Study On The New Characteristics And Analytical Applications Of Some Electrochemiluminescence Systems

Electrochemiluminescence (ECL) is a new analytical technique, which is developed based on the combination of electrochemistry with chemiluminescence. It not only has high sensitivity, but also is easier to control the process of chemiluminescence by adjusting the potentials. Therefore, it has been attracted by more and more chemists.ECL measures relative dynamic luminescence and electrochemical parameters during the process of electrochemical reaction. There are many factors, which would affect the result of measurement, and the preconditions of analytical application can be optimized to improve the selectivity and reliability of the method. Though combining flow injection analysis (FIA) with ECL redounds to reproducibility and relative easiness to be automatically controlled, it is not propitious to biological and pharmic applications due to the sample volumes and reagent consumption. Therefore, the study was focus on static ECL in the whole thesis.In addition, although many people have studied ECL and found some ECL active compounds, such as tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)32+], lucigenin and luminol, the mechanisms of many ECL systems are still unclear and the analytical applications are limited. In this thesis, the new ECL behaviors of Ru(bpy)32+ and lucigenin systems and their applications in analytical practice were investigated by using differential pulse voltammetry (DPV), respectively. Apart from which, we also did some work to explore a new ECL label for biomacromolecules.This thesis consists of five Chapters. In Chapter 1, the general introduction, the historical perspective of ECL, classifications and mechanisms of ECL, analytical applications of ECL, developing direction of ECL and the purpose and signification of this thesis were described.In Chapter 2, ECL of Ru(bpy)32+ produced by DPV was studied in detail. In the presence of the nonionic surfactant, Triton X-100, the ECL efficiency was increasedgreatly and three ECL waves at 0.7V, 0.95V and 1.5V were firstly observed at glassy carbon electrode by DPV. According to abundant experiments of electrochemistry and ECL emission spectrum, the possible mechanisms for ECL waves at 0.7V, 0.95V and 1.5V were proposed respectively. Furthermore, hydrogen peroxide was found to inhibit this ECL system. Therefore, the ECL system is likely to be developed a sensitive method for determination of hydrogen peroxide.In Chapter 3, the ECL of lucigenin system was studied by using the anodic potential sweep in detail and epinephrine was found to be able to enhance the ECL strongly. Based on which, a novel ECL method for the determination of epinephrine was developed. The method was successfully applied to the determination of epinephrine in pharmaceutical samples with satisfactory results. In addition, the possible mechanism for the ECL generated by lucigenin during the anodic potential sweep and the effect factors for the enhancement of the ECL were also discussed.In Chapter 4, several hydroxyanthraquinones, such as Emodin, Rhein and Physcion which were the major active constituents of Rhubard, an important Chinese traditional medicine, were found to be able to enhance the ECL of the lucigenin system strongly by using DPV. The enhanced chemiluminescence intensity was linear with the concentration of rhein, emodin and physcion. Additionally, the possible mechanism for enhancement of lucigenin ECL system by hydroxyanthraquinones was also discussed.In Chapter 5, the tetra-substituted sulphonated cobalt(â…¡) phthalocyanine (CoS4Pc) acting as a mimetic peroxidase of horseradish peroxidase was found to be able to catalyze the electrochemiluminescence (ECL) reaction of luminol-H2O2 at a glass carbon electrode. CoS4Pc also retained its ECL catalytic activity when it was conjugated to BSA. Moreover, the enhanced ECL intensity of the luminol-H2O2 system at pH 7.4 was proportional to the amount of target bovine serum albumin (BSA). Therefore, a novel quantitative method for determination of protein by using CoS4Pc as an ECL probe has been developed, and the...