Study On Capillary Electrophoresis-Chemiluminescence Technique And Its Application

Capillary electrophoresis (CE) is characterized by remarkable separation efficiency, short analysis time, simple instrumentation, small sample consumption and low operational cost. Chemiluminescence (CL) is characteristic of high sensitivity, wide linear range and reduced background noise. Combination of CE-CL as a sensitive, selective separation and analytical method is an attractive research project. In this thesis, some new CE-CL systems were set up and applied for the analysis in real samples. The thesis consists of four chapters, and introduce as following.Chapter one:The characters of CE and CL were introduced, and the applications of CE-CL technique in environmental science, biological science and clinical science were summarized.Chapter two:A rapid and sensitive method for simultaneous determination of Co(Ⅱ) and Cu(Ⅱ) has been developed using a miniaturized capillary electrophoresis-chemiluminescence (MCE-CL) system. The MCE-CL conditions for on-line determination of Co(Ⅱ) and Cu(Ⅱ), such as H2O2 content, running buffer concentration, water plug length, sample injection time and voltage, were respectively investigated and optimized. Under the optimal conditions, the Co(Ⅱ) and Cu(Ⅱ) was separated in less than 200 s, and the detection limits (S/N=3) were 9.4×10-13 g/L for Co(Ⅱ) and 5.9×10-9 g/L for Cu(Ⅱ). This method is characteristic of rapid and sensitive, has successfully been applied to the determination of trace Co(Ⅱ) and Cu(Ⅱ) from E. rutaecarpa by standard additions.Chapter three:A rapid and sensitive method for simultaneous determination of rutin, chlorogenic acid and caffeic acid in Osmanthus fragrans has been developed by micellar electrokinetic chromatography (MEKC) with on-line CL detection. For high efficiency and good reproducibility, polyoxyethyl ene sorbitan monolaurate (Tween 20) as a buffer additive and the polyacrylamide (PAA) coated capillaries were adopted in experiment. Various parameters affecting MEKC separation and CL detection were optimized systematically. Under the optimum conditions, the CL intensity was linear with concentrations of rutin in the range of 1.0-150.0μg/mL, chlorogenic acid in the range of 2.0-200.0μg/mL, and caffeic acid in the range of 6.7-333.3μg/mL, respectively. The detection limits (S/N=3) in turn were 0.32μg/mL for rutin,0.48μg/mL for chlorogenic acid and 1.56μg/mL for caffeic acid with relative standard deviations of less than 3%. The proposed method was applied in Osmanthus fragrans sample, and the results were satisfactory.Chapter four:A quick and sensitive method for the detection of melamine in alkaline medium has been developed by capillary electrophoresis-chemiluminescence based on decreasing effect of melamine to luminal-potassium ferricyanide system. Under the optimum conditions, the CL signal was proportional to the concentration of melamine in the range of 0.5-100μg/L, and the detection limit (S/N=3) was 0.12μg/L. For the determination of 0.5μg/L melamine solution, the RSD is 1.97%(n=5). The proposed method was applied to the determination of melamine in spiked urine samples and the results were satisfactory.