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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。
The automatic analytical method for the determination of total nitrogen in water by flow injection on-line digestion was studied. The method was based on the digestion of samples with alkaline potassium persulfate using electrothermal and UV. Both organic and inorganic forms of nitrogen were oxidized to nitrate nitrogen with a digestion efficiency of 93.0% -108.5%. Nitrates were reduced to nitrites by copper-plated cadmium columns, and azo dyes were formed between nitrite and 4-aminobenzenesulfonamide, N- (1-naphthyl) ethylenediamine hydrochloride at 540 nm . The linear range of the method was 20.0-2000.0μg.L-1 (r≥0.9995). The detection limit was 8.3μg.L-1 with a relative standard deviation of 0.8% -1.6% Water, groundwater, tap water and other actual water samples spiked recoveries of 95.9% -107.3%. For the determination of total nitrogen in sewage samples FIA GB 11894-89 compared with the national standard method, no significant difference.