Capillary Electrophoresis With Amperometric Detection And Its Application

Capillary electrophoresis (CE) is a new-style separation and analysis technique which is established and quickly developed in the early 1980's. Capillary electrophoresis has the advantages of high separation efficiency, analysis speed, high sensitivity, small amount of sample and easy automation. Nowadays, capillary electrophoresis has been widely used in the fields of food sanitation, agriculture, clinical medicine, pharmaceutical analysis, environment analysis, biochemistry analysis and so on. People have been concerned about sample preparation and improved sensitivity. In this thesis, these two issues are researched. On the one hand, a simple pretreatment method is estabilish. The dialysis membrane is made by phase-inversion process in the inlet end of the separation capillary, which achieve dialysis membrane in the column associated with the use of capillary electrophoresis. On the other hand, this paper improve the detection sensitivity of capillary electrophoresis by multi-walled carbon nanotube modified electrode and the field amplification enrichment technology to meet the analysis of trace samples. The contents of this dissertation include four chapters:Chapter 1. PrefaceFirst, the paper describes the historical development of capillary electrophoresis, the basic principle of separation modes, the detection and application of technology . Second, the paper introduce the microdialysis sampling technique, multi-wall carbon nanotubes modified electrode, the principle of capillary electrophoresis method for enrichment and other related knowledge.Chapter 2. Polysulfone membrane dialysis sampling system and performance evaluation of capillary electrophoresisCapillary electrophoresis combined with microdialysis sampling technique, the dialysis membrane is made by phase-inversion process in the inlet end of the separation capillary, which achieve dialysis membrane in the column associated with the use of capillary electrophoresis. This part investigate and optimize the production of membrane materials and processes with Dopamine. The ability of membrane cutting off macromolecules and particles is also assayed qualitatively. The membrane purification ability of the samples, the impact of membrane on electrophoresis, the membrane stability and reproducibility are evaluated. The method is simple, low cost, small die interface and the capillary can be directly used in this sample of complex samples by capillary electrophoresis without complicating sample pretreatment steps.Chapter 3. Preparation of nano-components of micro-electrode and the applications in capillary electrophoresisThe preparation of multi-walled carbon nanotubes/carbon fibre modified electrode is carried out by chemical adsorption. The efficiency of the electrode is evaluated, which is better than carbon fiber electrode in stability and reproducibility. The sensitivity is obviously improved. The electrode is used in the capillary electrophoresis to separate and determine sulphadiazine, trimethoprim and sulfamethoxazole. In this study, the prepared method of carbon nanotubes modified electrode has not been reported. The surface of carbon fiber microelectrode adsorbes carbon nanotubes directly. The operation is very simple. The detection sensitivity is effectively improved and well.Chapter 4. Multi-walled carbon nanotube modified electrode and field amplifier technology combined with capillary electrophoresis for determination of sulfonamides residues in milkFirst, multi-walled carbon nanotube / carbon fiber modified electrode is prepared by the methods of chemical adsorption. Second, the online enrichment of the samples is achieved by field amplification technology. The sensitivity has been improved significantly. Enrichment technology not only has the advantages of capillary electrophoresis, but also the need to adapt to the trace analysis. Under the optimum conditions, this paper separate and determin the standards of sulfadiazine (SD) ,Trimethoprim (TMP) and sulfamethoxazole (SMZ). The residues of these components in milk is determined. The methods of using modified electrodes with field amplifier technology to improve the detection sensitivity has not been reported. The result is satisfactory.