氧化褪色光度法测定食品中的碘

研究了在硫酸介质中,碘酸根在KBr催化作用下氧化罗丹明B,使其褪色的最佳条件,建立了测定微量碘的新方法。通过实验,测得最大吸收波长为490nm,表观摩尔吸光系数为1.5×104L·mol-1·cm-1,碘测定的线性范围为0～75μg/25mL,检测限为1.2×10-7mol/L。本方法的相对标准偏差为0.28%～1.9%;回收率为97.9%～101.2%。用于食品中碘的测定,结果令人满意。

A new method has been developed for the determination of trace iodine in food by oxidation-decoloration with rhodamine B. The color system has a maximum absorption at 490nm in the medium of sulfuric acid with a molar absorbance of 1.5×104L·moL-1·cm-1. Beer'S law is obeyed in the range of 0～75μg/25mL of iodine. The detection limit is 1.2×10-7mol/L. The relative standard deviation is in the range of 0.28%～1.9%. The recovery is 97.9%～101.2% . The method can be used for determination of the trace iodine in food.