流动注射-砷钼杂多酸分光光度法测定环境水样中砷(Ⅴ)

来源期刊：冶金分析2010年第12期

论文作者：魏良 代以春 张新申

文章页码：60 - 64

关键词：砷； 流动注射分光光度法； 砷钼杂多酸； 甲基绿

Key words：arsenic； flow injection spectrophotometry； heteromolybdoarsenic acid； methyl green

摘    要：在0.06 mol/L硫酸介质中,砷(Ⅴ)与钼酸铵形成砷钼杂多酸,在表面活性剂聚乙烯醇存在的条件下,砷钼杂多酸可以和甲基绿生成可溶于水的离子缔合物,该缔合物在655 nm处有最大吸收,据此建立了一种简单、快速的流动注射-分光光度法在线测定环境水中砷(Ⅴ)的方法。砷的质量浓度在5.0～240.0μg/L范围内符合比尔定律,检出限为0.442μg/L(3倍基线噪音)。对含量为160.0μg/L的砷标准溶液进行14次平行测定,其相对标准偏差为1.6%。本方法具有良好的选择性(SiO₃^2-、PO₄^3-对测定有干扰,加入草酸和柠檬酸作掩蔽剂,可消除其干扰),用于环境水样分析,回收率为93%～108%。

Abstract: Arsenic(Ⅴ) and ammonium molybdate could form heteropoly arsenomolybdic acid in 0.06 mol/L sulfuric acid medium.In the presence of polyvinylalcohol,heteropoly arsenomolybdic acid could form a water soluble ion-association compound with methyl green,which had maximum absorption at 655 nm.Based on this,a rapid and simple flow injection spectrophotometric method for online determination of arsenic(Ⅴ) in environmental water samples was proposed.Beer’s law was obeyed for arsenic(Ⅴ) in the concentration range of 5.0-240.0 μg/L and the detection limit was 0.442 μg/L calculated from three times of the average background noise.The relative standard deviation of 1.6% was obtained by determining 160.0 μg/L As(Ⅴ) standard solution(n=14).The proposed method had good selectivity (The interference of SiO₃^2- and PO₄^3- could be eliminated by adding oxalic acid and citric acid as masking reagents).Recoveries of the proposed method were between 93% and 108% for determination of arsenic(Ⅴ) in environmental water samples.