The Application Of CE In Food Analysis

Food safety and nutrition problems have attracted much concern currently, however, complicated food matrix put forward a huge challenge for testing work. At present, HPLC and GC, which have the disadvantages of complex previous process and strong reagent consumption, are mainly used in the analysis of food. As a new separation technology, CE has aroused the widespread attention in the field of food analysis, for the advantages of its simple pretreatment, small reagent dosage, economic and environment friendly. In this thesis, some CE-DAD methods have been built for determination of additives and compositions in food.Chapter 1:The development history, the basic theories, various separation modes, the injection techniques, the detection method and the characteristics of CE are briefly introduced. The various applications of CE have also been specifically stated.Chapter 2:An efficient high performance capillary electrophoresis (CE) method with ultraviolet detector has been successfully developed for the determination of five synthetic dyes. The running buffer were 10 mmol/L Na2B4O7-5 mmol/L NaH2PO4 with 0.7 mmol/L beta-cyclodextrin, pH 11.5, the detection wavelength was set at 250 nm and applied voltage 25 kV. Under these optimal conditions, brilliant blue, sunset yellow, amaranth, ponceau 4R and tartrazine in ice-cream were separated in 5 min. the linear range was 5 μg/mL to 1000 μg/mL with the correlation coefficient between 0.9975 and 0.9999 and the limit of detection varied from 1.2 μg/mL to 8.6 μg/mL(S/N=3). The average recoveries (n=3) were 93.8% to 108.5%, with a relative standard deviation less than 4.19%. This method is convenient operation, accurate and suitable for the simultaneous detection of synthetic dyes.Chapter 3:An efficient high performance capillary electrophoresis (CE) method has been successfully developed for the determination of flavonoids in buckwheat. The running buffer were 10 mmol/L Na2B4O7-NaH2PO4, pH 9.3, the detection wavelength was set at 218 nm and applied voltage 25 kV. Under these optimal conditions, four flavonoids could be fully separated from each other within seven minutes, the linear range was 0.03 to 0.97 mg/mL with the correlation coefficient between 0.9923 and 0.9987 and the limit of detection varied from 5.33×10-6 to 2.51×10-5 mg/mL (S/N=3). The average recoveries were 95.5% to 104.7%, with a relative standard deviation less than 4.48%. The proposed method has been successfully applied for the determination of flavonoids in buckwheat.Chapter 4:An efficient high performance capillary electrophoresis (CE) method has been successfully developed for the determination of aloe-emodin, kaempferol, chlorogenic and quercetin in Hemerocallis fulva. The running buffer were 10 mmol/L Na2B4O7-H3BO3, pH 9.15, the detection wavelength was set at 224 nm and 5 s hydrodynamic injection at 30 kV, four samples were separated in 6 min. Under these optimal conditions, the linear range was 0.01 to 0.99 mg/mL with the correlation coefficient between 0.9976 and 0.9996 and the limit of detection varied from 8.63×10-6 to 2.45×10-5mg/mL(S/N=3). The average recoveries were 97.55% to 101.2%, with a relative standard deviation less than 4.76%. This method is fast, accurate and suitable for the detection of active compounds in hemerocallis fulva.