Browsing by Author "El-Sayed Mohammed, Nancy"

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    Advanced electrochemical approaches for selective determination of selected drugs in different matrices
    (MSA university Faculty of pharmacy, 2020) Mohamed El-Saeed Saleh El-Zemaity, Mayar; Mahmoud Fathy, Nada; Maged Halim, Monica; El-Sayed Mohammed, Nancy
    Electrochemistry is a science that deals with different methods and techniques used in analytical chemistry by introducing and measuring the relationship between different phases that contain electrons and other phases that contain ions. The movement of those electrons from one element to other leads to the generation of electricity by a reaction called redox reaction. There are three main electrochemical methods including voltammetry, conductometry and potentiometry. Voltammetry is considered to be an approach of the electrochemical methods used in the analytical chemistry as it shows a lot of information about the analyte by measuring the relationship between voltage, current and time that arise in the cell. This cell consists of three electrodes which are counter electrode, working electrode and references electrode. There are many types of voltammetry that are classified according to the change in potential such as linear sweep voltammetry, staircase voltammetry, normal pulse voltammetry, deferential pulse voltammetry, square wave voltammetry and stripping voltammetry. Moreover, screen printed electrode is a modified type of carbon paste electrode. It is an appropriate technique because no complex or expensive tools are required, and printer operations are quick and fast. It was used for the determination of penciclovir and entecavir. The stock standard solutions of both drugs were prepared of concentration (1.0×10 −3 M). acetate buffer, phosphate buffer and working electrode were also prepared. Positive increase in the electric current by increasing the voltage was found which indicated the oxidation process for both penciclovir and entecavir. After the determination of optimization factors, it was found that penciclovir followed diffusion phenomena. While entecavir was found to follow adsorption with diffusion phenomena. Furthermore, the most suitable pH for the determination of penciclovir and entecavir were found to be 5 and 8 respectively where the highest current occurred. Carbon Paste Electrode (CPE) was constructed to optimize the voltametric determination of both drugs. The test of three screen printed electrodes were done in order to test for the analysis of both drugs which are screen-printed multi-walled carbon nanotube electrode (SMWCNTE), Screen-printed Nano Platine Electrode (SNPE) and Screen-printed Nano Gold Electrode (SNGE).