【摘要】 报导一种水溶液中测定弱酸弱碱性药物的固定ｐＨ滴定法。它以弱酸弱碱在水溶液中各种存在形式的分布系数与ｐＨ值的关系为理论依据，不要求滴定反应定量完成，是利用滴定到一定ｐＨ值时滴定剂消耗体积与弱酸碱物质的量之间的正比关系进行定量分析。离解常数小至１０－１２的极弱酸碱也适用。应用该法测定弱酸性药物盐酸左旋咪唑，结果与药典法一致，回收率在９９．６～１００．３％。试液浓度低至５×１０－４ｍｏｌ／Ｌ，也可用该法准确测定。操作简便、快速。制剂中的赋形剂及有色物无干扰。更多还原

【Abstract】 A simple,rapid and accurate titration method in aqueous solution for weak acidic and basic drugs,pH fixed titration,is reported.It is based on the fact that the distribution coefficients of various species of a weak acid or base in aqueous solution are constants at a fixed pH value.During the titration,the volume of the titrant consumed to reach a certain pH value is proportional to the amount of the weak acid or base in the solution.It is not necessary to ascertain the equivalent point and to know the concentration of the titrant.The method has been used to determine levamisole hydrochloide with very satisfactory results.The acid dissociation constant of the drug determined is 2×10 -9 .更多还原