催化动力学分析法测定超痕量钒的研究

Determination of Ultratrace Vanadium by Catalytic Kinetic Method

在稀磷酸介质及活化剂抗坏血酸存在下,痕量钒(Ⅴ)强烈催化溴酸钾氧化碱性品红褪色,据此建立了一个新的测定超痕量钒的催化动力学光度法.方法测定钒(Ⅴ)的线性范围为:0.0～400.0 pg/mL,检出限为27 pg/mL.实验考察了影响催化反应速率的各种因素,确定了实验的最佳条件.测定了催化反应的动力学参数:表观活化能E0'=170.1 kJ/mol,表观速率常数k'=2.8×10-3s-1,建立了动力学速率方程:-dCMR/dt=K'.CMR.CKBrO3.CVc.CV(Ⅴ).试验了25种共存离子的影响,发现大多数常见离子不干扰,方法直接用于环境水体中超痕量钒的测定,相对标准偏差为1.65%～2.03%.

According to the phenomenon that a trace amount of vanadium（V） can strongly catalyze the oxidation of Magenta red by potassium bromate to discolor in a dilute phosphoric acid medium with the existence of ascorbic acid,a new catalytic kinetic method for the ultratrace vanadium determination is established,which has the highest sensitivity among similar methods.Its linear range is： 0.0～400.0 pg/mL,the detection limit is 27 pg/mL.The influence factor of catalytic reaction rate and optimal experimental conditions,were investigated and determined.The catalytic reaction kinetic parameters are： apparent activation energy E0＇= 170.1 kJ/mol,apparent reaction rate constant k＇= 2.8×10-3 s-1,the dynamics speed equation：-dCMR/dt = K′CMR·CKBrO3·CVc·CV（V） has been established.After studying the interaction of 25 coexistent ions,it was discovered that the majority of common ions do not interfere.The method has been used to determine ultratrace vanadium in the environmental at water.The relatively standard deviation was 1.65%~2.03%.