痕量锡的邻苯二酚紫体系催化光度法测定

基于在0.5 mol/L的硫酸介质中,痕量锡对溴酸钾氧化邻苯二酚紫的褪色反应具有催化作用,建立了催化光度法测定痕量锡的动力学光度法。讨论了酸度,氧化剂,显色剂,反应时间,反应温度,干扰离子等因素的影响,确定了该体系反应的最佳条件为:0.5 mol/L硫酸1.5 mL;0.1 mol/L溴酸钾1.25 mL;2.0×10-4mol/L邻苯二酚紫3.5 mL;反应时间为7 min;反应温度为100℃。在最佳的条件下,方法的检出限为4.51×10-3g/mL,线性范围为0~3μg/25 mL。进行了平行测定(n=11),其相对标准偏差1.88%,该方法简便,设备简单,易于操作,并且具有较高的灵敏度和选择性。用于水样、人发中痕量锡的测定,相对标准偏差分别为0.312%和1.11%,标准加入回收率分别为99.8%和99.5%。

Determination of Trace Tin by Catalytic Spectrophotometry with Pyrocatechol Violet System

Based on tin catalyzed oxidation of pyrocatechol violet by potassium bromate a new catalytic spectrophotometric method for determination of trace tin was developed.The kinetic behavior of the action was investigated by orthogonal design method in order to find the optimum experimental condition： 0.5 mol/L surfuric acid is 1.5 mL;0.1 mol/L potassium bromate is 1.25 mL,2.0×10-4 mol/L pyrocatechol violet is 3.5 mL;the reaction time is 7 min;the reaction temperature is 100℃.Under the option conditions,Beer＇s law is obeyed in the concentration of 0~3 μg/25 mL for tin with the detection of 4.51×10-3 μg/mL.The relative standard deviation for the parallel tests of samples（n=11） was calculated to be 1.88%.The method was applied to the determination of trace tin in tap water and human hair samples with satisfactory results,and the respective relative standard deviation was 0.312% and 1.11% and the respective recovery was 99.8% and 99.5%.