Study On The Application Of CdTe Qds-Ru（bpy）₃²⁺ Electrochemiluminescence System In Analytical Chemistry

Electrochemiluminescence （ECL） detection technique takes advantagesincluding high-sensitivity, high-selectivity, excellent temporal and spatialcontrollability, and has been widely used in the field of analytical chemistry.ris（2,2’-bipyridyl） ruthenium（II）(Ru（bpy）₃²⁺) is widely used as ECL reagentsbecause of its high luminous efficiency, good water solubility, good chemical stabilityand reversible oxidation-reduction property. Quantum dots （QDs）, as a kind ofpotential luminescent reagents, possess good luminescent stability and highphotoluminescent efficiency. It is reported that some QDs could enhance the ECLintensity in different ECL systems. Capillary electrophoresis （CE） coupled with ECLdetection shows extensive application for the detection of pharmaceutical,environmental, food and biological samples since it combines high-efficiency of CEwith high-sensitivity of ECL.In this paper, CdTe QDs were synthesized and characterized, and then the effectof CdTe QDs on the cathodic ECL of Ru（bpy）₃²⁺was studied in detail. In addition, anew ECL method has been established for the determination of pyrocatechol based onthe cathodic electrochemiluminescence （ECL） of the Ru（bpy）₃²⁺-CdTe QDs system.On the other hand, a Ru（bpy）₃²⁺-based electrochemiluminescence （ECL） detectioncoupled with capillary electrophoresis （CE） has been developed for the determinationof oxycodone in rabbit plasma, using a chemically modified platinum electrode byeuropium （Ⅲ）-doped Prussian blue analogue film （Eu-PBAs） as a working electrode.The present work aims to extend the application of Ru（bpy）₃²⁺-based ECL methods,and to enlarge its application in environmental analysis particularly based on thedevelopment of ECL relating to quantum dots.This paper consists of four chapters:Chapter one ReviewThe electrochemiluminescence （ECL） technique, especially the basic principlesand applications of Ru（bpy）₃²⁺-based ECL are summarized first. The prospects ofECL is forecasted. Then the basic characteristics and ECL behavior of quantum dots （QDs） as well as its application in analytical chemistry field are reviewed. Finally, thebasic principles and theories of capillary electrophoresis （CE） are also introduced, andthe applications and prospects of CE-ECL methods are summarized as well. Totally131references are cited.Chapter two Enhancement of Ru（bpy）₃²⁺-based electrochemiluminescence onthe cathode by CdTe QDsCdTe Quantum Dots （QDs） capped with mercaptoacetic acid has beensuccessfully synthesized in aqueous phase. The effect of CdTe QDs on the cathodicelectrochemiluminescence （ECL） of Ru（bpy）₃²⁺was studied. The effects of severalparameters, such as acidity and concentration of phosphate buffer, concentration ofCdTe QDs and Ru（bpy）₃²⁺, and scan rate of the applied potential on ECL intensitywere investigated. Under the optimized conditions, the cathodic ECL intensity ofRu（bpy）₃²⁺in the mixture solution containing CdTe QDs was almost7times higherthan that of Ru（bpy）₃²⁺in the same solution, and was36times higher than that ofCdTe QDs in the same solution, respectively. The results suggested that the additionof CdTe QDs enhance significantly the cathodic ECL of Ru（bpy）₃²⁺.Chapter three Determination of pyrocatechol by cathodic electrochemilum-inescence of CdTe QDs-Ru（bpy）₃²⁺systemOn the basis of quenching effect of pyrocatechol on the cathodicelectrochemiluminescence （ECL） of the CdTe QDs-Ru（bpy）₃²⁺system, a new ECLmethod has been established for the determination of pyrocatechol. The effects ofseveral factors such as the acidity and concentration of buffer solution, concentrationof CdTe QDs and Ru（bpy）₃²⁺, scan rate and limit potential were investigated. Underthe optimized conditions, the logarithmic value of ECL intensity was in proportion tothe logarithmic value of the pyrocatechol concentration in range of7.0×10-8to4.0×10-5mol·L^-1with a detection limit （3σ） of2.3×10-8mol·L^-1. The relative standarddeviations of the ECL intensity was1.13%. The proposed method has beensuccessfully applied to determine pyrocatechol in simulated environmental watersamples, the recoveries of methods were between94.0%and105.4%. Chapter four Determination of oxycodone in rabbit plasma by capillaryelectrophoresis-electrochemiluminescenceA Ru（bpy）₃²⁺-based electrochemiluminescence （ECL） detection coupled withcapillary electrophoresis （CE） has been established for the determination ofoxycodone for the first time. A chemically modified platinum electrode by europium（Ⅲ）-doped Prussian blue analogue film （Eu-PBAs） was used as a working electrode.The effects of several parameters, such as detection potential, acidity andconcentration of running buffer, separation voltage, and injection conditions wereinvestigated for the improvement of separation ability and detection sensitivity. Underthe optimized conditions, oxycodone was separated within4min, and the ECLintensity was in proportion oxycodone concentration in range of7.0×10^-2to7.0μg/mL and7.0to70.0μg/mL with the detection limit （3σ） of4.2×10^-2μg/mL. Therelative standard deviations of ECL intensity and migration time were3.51%and0.48%, respectively （n=6）. The applicability of proposed method was illustrated forthe determination of oxycodone in rabbit plasma with recoveries between99.7%and101.0%.