固定pH值法测定盐酸麻黄碱含量

本文根据固定ｐＨ法测定极弱酸碱原理，直接用ＮａＯＨ溶液滴定盐酸麻黄碱注射液中盐酸麻黄碱至某一固定ｐＨ值。通过ＮａＯＨ溶液消耗体积与盐酸麻黄碱含量成正比关系，用单标准法求得盐酸麻黄碱的含量。本法在滴定过程中不需确定化学计量点，不需标定滴定剂准确浓度，具有简单、快速、试剂消耗少、结果准确等优点。

Direct Determination of Ephedrine Hydrochloride by Means of pH fixed Titration

This paper introduces a method for determining dircetly the content of ephedrine hydrochloride in its injection, based upon the principle of pH fixed titration determining very weak acid or bases. The ephedrine hydrochloride in its injection is titrated to a fixed pH value by sodium hydroxide agueous solution. So the content of ephedrine hydrochioride can be determined by the proportional relation of the content to the volume of sodium hydroxide used in titrimetry. There is no need to know the concentration of the titrant and to ascertain the equivalent point. The method is simple and vapid. It only needs a little reagent and the results are very accurate.