铬(Ⅵ)—结晶紫—过氧化氢体系催化动力学光谱法测定痕量铬(Ⅵ)

Catalytic Kinetic Spectrometric determination of trace Cr(Ⅵ) with Cr(Ⅵ)-Crystal Violet-Hydrogen Peroxide system

75℃温度下，在硫酸介质中，铬（Ⅵ）能显著催化过氧化氢氧化结晶紫褪色反应，铬（Ⅵ）浓度在一定范围内与催化和非催化反应的吸光度差值（△A）成线性关系，且△A在较长时间内稳定，以此建立起动力学光度法测定痕量铬（Ⅵ）的新方法．实验研究了该反应的动力学行为，确定了最佳反应条件．方法线性范围为0～96μg·L^-1，其线性回归方程为△A=0．0033＋0．1401C（Ⅵ）（μg·25mL^-1），r=0．9985，检出限为6．91μg·L^-1．本方法操作简单，选择性好，可用于电镀废水、工业废水和湖水样品中有毒金属铬（Ⅵ）含量的分析测定．

It was based on the chromium （ Ⅵ） which could catalyze the redox reaction between H2O2 and Crystal Violet in H2SO4 aqueous solution medium at 75 ℃. The absorbance difference （ △A ） between cat- alytic reaction and non - catalytic reaction was linear with the concentration of chromium （ Ⅵ ） in a certain range. On optimum conditions, calibration curve was linear in the range of 0 -96 μg . mL^-1, with the detection limit as low as 6.91 μg.mL^-1 （ regression coefficient was 0. 998 5 ）. The regression equation was △A = 0. 0033 ＋ 0. 1401C （μg/25mL）. The method was simple and selective. It has been applied satisfactorily to the determination of chromium （Ⅵ ） in wastewater samples.