Wentao Liu

Shenyang Pharmaceutical University, Shenyang, Liaoning, China

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Publications (6)12.31 Total impact

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    ABSTRACT: A three-phase solvent bar microextraction (TPSBME) technique combined with high performance liquid chromatography (HPLC)–fluorescence detection was evaluated for the quantitative determination of plasma protein binding of bisoprolol. Bisoprolol was extracted from a 5.6-mL basified plasma sample (donor phase) into the organic solvent (n-octanol) impregnated in the pores of a hollow fiber and then extracted into an acidic solution (acceptor phase) inside the lumen of the hollow fiber. Metoprolol was used as the internal standard. Several parameters influencing the efficiency of the method were investigated and optimized including organic solvent (n-butanol, n-octanol, dibutyl phthalate, dihexyl ether), stirring rate (100–1,000rpm), extraction time (5–35min), extraction temperature (15–45°C), concentration of the donor phase (0.1–2M NaOH) and the acceptor phase (0.5–5M formic acid), salt concentration (2.5–10%, w/v). Under the optimal condition, extraction recoveries from plasma samples were above 61.4% for bisoprolol. The calibration curves were obtained in the range of 10–100ngmL−1 with reasonable linearity (r>0.994). The method was successfully applied to determine the plasma protein binding rate of bisoprolol. KeywordsSolvent bar microextraction–Bisoprolol–HPLC–Plasma
    Chromatographia 05/2011; 73(9):897-903. · 1.44 Impact Factor
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    ABSTRACT: A sensitive and efficient liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the determination of p-coumaric acid (CA) in rat plasma. After addition of the internal standard (IS) hydrochlorothiazide and acidification with 2 M hydrochloric acid, plasma samples were extracted by ethyl acetate and separated on a Kromasil C(18) column (200 mm × 4.6 mm, 5 μm) using a mobile phase composed of methanol-0.5‰ acetic acid (60:40, v/v) within a runtime of 6.0 min. Analysis was performed in selected ion monitoring (SIM) mode with a negative electrospray ionization (ESI) interface. The target ions were m/z 163.15 for CA and m/z 295.95 for IS. The linear range was 0.01-15 μg·mL(-1), and the lower limit of quantification (LLOQ) was 0.01 μg·mL(-1). The intraday and interday precision (RSD %) were lower than 10% and accuracy (RE%) ranged from 97.1 to 103.2%. The validated method was successfully applied to the comparative pharmacokinetic study of CA in rat plasma after oral administration of CA and freeze-dried red wine, respectively. It was found that both AUC and T(1/2) of CA in freeze-dried red wine were increased significantly (p < 0.05) compared with that in monomer. In addition, a double-peak profile could be observed from the concentration-time curve after oral administration of freeze-dried red wine.
    Journal of Agricultural and Food Chemistry 11/2010; · 3.11 Impact Factor
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    ABSTRACT: A simple and sensitive LC-MS method for the determination of periplocin in rat plasma was developed and validated. The chromatographic separation was carried out using a reverse-phase Kromasil C(18) column(150 × 4.6 mm, i.d., 5 µm) with a mobile phase composed of methanol-water (76:24, v/v). The flow rate of mobile phase was 0.8 mL/min. The calibration curve was linear within the concentration range 1-1000 ng/mL. The intra- and inter-day precisions across three validation days over the entire concentration range was lower than 9.2% in terms of relative standard deviation. Accuracy determined at three quality control concentrations ranged from -2.0 to 6.0% in terms of relative error. The validated method was applied to the pharmacokinetic study of periplocin in rat plasma after intravenous and intramuscular administration.
    Biomedical Chromatography 10/2010; 24(10):1089-93. · 1.95 Impact Factor
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    ABSTRACT: A sensitive fluorescence liquid chromatographic analytical method was developed for the simultaneous determination of carnosine enantiomers in rat plasma. The method was applied to pharmacokinetic studies. Chiral separation of carnosine enantiomers was achieved by pre-column derivatization with o-phthaldialdehyde and the thiol N-acety-l-cysteine as derivating reagents. They were separated on an ODS column and detected by fluorescence detection (λex = 350 nm, λem = 450 nm). γ-Aminobutyric acid was used as internal standard. The method was linear up to 6,000 ng mL−1 for l-carnosine, 4,000 ng mL−1 for d-carnosine. Low limit of quantitation (LLOQ) was 40 ng mL−1 for each isomer. The relative standard deviations obtained for intra- and inter-day precision were lower than 12% and the recoveries were higher than 75% for both enantiomers. The method was applied to a stereoselective study on the pharmacokinetics of carnosine after oral administration with a single dose (carnosine, 75 mg kg−1 for each isomer) to a rat. The initial data indicated that l-carnosine had a larger value of the highest plasma concentration than d-carnosine (C max 5,344 vs. 1,914 ng mL−1), and that of l-carnosine had a lower value of AUC(0−∞) and t 1/2(h) (AUC(0−∞) 5,306 vs. 6,321 ng h mL−1, t 1/2 1.43 vs. 3.37 h). Our results indicated that the pharmacokinetic of l-carnosine and d-carnosine revealed enantioselective properties significantly.
    Chromatographia 01/2010; 71(7):603-608. · 1.44 Impact Factor
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    ABSTRACT: The feasibility of using cloud-point extraction as a simple and effective means of recovery of memantine from rat plasma before LC–MS analysis has been demonstrated. A non-ionic surfactant Triton X-114 was used for extraction of the memantine. On increasing the temperature to the cloud point, phase separation occurred, resulting in an aqueous phase, and a surfactant-rich phase containing most of the analytes. The extraction conditions, for example amount of surfactant, temperature, NaOH concentration, and time of incubation, were optimized. Chromatographic separation was accomplished on a C18 analytical column with 56:44 (v/v) methanol–0.2% aqueous formic acid as isocratic mobile phase at a flow rate of 0.8mLmin−1. Under the optimum experimental conditions recovery was satisfactory (91–101%) without interference from the surfactant. The method was shown to be reproducible and reliable with intraday precision below 6.6%, interday precision below 14.3%, and linear range from 1 to 400ngmL−1. The method was successfully applied to a pharmacokinetic study of memantine in rats after oral and intravenous administration.
    Chromatographia 01/2009; 69(9):837-842. · 1.44 Impact Factor
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    ABSTRACT: A rapid, sensitive and selective high-performance liquid chromatography tandem mass spectrometric method (HPLC-MS) has been developed and validated for the simultaneous determination of matrine (MT), oxymatrine (OMT) and oxysophocarpine (OSP) in rat plasma after oral administration of Sophora flavescens Ait. extract using pseudoephedrine hydrochloride as an internal standard (I.S.). The three analytes were extracted from the plasma samples by liquid-liquid extraction with chloroform. The chromatographic separation was accomplished on a Kromasil C18 column (150 mm x 4.6 mm). Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The total run time was 12 min between injections. The assay had a lower limit of quantification of 1.0 ng/ml for MT, 2.0 ng/ml for OMT and 2.0 ng/ml for OSP using 200 microl of plasma. The calibration curves were linear in the measured range. The overall precision and accuracy for all concentrations of quality controls and standards was better than 15%. The proposed method enables unambiguous identification and quantification of MT, OMT and OSP in vivo. This was the first report on determination of the major quinolizidine alkaloids in rat plasma after oral administration of Sophora flavescens Ait. extract. The results provided a meaningful basis for evaluating the clinical applications of the herbal medicine.
    Journal of Pharmaceutical and Biomedical Analysis 09/2008; 47(4-5):892-8. · 2.95 Impact Factor