 mM CT was prepared in pH 7.2 phosphate buffer solution (PBS) and modified at a scanning rate of 100 mV s-¹ in the potential range of 1.0 V to 2.1 V. CT/GC electrode was characterized by CV, scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS) techniques. 1 mM CAF solutions were prepared in different supporting electrolytes such as H₂SO₄, HCl, HNO₃, and CH₃COOH within the potential range of +0.5 V to +1.7 V using Square wave voltammetry (SWV) technique. Effect of the supporting electrolyte concentrations were investigated. CAF solutions in the concentration ranges of 0.75 to 0.05 mM and 0.025 to 0.0025 mM were prepared in 100 mM H₂SO₄ supporting electrolyte and calibration graphs were drawn. Line equations were created using the values ​​read from the drawn graphs. Correlation coefficient (R2) values ​​were calculated as 0.9947 and 0.9961, respectively. Using the calibration curves, limit of detection (LOD) and limit of quantification (LOQ) were found as 0.93 µM and 2.79 µM.

Determination of Bosentan in Pharmaceutical Preparations by Linear Sweep, Square wave and Differential Pulse voltammetry methods

Inactivation of water-soluble redox proteins and enzymes is often encountered in many biological systems under physiological conditions. In electrochemical experiments, if the initial redox form of a given water-soluble redox protein is engaged at the same time in an electrochemical transformation on the working electrode and in an irreversible chemical reaction, then the voltammetric outputs might show quite specific behavior due to the simultaneous interplay of electron transfer step and the chemical reaction. In this work, we present for the first time theoretical results of such a model applicable to the electrochemistry of hydrophilic redox proteins under conditions of Square-wave voltammetry. We present the readers a large tabular overview of a series of voltammetric patterns of this electrode mechanism calculated at different rates of electron transfer step and different kinetics of chemical step. Moreover, in the work we give hints to apply suitable methodology to recognize this mechanism under conditions of Square-wave voltammetry, while giving directions on how to assess the kinetics of both steps involved in this mechanism. The results elaborated in this work should be of help to experimentalists working in enzymatic voltammetry.

It is known truncated Nuclear matrix protein 22 (t-NMP22) could be used a biomarker for Bladder cancer. Therefore, in this paper a highly sensitive electrochemical technique was developed based on nanostructures modified glassy carbon (GC) electrode for detection of t-NMP22. In this measurement, immunosensor was fabricated based on the electrodeposition of gold in general the upper frequency limit is determined by the solution resistance, which depends on the specific conductivity of the electrolyte and the electrode radius. To increase the sensitivity of the electrochemical system for detection of t-NMP22, the most important parameters were optimized. The fabrication steps of the immunosensor were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. FFT Square wave voltammetry (FFTSWV) was used for measurements at optimum condition. Moreover, the effect of important parameters such pH the FFTSWV parameters were investigated. The modified electrode was used for determination of different concentrations of t-NMP22; a linear range from 0. 05 ng/mL to 30 ng/mL and a detection limit of 16. 4 pg/mL were obtained. The proposed detection technique does not need a redox probe and was evaluated in urine, which showed good selectivity, high sensitivity and stability, reproducibility.

Herein, fast Fourier transformation Square-wave voltammetry (FFT-SWV) as a novel electrochemical determination technique was used to investigate the electrochemical behavior and determination of Riboflavin at the surface of a nanocomposite modified carbon paste electrode. The carbon paste electrode was modified by nanocomposite containing Samarium oxide (Sm2O3)/reduced graphene oxide (RGO) (2:1) to improve detection sensitivity of Riboflavin under optimal experimental conditions. Furthermore, the signal-to-noise ratio was significantly increased by application of discrete fast Fourier transformation analysis, background subtraction and two-dimensional integration of the electrode response over the selected potential range and the time window. Obtained cyclic voltammograms demonstrated a diffusion-controlled reversible electron transfer reaction for Riboflavin in phosphate buffer solution (pH=7.2). The peak potential values were pH-dependent, involving the same numbers of protons and electrons. To obtain the maximum sensitivity, some effective parameters such as scan rate (10 mV/s), accumulation time (0.2 s) and potential (+400 mV), frequency (1420 Hz) and amplitude (20 mV) were optimized. As a result, determination of Riboflavin using FFT-SWV showed a linear range of response from 10 to 400 nM (R2=0.9993), with limit of detection of 0.86 nM. An acceptable recovery percent was also obtained for Riboflavin in human plasma samples as criteria of measurement applicability of the proposed modified electrode.

In the present paper, naltrexone determined at ultra-trace scale was performed by combining fast Fourier transform Square wave admittance voltammetry with electromembrane extraction in urine samples. On this approach, a constructed three-microelectrode setup positioned at the upper end of the hollow fiber in a micro-pipette tip, which was then applied for the extracted analyte determination. The employed membrane was consisted 85% of 2-nitrophenyl octyl ether and 15% di-(2-ethylhexyl) phosphate immobilized in the pores of a hollow fiber. A DC potential of 150 V within the time of 25 min was applied, followed by the analytes migration from 1 mM HCl as the sample solution, through the supported liquid membrane into an acidic acceptor solution with pH 3. 0 placed in the lumen of hollow fiber. Based on the obtained results, the introduced method exhibited one the linear range 5-1000 ng/mL (R2=0. 993). Besides, the detection limit of 0. 5 ng/mL was attained. Since the preconcentration factor was found to be 80 in the urine sample after the performed process, it can be concluded that the introduced method could be classified among qualified techniques for naltrexone detection in some complex samples.

This study describes the construction of a new electrochemical sensor and applies it for the determination of Hg2+ ion. This sensor was prepared using new nanographene on G-C3N4 nanosheets. Although the other methods (gas or liquid chromatographic, electrophoresis, flow injection) for measuring Hg2+ ion have advantages such as excellent accuracy and reproducibility, it has limitations such as long-time measure, high equipment cost. Here, we report the use of an electrochemical approach for analytical determination of Hg2+ ion that takes 120 s. The calibration curve was linear in the range of (0. 03 to 33. 0 nM). The current response was linearly proportional to the Hg2+ ion concentration with a R2~ 0. 999. We demonstrated a sensitivity a limit of detection of (0. 093 nM). Finally, Sensor nanosheets G-C3N4/CPE has been successfully applied for the determination of Hg2+ ion in different kind of water samples. The method introduced to measure Hg2+ ion in real samples such as water samples was used and can be used for other samples.

A fast, simple and sensitive Square-wave voltammetric (SWV) method for the determination of trace amounts of furazolidone (FZ) in urine is reported. A three-electrode system containing stationary mercury dropping (SMDE) working electrode, Pt auxiliary electrode and Ag/AgCl reference electrode was used throughout. Briton-Rabinson buffer solution is used as both pH adjusting agent and supporting electrolyte. The calibration graph showed good linearity in the concentration range of 20-900 ng ml-1 of furazolidone with a regression coefficient of 0.9996. The equation D(i) = 0.0095CFZ + 0.234 was used for calculation of furazolidone concentration in the sample solution, where CFZ is the concentration of furazolidone in ng ml-1 and D (i) is the difference between voltammogram peak currents of sample and blank solution. The RSD for 8 replicate measurements of a 60 ng ml-1 solution and LOD of the proposed method were found to be 2.2% and 5.2 ng ml-1, respectively. The procedure was successfully applied to the determination of furazolidone in urine samples.