This study presents the elaboration of a simple and cheap electrode made by carbon paste introduced into a cavity of electrode body, and used for the lead traces determination in tap water. A potentiostatic pre-electr...This study presents the elaboration of a simple and cheap electrode made by carbon paste introduced into a cavity of electrode body, and used for the lead traces determination in tap water. A potentiostatic pre-electrolysis at constant voltage enables the reduction of the lead (Pb2+) and the accumulation of the metallic lead at and into the carbon paste;the reoxidation of the Pb (Linear sweep voltammetry) leads to the anodic striping peak. The effect of the main operating parameters on the shape of the peak and the magnitude of the current was examined and their optimal values were determined. Then calibration was achieved and the method was successfully applied (using all the optimized parameters) to the determination of lead in water, with a detection limit of 0.138 μg·L-1. Compared to other methods (ICP-AES for example), the proposed method offers a satisfactory detection limit of the Pb2+ (0.138 μg·L-1) because of the important specific area of the carbon paste electrode, for a significantly lower cost. Besides, there is no observed loss in the electrode answer in terms of peak current, which means that there is no any irreversible steps nor deactivation of the electrode, even after ten successive measurements;only reduction of the lead followed by the deposit oxidation was observed at the electrode.展开更多
Structural analogues of bicyclic peroxides belonging to the G factors family have been synthesised under Mannieh type conditions, followed by an autoxidation step furnishing exclusively the peroxide. As electron trans...Structural analogues of bicyclic peroxides belonging to the G factors family have been synthesised under Mannieh type conditions, followed by an autoxidation step furnishing exclusively the peroxide. As electron transfer from heine or free iron to peroxide is the first step in the mode of action ofartemisinin -like compound, Fe（fl） induced reduction was studied and the reactivity of the intermediate C-centered radical formed was correlated to the antimalarial activity. Dissociative electron transfer was studied by electrochemistry and allowed the evaluation of the standard reduction potentials and other pertinent thermochemical information. These bicyclic peroxides were evaluated in vitro against Plasmodium falciparum and revealed moderate to good activity.展开更多
文摘This study presents the elaboration of a simple and cheap electrode made by carbon paste introduced into a cavity of electrode body, and used for the lead traces determination in tap water. A potentiostatic pre-electrolysis at constant voltage enables the reduction of the lead (Pb2+) and the accumulation of the metallic lead at and into the carbon paste;the reoxidation of the Pb (Linear sweep voltammetry) leads to the anodic striping peak. The effect of the main operating parameters on the shape of the peak and the magnitude of the current was examined and their optimal values were determined. Then calibration was achieved and the method was successfully applied (using all the optimized parameters) to the determination of lead in water, with a detection limit of 0.138 μg·L-1. Compared to other methods (ICP-AES for example), the proposed method offers a satisfactory detection limit of the Pb2+ (0.138 μg·L-1) because of the important specific area of the carbon paste electrode, for a significantly lower cost. Besides, there is no observed loss in the electrode answer in terms of peak current, which means that there is no any irreversible steps nor deactivation of the electrode, even after ten successive measurements;only reduction of the lead followed by the deposit oxidation was observed at the electrode.
文摘Structural analogues of bicyclic peroxides belonging to the G factors family have been synthesised under Mannieh type conditions, followed by an autoxidation step furnishing exclusively the peroxide. As electron transfer from heine or free iron to peroxide is the first step in the mode of action ofartemisinin -like compound, Fe（fl） induced reduction was studied and the reactivity of the intermediate C-centered radical formed was correlated to the antimalarial activity. Dissociative electron transfer was studied by electrochemistry and allowed the evaluation of the standard reduction potentials and other pertinent thermochemical information. These bicyclic peroxides were evaluated in vitro against Plasmodium falciparum and revealed moderate to good activity.
