L-苹果酸在酮类溶剂中溶解度的测定及关联

通过测定NaCl的溶解度校核了溶解度测定装置 ,其平均误差为 0 .6 91% ,并用该装置测定了L -苹果酸在丙酮、丁酮中的溶解度。实验结果表明 ,L -苹果酸在丙酮及丁酮中有一定的溶解能力 ,且随着温度的增大溶解度变大 ,因此可利用类溶剂与L -苹果酸中的微量水开成恒沸物 ,除去L -苹果酸中的微量水再结晶 ,从而改进晶形。实验数据用Wilson、NRTL、UNIQUAC活度系数模型进行了关联 ,用UNIQUAC方程关联的平均误差最小 ,在丙酮及丁酮中的平均误差分别为 0 .11和 0 .12℃。用Wilson、NRTL方程关联也可得到较满意的结果。

醛、酮类有机溶剂中水分的测定

探讨了改进的卡尔-费休试剂对醛、酮类有机溶剂中水分的测定。用乙二醇甲醚、吡啶、二氧化硫和碘配制成卡尔-费休试剂,合理设置卡尔-费休滴定仪参数,测定戊醛中的水分。改进的卡尔-费休试剂测定戊醛中的微量水分准确度和精密度较好。乙二醇甲醚代替甲醇的卡尔-费休试剂在测定醛、酮类有机溶剂中水分的结果稳定性好、可靠性高、方便快捷,值得进一步推广使用。

A comparative study of conventional and supercritical fluid extraction methods for the recovery of secondary metabolites from Syzygium campanulatum Korth

Syzygium campanulatum Korth is a plant, which is a rich source of secondary metabolites （especially flavanones, chalcone, and triterpenoids）. In our present study, three conventional solvent extraction （CSE） techniques and supercritical fluid extraction （SFE） techniques were performed to achieve a maximum recovery of two flavanones, chalcone, and two triterpenoids from S. campanulatum leaves. Furthermore, a Box-Behnken design was constructed for the SFE technique using pressure, temperature, and particle size as independent variables, and yields of crude extract, individual and total secondary metabolites as the dependent variables. In the CSE procedure, twenty extracts were produced using ten different solvents and three techniques （maceration, soxhletion, and reflux）. An enriched extract of five secondary metabolites was collected using n-hexane：methanol （1：1） soxhletion. Using food-grade ethanol as a modifier, the SFE methods produced a higher recovery （25.5%-84.9%） of selected secondary metabo- lites as compared to the CSE techniques （0.92%-66.00%）.