scholarly journals Electrochemical reduction of artemisinin: Chromatographic identification of bulk electrolysis products

2019 ◽  
Vol 9 (3) ◽  
pp. 165-174 ◽  
Author(s):  
Faraja Ombwayo ◽  
Zahilis Mazzhichette ◽  
Amos Mugweru
Keyword(s):  
Cyclic Voltammetry ◽  
Sesquiterpene Lactone ◽  
Electrode Surface ◽  
Reference Electrode ◽  
Carbon Electrode ◽  
Naturally Occurring ◽  
Bulk Electrolysis ◽  
Electrolysis Products ◽  
Peroxide Bond ◽  
Prominent Peak

Artemisinin is a naturally occurring sesquiterpene lactone with an endo-peroxide bond. This drug is used for treatment of many diseases including malaria. The reduction of this molecule on an electrode surface was carried out by cyclic voltammetry as well as amperometry. Cyclic voltammetry of artemisinin generated one prominent peak wave at -1.0 V and another, smaller one at -0.3 V vs Ag/AgCl reference electrode. The bulk electrolysis of artemisinin on a carbon electrode generated two other irreversible peak waves at around -0.7 and -0.1 V. The concentration of the products was dependent on the time of electrolysis. LC-MS was used to determine the bulk electrolysis products of artemisinin. Initially dihydroartemisinin was generated as the main reduction product. Other reduction products were formed after further reduction of dyhidroartemisinin.

scholarly journals Investigation of Electrochemical Behaviour of Quercetin on the Modified Electrode Surfaces with Procaine and Aminophenyl in Non-Aquous Medium

2008 ◽  
Vol 5 (3) ◽  
pp. 539-550 ◽  
Author(s):  
Ibrahim Ender Mulazimoglu ◽  
Erdal Ozkan
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Glassy Carbon ◽  
Electrode Surface ◽  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Carbon Electrode ◽  
Amine Group ◽  
Tetrabutylammonium Tetrafluoroborate

In this study, cyclic voltammetry and electrochemical ımpedance spectroscopy have been used to investigate the electrochemical behaviour of quercetin (3,3′,4′,5,7-pentahydroxyflavone) on the procaine and aminophenyl modified electrode. The modification of procaine and aminophenyl binded electrode surface with quercetin was performed in +0,3/+2,8 V (for procaine) and +0,4/+1,5 V (for aminophenyl) potential range using 100 mV s-1scanning rate having 10 cycle. A solution of 0.1 M tetrabutylammonium tetrafluoroborate in acetonitrile was used as a non-aquous solvent. For the modification process a solution of 1 mM quercetin in 0.1 M tetrabutylammonium tetrafluoroborate was used. In order to obtain these two surface, a solution of 1 mM procaine and 1 mM nitrophenyl diazonium salt in 0.1 M tetrabutylammonium tetrafluoroborate was used. By using these solutions bare glassy carbon electrode surface was modified. Nitrophenyl was reduced to amine group in 0.1 M HCl medium on the nitrophenyl modified glassy carbon elelctrode surface. Procaine modified glassy carbon electrode surface was quite electroactive. Although nitrophenyl modified glassy carbon elelctrode surface was electroinactive, it was activated by reducing nitro group into amine group. For the characterization of the modified surface 1 mM ferrocene in 0.1 M tetrabutylammonium tetrafluoroborate for cyclic voltammetry and 1 mM ferricyanide/ferrocyanide (1:1) mixture in 0,1 M KCl for electrochemical impedance spectroscopy were used.

THE DEVELOPMENT OF GLUCOSE SENSOR BASED ON SiO2-CuO MATERIALS USING SCREEN PRINTED CARBON ELECTRODE (SPCE)

2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Intan Frina Utamiyanti
Keyword(s):  
Cyclic Voltammetry ◽  
Glucose Sensor ◽  
Reference Electrode ◽  
Synthesis Process ◽  
Potential Range ◽  
Carbon Electrode ◽  
Screen Printed Carbon Electrode ◽  
Cyclic Voltammetry Method ◽  
Cyclic Voltammetry Analysis ◽  
Screen Printed

<p>The development of material-based glucose sensor SiO<sub>2</sub>-CuO using Screen Printed Carbon Electrode (SPCE) had been done. Three types of materials were used to detect glucose, i.e Multi Wall Carbon Nanotube (MWCNT)-SiO2-CuO, SiO2-CuO (A) dan SiO2-CuO (B). The differences composition of SiO<sub>2</sub>-CuO(A) and SiO<sub>2</sub>-CuO(B) occurred during the addition of NaOH in synthesis process of SiO2-CuO (B). The prepared materials were analyzed by Scanning Electron Microscopy (SEM), cyclic voltammetry method and chrono-amperometry. Cyclic voltammetry analysis was conducted at a potential range of -1.0 - 1.5 V with Ag/AgCl as reference electrode. The scan rate was 100 mV/sec and the potential was varied at (-0.6), (-0.5) and (-0.4) V, in which the duration of each analysis was 5 second. Based on the result of analysis, whether by SEM, cyclic voltammetry and chrono-amperometry, the SiO<sub>2</sub>-CuO (B) was found to be the best material for detection of glucose.</p>

Covalent grafting of three flavonoids onto the glassy carbon electrode surface by cyclic voltammetry

2011 ◽  
Vol 30 (3-4) ◽  
Author(s):  
Ïbrahim Ender Mülazımoğlu ◽  
Zafer Üstündağ ◽  
Erdal Özkan ◽  
Ali Osman Solak
Keyword(s):  
Cyclic Voltammetry ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Electrode Surface ◽  
Carbon Electrode ◽  
Covalent Grafting

scholarly journals THE DEVELOPMENT OF GLUCOSE SENSOR BASED ON SiO2-CuO MATERIALS USING SCREEN PRINTED CARBON ELECTRODE (SPCE)

2016 ◽  
Vol 12 (1) ◽  
pp. 50
Author(s):  
Intan Frina Utamiyanti ◽  
Barlah Rumhayati ◽  
Ani Mulyasuryani
Keyword(s):  
Cyclic Voltammetry ◽  
Glucose Sensor ◽  
Reference Electrode ◽  
Synthesis Process ◽  
Potential Range ◽  
Carbon Electrode ◽  
Screen Printed Carbon Electrode ◽  
Cyclic Voltammetry Method ◽  
Cyclic Voltammetry Analysis ◽  
Screen Printed

The development of material-based glucose sensor SiO<sub>2</sub>-CuO using Screen Printed Carbon Electrode (SPCE) had been done. Three types of materials were used to detect glucose, i.e Multi Wall Carbon Nanotube (MWCNT)-SiO2-CuO, SiO2-CuO (A) dan SiO2-CuO (B). The differences composition of SiO<sub>2</sub>-CuO(A) and SiO<sub>2</sub>-CuO(B) occurred during the addition of NaOH in synthesis process of SiO2-CuO (B). The prepared materials were analyzed by Scanning Electron Microscopy (SEM), cyclic voltammetry method and chrono-amperometry. Cyclic voltammetry analysis was conducted at a potential range of -1.0 - 1.5 V with Ag/AgCl as reference electrode. The scan rate was 100 mV/sec and the potential was varied at (-0.6), (-0.5) and (-0.4) V, in which the duration of each analysis was 5 second. Based on the result of analysis, whether by SEM, cyclic voltammetry and chrono-amperometry, the SiO<sub>2</sub>-CuO (B) was found to be the best material for detection of glucose.

scholarly journals Homogeneous electron-transfer of chlorophyll and its derivative chlorophyllin at gold electrode

2019 ◽  
Vol 7 (1) ◽  
pp. 1-17
Author(s):  
Alhasan H ◽  
Alahmadi N ◽  
Wadhawan J
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Electrode Surface ◽  
Gold Electrode ◽  
Reference Electrode ◽  
Surface Preparation ◽  
Active Species ◽  
Bulk Solution ◽  
Photovoltaic Properties ◽  
Working Electrode

Introduction: Chlorophyll is a light harvesting pigment, which absorbs light in the visible spectrum of sunlight and promotes electron transfer, Chlorophyllin (CHL) is One of the most important derivative molecules of chlorophyll. Nowadays, chlorophyll pigment and its derivatives are utilised in organic photosynthetic solar cells for their desirable photovoltaic properties. Cyclic voltammetry (CV) is an essential technique. It is extensively used to study electroactive species to interpret the intermediates of reactions, supply information about the thermodynamics of oxidation-reduction reactions and elucidate the kinetics of electron transfer reactions. Materials and Methods: Prior to the electrochemical study, the working gold (Au) electrode surface was prepared by immersing it in the various concentrations of chlorophyllin for a period time. The electrolyte was degassed by using N2 for approximately 30 minutes inside a Faraday cage before any electrochemical experiment was performed. A three electrode system was used with, Ag/AgCl as a reference electrode, graphiteas a counter and the working electrode (Au). Results and Discussion: As a route to develop new chemical systems for artificial photosynthesis, this work reports the effectiveness of different parameters in transferring electrons between chlorophyllin (CHL) pigment and the working electrode surface (gold). These parameters such as the adsorption time, the electrolyte nature and concentration and chlorophyllin concentration are investigated. The use of chlorophyllin as a redox mediator is examined, with a gold electrode being employed. The importance of gold electrode surface preparation in determining the mechanism of redox is described, and the environment of adsorption process of the different concentrations of chlorophyllin on the surface of the gold electrode has been elucidated in this study. Conclusiones: The electrochemical method showed that the cyclic voltammetry responses of studied adsorption chlorophyllin pigment on the gold electrode were more efficient. In addition, the redox reaction was successful electrochemically in aqueous solution thanthe organic solution. It was suggested that electrons reduce to the chlorophyllin pigment by adding active species in the bulk solution homogeneous transfer. Finally, detections of chl on spinach leaves using various methods are reported.

scholarly journals THE DEVELOPMENT OF GLUCOSE SENSOR BASED ON SiO2-CuO MATERIALS USING SCREEN PRINTED CARBON ELECTRODE (SPCE)

2016 ◽  
Vol 12 (1) ◽  
pp. 50
Author(s):  
Intan Frina Utamiyanti ◽  
Barlah Rumhayati ◽  
Ani Mulyasuryani
Keyword(s):  
Cyclic Voltammetry ◽  
Glucose Sensor ◽  
Reference Electrode ◽  
Synthesis Process ◽  
Potential Range ◽  
Carbon Electrode ◽  
Screen Printed Carbon Electrode ◽  
Cyclic Voltammetry Method ◽  
Cyclic Voltammetry Analysis ◽  
Screen Printed

The development of material-based glucose sensor SiO<sub>2</sub>-CuO using Screen Printed Carbon Electrode (SPCE) had been done. Three types of materials were used to detect glucose, i.e Multi Wall Carbon Nanotube (MWCNT)-SiO2-CuO, SiO2-CuO (A) dan SiO2-CuO (B). The differences composition of SiO<sub>2</sub>-CuO(A) and SiO<sub>2</sub>-CuO(B) occurred during the addition of NaOH in synthesis process of SiO2-CuO (B). The prepared materials were analyzed by Scanning Electron Microscopy (SEM), cyclic voltammetry method and chrono-amperometry. Cyclic voltammetry analysis was conducted at a potential range of -1.0 - 1.5 V with Ag/AgCl as reference electrode. The scan rate was 100 mV/sec and the potential was varied at (-0.6), (-0.5) and (-0.4) V, in which the duration of each analysis was 5 second. Based on the result of analysis, whether by SEM, cyclic voltammetry and chrono-amperometry, the SiO<sub>2</sub>-CuO (B) was found to be the best material for detection of glucose.

Solar Exfoliated Graphene Oxide: A Platform for Electrochemical Sensing of Epinephrine

2020 ◽  
Vol 16 (4) ◽  
pp. 393-403 ◽  
Author(s):  
Renjini Sadhana ◽  
Pinky Abraham ◽  
Anithakumary Vidyadharan
Keyword(s):  
Cyclic Voltammetry ◽  
Graphene Oxide ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Simultaneous Detection ◽  
Differential Pulse ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Reduced Graphene ◽  
Pulse Voltammetry

Introduction: In this study, solar exfoliated graphite oxide modified glassy carbon electrode was used for the anodic oxidation of epinephrine in a phosphate buffer medium at pH7. The modified electrode showed fast response and sensitivity towards Epinephrine Molecule (EP). The electrode was characterized electrochemically through Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). Area of the electrode enhanced three times during modification and studies reveal that the oxidation process of EP occurs by an adsorption controlled process involving two electrons. The results showed a detection limit of 0.50 ± 0.01μM with a linear range up to 100 μM. The rate constant calculated for the electron transfer reaction is 1.35 s-1. The electrode was effective for simultaneous detection of EP in the presence of Ascorbic Acid (AA) and Uric Acid (UA) with well-resolved signals. The sensitivity, selectivity and stability of the sensor were also confirmed. Methods: Glassy carbon electrode modified by reduced graphene oxide was used for the detection and quantification of epinephrine using cyclic voltammetry and differential pulse voltammetry. Results: The results showed an enhancement in the electrocatalytic oxidation of epinephrine due to the increase in the effective surface area of the modified electrode. The anodic transfer coefficient, detection limit and electron transfer rate constant of the reaction were also calculated. Conclusion: The paper reports the determination of epinephrine using reduced graphene oxide modified glassy carbon electrode through CV and DPV. The sensor exhibited excellent reproducibility and repeatability for the detection of epinephrine and also its simultaneous detection of ascorbic acid and uric acid, which coexist in the biological system.

Glassy carbon electrode activation – A way towards highly active, reproducible and stable electrode surface

2019 ◽  
Vol 299 ◽  
pp. 963-970 ◽  
Author(s):  
Tomas Bystron ◽  
Eva Sramkova ◽  
Filip Dvorak ◽  
Karel Bouzek
Keyword(s):  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Electrode Surface ◽  
Carbon Electrode ◽  
Highly Active

Electrode and cuvette for rapid continuous CO2 tension and pH measurement in blood

1985 ◽  
Vol 59 (5) ◽  
pp. 1660-1664
Author(s):  
S. A. Katz ◽  
A. C. Roth ◽  
E. O. Feigl
Keyword(s):  
Carbonic Anhydrase ◽  
Response Time ◽  
Electrode Surface ◽  
Porous Ceramic ◽  
Reference Electrode ◽  
Silicone Membrane ◽  
Dimethyl Silicone ◽  
Glass Ph Electrode ◽  
Co2 Electrode ◽  
Ph Electrode

An electrode and cuvette system has been developed for the continuous and rapid measurement of either blood CO2 tension or pH. The CO2 electrode consists of a 1.5-mm-diameter flat-tip glass pH electrode covered by a film of carbonic anhydrase solution, over which a 25-micron-thick dimethyl silicone membrane is attached. Porous ceramic filled with 20% polyacrylamide, equilibrated with a salt solution, serves as a salt bridge between a Ag-AgCl reference electrode and the pH electrode surface. The electrode is housed in a four-port cuvette assembly. Blood from a vessel of interest is delivered to the cuvette by means of an occlusive roller pump. The cuvette maintains the electrode and blood at a constant temperature and directs a continuous jet of blood against the electrode surface. The cuvette also allows for easy and frequent calibration of the electrode with either gas or liquid standards. The 90% response time of the CO2 electrode is 3.0 s for liquids and 1.3 s for gases. Removal of the dimethyl silicone membrane and carbonic anhydrase film yields a pH electrode that can continuously measure blood pH with a 90% response time of 1.6 s.

Biological Multilayer Films Assembled by Redox Polymer and HRP on Screen-Printed Carbon Electrode

2012 ◽  
Vol 571 ◽  
pp. 56-59
Author(s):  
Yu Fang Sha ◽  
Mei Zhao ◽  
Ming Quan Yang ◽  
Hai Xin Bai ◽  
Man Zhao
Keyword(s):  
Horseradish Peroxidase ◽  
Electrostatic Interaction ◽  
Electrode Surface ◽  
Multilayer Films ◽  
Carbon Electrode ◽  
Layer By Layer ◽  
Redox Polymer ◽  
Screen Printed Carbon Electrode ◽  
Positively Charged ◽  
Screen Printed

Biological multilayer films of redox polymer and horseradish peroxidase (HRP) were successfully assembled on a screen-printed carbon electrode using layer-by-layer (LBL) assembled method based on the electrostatic interaction. The screen-printed carbon electrode surface was modified by the positively charged redox polymer, and the negatively charged HRP by LBL method.

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