自来水中硝酸根的流动注射分光光度在线检测

On-line Spectrophotometric Determination of Nitrate Nitrogen in Tap Water by Flow Injection

建立了在线测定水中硝酸根的流动注射分光光度法.水样通过镉粒还原柱与对氨基苯磺酰胺溶液混和,将N- (1-萘基)-乙二胺溶液注入到此混合流,在λmax=540 nm处进行光度检测.线性范围为0.01～2.0 mg/L,检出限分别为 0.01 mg/L,测定频率为50次/h.本法灵敏度高、选择性好、分析速度快.应用本法测定自来水中硝酸根,获得满意结果.

On-line flow injection-spectrophotometric determination of nitrate nitrogen in tap water was studied. The sample flew through cadmium reductor which reduced nitrate to nitrite, then merged with sulfanilamide solution. N-(-Naphthyl)ethylenediamine dihydrochloride solution was injected into the mixed flow. Red dye formed by the reaction was spectrophotometrically detected at λmax = 540 nm. The linear range is 0. 01 to 2. 00 mg/L nitrate nitrogen with the detection limit of 0. 01 mg/L and the determination frequency of 50 times/h. This method has high sensitivity,good selectivity and fast analytical speed. It has been applied to the determination of nitrate nitrogen in tap water with relative standard deviation of 3. 5% for the determination results, indicating satisfactory accuracy.