应用库仑滴定法测定了新洁尔灭溶液中溴化苄烷铵的含量。用0.09 mol·L-1硝酸溶液和0.5%(w)明胶溶液以体积比10比1混合的混合溶液作电解液,银棒作阳极进行恒电流电解,电解电流为10 mA。电解过程中,从银电极释放出的Ag+与试液中溴化苄烷铵的Br-反应生成沉淀。Br-被完全沉淀时,电流上升,滴定到达终点,根据法拉第定律计算溴化苄烷铵的含量。溴化苄烷铵的质量浓度在0.422 8~1.480 g·L-1范围内与所消耗的电量之间呈线性关系。对同一样品的分析,本方法的测定结果与四苯硼钠滴定法的测定结果相符,本方法测定结果的相对标准偏差(n=6)为0.9%。用标准加入法进行回收试验,测得回收率在99.6%~102%之间。

Coulometric titrimetry was applied to the determination of benzalkonium bromide (BKB) in Xin Jie Er Mie liquid. A mixed solution of 0.09 mol·L-1 HNO3 solution and (w) 0.5% gelatin solution (10+1) was used as electrolytic solution, and silver rod was used as anode. A portion (5.00 mL) of the drug sample was added to the electrolyte and electrolyzed at a constant current of 10 mA. During electrolysis, precipitate of AgBr was formed between Ag+ liberated at the anode and Br- dissociated from BKB. When all the Br- was reacted and precipitated by Ag+, an abrupt increase of current occured denoting the end of titration. Content of BKB was calculated by the Faraday′s Law. Linear relationship between values of mass concentration of BKB and respective quantities of current consumed was kept in the range of 0.422 8-1.480 g·L-1 of BKB. In analysis of a same sample of the drug by this method and by the sodium tetraphenylboron titrimetry, consistent results were obtained by the 2 methods. Values of RSD (n=6) found for the coulometric titrimetric method was 0.9%. Values of recovery found by standard addition method were ranged from 99.6% to 102%.