Determination of hesperidin and synephrine in Pericarpium Citri Reticulatae by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed for the determination of hesperidin (HP) and synephrine (SP) in the Chinese traditional herbal drug, Pericarpium Citri Reticulatae, the dried rind of the ripe fruits of Citrus reticulata Blanco (mandarin orange). The effects of some important factors such as the acidity and concentration of running buffer, separation voltage, and detection potential were investigated to determine the optimum conditions. The working electrode was a 300 microm diameter carbon disc electrode positioned opposite the outlet of the capillary. Both analytes could be well separated within 5 min in a 40 cm long capillary at a separation voltage of 12 kV in 50 mmol L(-1) borate buffer (pH 9.0). Excellent linearity was observed for the dependence of peak current on analyte concentration in the range from 2.5 x 10(-6) to 1.0 x 10(-3) mol L(-1) for SP and from 5.0 x 10(-6) to 1.0 x 10(-3) mol L(-1) for HP. The detection limits (S/N=3) for SP and HP were 4.96 x 10(-7) mol L(-1) and 6.54 x 10(-7) mol L(-1), respectively. This method has been successfully applied for the analysis of real samples, with satisfactory results.     

Simultaneous determination of pharmacologically active ingredients in Rhodiola by capillary chromatography with electrochemical detection

Rhodiola, in which there are abundant pharmacologically active ingredients, is one of the functional adaptogenic agent that aid specific bodily functions to adapt to the changes and stress of life in addition to being tonic. In an attempt to qualitatively and quantitatively determine the pharmacologically active ingredients in Rhodiola, a new method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, applied potential and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be well separated within 24 min at the separation voltage of 18 kV in a 80 mmol L(-1) borax running buffer (pH 9.0). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranged from 3.16 x 10(-7) to 1.11 x 10(-7)g mL(-1) for all target ingredients. This proposed method has been successfully applied for the analysis of real samples, with satisfactory results.     

中药菟丝子中生物活性成分的毛细管电泳-电化学检测

采用毛细管电泳-电化学检测法(CE-ECD)同时测定了菟丝子中芦丁、金丝桃甙、山柰酚、对香豆酸和槲皮素等5种主要生物活性成分的含量,考察了运行缓冲液酸度和浓度、分离电压、氧化电位和进样时间等实验参数对分离检测的影响。在最佳实验条件下,以直径300 μm的碳圆盘电极为工作电极,检测电位为+950 mV(vs. 参比电极),以50 mmol/L的硼砂缓冲溶液(pH 9.0)为运行缓冲液,上述各组分在19 min内能完全分离。芦丁、金丝桃甙、山柰酚、对香豆酸和槲皮素在两个数量级的范围内呈良好线性关系,检测下限(按S/N=3计) 分别为1.93×10-5,3.55×10-4,3.65×10-5,1.73×10-5和1.46×10-4 g/L。该法已成功地应用于菟丝子中活性成分的分离检测,结果令人满意。     

Determination and Comparison of Phytoestrogens in Both Crude and Parched Flos Sophorae Immaturus by Capillary Electrophoresis with Electrochemical Detection

A method using high-performance capillary electrophoresis with electrochemical detection (CE-ED) has been developed for content comparison of phytoestrogens in both crude and parched Flos sophorae immaturus. Genistin, genistein, rutin, kaempferol and quercetin are important active constituents in this plant. The effects of several factors, such as acidity and concentration of running buffer, separation voltage, applied potential and injection time, were investigated to find the optimum conditions. Detection limits (S/N=3) ranged from 1.1 × 10^–7 to 2.8 × 10^–7gmL^–1 for all five analytes. This method was successfully used to analyse both crude and parched Flos sophorae immaturus after a relatively simple extraction procedure, and the assay results were satisfactory.     

毛细管电泳-电化学检测法测定饲料中的磺胺类药物

采用毛细管电泳-电化学检测法(CE-ED),对饲料中的6种磺胺类药物磺胺脒、磺胺二甲嘧啶、磺胺甲嘧啶、磺胺二甲氧嘧啶、磺胺嘧啶、磺胺甲恶唑进行了分离和测定。分别考察了工作电极电位、运行缓冲液的pH和浓度、分离电压和进样时间等实验参数对实验结果的影响。在优化的实验条件下,以直径300μm的碳圆盘电极为工作电极,检测电位为0.95 V(vs.SCE),在30 mmol/L硼砂-KH2PO4(pH7.6)的运行缓冲溶液中,6个分析物能够在16 min内实现很好的基线分离,被测物浓度与峰电流在3个数量级呈良好的线性,检出限(S/N=3)范围0.08～0.20μg/mL。该方法已应用于实际样品的分析。     

Determination of rate constants and activation energy of 3-chloro-1,2-propanediol hydrolysis by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection (CE-ED) to calculate the rate constants and activation energy of 3-chloro-1,2-propanediol (3-MCPD) hydrolysis was described. Effects of several factors, such as the pH value and the concentration of the running buffer, separation voltage, injection time and the potential applied to the working electrode, were investigated to find the optimum conditions. With a 50 cm length of 25 microm diameter fused-silica capillary at a separation of 10 kV, well-defined separation of 3-chloro-1,2-propanediol from glycerol was achieved in 30 mmol/l borax (pH 9.24) within 13 min. Operated in a wall-jet configuration, a 328 microm copper-disk electrode used as the working electrode exhibits good response at 0.65 V (versus SCE) for 3-MCPD and glycerol. The rate constants of 3-MCPD hydrolysis at different temperatures were determined by monitoring the concentration changes of 3-MCPD. At 80, 85 and 90 degrees C, the measured rate constants of 3-MCPD hydrolysis were 3.8 x 10(-3) min(-1), 7.1 x 10(-3) min(-1) and 11.5 x 10(-3) min(-1), respectively. The activation energy for 3-MCPD hydrolysis was calculated to be 118.1 kJ/mol, which is in good agreement with the value in the literature.     

毛细管电泳-电化学检测法测定黄芪及其制剂中的活性成分

采用毛细管电泳-电化学检测法(CE-ED)对中药黄芪的主要活性成分芦丁、阿魏酸、香草酸、绿原酸、槲皮素和咖啡酸进行了分离和测定。分别考察了工作电极电位、运行缓冲液的pH值和浓度、分离电压和进样时间等实验参数对实验结果的影响。在优化的实验条件下,以直径300 μm的碳圆盘电极为工作电极,检测电位为+0.95 V(相对于饱和甘汞电极),在10 mmol/L硼酸盐(pH 8.2)的运行缓冲溶液中,上述6种活性成分能在17 min内实现很好的基线分离,被测物浓度与峰电流在3个数量级范围呈良好的线性关系,检出限(S/N=3)范围为78～110 μg/L。在不同的加标水平下,6种活性成分的平均回收率为96.0%～103.0%,相对标准偏差为1.9%～3.6%(n=3)。该方法样品处理简单,无需预富集,已应用于实际样品的分析,并获得了令人满意的结果。     

Determination of baicalein, baicalin and quercetin in Scutellariae Radix and its preparations by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection (CE-ED) was developed for the determination of baicalein, baicalin and quercetin in Scutellariae Radix and its pharmaceutical preparations. The effects of some important factors such as the acidity and concentration of running buffer, separation voltage, injection time, and the potential of working electrode were investigated to acquire the optimum condition. The working electrode was a 300-mum diameter carbon disc electrode positioned opposite the outlet of capillary. The three analytes could be well separated within 12 min in a 40 cm length capillary at the separation voltage of 12 kV in a 100 mmol l(-1) borate buffer (pH 9.0). The response was linear over three orders of magnitude with detection limits (S/N=3) ranged from 0.224 to 0.548 mumol l(-1) for all three analytes. This proposed method demonstrated good long-term stability and reproducibility with R.S.D. of less than 5% for both migration time and peak current (n=7). It has been successfully applied to analyze the actual samples with satisfactory assay results.     

Simultaneous determination of active ingredients in ethnomedicine Gaultheria leucocarpa var. yunnanensis and its medicinal preparation by capillary electrophoresis with electrochemical detection

A simple and rapid capillary electrophoresis (CE) with electrcochemical detection (ED) method has been established for the simultaneous determination of seven active ingredients in the stems and roots of Gaultheria leucocarpa var. yunnanensis and its medicinal preparation, including (+)-catechin, rutin, gentisic acid, vallinic acid, salicylic acid, quercetin, and protocatechuic acid. The effects of working potential, pH, and concentration of running buffer, separation voltage, and injection time on CE-ED are systematically investigated. Under the optimum conditions, the seven analytes could be completely separated within 23 min in a borax running buffer (pH 8.7). A good linear relationship is obtained over three orders of magnitude with detection limits (signal-to-noise ratio=3) ranging from 5x10(-8) g/mL to 3x10(-7) g/mL for the analytes. The proposed method is successfully used in the analysis of real samples after a relatively simple extraction procedure, and the assay results are satisfactory.     

Determination of Bioactive Flavonoids in Rhododendron Dauricum L. by Capillary Electrophoresis with Electrochemical Detection

A method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed for the determination of bioactive flavonoids in the traditional Chinese herbal medicine, Rhododendron dauricum L. The effects of working electrode potential, 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^?1 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 limits (S/N = 3) ranging from 2 × 10^?8 g mL^?1 to 2 × 10^?7 g m^?1 for the analytes. The method has been successfully applied for the analysis of real sample, with satisfactory results.     

Determination of active constituents in Lonicera confusa DC. by capillary electrophoresis with amperometric detection

A method based on capillary electrophoresis with amperometric detection has been developed for the determination of luteolin, chlorogenic acid, 3,5-dicaffeoylquinic acid and caffeic acid in the dried flower buds, leaves and stems (three medicinal parts) of Lonicera confusa DC., respectively. The effects of several important factors such as detection potential, the concentration of the running buffer, separation voltage and injection time were investigated to acquire the optimum conditions. The detection electrode was a 300 microm diameter carbon disc electrode at a working potential of + 0.90 V (vs saturated calomel electrode). The four analytes can be well separated within 10 min in a 40 cm-long fused silica capillary at a separation voltage of 12 kV in a 50 mM borate-25 mM phosphate buffer (pH 8.0). The relationship between peak current and analyte concentration was linear over about 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.35 to 0.52 microM for all analytes. The proposed method has been successfully applied to the monitoring of bioactive constituents in the real plant samples with satisfactory assay results.     

Simultaneous determination of positional isomers of benzenediols by capillary zone electrophoresis with square wave amperometric detection

A capillary zone electrophoresis method coupling square wave amperometric detection (SWAD) for the simultaneous determination of positional isomers of benzendiols (i.e. o-, m-, p-benzenediols) has been developed. Effects of several factors, such as the composition of the running buffer, the pH value, separation voltage, injection time and the potential applied to the working electrode, were investigated to acquire the optimum conditions. The efficacy of the boric acid and ascorbic acid in the running buffer were discussed. o-, m-, p-Benzendiols can be well separated within 8 min in a 50 cm length of 50 microm diameter fused-silica capillary at a separation voltage of +15 kV. Operated in a wall-jet configuration, a 100 microm Pt-disk electrode used as the working electrode exhibits good response for the analytes. The relation between peak current and analyte concentration was linear over two orders of magnitude with detection limits (S/N = 3) ranging from 0.5 to 1.5 microM for all analytes. The proposed method has been successfully applied to monitor the o-, m-, p-benzendiols contents in the environmental wastewater samples with satisfactory assay results.     

Capillary electrophoresis coupled with electrochemical detection using porous etched joint for determination of antioxidants

Capillary electrophoresis coupled with electrochemical detection (CE-EC) for determination of antioxidants, propyl gallate (PG) and tert-butylhydroquinone (TBHQ), in cosmetic samples was proposed in this work. A porous etched joint was used to isolate the electrochemical detection from the electrophoretic high voltage. Compared with the 25 microm i.d. capillary without a decoupler in a CE-EC system, a 75 microm i.d. capillary applied in the present system gave an improvement in both sample injection and sensitivity. Moreover, the carbon fiber working electrode could be directly in touch with the end of separation capillary due to the elimination of the effect of separation voltage on the EC detection, so the alignment of working electrode and capillary became easy and the dead volume was also decreased. Baseline separation of the two antioxidants was achieved by CE in a 50 cm long x 75 microm i.d. capillary at 20 kV using 5.0 mmol L(-1) phosphate buffer (pH 8.00). 0.7 V (versus Ag/AgCl) was applied to the carbon fiber electrode for electrochemical detection. Under the optimal condition, the precisions (RSD, n=4) of peak height and migration time of PG and TBHQ were 2.39-3.59% and 0.34-0.44%, respectively. The detection limits of PG and TBHQ were 2.51x10(-6) and 4.88 x 10(-6) mol L(-1) for standard solution and 0.0751 and 0.0328 mg g(-1) for the real cosmetic samples with consumption of 0.3g sample. Analysis of TBHQ and PG in cosmetics samples was also achieved with the present system and the spiked recoveries of two analytes in cosmetics samples were in the range of 93.6-98.8%.     

Determination and Differentiation of Two Seemingly Identical Medicinal Herbs by Capillary Electrophoresis with Electrochemical Detection

A high-performance capillary electrophoresis with electrochemical detection (CE-ED) method has been employed for the determination of six bioactive ingredients in traditional Chinese herbs, Herba cepbalanoplosis segeti and Herba cirsii japonici. 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 six analytes could be well separated within 21 min in a 75 cm length capillary at the separation voltage of 15 kV in a 50 mmol L^–1 borax running buffer (pH 8.4). A 300 m diameter carbon disk electrode was used as the working electrode positioned carefully opposite the outlet of the capillary in a wall-jet configuration at potential of +950 mV (vs. SCE). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranged from 1.5×10^–7 to 6.0×10^–7 g mL^–1 for all six analytes. This proposed method has been successfully applied for the analysis of traditional Chinese herbs after a relatively simple extraction procedure, further on, for the differentiation of these above two seemingly identical herbs based on their electropherograms or characteristic electrochemical profiles.     

Simultaneous determination of aminothiols, ascorbic acid and uric acid in biological samples by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection has been employed for the separation and determination of homocysteine, cysteine, reduced glutathione, ascorbic acid and uric acid. Effects of several important factors such as the acidity and concentration of the running buffer, separation voltage, injection time and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 500 microm diameter platinum disk electrode at a working potential of +1.05 V (vs saturated calomel electrode). The five analytes were well separated within 10 min in a 50 cm long fused silica capillary at a separation voltage of 18 kV in a 100 mm phosphate buffer (pH 7.8). The relation between peak current and analyte concentration was linear over about 3 orders of magnitude with the detection limits (S/N = 3) ranging from 0.83 to 2.58 microm. The proposed method was successfully applied to determine cysteine, reduced glutathione, ascorbic acid and uric acid in human whole blood and rat brain tissues with satisfactory assay results and should find a wide range of bioanalytical applications.     

毛细管电泳-电化学检测法测定硫酸铜-维生素C反应体系中的羟基自由基和菊花的抗氧化活性

采用毛细管电泳-电化学检测方法,以对羟基苯甲酸为自由基捕捉剂,测定了硫酸铜-维生素C反应体系(pH 7.4)中生成的羟基自由基。研究了电极电位、运行液的pH值、电泳电压及进样时间对体系中反应物和产物分离的影响,得到了最优化的测定条件;讨论了体系中各反应物浓度和反应时间对产物浓度的影响。以直径为300 μm的碳圆盘电极为检测电极,工作电极电位为0.95 V(vs.SCE),目标产物3,4-二羟基苯甲酸在1.5×10-4~6.0×10-6 mol/L范围内线性关系良好,检测限（S/N=3）为1.5×10-6 mol/L。应用该方法,研究测定了不同品种菊花的抗氧化活性。     

Analysis of nephroloxic and carcinogenic aristolochic acids in Aristolochia plants by capillary electrophoresis with electrochemical detection at a carbon fiber microdisk electrode

Aristolochic acids (AAs) are the main bioactive ingredients in the most of Aristolochia plants, which are used to make dietary supplements, slimming pills and Traditional Chinese Medicines (TCMs). Excessive ingestion of AAs can lead to serious nephropathy. Therefore, quantitative analysis and quality control for the plants containing AAs is of great importance. In this paper, capillary electrophoresis (CE) with electrochemical detection (ED) at a 33 microm carbon fiber microdisk electrode (CFE) has been applied to detect AA-I and AA-II in Aristolochia plants. Under the optimum conditions: detection potential at 1.20 V, 2.0 x 10(-2) mol L(-1) phosphate buffer solution (PBS) (pH 10.0), injection time 25 s at a height of 17 cm and separation voltage at 12.5 kV, the AA-I and AA-II were baseline separated within 5 min. Low detection limits for AA-I and AA-II were 4.0 x 10(-8) mol L(-1) and 1.0 x 10(-7) mol L(-1), respectively. Wide linear ranges were from 4.0 x 10(-8) mol L(-1) to 1.9 x 10(-5) mol L(-1) and 1.0 x 10(-7) mol L(-1) to 5.0 x 10(-5) mol L(-1) for AA-I and AA-II, respectively. The proposed method has been successfully applied to analyze AAs contents in plant extracts. The results indicated that the contents of AAs in each part of Aristolochia debilis Sieb. Et Zucc. plant were different. Meanwhile, the CE-ED method was utilized for fingerprint analysis of medicine herbs. Six herbs (Radix aristolochiae, Fructus aristolochiae, Herba aristolochiae, Caulis aristolochiae manshuriensis, Caulis clematidis armandii, Caulis akebiae) were well distinguished by comparing their electropherograms obtained by CE-ED method.     

Determination of three bioactive constituents in moutan cortex by capillary electrophoresis with electrochemical detection.

Capillary electrophoresis with electrochemical detection has been employed for the separation and determination of the three active constituents (paeonol, benzoyloxypaeoniflorin, and oxypaeoniflorin) in traditional Chinese medicine, Moutan Cortex (root cortex of Paeonia suffruticosa Andrews). The effects of several important factors, such as the concentration of running buffer, the separation voltage, the injection time, and the detection potential, were investigated to determine the optimum conditions. The detection electrode was a 300 microm diameter carbon-disc electrode at a working potential of +0.90 V (versus SCE). The three analytes could be well separated within 7 min in a 40 cm length fused-silica capillary at a separation voltage of 12 kV in a 50 mM borate buffer (pH 9.2). The relation between the peak current and the analyte concentration was linear over 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.4 to 0.7 microM for all analytes. The proposed method has been successfully applied to the determination of paeonol, benzoyloxypaeoniflorin, and oxypaeoniflorin in real plant samples with satisfactory assay results.     

毛细管电泳-柱端安培检测测定莲子心中荷叶碱、芦丁和金丝桃甙的含量

采用毛细管电泳-柱端安培检测测定莲子心中荷叶碱、芦丁和金丝桃甙的含量．研究了检测电位、运行缓冲液浓度和pH值,分离电压和进样时间对分离和检测的影响．以微碳圆盘电极（Ф=0.5ram）为工作电极,检测电位为＋0．95V（vs．Ag／AgCl）,pH为7．25的50mmol／L Na2B4O7和100mmol／L NaH2PO4缓冲液为运行液,当分离电压为15kV时,3种分析物在15min内完全分离．荷叶碱、芦丁和金丝桃甙的检出限（S／N=3）分别为0．02μg／mL、0．05μg／mL和0．04μg／mL．该方法已成功地应用于莲子心中上述3种活性成分的测定．     

Determination of puerarin, daidzein and rutin in Pueraria lobata (Wild.) Ohwi by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection was developed for the determination of puerarin, daidzein and rutin. Effects of several important factors such as the acidity and concentration of running buffer, separation voltage, injection time, and detection potential were investigated to acquire the optimum conditions. The working electrode was a 300-microm diameter carbon disc electrode positioned opposite the outlet of capillary. The three analytes could be well separated within 12 min in a 40 cm length capillary at a separation voltage of 9 kV in a 50 mmol/l borate buffer (pH 9.0). The relationship between peak currents and analyte concentrations was linear over about three orders of magnitude with detection limits (SIN=3) ranging from 0.241 x 10(-6) to 0.511 x 10(-6) mol/l for all compounds. This proposed method demonstrated long-term stability and reproducibility with relative standard deviations of less than 5% for both migration time and peak current (n=7). It has been successfully applied for the determination of puerarin, daidzein and rutin in Chinese traditional drugs, the vines of Pueraria lobata (Wild.) Ohwi and Puerariae Radix.