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The electrodes can be functionally designed in the molecular level and the fixation of electrochemical active molecules, ions, and polymers on the surfaces of electrodes can improve the selectivity and sensitivity of the modified electrodes. In this thesis, three kinds of chemically modified electrodes have been developed for the detection of water content in organic solvents and saccharide contents. The main points of this thesis are summarized as follows:1. Based on the electrochemical deposition method, a chemically modified electrode based on PAH-Fe(CN)64" films was developed for the detection of trace water in CH3CN. With the chemically modified electrode, it was found that its current responses were linear to trace water content which was over 0.3% in acetonitrile and the limit of detection(LOD, S/N=3) was 0.068%.2. A microgap impedance sensor was developed for the determination of trace water in organic solvents by polymer coating method. Under optimized conditions, the linear range for the determination of trace water was 0-0.06% for chloroform (CHCl3),0-0.1% for acetone (CH3COCH3),0-0.12% for tetrahydrofuran (THF), and 0-0.10%for acetonitrile (CH3CN), and the detection limits were 0.65,1.54,0.61, and 1.72 ppm, respectively.3. Based on the self-assembly method, a boric acid modified gold electrode was developed for the determination of saccharides. The electrochemical characteristics of the sensor were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The linear range was 0-10-5μM and the detection limits were 3.3×10-7 M (Glucose),2.4×10-7 M (Fructose),1.7×10-7 M (Galactose),8.5×10-7 M (Mannose). The binding constants were 3.02×106 M-1 for Glucose,2.63×106 M-1 for Fructose,1.24×106 M-1 for Galactose, and 1.03×106 M-1 for Mannose, respectively.4. With the electrochemical method coupled with fluorescence microscopy, the fluorescence intensity of pyrene compounds on the surface of ITO electrode has been successfully modulated. According to PET (Photoinduced Electron Transfer) principle, fluorescent molecules will release the electrons when their fluorophores are excited by specific wavelengths of light. As a result, by applying positive/negative potentials, the process of electron transfer from excited fluorescence molecules to the gold nanocores can be inhibited/promoted to modulate the fluorescence intensity.
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