Study on Determination of Iodine by Catalytically Potentiometric Method Using Crystal Violet Selective Electrode

A new catalytic potentiometric method for the determination of iodine was developed,based on the ability of iodide ion to catalyze.The redox reaction of crystal violet with sodium periodate in a phosphoric acid solution.A crystal violet ion selective electrode was used to indicate the change of the concentration of crystal violet in the reaction solution.This method can be operated conveniently.It showed high sensitivity and good selectivity,and had a linear relation within the range of 0.20～5 5 μg/25mL of I - and a detection limit of 4.1×10 -9 g/mL of I -.This method was used to determine iodine in table salt and drinking water samples with satisfactory results.The relative standard deviration (RSD) is less than 4.1% and the average recovery is 95.1% .