偶氮胂Ⅲ-重铬酸钾动力学光度法测定痕量锡

Kinetic Spectrophotometric Determination of Trace Tin Based on Discoloring of ArsenazoⅢ Oxidized by Potassium Dichromate

基于 0 .0 2mol/LH2 SO4介质中 ,以抗坏血酸为活化剂 ,痕量Sn对K2 Cr2 O7氧化偶氮胂Ⅲ褪色反应的催化作用 ,建立了测定痕量锡的动力学光度法。方法检出限为 0 .0 5 μg/L ,线性范围为 0～ 4.0 μg/L ,终止反应后 ,吸光度可稳定 4h。结合磷酸三丁酯色谱分离 ,对水系沉积物国家一级标准物质进行分析 ,结果与标准值相符。以w(Sn)为 1 0 - 6水平的试样进行精密度检测 ,其RSD(n =6 )≤ 6 .0 %

Based on the catalytic effect of trace tin on discoloring reaction of arsenazoⅢ with potassium dichromate in 0.02 mol/L H 2SO 4 solution, while ascorbic acid acts as activator, a method for the determination of trace tin by kinetic spectrophotometry has been developed. The detection limit is 0.05?μg/L with linearity of 0～4.0?μg/L for Sn. The absorbance can keep constant within 4 hours after terminating the reaction.Combined with tributyl phosphate (TPB) chromatographic separation, the method has been applied to the determination of trace tin in national standard reference samples.The results are in agreement with certified values. The precision for samples with w (Sn)=10 -6 is ≤6.0% RSD ( n =6).