| 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 often more sensitive than UV detection, 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 follews:1. PrefaceThe characteristics of CE, the separation modes, the basic theories of CE, the CE detectors, the studies and applications of CE-ED are introduced simply. The goal and significance of this thesis are introduced too.2. Determination of Bioactive Ingredients in Eucommia ulmoides Oliv. and Related Healthy Food by Capillary Electrophoresis with Electrochemical DetectionA high-performance capillary electrophoresis with electrochemical detection (CE-ED) method has been employed for the determination of five bioactive ingredients, including rutin, ascorbic acid, hyperoside, chlorogenic acid, and quercatin, in Eucommia ulmoides Oliv. and related healthy food. 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-ED were investigated. Under the optimum conditions, the analytes could be well separated within 20 min in a 75 cm length capillary at a separation voltage of 16 kV in a 50 mmol/L borate buffer (pH 9.0). 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 3.27×10-8 to 9.57×10-8 g/mL for all analytes. This proposed method has been successfully applied for the study on the Eucommia ulmoides Oliv. and related products, and the assay results were satisfactory.3. Study on Bioactive Ingredients in Cortex Lycii by Capillary Zone Electrophoresis with Amperometric DetectionA high-performance capillary zone electrophoresis with amperometric detection (CZE-AD) method has been developed for the determination of bioactive ingredients in Cortex lycii, including acacetin, scopoletin, kaempferol, p-coumaric acid, vanillic acid, luteolin and quercetin. 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 CZE-AD were investigated. Under the optimum conditions, the seven analytes could be well separated within 24 min in a 75 cm length capillary at the separation voltage of 16 kV in a 80 mmol/L borax running buffer (pH 9.0). 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 3.5×10-5 to 6.0×10-5 g/L for all analytes. This proposed method has been successfully applied for the study on the electrochemical bioactive ingredients in polar extract of Cortex Lycii, and the assay resultswere satisfactory.4. Determination of Polyphenols in Dandelion by Capillary Zone Electrophoresis with Amperometric DetectionCapillary electrophoresis with electrochemical detection (CE-ED) was applied for the determination of polyphenols in dandelion in this work. Under the optimum conditions, diosmetin, ferulic acid, chlorogenic acid, luteolin, and caffeic acid could be well separated within 17 min at the separation voltage of 16 kV in a 50 mmol/L borax running buffer (pH 8.0). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranging from 1.7×10-7 to 7.0×10-7 mol/L for all analytes. This proposed method has been successfully applied for the study on the polyphenols in dandelion, and the assay resultswere satisfactory.5. Determination of Active Ingredients in Corn Silk, Leaf and Kernel by Capillary Electrophoresis with Electrochemical DetectionCorn has been known for its accumulation of flavones and phenolic acids. However, many parts of corn except kernel have not drawn much attention. In this work, a method based on capillary zone electrophoresis with electrochemical detection has been used for the separation and determination of epicatechin, rutin, ascorbic acid (Vc), kaempferol, chlorogenic acid and quercetin in corn silk, leaf and kernel. The distribution comparision of the ingredients among silk, leaf and kernel was discussed. 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 19 min in a 40 mmol/L borate buffer (pH 9.2). The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 4.97×10-8 to 9.75×10-8 g/mL. The method has been successfully applied for the analysis of corn silk, leaf and kernel with satisfactory results. 6. Study on Extraction efficiency of Natural Antioxidants in Coffee by Capillary Electrophoresis with Amperometric DetectionCapillary zone electrophoresis with electrochemical detection (CE-AD) has been used for and determination of catechin, rutin, ferulic acid, o-dihydroxybenzene, chlorogenic acid, caffeic acid, gallic acid, and protocatechuic acid in coffee. Comparison of extraction efficiency of antioxidants using different polar solvents was also conducted. Effects of several important factors including running buffer acidity, separation voltage and working electrode potential, were evaluated to acquire the optimum analysis conditions. The working electrode was a 360 um carbon disc electrode at a working potential of + 0.95 V (vs. SCE). Under the optimum conditions, the analytes can be well separated within 26 min in a 75 cm length fused-silica capillary. The current response was linear over three orders ofmagnitude with detection limits (S/N = 3) ranging from 6.0×10-8 g·mL-1 to 3.6×10-7 g·mL-1 for all analytes.7. Determination of Uric Acid in Human Saliva and Urine Using Miniaturized Capillary Electrophoresis with Amperometric DetectionAn improved method based on a novel miniaturized capillary electrophoresis with amperometric detection (CE-AD) system was described to study the correlation between the trace amount of uric acid (UA) in human saliva and urine samples for patients suffering from gout disease. Under the optimum conditions, UA can been well separated from its co-existing potential interferences, namely xanthine (Xan), hypoxanthine (HX), and ascorbic acid (Vc), within 170 s with estimated separation efficiency of 111, 210 TP/m. The proposed miniaturized CE-AD system has been successfully applied for the analysis of UA in less invasive biological samples, which could provide potential application in fast diagnosis of gout.
|
PDF Full Text Request