Development And Application Of New Capillary Eletrophoresis-Chemiluminescence System

Since the1980s, capillary electrophoresis(CE) has been developed into one of the most effective analytical separation techniques. Due to its high separation efficiency, fast analysis, less sample consumption, easy to realize automation, simple operation, less environmental pollution, CE has been widely used in almost all of the analytical chemistry such as environmental analysis, pharmaceutical analysis, food analysis, biological and chemical analysis, etc. Due to high sensitivity, wide linear range, fast analysis speed and simple equipment, Chemiluminescence(CL) method has been widely used in the field of inorganic metal, biological active substances, etc. Any substances which can influence chemiluminescence reaction, such as light intensity, wavelength and rate of reaction can be a chemiluminescence analysis object. Hence capillary electrophoresis-chemiluminescence detection has been widely flourishing in analytical chemistry.Based on the relative chemiluminescence reaction of luminol, this paper attempted to establish a new CE-CL detection system, find ultra-fast CL reaction process, make the static reaction pool as a convenient and effective way of CE-CL interface and extend the application of CE-CL technology. We successfully realized the indirect CE-CL determination of saccharides and phenol compounds, and had a deeper comprehension on the chemiluminescence reaction mechanism of luminol and the catalytic properties of hemin. The paper was composed of four chapters as following:Chapter one was the introduction. The process of development separation principle、separation models and the detection methods were overviewed briefly. Then the theories and characters of CL、the usual CL reaction systems the kinds of CE-CL interfaces and the application and the developing tendency were summarized simply. The purpose and meaning of this paper were also introduced here.In chapter two, based on the luminol-KIO4-K3Fe(CN)6reaction system, the static reaction cell interface mode were built and used to the indirect CE-CL determination of saccharides. In alkaline solution, with proper concentration of K3Fe(CN)6as catalyst and KIO4as oxidant, this system could give a strong CL signal and ba accomplished in0.65s, which make the CE-CL detection system perform efficiently in a static reaction cell. Based on this CE-CL system, we found saccharides produced negative signals in the CE-CL baseline of luminol and finished the indirect CE-CL determination of rhamnose, D-fructose, sucrose and β-cyclodextrin, which have good sensitivities, repeatabilities and linear ranges. As a novel analysis method for carbohydrates, it could be used to complete rapid determination for mono-, di-and oligo-saccharides, which developed new application area of CE-CL detection method and provided a new approach for the simplify and micromation of CE-CL detection device.In chapter three, based on the CE-CL static reaction cell built in the last chapter, the indirect CE-CL determination of carbohydrates was deeper investigated. Used the mixed liquor of α-、β-、γ-CDs as test sample, the efficiency of this CE-CL method for the determination of oligosaccharides was investigated. And this system was used to determine the cyclodextrin additives in a real sample. We observed the effects of the concentration of the alkaline and dimethylsulfoxide (DMSO) in separation electrolyte on the separation and detection of saccharides and give the appropriate reasons. We found increasing the concentration of DMSO would make the CE-CL process more stable and the separation efficiency better, but the baseline would be weaker and the electrophoresis time be longer. So we increased the baseline by increasing the separation voltage. When the separation voltage increased to24kV, the three CDs could be separated and determined in24min with40%DMSO in separation electrolyte. The LOD for α-、β-、 γ-CD were6.0×10-5mol/L、6.5×10-5mol/L、5.5x10-5mol/L respectively. This method also determined the content of the cyclodextrin additives in wax gourd tee drink, which confirmed the practical value of the method.In chapter four, the catalytic charaters of hemin as a CL catalyst and its potential application in CE-CL detection were explored. Based on the establishment of luminol-H2O2-hemin CL system, we realized the indirect determination of phenols. First we investigated the catalytic charaters of hemin on luminol-H2O2with static injection tests. We found hemin has the best catalytic ability in neutral solution and halide ions, such as Br, F could further enhance the CL signal catalyzed by hemin. But as the self-polymerization of hemin, it’s different to couple this CL system with CE. Though many further jobs, we found when we added high concentration of NH3-H2O into separation electrolyte, the self-polymerization of hemin was restrained effectively and the CE-CL baseline was stable. Based on this system, we realized the indirect CE-CL determination of five phenols and given the luminescent mechanism of the system. Under optimum conditions, the five phenols could be separated and determined in15min with LODs between4.8×10-8mol/L and7.1×10-8mol/L. And we think the negative signals of phenols were attributed to the displacement of luminol by phenols in CE process.