| In this thesis, the development and application of capillary electrophoresis (CE) and several kinds of on-line preconcentration methord were reviewed. The methord of sweeping micellar electrokinetic chromatography (MEKC) combined with field amplified sample stacking (FASS) and selective exhaustive injection (SEI) were mainly studied on, the application of which involved drug analysis, food analysis and enviromental analysis. Then the basic principles and characteristics were introduced, and the following aspects were investigated. The major content is described as follows:1. A method for the Simultaneous Determination of Promethazine hydrochloride, Ephedrine Hydrochloride and Tramadol Hydrochloride was established by the micelle capillary electrophoresis on–line sweeping enrichment technique. The effect of pH in background solution, the concentration of sodium dodecyl sulfate (SDS), injection time, etc were investigated. The experiments were carried out in an uncoated fused silica capillary (60cm×45μm, effective length 47cm) under the following conditions: background solution of 20mmol/L NaH2PO4 and 80mmol/L SDS containing 18% methanol (pH=2.20); detection wave-length 200nm; run voltage -18kv. The detection limits of Promethazine hydrochloride, Ephedrine Hydrochloride and Tramadol Hydrochloride were 0.500μg/mL,0.125μg/mL and 0.250μg/mL. The new method was applied to analysis of Promethazine hydrochloride, Ephedrine Hydrochloride and Tramadol Hydrochloride in medicine with satisfactory results.2. On–line sweeping micellar electrokinetic chromatography were used for the determination of Cafeic Acid and Chlorogenic Acid. The conditions is: NaH2PO420mmol/L, SDS 100mmol/L and 15% methanol, pH=2.20, the detection wave-length was 214nm, run voltage was -20kv. The detection limits of Cafeic Acid and Chlorogenic Acid were 1.02μg/mL and 0.168μg/mL, respectively. The new method was successfully applied to the analysis of Cafeic Acid and Chlorogenic Acid in Shuanghuanglian Oral Liquid.3. A method for the Determination of melamine was established by the On-line sweeping micellar electrokinetic chromatography. The sensitivity was improved about 60 times by Sweep-MEKC, compared to CZE. The buffer medium was 140mmol/L SDS, 20mmol/L NaH2PO4 (pH=2.20) and 10% methanol, the separation voltage was -18kV and the sample injection time was 30s, detection wave was 214 nm. The determination time was within 9 minutes with RSDs of peak area less than 3.6%, under the optimum conditions. The LODs was 0.125μg/mL, calibration plot was linear in the range of 0.5~32.0μg/mL, r≥0.9997. Therefore, the sweeping-MEKC method was successfully applied for the detection of melamine.4. Micellar Electrokinetic Chromatography was used for the determination of Vanillic Acid, Cinnamic Acid and Ferulic Acid. Compared with common sweeping method, the sensitivity was improved about 30 times by FASS-Sweep, the LODs was decreased to 3.6μg/L, and the linear range was extended to 14μg/L. The buffer medium contains 100 mmol/L SDS, 20 mmol/L NaH2PO4 (pH=2.20), and 15% methanol. Separation voltage was -20 kV, sample injection voltage was -8 kV, injection time was 20s, water injection time was 160s, detected at 214 nm. Under the optimum conditions, the determination time was within 10 minutes with RSDs of peak area less than 5.9%. The calibration plots were linear in the range of 14~460μg/L, r≥0.9994, and the LODs were 3.64μg/L for Vanillic Acid, 9.85μg/L for Cinnamic Acid and 11μg/L for Ferulic Acid. Further more, this proposed FASS-sweeping-MEKC method was successful applied for the detection of the three organic acids in rhizoma picrorhiza.5. Sweeping Micellar Electrokinetic Chromatography in Combination with Cation-Selective Exhaustive Injection (CSEI) was used for the determination of Promethazine Hydrochloride and Codeine Phosphate. Compared with common sweeping method, the sensitivity was improved 800 times by CSEI-Sweep-MEKC. The LODs was decreased to 0.12μg/L, and the linear range was extended to 0.50μg/L. The buffer medium contains 80 mmol/L SDS, 20 mmol/L NaH2PO4 (pH=2.40), and 16% acetonitrile, which was detected at 214 nm.The sample injection voltage 10 kV and injection time 100s. Under the optimum conditions, the determination time was within 8 minutes with RSDs of peak area less than 4.6%. The calibration plots were linear in the range of 0.50~81.3μg/L, r≥0.9989, the LODs was 0.16μg/L for Promethazine Hydrochloride, and these of Codeine Phosphate were 0.78-62.5μg/L, r≥0.9988, 0.12μg/L. So this proposed CSEI-Sweeping-MEKC method was successful applied for the detection of Promethazine Hydrochloride and Codeine Phosphate in Compound Codeine Phosphate Syrup. The recoveries are between 95.8% and 106%.
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