从紫薯中提取天然花青素,作测定汞(Ⅱ)的阻抑反应的指示剂.汞(Ⅱ)在硫酸介质中,对溴酸钾氧化天然花青素褪色反应有灵敏的阻抑作用,由此建立了测定汞(Ⅱ)的阻抑动力学新体系.探索了阻抑褪色反应最佳测定条件和动力学参数.在最佳测定波长530nm条件下,汞(Ⅱ)的质量浓度在0.01～0.26μg·mL-1范围内与阻抑反应溶液和非阻抑反应溶液的吸光度差值具有良好的线性关系,检出限为2.64×10-9g·mL-1.动力学实验表明,阻抑褪色反应为准零级反应,表观活化能为40.88kJ·mol-1,表观反应速率常数为5.57×10-4 s-1.实验考察了二十多种共存离子的影响.运用该法测定氯碱工业废水中的汞(Ⅱ),加标回收率为98.3％～102.0％,相对标准偏差小于3.1％,本法测得值与原子吸收光谱法测得的结果一致.%The natural anthocyanins was extracted from purple sweet potato as indicator for the determination of mercury. A new ki-netic spectrophotometric method for determination of trace mercury has been proposed. Mercury can sensitively inhibit the discolora-tion reaction of f natural anthocyanins and potassium bromate in H2 SO4 medium. The optimum kinetic conditions of the inhibited re-action has been investigated. The wavelength for the determination is 530 nm. The linear range for determination of mercury is 0. 01～0. 26μg·mL-1 with the detection limit of 2. 64×10-9g·mL-1. The results from the studies suggested that the inhibited reaction was zero-order and the apparent activation energy of this reaction was 40. 88kJ·mol-1,and the apparent rate constant was 5. 57× 10-4s-1. The interferences of twenty kinds of foreign ions were also studied. The procedure has been used to determine mercury in caustic alkali and polyvinyl chloride industry wastewater,with the relative standard deviation of below 3. 1％and the average recov-ery of 98. 3％ ～102. 0％. Results obtained by this method were consistent with the results found by atomic absorption spectropho-tometry. .
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