| Capillary electrophoresis(CE), one of the innovative separation techniques, was a powderful method for the food analysis. In this thesis, the applications of capillary electrophoresis to the determination of melamine, sudan dyes in food and investigation of the adsorption characteristics of juncus effusus L. have been carried out.The main contents of the dissertation could be described as follows:Chapter 1:ReviewA review of capillary electrophoresis in terms of the fundamental principle, separation models, instrumentation system, and its applications in food analysis was given. The sample pretreatment methods, such as solid-phase extraction, solid-phase microextraction and so on, were also reviewed.Chapter 2:Determination of melamine in milk and toffee by capillary electrophoresisA new separation method for melamine by capillary electrophoresis was developed in the paper. Under the optimized experiment conditions, the melamine was separated and determined with 10mmol·L-1 citric acid monohydrate buffer at pH5.00. Linearity was established over the concentration range 1～100μg·mL-1 with the correlation coefficient 0.9990, and the limit of detection was 0.27μg·mL-1 (S/N=3). The method has been successful applied to determination of melamine in milk and toffee. The recoveries were 81.36%～93.52% and the relative standard deviations were between 2.8% and 5.9%.Chapter 3:Determination of sudan azo dyes in food by micellar electrokinetic chromatographyA determination method of sudan II and sudan III by capillary electrophoresis was developed. The background electrolyte was consisted of 8mmol·L-1 borate (pH9.0),25 mmol·L-1 sodium dodecyl sulfate and 25% acetonitrile. The applied voltage was 20 kV and the detected wavelength was 228nm. Sudan azo dyes were completely separated and determined within 8min. The correlation coefficients were 0.9927 and 0.9985 in the linear rang of 0.5～10μg·mL-1 for SudanⅡand 0.5～5μg·mL-1 for sudanⅢ, with the detection limits were 0.1μg·mL-1 and 0.13μg·mL-1, respectively. The method has been applied to determination sudan azo dyes of sausage and chilli powder. The average recoveries were between 82% and 94%, with the relative standard deviations over the rang of 3.6%～6.0%.Chapter 4:Study on the adsorption characteristics of methylene blue onto juncus effusus L.The adsorption kinetics of juncus effusus L. for the removal of methylene blue (MB) with respect to the initial dye concentration, pH and temperature were investigated. The rate and the transport/kinetic processes of the adsorption were described by applying the pseudo-first-order and the pseudo-second-order models. The results showed that the kinetic datas were well described by the pseudo-second-order kinetic model. Adsorption activation energy was 34.02kJ·mol-1. The values of activation parameters, such as free energy (△G*), enthalpy (△H*) and entropy (△S*), were determined to be 41.40kJ·mol-1,31.47kJ·mol-1 and -33.88J·mol-1·K-1, respectively. Non-linear form of Langmuir isotherm model can well agree with the experiment datas and the maximum adsorption capacity was found to be 26.32 mg·g-1.Chapter 5:Separation and determination of dyes by nonaqueous capillary electrophoresis coupled with solid phase extraction using juncus effusus L. as sorbentA determination method of methylene blue(MB), malachite green(MG) and crystal violet(CV) by nonaqueous capillary electrophoresis coupled with solid phase extraction using the juncus effusus L. as sorbent was developed. In the paper, juncus effusus L. was firstly introduced as an adsorptive material. Using 20mg juncus effusus L. to extract dyes from 100 mL 0.1μg·mL-1 dyes aqueous solution, the average recoveries of MB, MG and CV were 96%, 97% and 91%, respectively. This method was efficiently, easily and friendly with environment, and can be considered as a green analytical method.
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