催化动力学极谱法测定痕量亚硝酸根

CATALYTIC POLAROGRAPHIC DETERMINATION OF TRACE AMOUNTS OF NITRITE

在硫酸介质中 ,痕量亚硝酸根对溴酸钾氧化酸性铬深蓝的反应有极强的催化作用 ,研究了最佳反应条件 ,发现在氨缓冲溶液中酸性铬深蓝具有良好的极谱峰 ,以极谱法监测催化反应过程中酸性铬深蓝浓度的变化 ,建立了催化动力学极谱法测定痕量亚硝酸根的方法。方法的线性范围为 0 .2 0～ 1.34μg·ml- 1,检出限为 0 .0 88μg·ml- 1,应用于雪水、雨水中痕量亚硝酸根的测定 ,结果满意。

In a dilute sulfuric acid medium, trace amounts of NO - 2 ion showed a strong catalytic effect on the oxidation reaction between acid chrome dark blue (ACDB) and potassium bromate. Furthermore, in an ammoniacal buffer solution, ACDB gave a sensitive polarographic adsorptive wave at E p=-0.65V( vs .SCE). It was found that the peak current difference Δ I between the values of catalytic reaction ( I p) and non catalytic reaction ( I 0) kept a linear relationship with concentration of NO - 2 ion in the range of 0.20～1.34μg·ml -1 . Based on these phenomenon, a sensitive kinetic polarographic method of determination of trace amounts of NO - 2 ion was established. The detection limit of the method was found to be 0.088μg·ml -1 . Satisfactory results were obtained in its application to the determination of NO - 2 in snow and rain water.