Electrogenerated Reductant Chemiluminescence Analysis

Two parts, review and research report, are included in this thesis. The recentdeve1opment of electrochemiluminescence(electrogenerated chemiluminescence, ECL)and its applications in analytical chemistry before 2000 are reviewed. The researchreport is mainly studied on Chemiluminescence reaction of luminol withelectrogenerated reducing agents.The phenomenon of ECL was first observed by Harvey at 1929. Since then, greatinterests dressed in this system. But only during l980s, it was being studied anddeveloped as a new tool in analytical chendstry ECL is a technique by which achemiluminescence reacion is produced at or near an electrode surface byelectrochemically generating species capable of forming exited states. The first ECLreactions involved electron transfer between electrogenerated radical cation (oxidized)and radical anion (reduced) forms of a parent species in self-annihilation reaotions toform exited states. Alternative1y ECL can be generaed by the reaction between theoxidized or reduced forms of a parent species and a coreactant (e.g., C₂O₄^2-, S₂O₈^2-),upon oxidation or reduction, can undergo a chemical reaction to form strong reducingor oxidizing agents capable of undergoing highly energetic electron-transfer reactionsto form exited states.There are only four main ECL systems that have been investigated in any detailalthough the ECL of many compoiunds has been reported. The first of them is based onthe DPA direct reaction. The second is on the luminol direct and indirect reaction inalkaline solution. The third concerns the investigation of the ECL reaction ofruthenium (Ⅱ) tris(2,2'-bipyridine). The forth is the cathodic ECL at disposableokide-covered electrode.ECL has three boortant advantages over conventional CL. First, the reaction ofECL iS easily regulated and manipulated by the electrode POtential. Secondly, the1uminescence is 1Ocalized on the electrode surface, which allows the design of anefficient measurement system. Thirdly, luminescence is electrochendcally genefated insitu whhout any contMion due to addition of analytical reagents.ECL has become increasingly attractthe for the detection of numerous chemicaland biolOgical molecules, and many of its known applications luve been reviewed.And noW it has been aPplied successfully to many fields, such as life science, clinicalmedicine, bounoassays, DNA probe analysis, surface analysis, electron transferresearch, and environmnt analysiS.A highly selective flow injection e lectro chemi lumine scence methO d fo rdetennination of vanadium, molybdenum and uranium has been established in thispaPer. It was based on the chemiluIninescence reaction of luxninol with vanadium(II ),molybdenum(IIl) and uranium(III), which were on line electrogenerated using theflow-through carbon electrolytic cell. The CL reaction of e1ectrogenerated reducingagents with luInjnol probably performed as fOllows: electrogenerated reducing agentsreduced dissolved oxygen to superoxide anion radical (O2-') in alkaline solution. Thenproduced O2-. oxidised luIninl, producing CL. The linear range of the methOd was5.0x 10-lo-1 .0x l0-'g Inl-l for vMiuIn, 2.0x 10-,-l .0x l0' g tnll fOr molybdenum and1.5 X 10-s--2.0X 10-'g ml-l for urhaum The detectiOn limit was 2x10lo g ndl forvanadinm, 9x it-8 g nil-l for molybdenum and 7 X 104 g rnl-l fOr uranha. The methodwas aPplied to detennination of vanadiuIn, molybdenum and uraniUm inenvironmntal water samPles whh a satisfaCtory result.