紫外吸光光度法测定碘离子  

UV-SPECTROPHOTOMETRIC DETERMINATION OF IODIDE

作　　者：魏丹毅[1] 刘绍璞[2] 胡小莉[2] 

机构地区：[1]宁波大学化学系 [2]西南师范大学环境化学研究所,重庆400715

出　　处：《理化检验（化学分册）》2001年第11期505-507,共3页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

摘　　要：利用溴水氧化I- 形成IO- 3 ,过量溴水用甲酸除去后在过量碘化物存在下 ,IO- 3 氧化I-产生 3倍摩尔量I- 3 ,而I- 3 在紫外光区的 2 86nm具有最大吸收 ,并在 34 5nm处另有一略低的吸收峰 ,ε2 86=1.3× 10 5L·mol- 1·cm- 1,ε34 5=8.1× 10 4 L·mol- 1·cm- 1,均具有很高的灵敏度。I- 在 0～16μg/2 5ml范围内遵守比耳定律 ,方法有较好的选择性 ,方法简便快速 ,用于碘盐中碘离子的测定 。It is found that iodide (I -) can be quantitatively oxidized to iodate (IO - 3) by bromine. After the elimination of the excess bromine through its reaction with formic acid, the iodate formed is reacted with excess of iodide in an acidic medium to give free iodine in the ratio of one mole of IO - 3 giving three moles of iodine. The iodine in the solution, showing its absorption maxima at 286nm and a lower absorption peak at 345nm, can thus be determined photometrically in the UV spectrum region. The determination at both the above mentioned wavelengths showed relatively high sensitivity ( ε 286 =1.3×10 5L·mol -1 ·cm -1 , ε 345 =8.1×10 4L·mol -1 ·cm -1 ), and high selectivity. Beer′s law is obeyed in the range of 0～16μg of iodide per 25ml of solution. The method is proved to be simple and rapid, and has been applied to the determination of iodide in table salt with satisfactory results.

关 键 词：紫外分光光度法 碘离子 碘酸根离子 溴水 碘盐 测定 

分 类 号：TS365[轻工技术与工程] TS37