银微盘电极上碘离子的示差脉冲溶出伏安法

Differential Pulse Stripping Voltammetry of Iodine at Silver Micro-disk Electrode

基于Ｉ－能与Ａｇ＋生成难溶化合物特性，在银微盘电极上研究了Ｉ－的示差脉冲溶出伏安法（ＤＰＳＶ）。该法不需镀汞，不要搅拌，可在较稀的支持电解质溶液中实施。于０．０８ ｍｏｌ／Ｌ ＨＡｃ－ＮａＡｃ及 ０．０１ ｍｏｌ／Ｌ ＥＤＴＡ介质中，能检出 １．００×１０－８ｍｏｌ／Ｌ的Ｉ，Ｉ－的浓度为５．００ × １０－８～１．２０×１０－６ｍｏｌ／Ｌ范围与峰电流有良好的线性关系。该法用于自来水中Ｉ－的测定，相对偏差为４．３％；标准加入回收率为９４％，用于加碘食盐中Ｉ－的测定，与标准分析法比较，相对误差为－４．０％。

I- may combine with Ag+ to form insoluble AgI. On this basis the cathodic strip- ping voltammetry(CSV) of iodine at silver microdisk electrode was investigated. CSV for the determination of I- was carried out in very diluted media under no stirring. The optimal ex- perimental conditions were discussed. The detection limit is about 1 × 10-8 mol/L I- with differential pulse cathodic stripping voltammetry (DPSV). A good proportionality between the peak current of DPSV and iodide concentration in the range of 5. 0 × 10-8 - 1. 2 × 10-6 mol/L has been observed. This method was successfully applied to the direct determination of trace iodine in tap water and iodized edible salt. For tap water a mean value of 1. 46 × 10-7 mol/L I- was found, while for iodized edible salt the value was 28. 7 μg/g I-. The relative standard deviation for iodine is 4. 3% and 4. 0% respectively.