Two trace impurities in the bulk drug lisinopril were detected by means of high-performance liquid chromatography coupled with mass spectrometry （HPLC/MS） with a simple and sensitive method suitable for HPLC/MSn ana...Two trace impurities in the bulk drug lisinopril were detected by means of high-performance liquid chromatography coupled with mass spectrometry （HPLC/MS） with a simple and sensitive method suitable for HPLC/MSn analysis. The fragmentation behavior of lisinopfil and the impurities was investigated, and two unknown impurities were elucidated as 2-（6-amino- l-（l-carboxyethylamino）- l-oxohexan-2-ylamino）-4-phenylbutanoic acid and 6-amino-2-（l-carboxy-3-phenylpropylamino）-hexanoic acid on the basis of the multi-stage mass spectrometry and exact mass evidence, The proposed structures of the two unknown impurities were further confirmed by nuclear magnetic resonance （NMR） experiments after preparative isolation.展开更多
Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mi...Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mixtures is presented in attempt to address the discrepancy between the theoretical predictions and practical observations of cavitation rates in water at normal temperatures. The extension takes into account the non-equilibrium (dissipative) effects involved in nuclei formation through a substance dependent correction coefficient to be determined experimentally. The theory of thermodynamic fluctuations is applied to derive the work of formation of a bubble nucleus. The value of the correction coefficient is estimated using preliminary experimental data from a convergent-divergent nozzle. An application of the results to the numerical prediction of the cavitation zones in a radial-flow water pump is shown.展开更多
基金Project (No. 20772109) supported by the National Natural ScienceFoundation of China
文摘Two trace impurities in the bulk drug lisinopril were detected by means of high-performance liquid chromatography coupled with mass spectrometry （HPLC/MS） with a simple and sensitive method suitable for HPLC/MSn analysis. The fragmentation behavior of lisinopfil and the impurities was investigated, and two unknown impurities were elucidated as 2-（6-amino- l-（l-carboxyethylamino）- l-oxohexan-2-ylamino）-4-phenylbutanoic acid and 6-amino-2-（l-carboxy-3-phenylpropylamino）-hexanoic acid on the basis of the multi-stage mass spectrometry and exact mass evidence, The proposed structures of the two unknown impurities were further confirmed by nuclear magnetic resonance （NMR） experiments after preparative isolation.
文摘Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mixtures is presented in attempt to address the discrepancy between the theoretical predictions and practical observations of cavitation rates in water at normal temperatures. The extension takes into account the non-equilibrium (dissipative) effects involved in nuclei formation through a substance dependent correction coefficient to be determined experimentally. The theory of thermodynamic fluctuations is applied to derive the work of formation of a bubble nucleus. The value of the correction coefficient is estimated using preliminary experimental data from a convergent-divergent nozzle. An application of the results to the numerical prediction of the cavitation zones in a radial-flow water pump is shown.
