硫脲介质中单扫描示波极谱法测定臭氧

Single Sweep Oscillopolarographic Determination of Trace Amounts of Ozone in Acidic Thiourea Medium

本文提出了一种线性扫描极谱检测臭氧的方法。在酸性磷酸盐缓冲溶液中（pH2．5）硫脲与臭氧进行反应。反应产物二硫二甲脒强烈地吸附在汞电极上，随着阴极化过程，在约－0．31V和－0．87V（vs．SCE，下同）产生两个还原峰。－0．31V的峰对于微量O3的极谱检测具有高灵敏度和选择性。其导数峰电流与O3浓度的线性范围为1．0×10－7～2．5×10－5mol／L检测限为4×10－8mol／L（1．9μg／L）。该方法已用大气中O3含量的连续监测。用循环伏安法，恒电位电解法研究了反应机制。第一个峰（－0．31V）归因于吸附的二硫二甲脒与汞通过前置化学反应产生HgS，然后此表面薄膜阴极溶出还原。

The single-sweep oscillopolarographic determination of ozone is based on its reaction with thiourea in acidic phosphate buffer(pH 2. 5). The product dithiodiformamidine is strongly adsorbed and then reduced at a mercury electrode with two peaks of about -0. 31 Vand -0. 87 V(vs. SCE). The peak of -0. 31 V provides high sensitivity and selectivity for the determination of trace amounts of ozone. The linear range is 1. 0×107～2. 5 × 10-5 mol/L and detection limit is 4× 10-8 mol/L (1. 9 μg/L). The method is used for direct determination of ozone content in atmosphere. The mechanism of the reaction was studied in detail by cyclic voltammetry, electrolysis, etc. The first peak (-0. 31 V ), i. e. the 'ozone peak' is ascribed to the reduction of a HgS film produced by preceding reaction of the adsorbed dethiodiformamidine product with mercury.