The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Hui Chen - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Yang Ni, Ying Zhou, Mingzhen Xu, Xiaomeng He, Huqun Li, Satter Haseeb, Hui Chen, Weiyong LiAbstract:Abstract A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile–20 mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m / z 150.0/91.0 for phentermine, m / z 452.1/344.3 for Doxazosin, and negative m / z 338.3/77.9 for topiramate, m / z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1–800 ng mL −1 for phentermine, 1–1000 ng mL −1 for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Ying Zhou, Satter Haseeb, Hui ChenAbstract:A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile-20mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 150.0/91.0 for phentermine, m/z 452.1/344.3 for Doxazosin, and negative m/z 338.3/77.9 for topiramate, m/z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1-800 ng mL(-1) for phentermine, 1-1000 ng mL(-1) for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of <15% at all concentrations. Blood samples were collected into heparinized tubes before and after administration. The simple and robust LC/MS/MS method was successfully applied for the simultaneous determination of phentermine and topiramate in a pharmacokinetic study in healthy male Chinese volunteers.
Ying Zhou - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Yang Ni, Ying Zhou, Mingzhen Xu, Xiaomeng He, Huqun Li, Satter Haseeb, Hui Chen, Weiyong LiAbstract:Abstract A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile–20 mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m / z 150.0/91.0 for phentermine, m / z 452.1/344.3 for Doxazosin, and negative m / z 338.3/77.9 for topiramate, m / z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1–800 ng mL −1 for phentermine, 1–1000 ng mL −1 for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Ying Zhou, Satter Haseeb, Hui ChenAbstract:A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile-20mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 150.0/91.0 for phentermine, m/z 452.1/344.3 for Doxazosin, and negative m/z 338.3/77.9 for topiramate, m/z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1-800 ng mL(-1) for phentermine, 1-1000 ng mL(-1) for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of <15% at all concentrations. Blood samples were collected into heparinized tubes before and after administration. The simple and robust LC/MS/MS method was successfully applied for the simultaneous determination of phentermine and topiramate in a pharmacokinetic study in healthy male Chinese volunteers.
Weiyong Li - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Yang Ni, Ying Zhou, Mingzhen Xu, Xiaomeng He, Huqun Li, Satter Haseeb, Hui Chen, Weiyong LiAbstract:Abstract A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile–20 mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m / z 150.0/91.0 for phentermine, m / z 452.1/344.3 for Doxazosin, and negative m / z 338.3/77.9 for topiramate, m / z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1–800 ng mL −1 for phentermine, 1–1000 ng mL −1 for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of
Satter Haseeb - One of the best experts on this subject based on the ideXlab platform.
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Yang Ni, Ying Zhou, Mingzhen Xu, Xiaomeng He, Huqun Li, Satter Haseeb, Hui Chen, Weiyong LiAbstract:Abstract A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile–20 mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m / z 150.0/91.0 for phentermine, m / z 452.1/344.3 for Doxazosin, and negative m / z 338.3/77.9 for topiramate, m / z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1–800 ng mL −1 for phentermine, 1–1000 ng mL −1 for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of
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simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography tandem mass spectrometry with positive negative ion switching electrospray ionization and its application in pharmacokinetic study
Journal of Pharmaceutical and Biomedical Analysis, 2015Co-Authors: Ying Zhou, Satter Haseeb, Hui ChenAbstract:A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile-20mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin Mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 150.0/91.0 for phentermine, m/z 452.1/344.3 for Doxazosin, and negative m/z 338.3/77.9 for topiramate, m/z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1-800 ng mL(-1) for phentermine, 1-1000 ng mL(-1) for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of <15% at all concentrations. Blood samples were collected into heparinized tubes before and after administration. The simple and robust LC/MS/MS method was successfully applied for the simultaneous determination of phentermine and topiramate in a pharmacokinetic study in healthy male Chinese volunteers.
Chris H Senanayake - One of the best experts on this subject based on the ideXlab platform.
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practical chemical and enzymatic technologies for s 1 4 benzodioxan 2 carboxypiperizine intermediate in the synthesis of s Doxazosin Mesylate
Tetrahedron-asymmetry, 2001Co-Authors: Kevin Q Fang, Paul Grover, Fran X Mcconville, Richard F Rossi, Damase J Olsson, Donald W Kessler, Stephen A Wald, Chris H SenanayakeAbstract:Abstract ( S )-1,4-Benzodioxan-2-carboxypiperazine ( S )- 2 , the key chiral intermediate for the synthesis of ( S )-Doxazosin, was prepared utilizing two approaches: (i) enzymatic resolution of ethyl 1,4-benzodioxan-2-carboxylate with an esterase ( Serratia ) followed by amide formation; (ii) direct resolution of 1,4-benzodioxan-2-carboxypiperazine 2 with d -tartaric acid. An efficient process for the conversion of ( S )- 2 to ( S )-Doxazosin Mesylate was developed (80% yield, 99.9% e.e.).