The adsorptive and electrochemical behaviour of phoxim on a hanging mercury drop electrode were explored in NH3·H2O-NH4Cl buffer by using cyclic and linear sweep voltmmetry. The procedure was successfully applied...The adsorptive and electrochemical behaviour of phoxim on a hanging mercury drop electrode were explored in NH3·H2O-NH4Cl buffer by using cyclic and linear sweep voltmmetry. The procedure was successfully applied for the assay of phoxim in vegetable and fruit samples.展开更多
The presence of the pesticide ethion was determined using an electroanalytical method, i. e. , linear sweep stripping voltammetry at a hanging mercury drop electrode in the Britton-Robbinson buffer with pH = 8. 36, ba...The presence of the pesticide ethion was determined using an electroanalytical method, i. e. , linear sweep stripping voltammetry at a hanging mercury drop electrode in the Britton-Robbinson buffer with pH = 8. 36, based on its reduction peak observed at - 690 mV following its alkaline hydrolysis. The experimental parameters, namely, the preconcentration potential, the preconcentration time, and the scan rate were investigated and - 300 mV （vs. Ag/ AgCl）, 270 s, and 100 mV/s were selected as the optimal values, respectively. The linear relationship between the peak current and the concentration was found to be in the range of 0.02-0. 16 mg/L, with a detection limit of 0.0087 mg/L. The proposed method was applied to the determination of ethion in spiked vegetable and fruit samples via a preextraction with anhydrous ethanol.展开更多
This paper reports the electrochemical properties of sulpiride at a mercury electrode, especially its adsorptive characteristic. Sulpiride dissolved in a supporting electrolyte of a McIlvaine buffer at pH 6 8 represe...This paper reports the electrochemical properties of sulpiride at a mercury electrode, especially its adsorptive characteristic. Sulpiride dissolved in a supporting electrolyte of a McIlvaine buffer at pH 6 8 represents a sensitive and well defined reduction wave by linear sweep stripping voltammetry. This method is based on the pre concentration and the reduction of sulpiride at a hung mercury drop electrode. The reduction peak potential is -1 72 V( vs . Ag AgCl) and the peak current is proportional to the concentration of sulpiride in the range of 0 1-0 6 μg/mL. The detection limit is 0 025 μg/mL obtained under the experimental conditions selected in this work. The electrochemical properties of this system were investigated, and the proposed method was applied to the determination of sulpiride in pharmaceutical tablets with satisfactory results. It was compared well with the UV spectrophotometric method, showing a superior sensitivity.展开更多
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
A stripping method for the determination of hypoxanthine in the presence of copper at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of hypoxanthine-copp...A stripping method for the determination of hypoxanthine in the presence of copper at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of hypoxanthine-copper at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10﹣3 mol·L﹣1 NaOH solution as electrolyte supporting, an accumulation potential of ﹣0.50 V and a linear scan rate of 200 mV·s﹣1. The response of hypoxanthine-copper is linear over the concentration ranges of 10 - 60 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 250 ppt (1.8 × 10﹣9 mol·L﹣1). Adequate conditions for measuring the hypoxanthine in the presence of metal ions, xanthine, uric acid and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of hypoxanthine associated in ATP or ssDNA.展开更多
基金the National Natural Science Foundation of China （No. 20365002, 20562009） the Natural Science of Jiangxi Province Foundation （No. 0320014） the foundation of the State Key Laboratories of Electroanalytical Chemistry of Changchun Applied Chemical Institute （No. SKLEAC2004-3） wen gratefully acknowledged.
文摘The adsorptive and electrochemical behaviour of phoxim on a hanging mercury drop electrode were explored in NH3·H2O-NH4Cl buffer by using cyclic and linear sweep voltmmetry. The procedure was successfully applied for the assay of phoxim in vegetable and fruit samples.
基金Supported by the National Natural Science Foundation of China(Nos. 20365002 and 20562009), the State Key Laboratory ofElectroanalytical Chemistry of Changchun Applied Chemistry Institute(No. 2004-3) and State Key Laboratory Chemo/Biosensing andChemometrics of Hunan University(No. 2005-22), the Jiangxi Provincial Natural Science Foundation(No. 0620041), and the Pro-gram for Changjiang Scholars and Innovative Research Team in Universities(No. 0540)
文摘The presence of the pesticide ethion was determined using an electroanalytical method, i. e. , linear sweep stripping voltammetry at a hanging mercury drop electrode in the Britton-Robbinson buffer with pH = 8. 36, based on its reduction peak observed at - 690 mV following its alkaline hydrolysis. The experimental parameters, namely, the preconcentration potential, the preconcentration time, and the scan rate were investigated and - 300 mV （vs. Ag/ AgCl）, 270 s, and 100 mV/s were selected as the optimal values, respectively. The linear relationship between the peak current and the concentration was found to be in the range of 0.02-0. 16 mg/L, with a detection limit of 0.0087 mg/L. The proposed method was applied to the determination of ethion in spiked vegetable and fruit samples via a preextraction with anhydrous ethanol.
基金Supported by the National Natural Science Foundation of China(No.2 0 0 6 5 0 0 1) the Jiangxi Province Natural ScienceFoundation(No.0 0 2 0 0 2 2 ) and the State Key L aboratory of Chemo/ Biosensing and Chemometrics of Hunan U niversity.
文摘This paper reports the electrochemical properties of sulpiride at a mercury electrode, especially its adsorptive characteristic. Sulpiride dissolved in a supporting electrolyte of a McIlvaine buffer at pH 6 8 represents a sensitive and well defined reduction wave by linear sweep stripping voltammetry. This method is based on the pre concentration and the reduction of sulpiride at a hung mercury drop electrode. The reduction peak potential is -1 72 V( vs . Ag AgCl) and the peak current is proportional to the concentration of sulpiride in the range of 0 1-0 6 μg/mL. The detection limit is 0 025 μg/mL obtained under the experimental conditions selected in this work. The electrochemical properties of this system were investigated, and the proposed method was applied to the determination of sulpiride in pharmaceutical tablets with satisfactory results. It was compared well with the UV spectrophotometric method, showing a superior sensitivity.
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A stripping method for the determination of hypoxanthine in the presence of copper at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of hypoxanthine-copper at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10﹣3 mol·L﹣1 NaOH solution as electrolyte supporting, an accumulation potential of ﹣0.50 V and a linear scan rate of 200 mV·s﹣1. The response of hypoxanthine-copper is linear over the concentration ranges of 10 - 60 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 250 ppt (1.8 × 10﹣9 mol·L﹣1). Adequate conditions for measuring the hypoxanthine in the presence of metal ions, xanthine, uric acid and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of hypoxanthine associated in ATP or ssDNA.
