偶氮胂Ⅲ褪色分光光度法测定食盐中碘

Spectrophotometric Determination of Iodine in Table Salt by Color Fading Reaction of Arsenazo Ⅲ

在硝酸介质中 ,有溴化钾存在下 ,碘酸根对偶氮胂 有褪色作用 ,且褪色的程度与碘酸根的量在一定范围内呈正比。据此建立了测定微量碘的新方法。最大吸收在 5 33nm处 ,碘浓度在 0— 8.0 μg/ 10 m L 范围内符合比耳定律 ,检出限为 8.38× 10 - 9g/ m L,方法操作简单 ,重现性好 ,用于加碘食盐中碘的测定 。

The fading reaction of arsenazo Ⅲ in the medium of nitric acid is quickened by IO - 3.The fading degree of the color intensity is found to be directly proportional to the amount of present iodate.Based on this fact,a spectrophotometric method for the determination of iodine in table salt is proposed.The decrease in absorbance(Δ A ) is measured at the wavelength of 533nm which is the absorption maximum of arsenazo Ⅲ.The detection limit is 8.38×10 -9 g/mL and linear range is in the range of 0-8.0μg/10mL for iodine.The results are satisfactory.