Publications (19)54.44 Total impact
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Article: Ionic liquids coated multi-walled carbon nanotubes as a novel pseudostationary phase in electrokinetic chromatography.
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ABSTRACT: A new CE system using ionic liquids coated multi-walled carbon nanotubes (ILs-MWNTs) as pseudostationary phase was developed for the simultaneous determination of four flavonoids, four phenolic acids and two saponins. Several parameters affecting the separation were studied, including the choice of ILs, ILs-MWNTs concentration, the respective use of ILs and MWNTs, buffer pH, SDS concentration and borate content. Results revealed that the addition of ILs-MWNTs in running electrolytes enhanced the separation of target compounds compared to conventional micelle because the surface of carbon nanotubes interacted favorably with the analytes. Under the optimum conditions, a baseline separation was achieved for these analytes within 11 min in a 41.5 cm of effective length fused-silica capillary. At a voltage of 28.0 kV, the separation was carried out in a 10mM borate buffer (pH 9.0) containing 100mM SDS, 6% propanol and 4 μg mL(-1) ILs-MWNTs. All calibration curves showed good linearity (r(2)>0.9990) within the test ranges. The intra- and inter-day precisions as determined from standard solutions were below 3.30% and 6.23%, respectively. The recoveries for ten compounds were found to range from 85.5 to 101.8%. The method was successfully applied for the determination of three types of compounds in Qishenyiqi dropping pills. Our experimental results indicated that the proposed method offered new opportunities for the analysis of complex samples.Journal of chromatography. A 11/2011; 1218(52):9428-34. · 4.19 Impact Factor -
Article: On-line concentration of neutral analytes by complexation and acetonitrile sweeping in nonionic microemulsion electrokinetic chromatography with direct ultraviolet detection.
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ABSTRACT: To separate and detect neutral solutes in nonionic microemulsion electrokinetic chromatography (MEEKC), a novel method was developed, combining complex formation and acetonitrile (ACN) sweeping. In this report, dynamic borate complexation and on-line sweeping occurred simultaneously during a run. The operating parameters which affected the performance of analyte sweeping in nonionic MEEKC were examined in terms of borate complexation, ACN content, Brij-35 concentration and sample plug length. In addition, the validation of the method included tests of the limit of detection, reproducibility and sensitivity enhancement. 60-110-Fold of magnitude improvement in detection sensitivity for model compounds (ginsenoside Rf, ginsenoside Rb2, ginsenoside Re) using Brij-35 microemulsion was demonstrated. Furthermore, the method was applied to the determination of glucosides in the plant extract.Journal of chromatography. A 08/2009; 1216(29):5608-13. · 4.19 Impact Factor -
Article: Direct on-line analysis of neutral analytes by dual sweeping via complexation and organic solvent field enhancement in nonionic MEKC.
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ABSTRACT: Conventionally, neutral compounds cannot be separated by nonionic micelle capillary electrophoresis. In this report, the development of a novel on-line preconcentration technique combining dual sweeping based on complexation and organic solvent field enhancement is applied to the sensitive and selective analysis of three neutral glucosides: ginsenoside Rf, ginsenoside Rg1, and ginsenoside Re. Nonionic micelle detectability by CE is demonstrated through effective focusing of large sample volumes (up to 38% capillary length) using a dual sweeping mode. This results in a 50- to 130-fold improvement in the LODs relative to conventional injection method. Neutral compounds sweeping is examined in terms of analyte mobility dependence on borate complexation, solvent viscosity difference, and Brij-35 interaction. Enhanced focusing performance by this hyphenated method was demonstrated by a greater than fourfold reduction in glucoside bandwidth, as compared with common sweeping (devoid of organic solvent-mediated sweeping method in the sample matrices). Moreover, separation efficiencies greater than a million theoretical plates can be achieved by sweeping large sample volumes into narrow zones. The designated method was also tested for its ability to determine the presence of glucosides in the crude extracts obtained from plant sample.Electrophoresis 05/2009; 30(8):1372-9. · 3.30 Impact Factor -
Article: Determination of sweroside in rat plasma and bile for oral bioavailability and hepatobiliary excretion.
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ABSTRACT: Sweroside is an active ingredient of iridoid glycoside isolated from the flower buds of Lonicera japonica THUNB. A quantitative HPLC-UV method was developed for monitoring sweroside in rat plasma, urine, feces and bile. The method was successfully applied for a basic pharmacokinetic study. The obtained data of pharmacokinetics were applied to evaluate the oral bioavailabilities of sweroside and the active ingredients of purified herbal extracts (IGEs-1). The absolute bioavailability was estimated to F(sweroside) 0.31% and F(IGEs-1) 0.67%. The majority of sweroside excreted to feces revealed one reason of the low oral bioavailability. The values of F(IGEs-1) much higher than that of F(sweroside) reveals that ingredients in IGEs-1 such as loganin, secoxyloganin and some phenolic acids may promote the absorption of sweroside. The study of hepatobiliary excretion was achieved by an in vivo microdialysis sampling method after intravenous administration of sweroside. The percentage of accumulation of free form sweroside in bile duct was 31.2+/-7.2% of the total dosage. It may be one reason why sweroside possesses strong hepatoprotective effect.CHEMICAL & PHARMACEUTICAL BULLETIN 02/2009; 57(1):79-83. · 1.59 Impact Factor -
Article: Determination of Phenolic Acids in Danshen Preparations by LC with Chemiluminescence Detection
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ABSTRACT: A simple and sensitive method has been developed for the simultaneous determination of eight phenolic acids in Danshen preparations based on liquid chromatography with chemiluminescence detection. Chemiluminescence parameters including flow rate, buffer pH, the concentration of luminescent and reactive solutions, were optimized. The analytical performance of the optimized luminol-H2O2 detection was compared with those of luminol-pyrogallol and UV detection. Under the optimized conditions, the method was validated with respect to linearity, precision, limits of detection and quantification. The method offers an attractive alternative to be used to evaluate the quality of Danshen preparations.Chromatographia 01/2009; 69(3):319-323. · 1.20 Impact Factor -
Article: High-speed separation and characterization of major constituents in Radix Paeoniae Rubra by fast high-performance liquid chromatography coupled with diode-array detection and time-of-flight mass spectrometry.
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ABSTRACT: A fast high-performance liquid chromatography (HPLC) method coupled with diode-array detection (DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) has been developed for rapid separation and sensitive identification of major constituents in Radix Paeoniae Rubra (RPR). The total analysis time on a short column packed with 1.8-microm porous particles was about 20 min without a loss in resolution, six times faster than the performance of a conventional column analysis (115 min). The MS fragmentation behavior and structural characterization of major compounds in RPR were investigated here for the first time. The targets were rapidly screened from RPR matrix using a narrow mass window of 0.01 Da to restructure extracted ion chromatograms. Accurate mass measurements (less than 5 ppm error) for both the deprotonated molecule and characteristic fragment ions represent reliable identification criteria for these compounds in complex matrices with similar if not even better performance compared with tandem mass spectrometry. A total of 26 components were screened and identified in RPR including 11 monoterpene glycosides, 11 galloyl glucoses and 4 other phenolic compounds. From the point of time savings, resolving power, accurate mass measurement capability and full spectral sensitivity, the established fast HPLC/DAD/TOFMS method turns out to be a highly useful technique to identify constituents in complex herbal medicines.Rapid Communications in Mass Spectrometry 01/2009; 23(1):119-30. · 2.79 Impact Factor -
Article: Separation and on-line preconcentration by stacking and sweeping of charged analytes in the plant by microemulsion electrokinetic chromatography with nonionic surfactants.
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ABSTRACT: A novel on-line technique for stacking and sweeping of long sample plugs with simultaneous determination of charged analytes in the plant (protocatechuic aldehyde, rosmarinic acid, danshensu, salvianolic acid B, and protocatechuic acid) by the nonionic microemulsion electrokinetic chromatography (MEEKC) is presented. The preconcentration efficiency provided about 9-28-fold for stacking and 7-14-fold for sweeping in the enhancements of LOD. The effects of oil phase, Brij-35 and buffer concentrations on stacking and sweeping efficiency were examined in order to optimize the two methods. In nonionic MEEKC, the effect of the type of oil and buffer contents on preconcentration mechanism is often sophisticated. This study had demonstrated that the oil type and buffer content in nonionic microemulsion indeed markedly altered the affinity of microemulsion with analytes. Finally, in comparison to the stacking method, the most apparent disadvantages of the sweeping method were the relatively high limits of detection and poor peak shapes.Journal of Pharmaceutical and Biomedical Analysis 12/2008; 49(2):475-80. · 2.97 Impact Factor -
Article: Simultaneous Determination of Twelve Saponins in Radix et Rhizoma Notoginseng by Rapid Resolution LC-ESI-TOF-MS
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ABSTRACT: Rapid resolution liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry was developed for simultaneous determination of twelve saponins in Radix et Rhizoma Notoginseng (RRN) with macranthoidine A as internal standard. All calibration curves showed good linear regression (r 2>0.9935) within test range. The limits of detection of the twelve compounds were in the range of 1.53–5.08ngmL−1. This method was successfully applied to analyze the saponins in fifteen samples of RRN.Chromatographia 11/2008; 68(11):1033-1038. · 1.20 Impact Factor -
Article: Pressure and electrokinetic injections for on-line sample stacking neutral analytes in microemulsion electrokinetic chromatography with salt-containing matrixes.
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ABSTRACT: An on-line technique for pressure and electrokinetic injections of long sample plugs with simultaneous stacking of neutral analytes (notoginsenoside R(1), ginsenoside Rg(1), ginsenoside Rf, ginsenoside Rh(1), ginsenoside Rd, ginsenoside Rg3) in microemulsion electrokinetic chromatography is presented. The effects of salt concentration, sample plug length, organic modification of the sample matrix, oil phase and SDS concentration on stacking efficiency were examined in order to optimize the two injection methods. In microemulsion electrokinetic chromatography, the effect of the type of oil and SDS content on stacking mechanism is often sophisticated. This study had demonstrated that the oil type and SDS content in microemulsion indeed markedly altered the affinity of microemulsion with analytes. Finally, in comparison with the electrokinetic injection method, the most apparent disadvantages of the pressure injection method were the relatively high LOD and poor reproducibility.Electrophoresis 11/2008; 29(21):4422-30. · 3.30 Impact Factor -
Article: Rapid and sensitive quantitation of major constituents in Danggui Buxue Tang by ultra-fast HPLC-TOF/MS.
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ABSTRACT: A quantitative method by ultra-fast HPLC coupled with time-of-flight mass spectrometry (TOF/MS) has been developed for analysis of 15 major constituents in Danggui Buxue Tang (DBT) preparations. Its performance was compared with a conventional HPLC method with diode array detection/evaporative light scattering detection (DAD/ESLD). Accurate mass measurements within 3ppm error were obtained for all the compounds. The analytical time by an ultra-fast system is 4 times faster than conventional HPLC, the limits of detection by TOF/MS are low to 0.004-0.08ng compared with 1-200ng for HPLC-DAD-ELSD, and acceptable linearity of response was demonstrated over two orders of magnitude (r(2)>0.99) for all analytes. Intra-day reproducibility was below 3% and inter-day values were below 5% R.S.D. Robustness and applicability of the method was validated for the analysis of market DBT real samples, proposing a rapid, sensitive and validated method for routine analysis and quality control of DBT.Journal of Pharmaceutical and Biomedical Analysis 11/2008; 49(2):502-7. · 2.97 Impact Factor -
Article: Identification of key metabolites of tectorigenin in rat urine by HPLC-MS(n).
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ABSTRACT: This is a report about the identification of key metabolites of tectorigenin in rat urine using high-performance liquid chromatography-electrospray ionization ion trap tandem mass spectrometric method (HPLC-ESI-MS(n)). Six healthy rats were administered a single dose (80 mg/kg) of tectorigenin by oral gavage. Urine was sampled for 0-24 h and centrifuged at 12,000 rpm for 10 min to obtain the supernatants, then the supernatants were purified by solid-phase extraction with a C(18) cartridge. The chromatographic separation was carried out on a reversed-phase C(18) column with a gradient elution program whereas acetonitrile-0.1% formic acid water was used as mobile phase. Mass spectra were acquired in negative ionization mode and a data-dependant scan was used for the identification of the key metabolites of tectorigenin in the urine samples. As a result, four phase II metabolites and the parent drug tectorigenin were found and identified in rat urine for the first time.Biomedical Chromatography 10/2008; 23(2):219-21. · 1.97 Impact Factor -
Article: Application of liquid chromatography-electrospray ionization time-of-flight mass spectrometry for analysis and quality control of compound Danshen preparations.
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ABSTRACT: A liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry (LC-ESI-TOF-MS) method has been developed to evaluate the quality of three formulas of compound Danshen preparations (CDPs), through a simultaneous determination of 22 marker constituents (nine major phenolic acids, eight major saponins and five major diterpenoids). Optimum separations were obtained with a Zorbax C(18) column, using a gradient elution with 0.1% aqueous formic acid and acetonitrile. Limits of detection and quantification were in ranges of 1.58-10.10 and 4.85-28.56 ng/mL. All calibration curves showed good linear regression (r(2 ) > 0.9900) within the test range, and the recoveries were between 78.4 and 103.1% for all analytes. The assay was successfully utilized to analyze the 22 marker components in 26 samples. The overall results demonstrated that this method is sensitive, accurate and reliable for the quality control of CDPs.Biomedical Chromatography 10/2008; 23(4):397-405. · 1.97 Impact Factor -
Article: The antioxidant-activity-integrated fingerprint: an advantageous tool for the evaluation of quality of herbal medicines.
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ABSTRACT: The activity-integrated fingerprints of Danshen injections have been established by high-performance liquid chromatography coupled with chemiluminescence detection (HPLC-CL) according to their antioxidants activity scavenging hydrogen peroxide. The authentication and validation of the activity-integrated fingerprints were performed. Then, a data-level information fusion method was employed to capture the chemical and antioxidant information encoded in HPLC-CL fingerprints. Finally, based on the fusion results, the quality of different batches of Danshen injections samples were further evaluated by similarity measure. In comparison with conventional fingerprints, the activity-integrated fingerprints, which simultaneously contained the chemical characteristics and antioxidant activities of constitutions could comprehensively and properly reveal the quality characteristics of the Danshen injections. In conclusion, the antioxidant-activity-integrated fingerprints were suitable for quality control of Danshen injections. This study could clearly demonstrate that the activity-integrated fingerprint was a powerful and meaningful tool to comprehensively improve the quality control of complex herbal medicines.Journal of Chromatography 09/2008; 1208(1-2):76-82. · 4.53 Impact Factor -
Article: Qualitative and quantitative analysis of Radix Astragali products by fast high-performance liquid chromatography-diode array detection coupled with time-of-flight mass spectrometry through dynamic adjustment of fragmentor voltage.
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ABSTRACT: A novel fast high-performance liquid chromatography (HPLC) method coupled with diode array detection (DAD) and time-of-flight mass spectrometry (TOF/MS) was developed for qualitative and quantitative analysis of Radix Astragali products. The potential of fast HPLC on 1.8-microm particles was compared with the performance of HPLC on conventional 5-microm particles columns. Significant advantages of fast HPLC include high-speed chromatographic separation, four times faster than HPLC with conventional columns, and great enhancement in sensitivity with limits of detection low to 0.001 ng. With dynamic adjustment of fragmentor voltage in TOF/MS, an efficient transmission of the ions was achieved to obtain the best sensitivity and abundant fragmentation. By accurate mass measurements within 5 ppm error for each molecular ion and subsequent fragment ions, a reliable identification and differentiation of six major saponins including two groups of isomers and twelve main isoflavonoids was described here for the first time. For quantitative analysis by fast HPLC-TOF/MS, linearity of response over two orders of magnitude was demonstrated (r(2)>0.99) for all analytes. Intra-day reproducibility was below 3% RSD and inter-day values were below 5% RSD. A good correlation (slope=1.1108, r(2)=0.9853) was observed for accuracy test. It is concluded that the fast and sensitive HPLC-DAD-TOF/MS is powerful in qualitative and quantitative analysis of complex herbal medicines in terms of time savings, sensitivity, selectivity, precision, accuracy as well as increasing sample throughout and lowering solvent consumption.Journal of Chromatography 08/2008; 1203(1):27-35. · 4.53 Impact Factor -
Article: Rapid and sensitive screening and characterization of phenolic acids, phthalides, saponins and isoflavonoids in Danggui Buxue Tang by rapid resolution liquid chromatography/diode-array detection coupled with time-of-flight mass spectrometry.
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ABSTRACT: A novel rapid resolution liquid chromatography (RRLC) method coupled with diode-array detection (DAD) and time-of-flight mass spectrometry (TOFMS) in both positive and negative modes has been developed for quick and sensitive identification of the major compounds in Danggui Buxue Tang (DBT) preparation. Significant advantages of the use of RRLC with 1.8-microm porous particles include the much higher speed of chromatographic separation and great enhancement in sensitivity, compared with the conventional high-performance liquid chromatography (HPLC). With dynamic adjustment of the key role as fragmentor voltage in TOFMS, an efficient transmission of the ions was achieved to obtain the best sensitivity for providing the molecular formula for each analyte, and abundant fragment ions for structural information. The structural characterization of the major compounds in DBT was elucidated with authentic standards by DAD-TOF/MS, including phenolic acids, phthalides, saponins and isoflavonoids. The targets were rapidly screened from the complicated DBT matrix using a narrow mass window of 0.01 Da to restructure extracted ion chromatograms. By accurate mass measurements within 3 ppm error for each molecular ion and subsequent fragment ions, ten phenolic acids and phthalides including three groups of isomers, thirteen major saponins with a 20,24-epoxy-9,19-cyclolanostane-3,6,16,25-tetrol skeleton, sixteen isoflavonoids, corresponding glycosides, malonylglycosides, and acetylglycosides were identified in DBT preparation. The appropriate fragmentation pathways for them were also proposed based on definite elemental composition of the fragment ions.Rapid Communications in Mass Spectrometry 08/2008; 22(16):2493-509. · 2.79 Impact Factor -
Article: Comparison of oil-in-water and water-in-oil microemulsion electrokinetic chromatography as methods for the analysis of eight phenolic acids and five diterpenoids.
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ABSTRACT: Oil-in-water (O/W) and water-in-oil (W/O) MEEKC were compared for their abilities to separate and detect eight phenolic acids and five diterpenoids in Radix et Rhizoma Salviae Miltiorrhizae (RRSM). The effects of oil type and concentration, organic modifier, SDS, and buffer concentration on separation were examined in order to optimize the two methods. Oil contents and organic modifier were found to markedly influence the separation selectivity for both O/W and W/O systems. SDS concentration rarely affected separation resolution for O/W MEEKC, and separation of eight phenolic acids and five diterpenoids could be improved by changing the buffer concentration for W/O MEEKC. A highly efficient O/W MEEKC separation method, where the 13 compounds were separated with baseline resolution, was achieved by using a microemulsion solution of pH 8.0 containing 0.6% cyclohexane, 3.0% SDS, 6.0% 1-butanol, and 3.0% ACN. The W/O MEEKC was unable to resolve all the components. In addition, the analytic time in O/W MEEKC was shorter than that in W/O MEEKC. Finally, the developed O/W MEEKC method was successfully applied to determine analytic compounds in RRSM samples.Electrophoresis 07/2008; 29(11):2310-20. · 3.30 Impact Factor -
Article: Comparison of oil‐in‐water and water‐in‐oil microemulsion electrokinetic chromatography as methods for the analysis of eight phenolic acids and five diterpenoids
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ABSTRACT: Oil-in-water (O/W) and water-in-oil (W/O) MEEKC were compared for their abilities to separate and detect eight phenolic acids and five diterpenoids in Radix et Rhizoma Salviae Miltiorrhizae (RRSM). The effects of oil type and concentration, organic modifier, SDS, and buffer concentration on separation were examined in order to optimize the two methods. Oil contents and organic modifier were found to markedly influence the separation selectivity for both O/W and W/O systems. SDS concentration rarely affected separation resolution for O/W MEEKC, and separation of eight phenolic acids and five diterpenoids could be improved by changing the buffer concentration for W/O MEEKC. A highly efficient O/W MEEKC separation method, where the 13 compounds were separated with baseline resolution, was achieved by using a microemulsion solution of pH 8.0 containing 0.6% cyclohexane, 3.0% SDS, 6.0% 1-butanol, and 3.0% ACN. The W/O MEEKC was unable to resolve all the components. In addition, the analytic time in O/W MEEKC was shorter than that in W/O MEEKC. Finally, the developed O/W MEEKC method was successfully applied to determine analytic compounds in RRSM samples.Electrophoresis 05/2008; 29(11):2310 - 2320. · 3.30 Impact Factor -
Article: Determination of fifteen bioactive components in Radix et Rhizoma Salviae Miltiorrhizae by high-performance liquid chromatography with ultraviolet and mass spectrometric detection.
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ABSTRACT: A high-performance liquid chromatographic (HPLC) method coupled with ultraviolet (UV) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) was established for simultaneous qualitative and quantitative determination of nine phenolic acids and six diterpenoids in Radix et Rhizoma Salviae Miltiorrhizae (RRSM). The optimal chromatographic conditions were achieved on a Zorbax C(18) column by gradient elution with 0.1% (v/v) aqueous formic acid and acetonitrile as mobile phase at the flow rate of 1.0 mL/min. The detection wavelength at 281 nm was chosen to determine the 15 bioactive components, namely danshensu (1), protocatechuic acid (2), protocatechuic aldehyde (3), caffeic acid (4), rosmarinic acid (5), lithospermic acid (6), salvianolic acid B (7), salvianolic acid A (8), salvianolic acid C (9); dihydrotanshinone I (10), cryptotanshinone (11), tanshinone I (12), methylene tanshiqunone (13), tanshinone IIA (14) and miltirone (15). Additionally, LC-ESI-TOF/MS was used to make definite identification of the constituents in samples in comparison with those reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, stability and recovery. The proposed method was successfully applied to quantify the 15 components in 21 samples; significant variations were demonstrated in the contents of the samples from diverse species and origins. The developed method could be used to effectively and comprehensively evaluate the quality of RRSM for its clinical safety and efficacy.Biomedical Chromatography 03/2008; 22(2):164-72. · 1.97 Impact Factor -
Article: Advances of modern chromatographic and electrophoretic methods in separation and analysis of flavonoids.
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ABSTRACT: Flavonoids, one of the largest groups of secondary metabolites, are widespread in vegetable crops such as herbs, fruits, vegetables, grains, seeds and derived foods such as juices, wines, oils, etc. They receive considerable attention due to their biological and physiological importance. Hundreds of publications on the analysis of flavonoids have appeared over the past decade. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review intends to provide an updated, concise overview on the recent development and trends of separation, identification and quantification for flavonoids by modern chromatographic and spectrophotometric analytical techniques, including gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). The sample preparation before analysis is also briefly summarized.Molecules 02/2008; 13(10):2521-44. · 2.39 Impact Factor
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Institutions
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2011
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Hangzhou Normal University
Hangzhou, Zhejiang Sheng, China
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2008–2009
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China Pharmaceutical University
Nanjing, Jiangxi Sheng, China
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