流动注射在线消解测定水中总氮

研究了流动注射在线消解测定水中总氮的自动分析方法。方法基于使用电热和紫外在碱性过硫酸钾体系中消解样品,有机形态和无机形态的氮都被氧化为硝酸盐氮,消解效率为93.0%—108.5%。硝酸盐通过镀铜的镉柱还原为亚硝酸盐,亚硝酸盐与4-对氨基苯磺酰胺、N-（1-萘基）乙二胺盐酸盐形成偶氮染料,在540nm处进行测定。方法的线性范围为20.0—2000.0μg.L-1（r≥0.9995）,检出限为8.3μg.L-1,相对标准偏差为0.8%—1.6%;样品测定频率为35样/h,地表水、地下水、自来水等实际水样的加标回收率为95.9%—107.3%。对于污水样品中的总氮测定FIA与国标方法GB 11894-89对比,无显著差异。

Determination of Total Nitrogen in Water by OnLine Digestion with Flow Injection

An automatic method for the determination of total nitrogen in water by flow injection with on-line digestion was developed.The sample was digested with potassium persulphate in basic medium under electric heating and UV radiation.The organic and inorganic nitrogen compounds were oxidized to nitrate with the efficiency of 93.0%—108.5%.Nitrate was reduced to nitrite in a copperized cadmium column,and reacted with N-（1-naphthyl）ethylenediamine dihydrochloride and sulfanilamide to form azo dye and formed a color complex with maximum absorption peak at 540nm.The calibration curve was linear in the range of 20.0—2000.0μg·L-1（r≥0.9995）.Detection limit was 8.3μg·L-1.The relative standard deviation was 0.8%—1.6% with the sample throughput of 35 samples every one hour.Total nitrogen was determined in the real samples of river water,underground water and tap water with the recovery of nitrate of 95.9%—107.3%.There was no difference between FIA and batch method（GB 11894-89） through the determination of the total nitrogen in waste water.