Derivative Voltammetric Determination of Microamounts of Iodine

Iodine in the test solution was oxidized to IO-3 by excessive amounts of potassium permanganate solution and sodium hypochlorite solution,and excess of the oxidants was removed by reacting with sodium sulfite solution.Based on the electroactivity of iodate ion,a new method of linear-scanning derivative voltammetric determination of microamounts of iodine in a base solution containing sodium tetraborate and Tween-80 was proposed.Under the optimized experimental conditions,linear relationship between the values of 1st derivative of peak current (I′p) and concentration of iodine was obtained in the range of 0-16 μg·L-1 (r=0.996 4),with a detection limit of 0.6 μg·L-1.As proved by the results of interference tests,the proposed method showed good selectivity.In its application to the determination of iodine in some samples of foodstuffs,values of RSD′s (n=6) and average recoveries were found to be less than 0.9% and in the range of 97.8%-99.2% respectively.