催化动力反应—离子选择电极法测定微量汞

催化动力反应—离子选择电极法测定微量汞 DETERMINATION OF TRACE AMOUNTS OF Hg2+ BY CATALYTIC REACTION-ISE MONITORING METHOD 路纯明 first-author 洪庆军 赵藻藩 < 正 > 催化动力分析法测定汞的指示反应多为氧化还原反应,也有人[1-7]采用亚铁氰化钾与邻菲啰啉的配位体取代反应。我们[8] 在研究Au 3+ 对铁氰化钾与EDTA的配位体取代反应的催化作用时,发现Hg 2+ 也有一定的催化作用,因此有可能利用这一指示反应来测定微量Hg 2+ 。实验证明,在邻苯二甲酸缓冲溶液（pH3.50—3.80）中,采用固定时间法和离子选择电报监测反应产物CN - ,可测定微量汞,线性范围为5.0×10 -8 —5.0×10 -6 MHg 2+ ,检测限为2.0×10 -8 M。本法与同类配位体取代反应的催化动力分析法相比,具有灵敏度高和线性范围宽的优点。 A new catalytic method for determination of Hg 2+ based on ligand exchange reaction between Fe（CN） 6 3- and EDTA catalyzed by Hg 2+ and monitored by Cyanide Selectrode with fixed-time procedure has been developed. The optimum condition for indicator reaction is: phthalate buffer solution （pH3.50—3.80）, 4×10 -4 M EDTA, 4×10 -4 M Fe（CN） 6 3- ,70℃.In the presence of traces Hg 2+ after the reaction runs for 15 min., it is stopped by adding 4×10 -4 M Pb 2+ solution which removes the excess EDTA immediately.The cyanide released from the catalytic reaction is determined by Cyanid Selectrode in NaOH medium. Its amountis proportional to the concentration of Hg 2+ over a range of 5×10 -8 -5×10 -6 M.The main interfering ions are Ag + , Au 3+ ,Co 2+ , Pd 2+ etc.. The method can be used to determine trace amounts of Hg 2+ in various samples after separating Hg 2+ from 0.1M HCl medium by sulfhydryl cotton. The mechanism of the catalytic reaction has been discussed. 中国科学院科学基金 1985-03-01 2021-04-01 3