| The history, the current situation and the future trend of capillary electrophoresis (CE) is reviewed. CE is becoming increasingly recognized as an important analytical separation technique 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. In combination with electrochemical detection (ED), CE-ED offers high sensitivity and good selectivity for electroactive species. The present thesis described the studies of CE-ED application in the analyses of foods and traditional Chinese medicines. The major content is described as follows:1. Determination of phenolic compounds of buchwheat (Fagopyrum esculentum Moench) hulls and flour by capillary electrophoresis with electrochemical detectionA simple, reliable and reproducible method, based on capillary electrophoresis with electrochemical detection (CE-ED), for the determination of phenolic compounds of buckwheat (Fagopyrum esculentiim Moench) hulls and flour was reported. The active ingredients mainly consist of (-)-epicatechin, rutin, hyperoside and quercetin. Operated in a wall-jet configuration, a 300 μm diameter carbon disk electrode was used as the working electrode, which exhibits good response at +0.90 V (vs. SCE) for all analytes. The effects of potential of working electrode, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be separated in a 50 mmol/L borate buffer (pH=8.7) within 20 min. The response was linear over three orders of magnitude with detection limit (S/N=3) ranging from 2*10-7 g/mL to 5*10-7 g/mL for all analytes. This method has been used for the determination of phenolic compounds of buchwheat (Fagopyrum esculentiim Moench) hulls and flour, and the assay result was satisfactory.2. Determination of active ingredients of Lonicera japonica Thumb, by capillaryelectrophoresis with electrochemical detectionCapillary electrophoresis with electrochemical detection was employed to analyse active ingredients of Lonicera japonica Thumb., an important crude herb frequently used in Chinese medicines. Hyperoside, chlorogenic acid, luteolin and caffeic acid are major important active ingredients. Operated in a wall-jet configuration, a 300-μm diameter carbon-disk electrode was used as the working electrode, which exhibits a good response at +0.90 V (vs. saturated calomel electrode) for four analytes. Under the optimum conditions, the analytes were baseline separated within 20 min in a 50 mmol/1 borax buffer (pH 8.7). Notably, excellent linearity was obtained over two orders of magnitude with detection limits (S/N) ranging from 1*10-7 g/ml to 5*10-7 g/ml for all the analytes. This method was successfully used in the analysis of Lonicera japonica Thumb, with relative simple extraction procedures, and the assay results were satisfactory.3. Determination of the bioactive flavonoids from rhododendron dauricum L. by capillary electrophoresis with electrochemical detectionA simultaneous determination of bioactive flavonoids from Rhododendron dauricum L. by capillary electrophoresis with electrochemical detection (CE-ED) was reported. The effects of potential of working electrode, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be separated in a 70 mmol/L borate buffer (pH=9.2) within 20 min. A 300 μm diameter carbon disk electrode has a good response at +0.90 V (vs. SCE) for all analytes.The response was linear over three orders of magnitude with detection limit (S/N=3) ranging from 2*10-8 g/mL to 2* 10-7 g/mL for all analytes. This method has been used for the determination of these analytes in Rhododendron dauricum L. after a relative simple extraction procedure, and the assay result was satisfactory.
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