甲基红褪色光度法测定食盐中碘的研究

Spectrophotometric Determination of Iodine in Table Salt by Color Fading Reaction of Methyl Red

在酸性介质中,溴化钾存在下,碘酸根对甲基红有褪色作用,且褪色的程度与碘酸根的量有关,从而建立了碘的光度测定新方法。方法的最大吸收在520nm处,碘定量测定的线性范围为0～16μg/10mL,检出限为1.47×10-8g/mL。方法操作简单、快速、重现性好,用于加碘食盐中碘的测定,结果满意。

It is found that in the medium of H2SO4, the fading reaction of Methyl Red is quickened by IO-3 with the presence of KBr. The color fading of Methyl Red is found to be directly proportional to the amount of iodinate. Based on these facts, a spectrophotometric method for the determination of iodine in table salt is proposed. The decrease in absorbence (ΔA) is measured at the wavelength of 520 nm which is the absorption maximum of Methyl Red. The detection limit is 1.47×10-8 g/mL and linear range is 0～16 μg/10 mL for iodine.