紫外分光光度法测定饮用水中碘离子

Determination of iodine ions in drinking water by using ultraviolet spectrophotometry

目的 探讨应用紫外分光光度法测定饮用水中碘离子的方法及测量条件的选择.方法 利用溴水定量氧化I^-生成IO3^-,再用甲酸除去过量的溴,IO3^-在过量碘化物存在下氧化I^-产生3倍摩尔量的I3^-,在紫外光区的286 nm具有最大吸收,并在345 nm处另有一略低的吸收峰,ε286=1.3×10^5 L·mol^-1·cm^-1,ε345=8.1×10^4 L·mol^-1·cm^-1,均具有很高的灵敏度.结果 I-浓度与其吸光值在10～100 μg·L^-1范围内成线性关系,标准曲线的相关系数分别为0.9990（286 nm处）和0.9991（345 nm处）.结论 用于饮用水中微量碘离子的测定,方法简便、快速,结果准确.

Objective To evaluate the methods and measurement conditions of the ullraviolet spectrophotometry for determinafion of iodine ions in drinking water. Methods IO3^- was prepared by quantitative oxidation of bromine water, with the excessive bromine removed with formic acid. In the presence of excessive iodide, I^- would be oxidized by IO3^- to form 3 times of I3^- in tool, displaying maximal absorption at 286 nm in ullraviolet zone and a slightly low apex at 345 nm. ε286=1.3×10^5 L·mol^-1·cm^-1,ε345=8.1×10^4 L·mol^-1·cm^-1, with both showing high sensitivity. Results A linearity relationship betwcen the concentration and the absorption value of I^- within the range of 10 - 100 μg·L^-1, with the correlation coefficients being 0. 9990 and 0.9991 at 286 nm and 345 nm respectively. Conclusion This is a simple, convenient and rapid method to yield precise results in the determination of trace iodine ions in drinking water.