结晶紫褪色分光光度法测定食盐中微量碘

Spectrophotometric determination of iodine in salt adding iodine by decoloration of crystal violet

在硫酸介质中和溴化钾存在下，碘酸根能使结晶紫氧化而褪色，且褪色的程度与碘酸根存在量成正比，从而建立了先度法测定碘的新方法。方法的最大吸收波长为630nm。碘酸根含量在5～42μg／10mL范围内符合比尔定律。表观摩尔吸光系数为1．1×10^4L·mol^-1·cm^-1。将该方法用于测定加碘食盐中的微量碘，结果满意。

In the medium of H2SO4 and in the presence of KBr, the color of crystal violet oxidized by iodide can be faded, and the degree of color fading is proportional to the concentration of iodide, and a new spectrophotometric method for determination of iodides reported. The maxium absorbance is at 630 nm. Beer＇s law is obeyed from 5 to 42μg of iodine per 10 mL of solution. The apparent molar absorptivity is 1.1 × 10^4 L ·mol^-1 ·cm^-1. The method has been used in the determination of iodine in iodine-spiked salt with satisfactory results.