| As an important approach, high performance liquid chromatography (HPLC) -electrochemical detection (ED) has been used in the fields of chemistry, medicine, biology, environment and other sciences because of its effective separation, small injection volume and high sensitivity. In the 21st century, the research on life science is the most active. To realize the in vivo and on-line determination of biological micro-samples plays a critical role to the development of biology, medicine and to the life science, and the analysis of biological samples is the key point. HPLC-ED accommodates itself to this situation properly. However, the conventional HPLC-ED has its disadvantages, such as selectivity and sensitivity, etc. So, the development of high-quality HPLC-ED plays are of great value not only in analytical chemistry but also in biology, medicine and even in life science.In this dissertation, we laid our emphasis on the research of novel electrochemical detectors (ED), and established some new methods of sample, separation and analysis in life science by HPLC-ED coupled with samples treating measures, such as microdialysis sampling technique. Several kinds of chemically modified electrodes (CME) which could enhance the sensitivity and selectivity in the analysis of biological samples were developed and used as HPLC-ED. Nano material was applied in the HPLC-ED to enhance the sensitivity. The dissertation includes three parts, 1. In vivo determination of monoamine neurotransmitters in rat brain microdialysate by liquid chromatography with a thioctic/palladium-iridium oxide modified electrodeThe fabrication and application of a novel electrochemical detector (ED) with the thioctic/ palladium-iridium oxide modified electrode for liquid chromatography (LC) were described. The chemically modified electrode (CME) had a good catalytic effect on monoamine neurotransmitters and their metabolites. It was also found that the CME could be selective to dopamine (DA) cations and exile the ascorbic acid (AA) anions inrat brain. NE, E, DA, DOPAC, 5-HT in rat brain were also separated and determined effectively at the CME. Because the monoamine neurotransmitters are important substantial basis for physiologic activity and central nervous system, it is important to determine the monoamine neurotransmitters in vivo for cerebral physiology and neuroscience.2. Liquid chromatography with amperometric detection at a nanocrystalline Me-doped lead dioxide film modified electrode for determination of neurotransmitters and tetrahydrobioptrinSince the tetrahydrobioptrin was an important cofactor for neurosystem, a method of its sensitively detection are therefore important. In this paper, the fabrication and application of a novel electrochemical detector (ED) with nano crystalline Me-doped lead dioxide film chemically modified electrode (CME) for liquid chromatography (LC) were described. The Mn-doped PbOi film was characterized by scanning tunnel microscope (STM). It was found that the CME exhibited efficiently electrocatalytic effect on tetrahydrobioptrin and monoamine neurotransmitters. The application of this method coupled with microdialysis sampling for the determination of tetrahydrobioptrin and monoamine neurotransmitters hi rat brain was satisfactory.3. Liquid chromatography with amperometric detection using functionalized multi-wall carbon nanotubes modified electrode for simultaneous determination glutathione and glutathione disulfideGlutathione (GSH) and glutathione disulfide (GSSG) are important thiols to provide defense against oxidative stress by scavenging free radicals or causing the reduction of hydrogen peroxide. The ratio GSH/GSSG is often used as a sensitive index of oxidative stress in vivo. However, the major method of determination of them, fluorescence assay, was indirect and time consuming. In this paper, a direct electrochemical method was described by liquid chromatography (LC) coupling with electrochemical detector (ED) using an electrode modified with founctionalized carbon nan...
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