羧甲司坦片(速效化痰片,羧甲基半胱氨酸片)为常用祛痰药,其含量测定方法中国药典采用溴酸钾滴定法,采用甲基红为指示剂,由于指示剂与滴定液的反应不可逆,因此滴定时需严格控制滴定的温度和速度,否则会出现假终点。本文采用电流滴定法,用溴酸钾滴定液滴定,永停滴定仪指示终点,终点时,稍有过量的滴定液即可使电极去极化,溶液中 Carboxystate tablets (quick-acting sputum tablets, carboxymethyl cysteine ​​tablets) as commonly used expectorants, the determination of content Chinese Pharmacopoeia using potassium bromate titration, the use of methyl red as an indicator, due to the indicator and titration Liquid reaction is not reversible, the titration should be strictly controlled titration temperature and speed, otherwise there will be false end point. In this paper, the current titration method, titration with potassium bromate titration, titration stop Yongtao end point, the end point, a little excess titration solution can make the electrode depolarization, the solution