采用过量联合氧化剂高锰酸钾-次氯酸钠氧化试液中碘至IO-3,剩余的高锰酸钾和次氯酸钠用过量的亚硫酸钠反应除去,利用IO-3的电活性,建立了在四硼酸钠-吐温-80底液中的线性扫描伏安法测定微量碘的方法.优化了试验条件,研究了伏安特性.在最佳试验条件下,一阶导数峰电流与碘质量浓度在0~16 μg·L-1范围内呈线性关系(r=0.996 4),检出限为0.6 μg·L-1.对共存离子作了干扰试验,表明方法的抗干扰能力较强,用于食品中微量碘的测定结果的相对标准偏差(n=6)值均小于0.9%,加标回收率在97.8%至99.2%之间.

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.