Publications (8)23.71 Total impact
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Article: Non-aqueous capillary electrophoresis for simultaneous separation and determination of three major active components in traditional medicinal preparations.
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ABSTRACT: A simple and sensitive non-aqueous capillary electrophoresis method has been developed for simultaneous assay of three bioactive components (puerarin, daidzein and wogonin) in three traditional medicinal preparations for the first time. Optimum separation of the analytes was obtained on a 47 cm x 75 microm i.d. capillary using a non-aqueous buffer system of 20% acetonitrile, 25 mm ammonium acetate and apparent pH 9.00, with applied voltage and capillary temperature of 20 kV and 16 degrees C, respectively. The relative standard deviations (RSDs) of the migration times and the peak areas of the three analytes were in the ranges 2.5--4.0% and 3.2--3.9%, respectively. Detection limits of puerarin, daidzein and wogonin were 0.090, 0.145 and 0.090 microg mL(-1), respectively. In the tested concentration range, good linear relationships (correlation coef fi cients: 0.9998 for puerarin, 0.9998 for daidzein and 0.9978 for wogonin) between peak areas and concentrations of the analytes were observed. This method has been successfully applied to simultaneous determination of the three bioactive components with recoveries from 91.0 to 114.0%.Biomedical Chromatography 07/2005; 19(5):369-74. · 1.97 Impact Factor -
Article: A novel double coating for microemulsion electrokinetic chromatography with laser-induced fluorescence detection: as tested with amino acid derivatives.
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ABSTRACT: A novel double coating (DC) was developed for fast and reproducible microemulsion electrokinetic chromatography (MEEKC), as tested with separation and determination of amino acids using laser-induced fluorescence (LIF) detection after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazol. The simple coating is a combination of a removable covalent layer and a dynamic SDS coating. Hexamethyldisilazane was utilized for the covalent layer that can be regenerated on-line. Compared with previous no-coating method, the analysis time was shortened; and the reproducibility of migration times was improved.Journal of Pharmaceutical and Biomedical Analysis 10/2004; 36(1):1-8. · 2.97 Impact Factor -
Article: Micellar electrokinetic chromatography with laser-induced fluorescence detection for sensitive determination of ephedrine and pseudoephedrine.
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ABSTRACT: A selective and sensitive micellar electrokinetic chromatography method with laser-induced fluorescence detection was developed for the quantification of ephedrine (E) and pseudoephedrine (PE) derivatized with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. After conducting a series of optimizations, a running buffer of 10 mM sodium borate + 16 mM SDS was used for separation of the derivatives. A linear relationship for E and PE was obtained in the range of 0.044-6.6 microg mL(-1) (correlation coefficient: 0.9943 for E, 0.9946 for PE), and the detection limits for E and PE were 0.70 and 0.30 ng mL(-1), respectively. The sensitivity of E and PE was improved by several multiples of ten over those of CZE-LIF method. The method was applied to the analysis of the two alkaloids in ephedra herbal medicine and preparations with recoveries in the range of 98.3-107.1%.Journal of Separation Science 10/2004; 27(14):1211-4. · 2.73 Impact Factor -
Article: Investigation of the factors that induce analyte peak splitting in capillary electrophoresis.
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ABSTRACT: Peak splitting has a detrimental effect on analyses by capillary electrophoresis. Many papers have reported it and several mechanisms have been proposed to explain the phenomenon. We investigated the electrophoretic behavior of an amphoteric analyte, levodopa, in phosphate buffer and observed a peak splitting phenomenon at moderate sample concentrations and under general analytical conditions, even without organic solvent. The dependence of effective mobility on pH was taken into account and pKa values of 2.30, 8.11, and 9.92 were obtained for levodopa. Then, we constructed pH-dependent distribution diagrams of levodopa and phosphate species present in aqueous solution and proposed that the most relevant factors contributing to peak splitting are the presence of ionizable groups in the analyte molecule and the occurrence of ionization, yielding charged species which interacted with buffer electrolyte species in a definite pH range to form complexes. This result is different from those presented in the literature and broadens our understanding of amphoteric analyte peak splitting.Journal of Separation Science 09/2004; 27(12):1005-10. · 2.73 Impact Factor -
Article: Spectrofluorimetric study of the binding of daphnetin to bovine serum albumin.
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ABSTRACT: Daphnetin (7,8-dihydroxycoumarin), one of the major bioactive components isolated from Daphne odora (as glucoside), is a chelator, an antioxidant and a protein kinase inhibitor. In this paper, we report for the first time studies on the binding of daphnetin to bovine serum albumin (BSA) under physiological conditions with BSA concentration of 1.5 x 10(-6) mol l(-1) and drug concentration in the range of 6.7 x 10(-6) to 2.0 x 10(-5) mol l(-1). Fluorescence quenching spectra in combination with Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy was used to investigate the drug-binding mode, the binding constant and the protein structure changes in the presence of daphnetin in aqueous solution. The curvature of Scatchard plot indicates that daphnetin binds to more than one class of sites on BSA. The thermodynamic parameters, enthalpy change (deltaH) and entropy change (deltaS) were calculated to be -24.21 kJ mol(-1) and 19.30 J mol(-1) K(-1) according to van't Hoff equation, which indicated that hydrophobic and electrostatic interaction played main role in the binding of daphnetin to BSA.Journal of Pharmaceutical and Biomedical Analysis 06/2004; 35(3):671-7. · 2.97 Impact Factor -
Article: Binding of wogonin to human serum albumin: a common binding site of wogonin in subdomain IIA.
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ABSTRACT: The binding of wogonin to human serum albumin (HSA) has been studied by spectroscopic method including circular dichroism (CD), infrared spectra (IR) and fluorescence spectra. The fluorescence properties of HSA were examined in presence of wogonin and the fluorescence intensity of HSA was significantly decreased in the presence of wogonin. The binding parameters of wogonin were studied from the fluorescence decreasing of HSA by the fluoremetric titrations. The Stern-Volmer plots indicated that the binding of wogonin to HSA at 296, 303, 310 K is characterized by one binding site with the binding constant K(S-V) at 1.872 x 10(5), 1.561 x 10(5), 1.392 x 10(5), respectively, which are good agreement with the results from the Scatchard plots. The binding process was exothermic, enthalpy driven and spontaneous, as indicated by the thermodynamic analyses, and the major part of the binding energy is hydrophobic interaction, which were consistent with the result of molecule modelling study, and there are also a numbers of hydrogen bonds between wogonin and HSA. Furthermore, the displacement experiments indicate that wogonin can bind to the subdomain IIA, that is, the site I of HSA, which is also good agreement with the result of molecule modelling study.Journal of Photochemistry and Photobiology B Biology 04/2004; 74(1):39-45. · 2.81 Impact Factor -
Article: Microemulsion electrokinetic chromatography with laser-induced fluorescence detection for sensitive determination of ephedrine and pseudoephedrine.
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ABSTRACT: A selective and sensitive microemulsion electrokinetic chromatography with laser-induced fluorescence detection method was developed for the quantification of ephedrine (E) and pseudoephedrine (PE) derivatized with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazol. By a series of optimization, a running buffer composed of 20 mM borate + microemulsion (23.3 mM Sodium dodecyl sulfate/180.85 mM 1-butanol/16.4 mM n-heptane) +8% acetonitrile was applied for the separation of the derivatives. A linear relationship for E and PE was obtained in the range of 0.058-11.58 microg.mL(-1) (correlation coefficient: 0.9993 for E, 0.9995 for PE), and the detection limits for E and PE were 5.3 and 3.9 ng.mL(-1). The method was applied to the analysis of the two alkaloids in Chinese traditional herbal preparations with recoveries in the range of 96.9-105.4%.Electrophoresis 02/2004; 25(1):74-9. · 3.30 Impact Factor -
Article: Sensitive determination of ephedrine and pseudoephedrine by capillary electrophoresis with laser-induced fluorescence detection.
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ABSTRACT: A CE-LIF method was developed for the separation and sensitive detection of ephedrine and pseudoephedrine after derivatization by 4-chloro-7-nitrobenzo-2-oxa-1,3-diazol (NBD-C1). The derivatization and separation conditions were investigated in detail and the optimum conditions were obtained. Under the optimum experiment conditions, good linearity relationships (correlation coefficients: 0.9942 for ephedrine and 0.9970 for pseudoephedrine) between the peak heights and concentrations of the analytes were obtained (0.7-140 microM). The detection limits were 0.16 microM for ephedrine and 0.17 microM for pseudoephedrine, which indicated that the sensitivities were at least ten times improved over those reported in the literature obtained by UV detection. The method was applied to the analysis of ephedrine and pseudoephedrine in ephedra herb plants and preparations with good results.The Analyst 05/2003; 128(4):369-72. · 4.23 Impact Factor
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2004–2005
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Lanzhou University
Lanzhou, Gansu Sheng, China
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