| Capillary Electrophoresis (CE) is one of the most important and rapidly growing separation techniques in recent twenty years and has been widely used in different fields, such as life science, agriculture, food, clinical medicine and chemistry. It has exhibited powerful capability for the analysis of complex samples due to its high separation speed and efficiency, low volume sample, the relatively simple instrument and low running costs. However, the small sample injection volume and very thin capillary bring about difficulties to detections. Because amperometric detector (AD) is more sensitive than UV-visible detector and much cheaper than Laser Induced Fluorescence (LIF) detector, it is preferred to couple with CE in many analysis areas.The Goal of this dissertation is to apply this CE-AD technique to resolve some actual analytical problems in food and pharmaceutical analysis. The contents of the dissertation include four chapters:Chapter 1 is Introduction. In this chapter, the principle, development and applications of capillary electrophoresis were outlined. The applications of capillary electrophoresis in food and Chinese herbal medicine analysis were highlighted.Chapter 2 In this chapter,a method based on capillary zone electrophoresis with amperometic detection (CZE-AD) at platinum disk electrode was developed for the determination of Sudan dye (â… ). The effects of working potential, pH and concentration of running buffer, separation voltage and injection time were investigated. Sudanâ… could be well separated in a 10 mM borate buffer (pH 9.3) and detected in a +1.05 V versus Ag/AgCl reference electrode. Excellent linearity was obtained in the concentration rang from 1.13×10-91.13×10-7 mol/L for Sudanâ… and recoveries were 93.5%102.7%. The limit of detection (S/N=3) was 1.13×10-9 mol/L. This method has been successfully applied for chilli powder samples with satisfactory results.Chapter 3 In this chapter, a method of Simutaneous separation and detection of tectoridin and tectorigenin using capillary electrophoresis with amperometric detection was established. The influences of buffer type and concentration, separation voltage, injection time and detection potential were investigated and optimized. The analytes could be separated in a 10 mmol·L-1 borate buffer (pH=9.00)with a separation voltage of 13 kV within 11 min. A 1 mm diameter platinum disk electrode has a good response at +1.05 V (vs. Ag/AgCl) for all analytes. The detection limits (S/N=3) for tectoridin and tectorigenin were 1.2×10-6 mol/L and 1.7×10-7 mol/L, respectively. The method had been applied to the detection of Rhizoma Belamcandae and Shegan-mahung decoction with recoveries from 95.3%102.0%.Chapter 4 In this chapter, a method was established for the simultaneous separation and determination of rutin, quercetin, ferulic acid, caffeic acid and gallic acid in Phyllanthus Urinaria L. by capillary electrophoresis with amperometric detection. The influences of working electrode potential, pH and concentration of buffer, separation voltage and injection time were investigated. The five analytes could be baseline separated in a 10 mmol/L sodium borate buffer (pH9.00) with a separation voltage of 15 kV. A 1 mm diameter platinum disk electrode generated good responses at 1.00 V (vs.Ag/AgCl) for all analytes. The response was linear over two orders of magnitude with detection limits ranging from 5.02×10-8～5.88×10-6 mol/L, recoveries ranging from 92.1%～105.1% and relative standard deviation(RSD) ranging from 2.1%～4.2%. The method had been successfully applied to analyze Phyllanthus Urinaria L.with satisfactory result.Chapter 5 In this chapter, a method was established for the separation of clenbuterol, salbutamol and terbutaline by capillary electrophoresis with amperometric detection. Separating effect for the three analytes was investigated using the mode of capillary zone electrophoresis and micellar capillary electrophoresis, respectively. It will be more effective for the separation of clenbuterol, salbutamol and terbutaline using the mode of micellar capillary electrophoresis. |
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