催化动力学分光光度法测定微量的汞

Determination of trace mercury(Ⅱ) by catalytic spectrophotometry

在pH=4．0的乙酸-乙酸钠缓冲溶液中，微量的Hg（Ⅱ）对亚铁氰化钾与1，10-邻菲哕啉（1，10-0-phen）显色反应有催化作用，加入硫脲能提高其灵敏度，显色程度与Hg（Ⅱ）量在一定范围内呈线性相关，借此建立测定微量Hg（Ⅱ）的分光光度法。实验表明，有色溶液最大吸收波长为515tim，摩尔吸光系数ε=3．72×106L／（mol·cm），相关系数为r=0．9991，催化程度与Hg（Ⅱ）浓度在（O．0-1．2）μg/25mL范围内符合比耳定律，选择性好，利用该方法直接测定人工合成水样中汞的含量，以及河水、池塘水中微量汞的含量分析，结果满意。

Trace mercury （Ⅱ） catalyzes chromogenic reaction of 1,10-phenanthroline （1,10-0-phen） with potassium ferrocyanide （K4Fe（CN） 6 ） in a weak acid medium （pH = 4.0 HOAc-NaOAc buffer solution） has been studied. The addition of thiourea can further increase the sensitivity of the reaction and the chromgenic extent is linear with the concentration of mercury （Ⅱ）. Based on this study,a spectrophotometric method for the determination of trace mercury（Ⅱ） was developed. The results show that the apparent molar absorptivity was 3. 72 × 10^6 L （ mol · cm ） at 515 nm and Beer＇ s law was obeyed for mercury （Ⅱ） in the range of （0.0 -1. 2 ） μg/25 mL. The relative standard deviation was less than 5 % and the recovery was 97.0% - 101.0% （n =6）. The method has been applied to the determination of trace mercury（Ⅱ） in rivulet and spring water and synthetic solution with satisfactory results.