Nourddine Ajermoun1, Abdelfattah Farahi2, Sara Lahrich1, Mina Bakasse3, Sana Saqrane1, Moulay Abderrahim El Mhammedi1. 1. Univ. Sultan moulay slimane, Laboratoire de Chimie et Modélisation Mathématique, Faculté Polydisciplinaire, Khouribga, Morocco. 2. Univ Chouaib Doukkali, Equipe d'Analyse des Micropolluants Organiques, Faculté des Sciences,Morocco to Univ Chouaib Doukkali, Equipe d'Analyse desMicropolluants Organiques, Faculté des Sciences, Eljadida, Morocco. 3. Univ Chouaib Doukkali, Equipe d'Analyse des Micropolluants Organiques, Faculté des Sciences, Eljadida, Morocco.
Abstract
BACKGROUND: Thiamethoxam (3-[(2-chloro-5-thiazolyl)methyl]tetrahydro-5-methyl-N-nitro-4H-1,3,5-oxadiazin-4-imine) belongs to a relatively new class of insecticides known as neonicotinoids, which can block irreversibly nicotinic acetylcholine receptors of the nervous system of insects. Its determination at trace levels is an acute analytical problem. Therefore, chromatography, spectroscopy, and electrochemical technics were reported. These last have several advantages (simple sensitive and less expensive). This work investigated the electro-reduction of Thiamethoxam using simple and rapid method in real samples using metallic silver electrode. RESULTS: Silver particles, known as effective catalysts in the reduction of nitro groups, were studied to explore their roles in the shift of thiamethoxam peak potential. Cyclic voltammetry, Tafel plot and electrochemical impedance spectroscopy analysis suggest that metallic silver electrodes have a significantly greater electrocatalytic activity in thiamethoxam electroreduction than glassy carbon electrodes and carbon paste electrodes. The electrocatalytic activity of metallic silver electrodes in thiamethoxam reduction was investigated by cyclic voltammetry and chronoamperometry. A linear variation in cathodic current with the square root of the scan rate was observed, suggesting that the process is diffusion controlled. Several supporting electrolytes were tested, and the best results were obtained with Britton-Robinson (BR) buffer, pH 10.4. A linear relationship between peak current and concentration was found in the range from 1.0 × 10-5 to 1.0 × 10-4 mol L-1 using square wave voltammetry (SWV) with a correlation coefficient of 0.994. The detection limit and quantification limit were 5.49 × 10-6 and 1.83 × 10-5 mol L-1 , respectively. CONCLUSION: Silve metallic electrode exhibits efficient catalytic activity towards the Thiamethoxam reduction. The proposed electrode was then used for the determination of thiamethoxam in tomato anad orage juice samples.
BACKGROUND:Thiamethoxam (3-[(2-chloro-5-thiazolyl)methyl]tetrahydro-5-methyl-N-nitro-4H-1,3,5-oxadiazin-4-imine) belongs to a relatively new class of insecticides known as neonicotinoids, which can block irreversibly nicotinic acetylcholine receptors of the nervous system of insects. Its determination at trace levels is an acute analytical problem. Therefore, chromatography, spectroscopy, and electrochemical technics were reported. These last have several advantages (simple sensitive and less expensive). This work investigated the electro-reduction of Thiamethoxam using simple and rapid method in real samples using metallic silver electrode. RESULTS:Silver particles, known as effective catalysts in the reduction of nitro groups, were studied to explore their roles in the shift of thiamethoxam peak potential. Cyclic voltammetry, Tafel plot and electrochemical impedance spectroscopy analysis suggest that metallic silver electrodes have a significantly greater electrocatalytic activity in thiamethoxam electroreduction than glassy carbon electrodes and carbon paste electrodes. The electrocatalytic activity of metallic silver electrodes in thiamethoxam reduction was investigated by cyclic voltammetry and chronoamperometry. A linear variation in cathodic current with the square root of the scan rate was observed, suggesting that the process is diffusion controlled. Several supporting electrolytes were tested, and the best results were obtained with Britton-Robinson (BR) buffer, pH 10.4. A linear relationship between peak current and concentration was found in the range from 1.0 × 10-5 to 1.0 × 10-4 mol L-1 using square wave voltammetry (SWV) with a correlation coefficient of 0.994. The detection limit and quantification limit were 5.49 × 10-6 and 1.83 × 10-5 mol L-1 , respectively. CONCLUSION: Silve metallic electrode exhibits efficient catalytic activity towards the Thiamethoxam reduction. The proposed electrode was then used for the determination of thiamethoxam in tomato anad orage juice samples.