催化荧光法测定痕量亚硝酸根

在稀磷酸介质中 ,溴酸钾可氧化吖啶橙使之褪色并伴随着吖啶橙荧光强度的减弱 ,但反应速率较慢。痕量亚硝酸根的存在对该反应可起到显著的催化作用 ,使反应的灵敏度明显提高 ,体系的荧光猝灭程度加强。基于此采用固定时间法提出了一种灵敏度高、选择性好的催化荧光法测定痕量亚硝酸根的新方法 ,并研究了该方法的动力学条件。催化反应在λex/λem =4 4 6 / 5 0 5nm处 ,5 5℃水浴中进行 10min。反应可允许较大量的 2 0多种常见离子存在 ,同倍量的Fe3 ,Br-、I-不干扰。亚硝酸根的线性范围为 0 0 5～ 5ng·mL-1,方法的检出限为 0 0 12ng·mL-1。用于水体和土壤中痕量亚硝酸根的测定 ,结果满意。

Catalysis-fluorescence Determination of Trace Nitrite Based on the Oxidation of Acridine Orange by Potassium Bromate

Acridine orange can be oxidized with discoloring and fluorescence quenching by potassium bromate in phosphoric acid medium, but the reaction rate is very low. The presence of trace nitrite can catalyze this reaction to improve the sensitivity of it apparently and to make the net fluorescence value of the system decrease greatly. Based on the above investigation, a new catalysis-fluorescence determination method of trace nitrite has been proposed. The method described is very sensitive and selective. The catalysis reaction is under the conditions of lambdaex/lambdaem = 446/505 nm, 55 degrees C and 10 min for the reaction time. The method permits the existence of more than 20 common foreign ions. There isn't interference by the same quantity of Fe3+, Br- and I-. The detection limit is 0.012 ng x mL(-1). The linear range of determination is 0.05-5 ng x mL(-1). The method has been used for the determination of trace nitrite in water and soil samples with satisfactory results.