| Capillary Electrophoresis(CE)is becoming increasingly recognized as one of the most important separation techniques in recent twenty years due to its speed, efficiency,reproducibility,ultra-small sample volume,and ease of clearing up the contaminants.CE has been widely applied in many fields.Electrochemical detection(ED)is more sensitive than UV detection for many analytes,and has many advantages when it combines with CE;CE-ED offers high sensitivity and good selectivity for electroactive species.The goal of this thesis is to explore some applications in pharmaceutical analysis,biochemical analysis and food analysis by CE-ED.The major content is as follows:1.PrefaceIn the fn'st section,the history,the current situation and the future trend of High-Performance Capillary Electrophoresis(HPCE)have been reviewed.The characteristics of CE,the separation models,the basic theories of CE,the CE detectors,the studies and applications of CE-ED are also introduced.The goal and significance of this thesis are also introduced.CE has been widely applied in many fields.It is applied in the analyses of carbohydrates,biomacromolecules,inorganic and organic small molecules,single cell,chiral molecules,environment,food, medicines and so on.The goal of this thesis is to explore some applications in biochemical analysis and food analysis by using CE-ED.2.Determination of five active ingredients in compound kendir leaves tablets by Capillary Zone Eleetrophoresis with Electrochemical DetectionA simultaneous determination of five ingredients,including catechin,rutin, hyperoside,chlorogenie acid and quercetin in compound kendir leaves tablets by capillary zone electrophoresis with electrochemical detection(CE-ED)was reported. The effects of several important factors such as the acdity and concentration of nmning buffer,separation voltage,injection time and detection potential were investigated to acquire the optimum conditions.A 300μm diameter carbon disc electrode was used as the working electrode positioned carefully opposite the outlet of capillary at potential of+0.95V(vs.SCE).The analytes could be well separated within 14 min in a 75cm length capillary at a separation voltage of 18 kV in a 60 mmol/L borate buffer(pH=8.7).There was an excellent linearity between peak current and concentration of analytes in the concentration range of 1.0×10-7-1.0×10-4g/mL for all five ingredients and the detection limits(S/N=3)ranged from 1.09×10-8g/mL to 5.69×10-8g/mL.This proposed method was successfully used in the analysis of traditional Chinese medicine,and the assay results were satisfactory.3.Determination of Effective Ingredients in Compound Sulfamethoxazole Tablets by Capillary Eleetrophoresis with Amperometric DetectionA high-performance capillary electrophoresis with amperometric detection (CE-AD)method has been employed for the determination of three antibacterial sulfa components,namely sulfamethoxazole(SMZ),sulfadiazine(SD),and trimethoprim(TMP).The effects of several factors such as the acidity and concentration of running buffer,the separation voltage,the applied potential and the injection time on CE-AD were investigated.Under the optimum conditions,the three components could be well separated within 14 min in a 70cm length capillary at the separation voltage of 18 kV in a 13 mmol/L borax-18 mmol/L potassium dihydrogen phosphate running buffer(pH=5.8).Good linear relationship was established between peak current and concentration of analytes over three orders of magnitude with detection limits(S/N=3)ranged from 8.0×10-8to 5.1×10-8g/mL for all analytes.This proposed method has been successfully applied for the determination of the main effective components in Compound Sulfamethoxazole Tablets.4.Determination and Comparison of Active Ingredients in Pu-erh Tea by Capillary Eleetrophoresis with Electrochemical DetectionTea has been known for its accumulation of flavones and phenolic acids.It has a long history in china,especially Pu-erh tea.In this work,a method based on capillary zone electrophoresis with electrochemical detection has been applied to the separation and determination of catechin,rutin,chlorogenic acid,quercetin,and gallic acid in Pu-erh tea.Several important factors including running buffer acidity, separation voltage and working electrode potential,and etc.were evaluated to acquire the optimum analysis conditions.Under the optimum conditions,the analytes could be well separated within 18 min in a 60 mmol/L borate buffer(pH= 8.7).The response was linear over three orders of magnitude with detection limits (S/N=3)ranging from 2.29×10-8to 6.02×10-8g/mL.The method has been successfully applied for the analysis of 3 Pu-erh tea samples with satisfactory results.5.Application of Capillary Electrophoresis to Study Phenolic Profiles of Honeybee-Collected PollenHoneybee-collected pollen is promoted as a health food with a wide range of nutritional and therapeutic properties.A high-performance capillary electrophoresis with amperometric detection method has been developed for the simultaneous determination of bioactive ingredients in 10 samples of honeybeecollected pollen in this work.Under the optimum conditions,15 phenolic components can be well separated or nearly baseline-separated(apigenin and vanillic acid peaks)within 29 min at the separation voltage of 14 kV in a 50 mM borax running buffer(pH=9.0), and adequate extraction was obtained with ethanol for the determination of the above 15 compounds.Recovery(94.1-104.0%),repeatability of the peak current(＜5.4%), and detection limits(6.9×10-7-6.4×10-9g/mL)for the method were evaluated.This procedure was successfully used for the analysis and comparison of the phenolic content of honeybee-collected pollen samples originating from different floral origins based on their electropherograms or "phenolic profiles".
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