磺胺多辛即磺胺邻二甲氧嘧啶是磺胺类药物，目前各国药典[1，2，3]都采用重氯化法，以永停满定法（即电流简定法）指示终点。重氯化滴定虽不是氧化还原反应，但当滴定至终点时，溶液中有多余的亚硝酸，电极即起氧化还原反应，使电位产生突跃’‘’，由此，我们利用自动电位滴定 Sulfadoxine or sulfamethazine is a sulfonamides, the current national pharmacopoeia [1,2,3] are used heavy chloride method to Yong stop full set (ie, current simple method) indicate the end point. Although the heavy chloride titration is not a redox reaction, but when the titration to the end point, the solution has excess nitrous acid, the electrode that redox reaction, so that potential potential jump ’’, thus, we use the automatic potentiometric titration