自动电位滴定法测定阿司匹林肠溶片中总羧酸和阿司匹林的含量

Content determination of total carboxylic acid and aspirin in aspirin enteric-coated tablets by automatic potentiometric titration method

建立自动电位滴定法测定阿司匹林肠溶片中总羧酸和阿司匹林含量的方法。自动电位滴定法以p H突跃监测终点,直接取数片阿司匹林肠溶片用25 m L 60%中性乙醇溶解;用0.2 mol·L^(-1)氢氧化钠标准溶液滴定总羧酸的含量,该终点为终点1;终点1后继续加入2倍量以上氢氧化钠标准溶液,在搅拌下60℃水浴加热5min,迅速冷却至室温,用0.1 mol·L^(-1)的盐酸标准溶液返滴剩余氢氧化钠溶液测定阿司匹林的含量。方法用于阿司匹林肠溶片分析(n=5),羧酸和阿司匹林的平均加标回收率分别在100.3%~100.8%和99.62%~100.4%,RSD在0.47%~2.1%。该方法仪器简单,操作方便,实验结果准确,为2010年版中国药典阿司匹林肠溶片中阿司匹林含量测定的标准修订提供参考。

A method was established for determination contents of total carboxylic acid and aspirin in aspirin enteric-coated tablets by automatic potentiometrie？ titration？ method （APTM）. The end-point of titration was measured with potential jump by APTM. Aspirin enteric-coated tablets were dissolved with 25 mL 60% ethanol water solution and the total earboxylie acids was titra- ted directly with 0. 2 mol. L-1 sodium hydroxide standard solution and the end-point was named as terminal one. More than 2 times the amount of sodium hydroxide standard solution was added after the terminal one and a5 min water bathe heating was taken at 60~C under oscillating conditions, then cooled quickly to room temperature. 0. 1 mol. L-1 hydrochloric acid standard solution was used for back drop of residual sodium hydroxide solutionto determine the content of aspirin. The proposed method was applied in the analysis of samples of aspirin enteric-coated tablets, giving values of the average recovery of earboxylic acids and aspirin werel00. 3% ~ 100. 8% and 99.62%- 100. 4% respectively and RSD＇ s （ n = 5 ） in the range of 0.47%-2. 1%. The improved method is simple, accurate and feasible. It provided a reference for revising the quality standards of aspirin enteric-coated tablet in the 2010 edition of China Pharmacopoeia（ChP）.