Analytical theory of the catalytic mechanism in square wave voltammetry at disc electrodes

2011 ◽  
Vol 13 (37) ◽  
pp. 16748 ◽  
Author(s):  
Angela Molina ◽  
Joaquín González ◽  
Eduardo Laborda ◽  
Yijun Wang ◽  
Richard G. Compton
Keyword(s):  
Square Wave Voltammetry ◽  
Catalytic Mechanism ◽  
Analytical Theory ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Disc Electrodes

Facile and Fast Detection of Genistein in Derris scandens by Square Wave Voltammetry using a Cobalt(II) Phthalocyanine-Modified Screen-Printed Electrochemical Sensor

2020 ◽  
Vol 16 (3) ◽  
pp. 341-348
Author(s):  
Surinya Traipop ◽  
Suchada Chuanuwatanakul ◽  
Orawon Chailapakul ◽  
Eakkasit Punrat
Keyword(s):  
Electrochemical Sensor ◽  
Square Wave Voltammetry ◽  
Silver Chloride ◽  
Reference Electrode ◽  
High Sensitivity ◽  
Plastic Substrate ◽  
Fast Analysis ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Screen Printed

Background: Recently, Derris scandens, a Thai herbal medicine with anti-inflammatory activity, is widely used as beverage and supplementary food. When the traditional medicine is a choice for health therapy, the simple and reliable equipment is required to control the suitable consuming amount of the active component. Objective: To develop the electrochemical sensor for genistein determination in Derris scandens with high sensitivity and rapid operation. Methods: An in-house screen-printed electrochemical sensor consisting of a three-electrode system was developed for genistein determination. A silver/silver chloride (Ag/AgCl) reference electrode, a carbon counter electrode and a carbon working electrode were prepared on a 0.3-mm-thick plastic substrate by the screen-printing technique using conductive ink. The dimensions of each sensor were 2.5×1.0 cm. Only 50 µL of sample solution was required on this device for the determination of genistein concentration by rapid response square wave voltammetry. Results: The oxidation peak of genistein appeared with good response in acidic media at a peak potential of 0.6 V. Moreover, the signal was enhanced by modifying the conductive carbon ink with cobalt( II) phthalocyanine. Under the optimized conditions, the linear range was found to be 2.5-150 µM and the detection limit was 1.5 µM. Moreover, the small volume extraction was successfully developed without any further pre-concentration. This proposed method was applied to determine genistein in Derris scandens with satisfying results. Conclusion: The proposed method is promising as an alternative method for genistein determination with facile and fast analysis.

Isopotential points in square-wave voltammetry of reversible electrode reactions

2009 ◽  
Vol 74 (10) ◽  
pp. 1489-1501 ◽  
Author(s):  
Marina Zelić ◽  
Milivoj Lovrić
Keyword(s):  
Square Wave Voltammetry ◽  
Electrode Reaction ◽  
Time Model ◽  
Model Calculations ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry ◽  
Electron Transfer Processes ◽  
Diagnostic Criterion ◽  
First Time

Isopotential points in square-wave voltammetry are described for the first time. Model calculations and real measurements (performed with UO22+ and Eu3+ in perchlorate and bromide solutions, respectively) indicate that such an intersection could be observed when backward components of the net response, resulting from an increase in frequency or reactant concentration, are presented together. The electrode reaction should be fully reversible because quasireversible or slower electron transfer processes give the isopoints only at increasing reactant concentrations but not at increasing square-wave frequencies. The effect could be used as an additional diagnostic criterion for recognition of reversible electrode reactions where products remain dissolved in the electrolyte solution.

scholarly journals Simultaneous Hydrolysis and Detection of Organophosphate by Benzimidazole Containing Ligand-Based Zinc(II) Complexes

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 714
Author(s):  
Gaber A. M. Mersal ◽  
Hamdy S. El-Sheshtawy ◽  
Mohammed A. Amin ◽  
Nasser Y. Mostafa ◽  
Amine Mezni ◽  
...  
Keyword(s):  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Organophosphorus Compounds ◽  
Organophosphorus Pesticides ◽  
Carbon Paste ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Carbon Past Electrode ◽  
Hydrolysis Of ◽  
Biomimetic Sensor

The agricultural use of organophosphorus pesticides is a widespread practice with significant advantages in crop health and product yield. An undesirable consequence is the contamination of soil and groundwater by these neurotoxins resulting from over application and run-off. Here, we design and synthesize the mononuclear zinc(II) complexes, namely, [Zn(AMB)2Cl](ClO4) 1 and [Zn(AMB)2(OH)](ClO4) 2 (AMB = 2-aminomethylbenzimidazole), as artificial catalysts inspired by phosphotriesterase (PTE) for the hydrolysis of organophosphorus compounds (OPs) and simultaneously detect the organophosphate pesticides such as fenitrothion and parathion. Spectral and DFT (B3LYP/Lanl2DZ) calculations revealed that complexes 1 and 2 have a square-pyramidal environment around zinc(II) centers with coordination chromophores of ZnN4Cl and ZnN4O, respectively. Both 1 and 2 were used as a modifier in the construction of a biomimetic sensor for the determination of toxic OPs, fenitrothion and parathion, in phosphate buffer by square wave voltammetry. The hydrolysis of OPs using 1 or 2 generates p-nitrophenol, which is subsequently oxidized at the surface of the modified carbon past electrode. The catalytic activity of 2 was higher than 1, which is attributed to the higher electronegativity of the former. The oxidation peak potentials of p-nitrophenol were obtained at +0.97 V (vs. Ag/AgCl) using cyclic voltammetry (CV) and +0.88 V (vs. Ag/AgCl) using square wave voltammetry. Several parameters were investigated to evaluate the performance of the biomimetic sensor obtained after the incorporation of zinc(II) complex 1 and 2 on a carbon paste electrode (CPE). The calibration curve showed a linear response ranging between 1.0 μM (0.29 ppm) and 5.5 μM (1.6 ppm) for fenitrothion and 1.0 μM (0.28 ppm) and 0.1 μM (0.028 ppm) for parathion with a limit of detection (LOD) of 0.08 μM (0.022 ppm) and 0.51 μM (0.149 ppm) for fenitrothion and parathion, respectively. The obtained results clearly demonstrated that the CPE modified by 1 and 2 has a remarkable electrocatalytic activity towards the hydrolysis of OPs under optimal conditions.

Insights into the Voltammetry of Cavity Microelectrodes Filled with Metal Powders: The Value of Square Wave Voltammetry

2021 ◽  
Vol 8 (4) ◽  
pp. 735-744
Author(s):  
Encarnación Torralba ◽  
Eduardo Laborda ◽  
Angela Molina ◽  
Christine Cachet‐Vivier ◽  
Stéphane Bastide
Keyword(s):  
Square Wave Voltammetry ◽  
Metal Powders ◽  
Square Wave ◽  
Wave Voltammetry

scholarly journals Electrochemical Detection of Phenanthrene Using Nickel Oxide Doped PANI Nanofiber Based Modified Electrodes

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Omolola E. Fayemi ◽  
Abolanle S. Adekunle ◽  
Eno E. Ebenso
Keyword(s):  
Nickel Oxide ◽  
Square Wave Voltammetry ◽  
Modified Electrodes ◽  
Oxidation Potential ◽  
Current Response ◽  
Modified Glassy Carbon Electrode ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Doped Polyaniline ◽  
Uv Visible

A nickel oxide doped polyaniline nanofibers (PANI-NiO) based electrochemical sensor was constructed for detection of phenanthrene. Successful synthesis of PANI-NiO nanocomposite was confirmed with techniques such as SEM, XRD, EDX, FTIR, and UV-visible spectroscopy. The electrocatalytic oxidation of phenanthrene on PANI-NiO on modified glassy carbon electrode (GCE-PANI-NiO) was studied using cyclic voltammetry, square wave voltammetry, and impedance spectroscopy and discussed. Results showed that detection of phenanthrene was enhanced by the nanostructure of PANI-NiO film. The square wave voltammetry analysis shows a very low detection limit of 0.732 pM for phenanthrene with the linear range of 7.6 pM–1.4 × 10−11 M. The Tafel value of 227 mVdec−1suggests adsorption of phenanthrene oxidation intermediates on the GCE-PANI-NiO electrode. The GCE-PANI-NiO modified electrodes gave better performance towards phenanthrene in terms of current response, oxidation potential, current recovery, stability, and resistance to electrode fouling effects.

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