Study On Electromigration Behavior In Capillary Electrophoresis And Determination Of Drugs Coupled With Contactless Conductivity Detection

Capillary Electrophoresis (CE) was a recently developed novel separation technology. Comparing to High Performance Liquid Chromatogragh (HPLC), CE is driven by electric field when the separation channel is capillary tube instead of chromatographic column. The basis of separation is due to the samples have different electrophoretic mobility. The superiority of CE is revealed in fast detection and less sample consumption than HPLC, which has been favored by more and more scientists. CE has been widely applied in plenty of fields like environmental pollution, food additive and nutrition, Chinese medicine, western medicine, medicinal properties, chemical composition of the body material and its physical and chemical constant. The diversification of detectors coupled to capillary electrophoresis which include UV-Vis, Mass spectrometry, Chemiluminescence, Fluorescence and Electrochemical detection is an important factor to promote its vigorous development. Capacitively coupled contactless conductivity detection (C4D) which belongs to the category of electrochemical detection is a new kind of detection technology developed in recent years. The major advantage of C4D is that the detection electrodes are placed side by side around the capillary, which can avoid electrodes contamination. Capillary electrophoresis with contactless conductivity detection technology will be discussed in four chapters.The first chapter is the introduction, in which the history of CE, separation principle, and the combination technology are introduced, as well as the development history of contactless conductivity, detection principle and application scope.In charpter Ⅱ, we built three theoretical models about electromigration by the use of CE-C4D. Firstly, the relationship between acidity, Zeta potential and electroosmotic flow was discussed, it was found that pH∝log ζ and pH∝log μeo. Secondly, the influence of metal ion concentration on Zeta potential and electroosmotic flow was elaborated. After doing the experiments, we got the results pM∝log ζ and pM∝logμeo Finally, we got pN∝logζ, pN∝logμeo when small neutral organic molecule additives were concerned. At the same time, we deduced that σ∝ζ∝μeo∝1/tCharpter Ⅲand Charpter IV focused on the application of CE on pharmaceutical field.In Chapter III, a method was validated and optimized to determine aminoglycoside antibiotics by CE-C4D. During the experiment, several important factors such as running buffer, sample injection time, separation voltage have been considered. In the buffer system of35mmol/L2-(N-Morphlino) ethanesulfonic acid (MES)/15mmol/L histidine (His), with17kV separation voltage,60V excitation voltage and600kHz excitation frequency, the optimal separation and detection were obtained. Under optimum experimental conditions, linear relationship was in the range from0.97～31.25mg/L. Meanwhile, this method can also be used to detect aminoglycoside antibiotics in urine samples.In Charpter IV, a new method has been established for simultaneous determination of Apomorphine hydrochloride, Galanthamine hydrobromide, Quetiapine fumarate and Clozapine in tablet by capillary electrophoresis with C4D. The experiment investigated the influence of different kinds and concentration of running buffer, separation voltage, injection time as well as additives. With optimized buffer of10mmol/L Tris-8mmol/L Cit-20%methanol, the samples were well separated and detected at the excitation voltage of60V and frequency of600kHz. Under optimum experimental conditions, linear relationship was in the range from0.97～15.6mg/L.