Study The Preconcentration And Two-dimentional Separation In Capillary Electrophoresis

Capillary electrophoresis (CE) possesses its advantages of high separation efficiency and fast analysis velocity, but it also has its disadvantages due to its small inner diameter, such as low sample loadability and poor detection sensitivity. To overcome these shortcomings, on-line preconcentration has bee studied; In addition, the peak capacity and resolve of one-dimentional capillary electrophoresis may be limited in the separation of complex samples, so two-dimentional capillary electrophoresis has been explored. The main results of this dissertation are as follows:1. A capillary electrophoresis and indirect detection method for the determination of inorganic anions in tobacco samples has been proposed. The separation voltage, modifier concentration of electroosmotic flow (EOF), background electrolytes and their concentration, and pH value of buffer solution have been investigated. It was found that the concentrations of background electrolytes influenced evidently on the effective mobilities of the inorganic anions. Under the specified conditions, six anions were completely separated within 10 min, the reproducibility (RSD) of migration time and peak height were in the range of 1.9～4.7 % and 1.2～3.8 %, respectively, and the detection limits were in the range of 0.2～0.8 mg/L. To evaluate the proposed method, it was successfully applied to analyze the inorganic anions in real tobacco samples.2. A dual and sequential electrostacking method based on anion-selective exhaustive injection (ASEI) and base stacking (BS) was developed for on-column concentration and separation of six inorganic anions with capillary zone electrophoresis (CZE). Tetradecyltrimethylammonium bromide (TTAB) as an EOF modifier, which can be dynamically adsorbed on the inner wall of separation capillary, was adopted to suppress EOF in the capillary. Before sample injection, a water plug was hydrodynamically injected into the capillary, which possesses three functions: (1) dissolving TTAB from the capillary inner wall and producing a negative zeta potential...