针对目前测定季铵盐型阳离子表面活性剂常用方法存在的问题和不足 ,提出了一种新的测定方法——百里酚蓝 -亚甲蓝混合指示剂法 .该法采用了百里酚蓝和亚甲蓝两种常见的指示剂进行测定 ,与国际标准 ISO- 2 781法及传统亚甲蓝法进行比较 ,结果表明 ,采用本方法比国际标准方法药品易得 ,测定成本低 ,毒性小 ,操作方便 ,测定误差 <0 .3% (与国际标准方法等效 )比亚甲蓝法的测定结果 (误差 <1 % )准确度高 ,且终点变化明显 ,容易观察到 . Aiming at the existing problems and deficiencies of the commonly used methods for the determination of quaternary ammonium cationic surfactants, a new measuring method, thymol blue-methylene blue mixed indicator method, is proposed. The method uses thymol blue And methylene blue two kinds of common indicator, compared with the international standard ISO-2 781 method and the traditional methylene blue method, the results show that the use of this method is more accessible than the international standard method of drug, the determination of low cost, low toxicity , Easy to operate, determination of error <0.3% (equivalent to the international standard method) Determination of methylene blue method (error <1%) accuracy, and the end point changes significantly, easy to observe.