刚果红光度法测定微量阳离子表面活性剂

Determination of Cationic Surfactants with Congo Red by Spectrophotometry

采用光度法研究了阳离子表面活性剂(CS)溴化十六烷基三甲铵(CTAB)、溴化十六烷基吡啶(CPB)与刚果红(CR)的显色反应。结果表明:在pH2.37的B-R缓冲液中,溴化十六烷基三甲铵(CTAB)、溴化十六烷基吡啶(CPB)均能与刚果红(CR)生成离子缔和物,最大吸收波长465nm,摩尔吸光系数分别为5.4×103 L.mol-1.cm-1(CTAB)、5.7×103 L.mol-1.cm-1(CPB),方法简便、快速,可用于水相中直接测定阳离子表面活性剂。探讨了酸度、温度、时间等反应条件对测定结果的影响,并应用于合成水样中进行微量阳离子表面活性剂的测定,取得满意的结果。

A spectrophotometric method is developed for the determination of cationic surfactants based on the formation of ion-aassociate compands of Congo red with cationic surfactants in aqueous solution . The maximum absorption exhibits at 465nm. the colour reaction conditions for CR-CS system isstudied.The result indicates that the colour reaction can be applied to direct spectrophotometric determination of cationic surfactants in aqueous solution.