I_3~-—Rhodamine dye system for the determination of Iodine in salt

Potassium iodate reacted with excess potassium iodide to form I3-in the medium of HCl,and I3-reacted with Rhodamine 6G,Rhodamine B and Butyl Rhodamine B respectively to form ionic association,which made the absorbency dropped obviously and the maximum absorption wavelength of the three systems was at 526,558 and 559 nm respectively.Beer's law was obeyed with the concentration of iodine in the range of 0.04~0.80 μg/mL and the apparent molar absorptivity was 1.77×105,1.87×105 and 2.06×105 L · mol-1 · cm-1 respectively.The method has been used for the determination of iodate in table salt with satisfactory results.