高效气相分子吸收法快速测定水中氨氮  

An Improved Method on Rapid Determination of Ammonia Nitrogen in Water by Gas Phase Molecular Absorption Spectrometry

作　　者：周珂[1] 刘燕燕[1] 郑燕萍[1] 

机构地区：[1]武汉市环境监测中心站,湖北武汉430015

出　　处：《环境科学与技术》2013年第12期149-152,222,共5页Environmental Science & Technology

摘　　要：气相分子吸收光谱法是测定水中氨氮的新方法。国标方法（HJ/T195—2005）采用次溴酸盐氧化剂将水中的氨氮氧化为亚硝酸盐进行测定，而这一过程需要30min才能完成，且低温条件会影响其氧化程度和测定灵敏度。为了在低温条件下实现快速准确的测定，建立了盐酸-乙醇溶液预处理-高温氧化-气相分子吸收法测定水中氨氮的方法。即先在待测水样中加入1mL盐酸-乙醇混合溶液并煮沸，以消除NO2-、SO#-、硫化物等干扰物质；待冷却至60～70℃后迅速加入氧化剂混匀，定容后立即测定。改进后的方法不受环境温度的影响，约2min即可完整分析一个样船，灵敏度提高T60％，标准溶液平行测定RSD=O．9‰改进后的校准曲线稳定，既可提前配制，又可在应急监测中直接调用。将该法用于地表水和各类废水中氨氮的测定中，样品回收率为97．5％～104．4％，完全满足测定的要求。Gas phase molecular absorption spectrometry is a new method for the determination of ammonia nitrogen in water. In national standard method HJ/T195-2005, hypobromite oxidation agent is used for the oxidation of ammonia to nitrite nitrogen, and the process takes about half an hour, and low temperature will affect the degree of oxidation and determination sensitivity. Under low temperature, an improved method was developed by using hydrochloric acid-ethanol mixed solution pretreatment-high temperature oxidation-gas phase molecular absorption spectrometric method. The sample was first pretreated with lmL hydrochloric acid-ethanol mixed solution and boiled, to eliminate interference components such as NO2-, SO32-, sulfides. Then it was cooled to 60~70 ~C and added hypobromite oxidation agent, immediately it can be measured by gas phase molecular absorption spectrometer. The improved method was not affected by environmental temperature, and it took about 2rain to test a sample, with the sensitivity improved by 60%, and RSD of practical water sample 0.9%. The improved calibration curve, as stable, can be prepared in advance or called directly in emergency monitoring. The method can be used in the determination of ammonia nitrogen in surface water and wastewater samples with recoveries as 97.5%~104.4%, fully satisfactory to requirements of determination.

关 键 词：气相分子吸收光谱法 氨氮 高温氧化 灵敏度 

分 类 号：X830.2[环境科学与工程—环境工程]