Electrochemical Behavior And Determination Of Environmental Estrogen On Modified Carbon Pasteelectrode

In this thesis,functional nanomaterials were modified onto carbon paste electrodes by using the doping method.It embodies the electrochemical catalysis function and the solid phase micro-extraction function applied to the electrocatalysis and detection of environmental pollutants.The carbon paste electrode was modified with polyvinylpyrrolidone,cobalt chloride nanoparticles and iron hydroxide nanoparticles as the main catalytic material.The environmental estrogen?diethylstilbestrol,estradiol,ethinyl estradiol?is then electrocatalyzed and electroanalyzed.And discuss this new approach.1.The electrochemical behavior of diethylstilbestrol was investigated on polyvinylpyrrolidone/cobalt chloride modified carbon paste electrode and the environmental water samples were determined.Cyclic voltammetry with solid-phase microextraction was used to investigate the enrichment behavior of diethylstilbestrol on PVP/Co²⁺modified carbon paste electrode.The results so that PVP/Co²⁺modified electrode can increase the oxidation peak current of diethylstilbestrol significantly to compared with the bare carbon paste electrode.The oxidation peak current increased linearly with the increase of sweep rate,indicating that the oxidation reaction was controlled by surface adsorption.The linear relationship between the oxidation peak current and the logarithm of diethylstilbestrol concentration in the range of 6×10^-92×10^-5mol·L^-1 could be used to determine the concentration of diethylstilbestrol with the detection limit of 6×10^-9mol·L^-1.The relative standard deviation was 4.17%for 1×10^-5mol·L^-1 diethylstilbestrol.A satisfactory results were obtained when the new method was used to measure diethylstilbestrol in the water sample.2.The electrochemical behavior of ethinylestnadiol was investigated on Fe?OH?₃modified carbon paste electrode.The environmental water sample were measured by the method.The enrichment behavior of ethinylestnadiol on ferric hydroxide colloidal particles modified carbon paste electrode was investigated by cyclic voltammetry with solid-phase microextraction.Compared with the bare carbon paste electrode,the iron hydroxide modified electrode increased the oxidation peak current of ethinylestradiol by a factor of seven.The reaction follows the law of solid phase microextraction.Under the optimal experimental conditions,the linear relationship between the oxidation peak current and the logarithm of ethinylestradiol concentration in the range of 1×10^-65×10^-5mol·L^-1 could be used to determine the concentration of ethinylestradiol with the detection limit of 8×10^-7mol·L^-1.The relative standard deviation was 2.57%for1×10^-5mol·L^-1 ethinylestradiol.The modified electrode has a good enrichment and extraction effect on ethinylestradiol,and the method for determining the environmental water sample can obtain satisfactory results.3.The modified electrode was further used in the study of electrochemical behavior of Environmental estrogen estradiol.The electrochemical behavior of estradiol was investigated on Fe?OH?₃ modified carbon paste electrode.The environmental water sample and the estradiol tablet content were measured by the method.The reaction also conforms to the solid phase microextraction law.At the modified carbon paste electrode,estradiol shows an electrochemical catalytic oxidation with oxidation peak potentials negatively shifted about 37mV,and peak current increase tripled compared with unmodified CPE.Under the optimal experimental conditions,the linear relationship between the oxidation peak current and the logarithm of estradiol concentration in the range of 8×10^-73×10^-5mol·L^-1 could be used to determine the concentration of estradiol with the detection limit of 5×10^-7mol·L^-1.The relative standard deviation was2.11%for 1×10^-5mol·L^-1 estradiol.The ferric hydroxide colloidal particles modified carbon paste electrode exhibits strong electrocatalytic activity toward the oxidation of estradiol.It can be applied to determine the content of estradiol tablets and the results were in consistency with the labelled values.