阻抑动力学分光光度法测定痕量镉

Determination of Trace Cd(Ⅱ)by Inhibitory Kinetic Spectrophotometry

基于在盐酸介质中,镉(Ⅱ)对溴酸钾氧化甲基蓝褪色反应有显著的阻抑作用,建立了测定痕量镉(Ⅱ)的动力学方法。以604nm为测定波长,镉(Ⅱ)在0.01—1.7μg·mL^(-1)内呈线性关系,检出限为5.6×10^(-3)μg·mL^(-1)。测定了动力学参数,该阻抑反应为一级反应,表观反应速率常数为1.58×10^(-3)s^(-1),活化能为67.89kJ·mol^(-1)。方法用于环境水样中痕量镉(Ⅱ)的测定,相对标准偏差为4.35%,回收率为96.1%—99.0%。

A kinetic methed for spetrophotometric determination of Trace Cd （ Ⅱ ） has been established based on significant inhibitory action of Cd （ Ⅱ ） on the oxidative fading reaction of methylene blue by potassium brominte in HC1 medium. Setting the catalyzed reaction at wavelength of 604nm,Cd （ Ⅱ ） has became linear relationship between the 0. 01-1. 7 μg/mL, which also has a detection limit of 5.64×10^-3μg/mL. Kinetic parameters were determined, which subject to a first-class catalytic reaction, and the apparent rate is a constant of K＇= 1.58 × 10^-3/s, while the apparent activation energy is 67.89kJ/mol. This method has a good selectivity for measuring the trace amount of Cd （ Ⅱ ） in waste water samples,and the RSD of the determination was 4.35%, the recovery percent was 96.1%-99.0%.