氨茶碱水分测定用溶剂的优化及与热分析法的比较

目的:为氨茶碱水分测定选择适宜溶剂;探讨氨茶碱分子中结晶水的数量.方法:采用费休氏水分测定法,以无吡啶卡氏试剂和含吡啶卡氏试剂为滴定液,以甲醇、氯仿-甲醇(1:1)、吡啶为溶剂测定氨茶碱的水分,用热重法测定氨茶碱的热失重.结果:以氯仿-甲醇(1:1)为溶剂测定氨茶碱水分,滴定终点易出现且样品能全部溶解;热分析结果表明:氨茶碱分子中可能含有不同数目的结晶水,实际样品可能是含不同数目结晶水的混合物.结论:以氯仿-甲醇(1:1)为溶剂测定氨茶碱水分结果准确;卡氏试剂中含有一定的吡啶可使测定结果灵敏度增加;<中国药典>2005年版收载的氨茶碱结构式中含有二分子结晶水似不够确切.

Solvent Optimization of Determing the Water Content in Aminophyllinum by Karl-Fischer Method and Comparison the Result with That Got by TG

Objective: The solvent for determining the water content in Aminophyllinum was optimized and the number of crystal water in Aminophyllinum was studied.Method: Karl-Fischer method was used,Karl-Fischer regents that contain pyridine and pyridine-free were used as titrants,methanol and chloroform-methanol(1:1)and pyridine were used as solvents,the weight loss in Aminophyllinum was determined by TG method.Result: When chloroform-methanol(1:1)was used as solvent the titrating end point was reached easily and the samples were Solubilized.The results of thermal analysis indicated that there are different number crystal water in Aminophyllinum sample.Conclusions: The result shown that Karl-Fischer method to determine water content in Aminophyllinum by using chloroform-methanol(1:1)as the solvent is more accurate,two crystal water in Aminophyllinum molecule suggested in Chinese Pharmacopoeia 2005 seems to be not accurate.