固定pH滴定法测定弱碱性药物西米替丁

Determination of Cimetidine by pH-fixed Titration Method

报导一种水溶液中测定弱酸弱碱性药物的新型滴定分析方法，固定ｐＨ滴定法。该法简单、快速、准确。其理论基础是弱酸弱碱在水溶液中各种存在形式的分布系数在ｐＨ值固定时为常数。用该法测定片剂中西米替丁，结果与药典法一致，回收率在９９．６～１００．

A simple, rapid and accurate new titration method in aqueous solution, pH-fixed titration, to determine weak acidic and basic drugs, is reported in this paper. It is based on the fact that the distribution coefficents of various species of a weak acid or base are constants at a fixed pH value. The method has been applied to the determination of cimetidine, a weak basic drug, in tablets. The results coincided with the phamacoopoeia's and recovery was in the range of 99 6￣100 2%.