铬蓝黑R褪色光度法测定食盐中碘含量

Decoloration Spectrophotometric Method for Determining Iodine in Iodized Salt with Chrome Blue Black-R

研究了在酸性介质中,碘酸根氧化铬蓝黑R的褪色反应。实验结果表明,碘酸钾-铬蓝黑R-硫酸反应体系的最大吸收波长为518nm,碘浓度在0-1.2mg/L范围内遵守朗伯-比尔定律,ΔA与浓度之间呈线性关系;518nm条件下该反应的相关系数为0.9992,表观摩尔吸光系数为2.538×104L.moL-1.cm-1。用于测定食盐中微量的碘,相对标准偏差为0.24%-0.28%,回收率为99.1%-102.7%,此方法准确度较高,操作简便、快捷,是测定加碘食盐中碘含量的较好方法之一。

This paper studies the decoloration reaction of iodate radicals oxidating chrome blue black-R in acidity medium.The study result indicates that the maximum absorption wavelength of potassium iodidechrome blue black R-vitriol reaction system is 518nm and the iodine chroma abides by the Lambert-Beer Law within 0-1.2mg/L. It also indicates that the relation between AA and chroma is linear relationship, the related quotiety of this reaction is 0.9992 under the condition of 518nm and the apparent molar absorption coefficient is 2.538×10^4L.moL^-1. cm^-1, The iodine used to determine the trace element in iodized salt the relative standard deviation of which is 0.24%-0.28% and the recovery rate of which is 99.1%-102.7%.With high precision and simple and short-cut operation,this method is a preferable method for determining iodine in iodized salt.