电极法测定废水中氨氮

Determination of Ammonia-Nitrogen in Waste Water by Ion Selective Electrode-Potentiometry

介绍了采用电极法测定废水中氨氮时,以吹气法代替蒸馏法对废水水样进行预处理,简化了水样预处理的程序,样品中氨氮的释出率可达90%,加标回收率在60%-98.8%之间。对两种废水样各分析8次,得出其RSD值均小于5%。按3倍标准偏差计算方法的检出限为0.008 mg.L-1。定量测定的最高值为350 mg.L-1。

Direct potentiometric method with ion selective electrode （ISE） was used in the determination of ammonia nitrogen in waste water. Ammonia in the sample solution was liberated by adding an alkali solution of EDTA and expelled from the sample solution by air-blowing with a micro air-pump. The liberated ammonia was absorbed in dil. H2 SO4 and its potential measured with an ammonia gas sensitized ISE. The rate of liberation of ammonia from the sample solution achieved to values of 90%. Recovery of the method was tested by the standard addition method, and the results obtained were in the range of 60. 0%-98. 8%. RSD （n=8） found was less than 5%. Detection limit （3S） found was 0. 008 mg· L^-1, and the upper limit of determination was 350 mg · L^-1.