Study Of Electrochemiluminescence In Metabolites Of Catecholamines

Electrochemiluminescence （also called electrogenerated chemiluminescence andabbreviated ECL） involves electrochemically generated intermediates at electrodesurfaces via an applied voltage that then undergoes a highly energeticelectron-transfer reaction. The reaction produces an electronically excited state andthen emits a photon of light when the excited molecule returned to the ground state.Ru（bpy）₃²⁺ECL has been widely used in biological analysis, clinical analysis,environmental analysis and food analysis because of its wide range of application,good ECL efficiency, high stability and reversible at electrode surfaces during theECL reaction. This thesis based on design and construction of an ECL detection cell,successfully established an ECL methods for the analysis of catecholaminemetabolites. The main contents are summarized as follows:1. Design and construction of an ECL detection cell. This detection cell wassimple construction, manufacture convenient, high universality and applicable to allkinds of conventional electrode （such as gold electrode, platinum electrode, glassycarbon electrode etc）; The working electrodes location was accurately controlled andeasily pulled out from the detection cell, which was helpful for treatment the detectioncell and electrode, meanwhile, it was to ensure good reproducibility of ECLmeasurement; The solution reservoir was small, which was helpful for decreasingconsumption of reagent, reducing cost of experiment and expanding range ofapplication.2. ECL of Ru（bpy）₃²⁺using metabolites of catecholamines: homovanillic acid（HVA） and vanillylmandelic acid （VMA） as co-reactants were investigated inaqueous solution for the first time. The formation of the excited state Ru（bpy）₃²⁺*wasconfirmed to result from the reaction between Ru（bpy）33+and the intermediates ofHVA or VMA radical. Meanwhile, it was found that the ECL intensity would bequenched significantly when the concentration of HVA and VMA were relativelyhigher. Therefor, the mechanism of self-quenching processes involved in theRu（bpy）₃²⁺/HVA and Ru（bpy）₃²⁺/VMA ECL systems are proposed in this study. 3. A novel method has been established for the analysis of HVA and VMA byECL of Ru（bpy）₃²⁺. Based on an available oxidant NaIO4to oxidative decarboxylationof-hydroxy acids and successfully inhibited the ECL intensity of VMA. Thereby wecan distinguish between these two structurally similar compounds. The linearcalibration range was from8.010-7to1.010-10mol/L for HVA and VMA. Thedetection limit （S/N=3） of the HVA and VMA was8.010-11mol/L. The resultsshowed that the proposed method was sensitive and selective for the determination ofHVA and VMA.