加碘酸钾食盐中碘含量的紫外分光光度法测定

Determination of Iodine in Edible Salt Added Potassium Iodate by Ultraviolet Spectrophotometry

根据碘 (I2 )、碘离子 (I-)和碘三离子 (I3 -)的紫外吸收光谱 ,拟订了加碘酸钾食盐中碘含量的光度测定方法 .在 pH 2 .4 ,KI浓度为 0 .0 1mol/L的HCl介质中 ,1mol碘酸钾可定量转变为 3molI3 -,通过测量I3 -在 2 88nm或 35 0nm处的吸光度 ,可计算食盐样品中碘的含量 .方法的加入回收率在 96 .8%～ 10 2 .6 %之间 .本文中 ,笔者分析了 2种市售碘盐样品 ,结果令人满意 .

According to the ultraviolet absorption spectra of iodine,iodide ion and triiodide ion, a method for determination of iodine in edible salt added potassium iodate was proposed. In the medium of HCl with pH 2.4, 0.01?mol/L KI, 1 mol potassium iodate may be quantitatively converted into 3?mol I 3-.By measuring the absorbance of I 3- at 288 or 350 nm, quantity of iodine in edible salt can be calculated. A recovery percent of this method was found to be 96.8?%～102.6?%. Two samples of edible salt purchased from market were analyzed. The results were satisfactory.