The resolution of ibuprofen enantiomers was conducted on a chiral stationary phase of Kromasil CHI-TBB column (250 mm×4.6 mm I.D.,5 μm,Eka Chemicals AB, Bohus, Sweden).The thermodynamic properties of the enantio...The resolution of ibuprofen enantiomers was conducted on a chiral stationary phase of Kromasil CHI-TBB column (250 mm×4.6 mm I.D.,5 μm,Eka Chemicals AB, Bohus, Sweden).The thermodynamic properties of the enantiomers in supercritical/subcritical fluid chromatography were investigated in the ranges of 293—323 K and 12.0—21.0 MPa,and compared with those in high performance liquid chromatography in the range of 288—328 K.The mobile phases were isopropanol/carbon dioxide (2∶98, by mass), 690.0 ml·min -1 (at ambient temperature and pressure), and isopropanol/hexane (3∶97, by volume),2.0 ml·min -1,respectively.The plots of lnk′ and lnα versus 1/T were straight lines in HPLC.The plots of lnα versus 1/T were still straight lines but the linear relationship of lnk′ versus 1/T could not be observed in SFC. The differences of enthalpy changes and entropy changes for the transfer of enantiomers from the mobile phase to the stationary phase were calculated.In both cases,｜Δ R,SΔH0｜>｜TΔ R,SΔS0｜, therefore,the enthalpic contribution to the overall enantiomer transfer energy is more important than the entropic contribution in the temperature range examined, and furthermore, lower temperature is better for chiral resolution of ibuprofen.展开更多
致敏分散染料是生态纺织品安全性指标的重点内容之一,本文综述了Oeko-Tex Standard 100标准中22种致敏性分散染料的现代仪器分析技术研究进展,并对染料标准品的获取、染料定量定性情况,以及现有检测技术存在问题等进行展望,以期为致敏...致敏分散染料是生态纺织品安全性指标的重点内容之一,本文综述了Oeko-Tex Standard 100标准中22种致敏性分散染料的现代仪器分析技术研究进展,并对染料标准品的获取、染料定量定性情况,以及现有检测技术存在问题等进行展望,以期为致敏性分散染料检测方法的研究提供一些参考。展开更多
文摘The resolution of ibuprofen enantiomers was conducted on a chiral stationary phase of Kromasil CHI-TBB column (250 mm×4.6 mm I.D.,5 μm,Eka Chemicals AB, Bohus, Sweden).The thermodynamic properties of the enantiomers in supercritical/subcritical fluid chromatography were investigated in the ranges of 293—323 K and 12.0—21.0 MPa,and compared with those in high performance liquid chromatography in the range of 288—328 K.The mobile phases were isopropanol/carbon dioxide (2∶98, by mass), 690.0 ml·min -1 (at ambient temperature and pressure), and isopropanol/hexane (3∶97, by volume),2.0 ml·min -1,respectively.The plots of lnk′ and lnα versus 1/T were straight lines in HPLC.The plots of lnα versus 1/T were still straight lines but the linear relationship of lnk′ versus 1/T could not be observed in SFC. The differences of enthalpy changes and entropy changes for the transfer of enantiomers from the mobile phase to the stationary phase were calculated.In both cases,｜Δ R,SΔH0｜>｜TΔ R,SΔS0｜, therefore,the enthalpic contribution to the overall enantiomer transfer energy is more important than the entropic contribution in the temperature range examined, and furthermore, lower temperature is better for chiral resolution of ibuprofen.
