Applications Of Capillary Electrophoresis In Analysis For Natural Products

Capillary electrophoresis (CE) was introduced as a new analytical technique in the 1970s and rapidly proved to be a powerful tool for the separation and detection of various classes of natural products.1. A rapid and practical capillary electrophoresis (CE) method was developed for the determination of ginsenoside Rg1, Re and Rb1 in ginseng samples. Rg1, Re and Rb1 were extracted by ultrasonication with water-saturated n-butanol. The CE method was optimized with a running buffer of 20 mM borate in 30% MeOH (pH 9.67), and an applied separation voltage of+18 kV over a capillary of 50 uμm i.d.×50 cm (41.5 cm to the detector window), which gave a baseline separation of Rg1, Re and Rb1 within 5 min. Under the detection at 203 nm, the method gave limits of quantification (S/N=10) at about 5.2-7.3μg/mL for Rg1, Re and Rb1, whereas the overall recoveries were larger than 83.0%. The proposed method has been successfully applied to measure three different kinds of ginseng samples (10 real samples) and the contents of Rg1, Re and Rb1 in actual samples were obtained and evaluated.2. Determining the key active flavonoids in Epimedium is critical for discovering new Epimedium species, assessing their potential pharmacological actions and controlling their quality. To achieve these aims, a reproducible, sensitive and practical analysis method is necessary. This paper describes a novel nonaqueous capillary electrophoresis (NACE) method for the separation and determination of Icariin, IcarisideⅡand Epimedin K in Epimedium leaves.Icariin, IcarisideⅡand Epimedin K in Epimedium leaves were extracted by ultrasonication with EtOH-H2O (70:30,v/v) followed by a cleanup procedure with a HP 20 wide-bore resin column. The optimized NACE conditions were obtained with an 8 mM borate MeCN/H2O (60:40 v/v) solution (pH 11.40) as the running solution,+20 kV as the applied voltage and 270 nm as the detection wavelength. The limits of quantification ranged from 0.24 to 0.84 mg/kg for Icariin, Icariside II and Epimedin K of the Epimedium leaves, whereas the overall recoveries were greater than 80.2%. The proposed NACE method has been successfully applied to measure 10 real samples, and the content profiles of three flavonoids in Epimedium leaves were obtained and evaluated.3. The separation and determination of three polyphenols has been investigated by CZE. The electrophoretic conditions were optimized with the running buffer of 20 mM borate in 15% MeOH (pH 9.35), and the applied voltage of+15 kV, the detection wavelength of 270 nm over a capillary of 75μm i.d.×50 cm (41.5 cm to the detector window). Under the optimal conditions, chlorogenic acid,rutin and scopoletin were baseline separated. This method has been successfully applied to the determination of polyphenols in tobacco.