动力学分光光度法测定地质样品中溴碘

Kinetic Spectrophotometric Determination of Trace Bromide and Iodide in Geological Samples

利用溴、碘在ＨＣｌ介质中对Ｈ２Ｏ２氧化邻苯二酚紫（ＰＶ）反应的催化，与高温热水解分解样品，离子交换预浓集和分离溴、碘相结合，建立了地质样品中溴、碘的测定方法。ＮＯ－２也能催化该反应严重干扰溴、碘的测定，加入氨基磺酸可以消除其对测定的影响。工作曲线在０～４μｇＢｒ－和０～２μｇＩ－时符合比尔定律，样品测定下限是０２×１０－６Ｉ－和０５×１０－６Ｂｒ－。对于含量为３０×１０－６Ｂｒ－和２０×１０－６Ｉ－的样品，其相对标准偏差分别为４９％和６６％（ｎ＝１２）。

A kinetic spectrophotometric method for the determination of bromide and iodide based on their catalytic effects on oxidation of pyrocatechol violet by hydrogen peroxide in HCl solution and sample digestion by high temperature hydrolysis is described in this paper. The Beers law is obeyed in ranges of 0～4 μg for Br - and 0～2 μg for I -. The limits of detection for Br - and I - in geological samples are 0.5×10 -6 and 0.2×10 -6 respectively. The interferences of NO - 2 on the determination for both elements are removed by the addition of sulfamic acid in sample solutions. The method has been applied to the determination of Br - and I - in geological samples with precision of 4.9% RSD for Br - and 6.6% RSD for I -( n =12).