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Gengli Duan

Publications and source records attributed to Gengli Duan.

12 recordsLinked to original sources
PubMed2006

Development of gas chromatography-mass spectrometry with microwave distillation and simultaneous solid-phase microextraction for rapid determination of volatile constituents in ginger.

In this study, gas chromatography-mass spectrometry (GC-MS) following microwave distillation and solid-phase microextraction (MD-SPME) was developed for the analysis of essential oil compounds in fresh ginger. In the proposed method, the isolation, extraction and concentration of volatile components in ginger were carried out in one single step, using the MD-SPME technique, and the analytes on the SPME fiber were analyzed by GC-MS. Some parameters, including SPME fiber coating, microwave power and irradiation time, were optimized. The optimal experiment parameters obtained were: 65 microm PDMS/DVB SPME fiber, a microwave power of 400 W and an irradiation time of 2 min. To demonstrate its feasibility, MD-SPME was compared with conventional SPME for the extraction of essential oil compounds in fresh ginger. Using MD-SPME followed by GC-MS, 54 compounds were separated and identified in ginger, which mainly included geranial (5.25%), zingiberene (15.48%), beta-sesquiphellandrene (5.54%) and beta-phellandrene (22.84%), whereas only 39 compounds were separated and identified by conventional SPME followed by GC-MS. The relative standard deviation (R.S.D.) values of less than 10% show that the proposed method has good repeatability. The result show that MD-SPME, followed by GC-MS, is a simple, rapid, solvent-free method for the determination of volatile compounds in ginger.

Gas Chromatography-Mass Spectrometry↗
PubMed2006

Fast determination of curcumol, curdione and germacrone in three species of Curcuma rhizomes by microwave-assisted extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

Curcumol, germacrone and curdione are the main active ingredients in a common traditional Chinese medicine (TCM) of Rhizoma Curcuma, and commonly used as the TCM quality control markers. In the present work, microwave-assisted extraction (MAE) followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative analysis of curcumol, curdione and germacrone in Rhizoma Curcuma. The MAE and HS-SPME parameters were studied, and the method was validated. The optimal MAE conditions obtained were: microwave power of 700 W and irradiation time of 4 min, and HS-SPME optimal conditions were: fiber coating of 100 microm PDMS, extraction temperature of 80 degrees C, extraction time of 20 min, stirring rate of 1,100 rpm, and salt concentration of 30% NaCl. The proposed method provided good precision (RSD less than 12%) and recoveries between 86% and 93%. The proposed method was applied to the determination of the three marker compounds in three species of Curcuma rhizomes (Curcuma wenyujin, Curcuma phaeocaulis, and Curcuma kwangsiensis). To demonstrate the proposed method reliability, a conventional technique of steam distillation was also used for the analysis of curcumol, germacrone and curdione in the TCMs. The results show that MAE-HS-SPME is a simple, rapid, solvent-free and reliable method for the determination of curdione, curcumol and germacrone in TCM, and also a potential and powerful tool for quality assessment of Rhizoma Curcuma.

Curcuma↗
PubMed2006

Simultaneous determination of captopril and hydrochlorothiazide in human plasma by reverse-phase HPLC from linear gradient elution.

A simple, rapid and sensitive high-performance liquid chromatographic method for the simultaneous determination of captopril and hydrochlorothiazide in human plasma samples was developed. Captopril was derivatized with 2,4'-dibromoacetophenone (pBPB) to form a captopril-pBPB adduct. From acidified serum plasma samples, the hydrochlorothiazide and derivatized captopril was extracted with 5 ml ether, then with 5 ml dichloromethane. Effective chromatographic separation was achieved using a C(18) column (DIAMONSIL 150 mmx4 mm i.d., 5 microm) based on an acetonitrile-trifluoroacetic acid-water gradient elution at a flow rate of 1.2 ml/min. The internal standard (IS), derivatized captopril and hydrochlorothiazide were detected at 263 nm and were eluted at 4.2, 6.8 and 16.9 min, respectively. No endogenous substances were found to interfere. The limit of quantification for hydrochlorothiazide and derivatized captopril in plasma were 3.3 and 7 ng/ml. The calibration curve for derivatized captopril showed linearity in the range 20-4000 ng/ml, with a regression coefficient corresponding to 0.9993 and the coefficient of the variation of the points of the calibration curve being lower than 10%. The calibration curve for hydrochlorothiazide showed linearity in the range 10-1200 ng/ml, with a regression coefficient corresponding to 0.9999 and the coefficient of the variation of the points of the calibration curve being lower than 10%. The method was suitably validated and successfully applied to the determination of captopril and hydrochlorothiazide in human plasma samples.

Administration, Oral↗
PubMed2006

Determination of apomorphine in canine plasma by liquid chromatography-electrospray ionization mass spectrometry and its application to a pharmacokinetic study.

An LC-ESI-MS method was developed and validated for the assay of apomorphine in canine plasma using one-step liquid-liquid extraction. The analytes were separated on a Phenomenex Gemini C18 (150 mm x 2.0 mm id 3 microm) column and determined by MS in the positive ion mode. The linear range was 0.4-40 ng/mL with an LOD of 0.2 ng/mL for apomorphine in plasma. The intraday and interday precision and accuracy of quality control samples were < 5.9% RSD and < 7.5% bias for apomorphine. Extraction recoveries were > 80%. The validated method was successfully applied to analyze canine plasma samples in a pharmacokinetic study of apomorphine in dogs and detailed pharmacokinetic parameters were calculated.

Administration, Intranasal↗
PubMed2006

Development of water-phase derivatization followed by solid-phase microextraction and gas chromatography/mass spectrometry for fast determination of valproic acid in human plasma.

In this study, a simple, rapid, and sensitive method was developed and validated for the quantification of valproic acid (VPA), an antiepileptic drug, in human plasma, which was based on water-phase derivatization followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS). In the proposed method, VPA in plasma was rapidly derivatized with a mixture of isobutyl chloroformate, ethanol and pyridine under mild conditions (room temperature, aqueous medium), and the VPA ethyl ester formed was headspace-extracted and simultaneously concentrated using the SPME technique. Finally, the analyte extracted on SPME fiber was analyzed by GC/MS. The experimental parameters and method validations were studied. The optimal conditions were obtained: PDMS fiber, stirring rate of 1100 rpm, sample temperature of 80 degrees C, extraction time of 20 min, NaCl concentration of 30%. The proposed method had a limit of quantification (0.3 microg/mL), good recovery (89-97%) and precision (RSD value less than 10%). Because the proposed method combined a rapid water-phase derivatization with a fast, simple and solvent-free sample extraction and concentration technique of SPME, the sample preparation time was less than 25 min. This much shortens the whole analysis time of VPA in plasma. The validated method has been successfully used to analyze VPA in human plasma samples for application in pharmacokinetic studies. All these results show that water-phase derivatization followed by HS-SPME and GC/MS is an alternative and powerful method for fast determination of VPA in biological fluids.

Anticonvulsants↗
PubMed2006

Development of gas chromatography/mass spectrometry following headspace solid-phase microextraction for fast determination of asarones in plasma.

Asarones (alpha-asarone and beta-asarone) are the active components in the traditional Chinese medicine (TCM) of Acorus tatarinowii Schott, which has been used to treat epilepsy for several thousand years. To perform the pharmacokinetics (PK) study of alpha- and beta-asarone from the TCM essential oil, a simple, rapid and sensitive method was developed for the determination of asarones from the TCM in rabbit plasma, based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) with electron ionization (EI). The extraction parameters of headspace volume, fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized. Furthermore, the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg/mL, R(2) > 0.99), low detection limit (<2.0 ng/mL) and good precision (RSD < 7.0%). Finally, HS-SPME followed by GC/MS was applied to fast determination of alpha- and beta-asarone in rabbit plasma at different time points after oral adminstration of the essential oil from A. tatarinowii. The experimental results suggest that the proposed method provides an alternative approach to the PK studies of volatile compounds in TCMs.

Acorus↗
PubMed2005

Stability indicating reversed-phase ion-pairing liquid chromatographic determination of vertilmicin sulfate as bulk drug and in injections.

A simple reversed-phase high performance liquid chromatographic method was developed for the analysis of vertilmicin sulfate, a novel aminoglycoside (AG). UV detection was used to determine vertilmicin sulfate and its related compounds in drug substance and products without sample derivatization. The method was used to determine the content of vertilmicin and its related compounds and test the stability of vertilmicin sulfate as drug substance and in injections, which was required for registration of new drug.

Aminoglycosides↗
PubMed2004

Solid-phase microextraction-gas chromatography-mass spectrometric analysis of volatile compounds in a compounded Chinese medicinal prescription, Xiao-Cheng-Qi-Tang.

In this paper, a headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was applied for the analysis of volatile compounds in a famous compounded Chinese medicinal prescription, Xiao-Cheng-Qi-Tang. Some parameters affecting the extraction efficiency such as stirring, extraction temperature, fiber exposure time and desorption time were optimized. The best results were obtained using a 100 microm PDMS fiber during headspace extraction at 90 degrees C with stirring at 1000 rpm for 20 min. Twenty-seven compounds were identified in Xiao-Cheng-Qi-Tang including some main compounds such as d-limonene and linalool. Inter- and intra-day relative standard deviations (R.S.Ds.) were less than 15.6%, showing that the method had a good reproducibility. The result might provide some foundation for building the convincing theory on the pharmacological activity of this prescription.

Drugs, Chinese Herbal↗
PubMed2004

Headspace solid-phase microextraction and capillary gas chromatographic-mass spectrometric determination of rivastigmine in canine plasma samples.

A simple, rapid and sensitive method for determination of rivastigmine in plasma samples was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography with mass spectrometry (GC-MS). The optimum conditions for the SPME procedure were: headspace extraction on a 65-microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber; 0.5 ml of plasma modified with 1.0 ml of sodium hydroxide-sodium carbonate solution (0.7 M:0.5M); extraction temperature of 100 degrees C, with stirring at 2000 rpm for 30 min. The calibration curve showed linearity in the range from 0.2 to 80 ng/ml with regression coefficient corresponding to 0.9965 and coefficient of the variation of the points of the calibration curve lower than 10%. The quantification limit for rivastigmine in plasma was 0.2 ng/ml. The method was applied to determination of rivastigmine in canine plasma samples from animals after a single oral administration.

Animals↗
PubMed2002

Rapid determination of anastrozole in plasma by gas chromatography with electron capture detection and its application to an oral pharmacokinetic study in healthy volunteers.

A rapid, sensitive and accurate capillary gas chromatographic assay with (63)Ni electron capture detection was developed for the determination of anastrozole in human plasma. It comprises a one-step liquid-liquid extraction procedure and gas chromatography on a capillary column using constant oven temperature. This method has been applied to the oral pharmacokinetic study of anastrozole in healthy Chinese male volunteers. Pharmacokinetic parameters of two anastrozole preparations were evaluated after single, oral administrations to 18 subjects at a dose of 1 mg in a single-blind cross-over trial. Plasma anastrozole concentration-time profiles were best described by a two-compartment model. After oral administrations of imported and domestic anastrozole tablets, the t(max) and C(max) were 1.52 +/- 1.04 h and 8.75 +/- 3.03 ng/mL for the former, and 1.43 +/- 1.12 h and 9.44 +/- 3.59 ng/mL for the latter; the elimination half-life was 46.0 +/- 25.2 h vs 41.2 +/- 8.8 h, and the area under the curve (AUC) was 423 +/- 114 ng h/mL vs 444 +/- 157 ng h/mL. The result indicates that the two products are bioequivalent.

Administration, Oral↗
PubMed2002

[The method for determination of aconitum alkaloids in Radix Aconiti Kusnezoffii].

The methods for the determination of Aconitum alkaloids in Radix Aconiti Kusnezoffii were established. Volumetric analysis with the indicator of methyl red-bromcresol green and colorimetric analysis with acid dye of bromecresol green under the wavelength of 416 nm were used for the assay of total alkaloids. Colorimetric analysis of hydroxamic acid-Fe was for the assay of total ester-diterpene type Aconitum alkaloids. Three kinds of diester-diterpene type Aconitum alkaloids (aconitine, hypaconitine and mesaconitine) were determined by HPLC method. The HPLC system consisted of C18 as the stationary phase and acetonitrile: buffer (acetic acid-triethylamine, pH 6.25) = 71:29 as the mobile phase. The wavelength was 235 nm.

Aconitine↗