砷(Ⅲ)-碘酸钾-中性红体系催化动力学荧光光度法测定痕量砷

摘要

A new kinetic fluorometric method for the determination of trace As(Ⅲ) was proposed based on the catalytic effect of As(Ⅲ) on the oxidation of neutral red by potassium iodate in H2SO4 medium,which lowered the fluorescence intensity. The effect of experiment conditions on the determination of arsenic(Ⅲ) was detailedly studied, including the dosages of neutral red, potassium iodate and sulfuric acid, the reaction temperature and the reaction time. The results indicated that the mass concentration of arsenic(Ⅲ) in the range of 2. 0-600 μg/L was linear to the change of solution fluorescence intensity.Detection limit was 0. 6 μg/L. The proposed method has been applied to the determination of arsenic (Ⅲ) in environmental water sample with relative standard deviations (RSD) less than or equal to 3. 5 ％ and standard addition recoveries of 98％-101％.%在H2SO4介质中,痕量As(Ⅲ)对碘酸钾氧化中性红的反应具有显著的催化作用,使其荧光强度减弱,据此提出了动力学荧光法测定As(Ⅲ)的新方法.详细研究了中性红、碘酸钾和硫酸的用量以及反应温度和时间对As(Ⅲ)测定的影响.结果表明,在最佳条件下,砷的质量浓度在2.0～600μg/L范围内与溶液荧光强度的改变值呈良好的线性关系,检出限为0.6μg/L.本法用于环境水样中As(Ⅲ)的测定,相对标准偏差小于或等于3.5%,加标回收率为98%～101%.