Palladium Nanoparticles Modified Micro Electrode In The Application Of Capillary Electrophoresis

Capillary electrophoresis is a powerful liquid phase separation technique owingto its high separation speed, good stability and reproducibility, low volume ofinstrumention needed. Capillary electrophoresis with electrochemical detection(CE-ECD) has already been applied to electro-active species owing to its highersensitivity and selectivity. CE-ECD has flourished in wide areas such as analyticalchemistry, pharmaceutical analysis, food analysis, environmental analysis and almostall the analysis field. In recent years, along with the development and application ofnanomaterials, nanoparticles as representative of the new modified electrodes inanalytical chemistry caused the development of the electricity workers’ attention.Nanoparticles can improve electron transfer rate of the modified electrodes, and thusimprove the electrical conductivity of the electrode, the sensitivity and lowerdetection limit.In this thesis, two kinds of Pd nanoparticles modified microelectrodes weredescribed for the direct quantification of dopamine and glucose by capillaryelectrophoresis with electrochemical detection. The methods have been successfullyapplied to the analysis of single cells.In the first chapter, the principle of CE was described. Applications in theanalytical chemistry, pharmaceutical analysis, food analysis and analysis of single cellwere reviewed. Finally, the applications of chemical modified microelectrodes usedwith CE-ECD and palladium (Pd) nanoparticles modified electrode, were reviewed indetail.In the second chapter, dopamine (DA) is one of the excitatory neurotransmittersthat play a crucial role in the functioning of central nervous, renal and hormonalsystems. Abnormal levels of DA are associated with neurological disorders such asParkinson’s, Schizophrenia. Therefore, one of the main tasks of neurochemistry is thedevelopment of a simple and quick method for dopamine detection and determination.A simple method was described for the direct quantification of DA by capillaryelectrophoresis with amperometric detection at palladium nanoparticles modified carbon fiber microdisk electrode (PdNPs-CFME) and the detection conditions wereoptimized. PdNPs-CFME had high catalytic ability for dopamine. The experimentalresult illustrated that the PdNPs-CFME has the properties of good reproducibility andstability, high sensitivity and rapid response to the determination of dopamine. Theexperiment showed that interfering species such as tryptophane, uric acid andL-cysteine did not interfere with the determination of dopamine. The method has beensuccessfully applied to the determination of DA in single pheochromocytoma cell.In the third chapter, the sensitive, simple-make electrochemical glucosebiosensor was based on the immobilization of single walled carbonnanotubes–glucose oxidase biocomposite at palladium nanoparticles modified Ptmicroelectrode. The experimental result illustrated that the biosensor has theproperties of good reproducibility and stability, high sensitivity and rapid response tothe determination of glucose. We developed a novel method for the determination ofglucose based on capillary electrophoresis coupled with novel glucose biosensor. Thedetection conditions were optimized including detection potential, separation potential,the concentration and pH value of phosphate buffer etc. Compared with the previousreported method, the biosensor exhibited good stability and durability in the analyticalprocedures. The method has been successfully applied to the determination of glucosein single human stomach cancer cells.