New PGE Modified Electrode Comprising Ni NPs/1,5-Diphenylcarbazide Film Capable for Analyzing Oxytocin

2020 ◽  
Vol 18 (11) ◽  
pp. 793-800
Author(s):  
Mahsa JaFari-Pouyani ◽  
Samineh Kaki ◽  
Arash Babakhanian
Keyword(s):  
Cyclic Voltammetry ◽  
Linear Response ◽  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Nano Particles ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Microscopy Techniques ◽  
Bare Surface ◽  
Human Blood Serum Sample

This study focuses on the compatibility of square wave voltammetry technique with new modified graphite pencil electrode to quantify Oxytocin. Ni-Nano particles and 1,5-diphenylcarbazide modifiers were quickly electro-deposited by cyclic voltammetry sweeping technique on the bare surface of a graphite pencil electrode. The electrochemical and morphological assessments were accomplished with cyclic voltammetry, square wave voltammetry and scanning electron microscopy techniques. The proposed electrochemical sensor revealed a good electro catalytic response to Oxytocin concerning the parameters α = 0.42, log Ks =3.44 and Γ = 8.72×10−10 in the optimized pH of 4 and the working potential of about 0.35 V. The new sensor also exhibited a linear response to Oxytocin over the concentration range of 125 to 350 nmolL−1 with the limit of detection of 41.53 nmolL−1. Moreover, the applicability of the proposed sensor was successfully examined and it became usable to determine Oxytocin accurately and precisely in real samples such as human blood serum sample without any serious side interference.

scholarly journals Cyclic and square-wave voltammetry for selective simultaneous NO and O<sub>2</sub> gas detection by means of solid electrolyte sensors

2020 ◽  
Vol 9 (2) ◽  
pp. 355-362
Author(s):  
Anastasiya Ruchets ◽  
Nils Donker ◽  
Jens Zosel ◽  
Daniela Schönauer-Kamin ◽  
Ralf Moos ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Solid Electrolyte ◽  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Inert Gases ◽  
Cyclic Voltammograms ◽  
Square Wave ◽  
Temperature Range ◽  
Wave Voltammetry ◽  
Scan Rate

Abstract. Solid electrolyte gas sensors (SESs) based on yttria-stabilized zirconia (YSZ) are suitable to detect traces of redox components in inert gases. Usually, their signals are generated as a voltage between two electrodes at open circuit potential or as a current flowing between constantly polarized electrodes. In these rather stationary modes of operation, SESs often lack the desired selectivity. This drawback can be circumvented if SESs are operated in dynamic electrochemical modes that utilize the differences of electrode kinetics for single components to distinguish between them. Accordingly, this contribution is directed to the investigation of cyclic voltammetry and square-wave voltammetry as methods to improve the selectivity of SESs. For this, a commercial SES of the type “sample gas, Pt|YSZ|Pt, air” was exposed to mixtures containing NO and O2 in N2 in the temperature range between 550 and 750 ∘C. On cyclic voltammograms (CVs), NO-related peaks occur in the cathodic direction at polarization voltages between −0.3 and −0.6 V at scan rates between 100 and 2000 mV s−1 and temperatures between 550 and 750 ∘C. Their heights depend on the NO concentration, on the temperature and on the scan rate, providing a lower limit of detection below 10 ppmv, with the highest sensitivity at 700 ∘C. The O2-related peaks, appearing also in the cathodic direction between −0.1 and −0.3 V at scan rates between 100 and 5000 mV s−1, are well separated from the NO-related peaks if the scan rate does not exceed 2000 mV s−1. Square-wave voltammograms (SWVs) obtained at a pulse frequency of 5 Hz, pulses of 0.1 mV and steps of 5 mV in the polarization range from 0 to −0.6 V also exhibit NO-related peaks at polarization voltages between −0.3 and −0.45 V compared to the Pt–air (platinum–air) electrode. In the temperature range between 650 and 750 ∘C the highest NO sensitivity was found at 700 ∘C. O2-related peaks arise in the cathodic direction between −0.12 and −0.16 V, increase with temperature and do not depend on the concentration of NO. Since capacitive currents are suppressed with square-wave voltammetry, this method provides improved selectivity. In contrast to cyclic voltammetry, a third peak was found with square-wave voltammetry at −0.48 V and a temperature of 750 ∘C. This peak does not depend on the NO concentration. It is assumed that this peak is due to the depletion of an oxide layer on the electrode surface. The results prove the selective detection of NO and O2 with SESs operated with both cyclic voltammetry and square-wave voltammetry.

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.

1,2-Dicyanoferrocene: synthesis and characterization

2016 ◽  
Vol 94 (6) ◽  
pp. 547-551 ◽  
Author(s):  
Mohammad A. Abdulmalic ◽  
Steve W. Lehrich ◽  
Heinrich Lang ◽  
Tobias Rüffer
Keyword(s):  
Cyclic Voltammetry ◽  
Solid State ◽  
Single Crystal ◽  
Square Wave Voltammetry ◽  
Molecular Structures ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Convenient Synthesis

A convenient synthesis of 1,2-dicyanoferrocene (3) was developed by using 2,4-dinitrofluorobenzene as a dehydrating agent for the treatment of 1,2-ferrocenedicarbaldehyde dioxime (2) to give 3 in yields exceeding 80%. Compounds 2 and 3 have been characterized by IR and NMR (1H, 13C{1H}) spectroscopy and by electrochemistry (cyclic voltammetry and square-wave voltammetry). Furthermore, the molecular structures of 2 and 3 in the solid state have been determined by single-crystal X-ray crystallographic studies.

Synthesis and characterization of novel conducting homopolymers based on amino β-styryl terthiophene

2008 ◽  
Vol 86 (11) ◽  
pp. 1010-1018 ◽  
Author(s):  
Hakim Mehenni ◽  
Lê H Dao
Keyword(s):  
Cyclic Voltammetry ◽  
Photoelectron Spectroscopy ◽  
Square Wave Voltammetry ◽  
Covalent Bonding ◽  
Modified Glassy Carbon Electrode ◽  
X Ray ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Amine Groups

Novel ECPs (electronic conducting polymers) based on amino β-styryl-substituted terthiophene (AST) were synthetized by direct electropolymerization. The ECPs were characterized by cyclic voltammetry, square-wave voltammetry, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The poly(amino β-styryl terthiophene) displayed cyclic and square-wave voltammograms with redox peaks that can be assigned to the aminophenyl moiety and the polyterthiophene backbone. The presence of free primary amine groups on the ECP film permitted further biological functionalization (i.e., covalent bonding of various bioreceptors on its surface). The electrochemical performance of Biotin grafted at the AST modified glassy carbon electrode was investigated to detect the Avidin protein in solution by cyclic voltammetry and square-wave voltammetry.Key words: electronic conducting polymer, electrode surface modification, biosensor, β-styryl-substitued terthiophene, functionalization, cyclic, square-wave voltammetry.

Simultaneous Determination of Amlodipine and Irbesartan in Their Pharmaceutical Formulations by Square-Wave Voltammetry

2021 ◽  
Vol 24 ◽  
Author(s):  
İsmail Murat Palabıyık ◽  
Aysegul Dogan ◽  
İncilay Süslü
Keyword(s):  
Simultaneous Determination ◽  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Pharmaceutical Formulations ◽  
Amlodipine Besylate ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Limit Of Quantitation ◽  
Active Substances

Background: Hypertension is one of the most important health problems in the world and irbesartan and amlodipine are used in combination in various dosages for the treatment of high blood pressure. Objective: The aim of this study is to develop a fast, easy, sensitive, accurate, and precise square-wave voltammetry method for simultaneous determination of irbesartan and amlodipine besylate from pharmaceutical formulations at a hanging mercury drop electrode. Methods: In the applied method, since both active substances gave a peak at different potentials, no interference occurred between them. In optimization studies Britton-Robinson buffer of pH 8.0 was chosen, in which the most appropriate peak shape and maximum peak current were observed. At the same time, as a result of instrumental parameter optimization to obtain reproducible results, 6 mV for scan increment, 30 mV for pulse amplitude, and 50 Hz for frequency were found suitable. Results: As a result of the calibration studies of the optimized method, linear working ranges were determined as 1.00-13.08 µg mL-1 for irbesartan and 5.83-16.51 µg mL-1 for amlodipine besylate. Limit of detection and limit of quantitation values were respectively calculated as 0.63 and 1.00 µg mL-1 for irbesartan and 0.50 and 1.98 µg mL-1 for amlodipine besylate. The results of precision values (RSD) ranged from 0.67% to 2.31% for irbesartan and 0.65% to 1.49% for amlodipine besylate. Accuracy values were calculated as -0.15% to 1.63% for irbesartan and -0.07% to 3.78% for amlodipine besylate. The results obtained from the recovery studies ranged from 101.05% to 102.78% and from 98.88% to 102.20% for amlodipine besylate and irbesartan, respectively. Conclusion: After the validation studies of the developed method were carried out, it was successfully applied to pharmaceutical formulations containing these active substances.

scholarly journals The Study of a New Method to Determine Copper Ion by Square-Wave Voltammetry-Extraction Iodometry at the Liquid/Liquid Interfaces

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Changyan Shi ◽  
Shaoai Xie ◽  
Jinping Jia
Keyword(s):  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Copper Ion ◽  
New Method ◽  
Limiting Current ◽  
Square Wave ◽  
Indirect Determination ◽  
Wave Voltammetry ◽  
Simulated Wastewater

A new method of indirect determination ofCu2+was developed based on square-wave voltammetry by the oxidation of iodide in organic solvent at the liquid/liquid (L/L) interface. The limit of detection for the determination ofCu2+in this method was found to be5×10−4 mol/L, and the concentration ranged up to1×10−2 mol/L gave a linear limiting current versus concentration response. For the same simulated wastewater, this method showed high accuracy compared with the result tested by sodium diethyldithiocarbamate extraction spectrophotometry. This approach could be applied to the indirect determination of the oxidative heavy metals in the industrial wastewater.

scholarly journals Determination of hydroquinone in a square wave voltammetry procedure using a graphite-polyurethane composite electrode

2006 ◽  
Vol 31 (4) ◽  
pp. 59-62 ◽  
Author(s):  
P. Cervini ◽  
E.T.G. Cavalheiro
Keyword(s):  
Confidence Level ◽  
Square Wave Voltammetry ◽  
Composite Electrode ◽  
Limit Of Detection ◽  
Voltammetric Sensor ◽  
Square Wave ◽  
Polyurethane Composite ◽  
Wave Voltammetry

In order to a better characterization of a graphite-polyurethane composite intended to be used as a voltammetric sensor, the performance in a square wave voltammetric procedure was investigated. Using hydroquinone (HQ) as a probe, the electrode showed to be useful in square wave voltammetry with limit of detection of 0.28 µmol L-1, with recoveries between 99.1 and 101.5%. The results of the proposed method agreed with HPLC ones within 95% confidence level.

Riboflavin detection by α-Fe2O3/MWCNT/AuNPs-based composite and a study of the interaction of riboflavin with DNA

RSC Advances ◽  
2015 ◽  
Vol 5 (23) ◽  
pp. 17888-17896 ◽  
Author(s):  
C. Sumathi ◽  
P. Muthukumaran ◽  
S. Radhakrishnan ◽  
G. Ravi ◽  
J. Wilson
Keyword(s):  
Cyclic Voltammetry ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Electrochemical Behavior ◽  
Square Wave Voltammetry ◽  
Carbon Electrode ◽  
Square Wave ◽  
Wave Voltammetry

The electrochemical behavior of riboflavin (RF) at a glassy carbon electrode modified with α-Fe2O3/MWCNT/AuNPs was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV).

scholarly journals A simple and fast method to detect freebase cocaine in artificial saliva by square wave voltammetry (SWV) using carbon paste electrode

2020 ◽  
Vol 10 (4) ◽  
pp. 361-371
Author(s):  
Bruno Ferreira ◽  
Leandro Oka Duarte ◽  
Érica Naomi Oiye ◽  
Maria Fernanda Muzetti Ribeiro ◽  
Juliana Midori Toia Katayama ◽  
...  
Keyword(s):  
Carbon Paste Electrode ◽  
Square Wave Voltammetry ◽  
Limit Of Detection ◽  
Artificial Saliva ◽  
Fast Method ◽  
Carbon Paste ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Analytical Curve ◽  
Paste Electrode

The consequences of consuming and commercializing illicit drugs including cocaine, con­stitute a serious problem for authorities and the whole society. Cocaine is usually identified in the laboratory conditions by chromatographic or spectroscopic methods. Electro­che­mical techniques have also gained prominence because they are fast and easy to use, have many applications, and provide reproducible and reliable results. Therefore, in the present study, a voltammetric method was developed to detect freebase cocaine using carbon paste electrode and methanol as the main cocaine solvent. The developed method was applied to detect cocaine in the artificial saliva by the square wave voltammetry (SWV). The current values increased linearly with the concentration of cocaine, which afforded construction of the analytical curve. The limit of detection (LoD) and the limit of quantify­cation (LoQ) were determined as 0.90 µg/mL and 2.41 µg/mL, respectively. For compa­rison purposes, HPLC-DAD chromatographic method was also applied to detect cocaine. The corresponding analytical curve gave LoD = 0.043 µg/mL and LoQ = 0.130 µg/mL. Although showing better analytical results, HPLC-DAD method could not detect cocaine in saliva samples without previous treatment, what makes the electrochemical method much more attractive for this type of detection.

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