emad.newair

Dr. Emad F. Newair

Professor - Analytical Chemistry & Director of the Measurement and Evaluation Center

Faculty of science

Address: Sohag University

126

Like
2022 | Keywords Oxidation Mechanism,
Identification of adducts between oxidized rosmarinic acid and glutathione compounds by electrochemistry, liquid chromatography and mass spectrometry
Natural polyphenols are omnipresent and are an integral part of the human diet as well as quinones. Glutathione (GSH) is present in a significant amount inside cells and consequently, GSH conjugates of polyphenols will be encountered in the body. In the current work, voltammetry and liquid chromatography–mass spectrometry were carried out to characterize the reaction mechanism of the electrochemical oxidation ... Read more

Mechanistic Pathways and Identification of the Electrochemically Generated Oxidation Products of Flavonoid Eriodictyol in the Presence of Glutathione
The metabolic oxidation pathways of dietary flavonoid eriodictyol (Er) are not very well-probed. In the present work, the electrochemical oxidation behavior of Er was studied in aqueous Britton-Robinson (B-R) buffer solution using cyclic voltammetry (CV), chronoamperometry (CA), and bulk-electrolysis (BE). The oxidation products and reaction pathways of Er in the absence and the presence of glutathione (GSH) were proposed and ... Read more

Square wave voltammetric analysis of polyphenol content and antioxidant capacity of red wines using glassy carbon and disposable carbon nanotubes modified screen-printed electrodes
The polyphenols present in different French red wines were characterized electrochemically using square wave voltammetry (SWV). The voltammetric measurements were carried out using a glassy carbon electrode and disposable screen-printed carbon electrodes unmodified and modified with single- and multi-walled carbon nanotubes. The single-walled carbon nanotubes-modified screen-printed carbon electrode (SWCNTs-SPCE) showed the best results for the voltammetric analysis of polyphenols in ... Read more

Electrochemical Determination of the Antioxidant Activity in Echinacea Purpurea Roots Using Square Wave Voltammetry
A simple and rapid electrochemical method was established to quantify the total polyphenol (TP) content and assess their antioxidant activity (AA) in roots of three _Echinacea purpurea_ (_E. purpurea_) species using square wave voltammetry (SWV). Individual polyphenol components were identified, and then quantified by ultra‐high performance liquid chromatography coupled with mass spectrometery (UPLC‐MS). Two major polyphenols, chicoric (ChA) and caftaric ... Read more

Mechanism of Chicoric Acid Electrochemical Oxidation and Identification of Oxidation Products by Liquid Chromatography and Mass Spectrometry
Electrochemical oxidation of chicoric acid (ChA) was investigated using cyclic voltammetry and chronoamperometry at a glassy carbon electrode. Chicoric acid generates single quasi‐reversible redox wave in cyclic voltammetry over a wide pH range, and an ECEC‐dimerization mechanism is proposed. Effect of glutathione (GSH) on the electrochemical oxidation of chicoric acid (ChA) was investigated in Britton−Robinson buffer solution. Ultra‐high performance liquid ... Read more

Voltammetric determination of polyphenolic content in pomegranate juice using a poly (gallic acid)/multiwalled carbon nanotube modified electrode
A simple and sensitive poly(gallic acid)/multiwalled carbon nanotube modified glassy carbon electrode (PGA/MWCNT/GCE) electrochemical sensor was prepared for direct determination of the total phenolic content (TPC) as gallic acid equivalent. The GCE working electrode was electrochemically modified and characterized using scanning electron microscope (SEM), cyclic voltammetry (CV), chronoamperometry and chronocoulometry. It was found that gallic acid (GA) exhibits a superior ... Read more

Electroanalytical Determination of Luteolin in Peanut Hulls Using Carbon Black Modified Glassy Carbon Electrode
The main objective of this research was to develop a simple and sensitive electrochemical method for determination of trace-level of luteolin using vulcan carbon black (VCB) modified glassy carbon electrode (GCE). Compared with the bare GCE, the VCB/GCE exhibits higher electrocatalytic ability toward luteolin oxidation. This is due to the large surface-to-volume ratio of the carbon black together with the ... Read more

Voltammetric Determination of Ferulic Acid Using Polypyrrole-Multiwalled Carbon Nanotubes Modified Electrode with Sample Application
A polypyrrole-multiwalled carbon nanotubes modified glassy carbon electrode-based sensor was devised for determination of ferulic acid (FA). The fabricated sensor was prepared electrochemically using cyclic voltammetry (CV) and characterized using CV and scanning electron microscope (SEM). The electrode shows an excellent electrochemical catalytic activity towards FA oxidation. Under optimal conditions, the anodic peak current correlates linearly to the FA concentration ... Read more

Adsorptive Stripping Voltammetric Determination of Gallic Acid Using an Electrochemical Sensor Based on Polyepinephrine/glassy Carbon Electrode and its Determination in Black Tea Sample
An efficient adsorptive stripping voltammetric (AdSV) method for determination of gallic acid, GA, was developed by using an electrochemical sensor based on polyepinephrine/glassy carbon electrode, PEP/GCE. Modification of GCE with PEP was done by electropolymersation of epinephrine, EP, in 0.2 M phosphate buffer solution using cyclic voltammetry, cv. A well-defined redox cv wave of epinephrine in potential range of -0.10 ... Read more

2013 | Keywords Caffeic acid, Biosensor, Damage, Protection,
Electrochemical behavior of antioxidants: Part 3. Electrochemical studies of caffeic Acid–DNA interaction and DNA/carbon nanotube biosensor for DNA damage and protection
Multi-walled carbon nanotubes-modified glassy carbon electrode biosensor was used for electrochemical studies of caffeic acid–dsDNA interaction in phosphate buffer solution at pH 2.12. Caffeic acid, CAF, shows a well-defined cyclic voltammetric wave. Its anodic peak current decreases and the peak potential shifts positively on the addition of dsDNA. This behavior was ascribed to an interaction of CAF with dsDNA giving ... Read more