非离子型微乳液增敏催化光度法测定痕量铊

Catalytic Ligand Dynamic Spectrophotometric Determination of Trace Thallium(Ⅲ) in Nonionic Microemulsion Mediumm

研究了在微乳液介质中，在pH=3．5的HAc—NaAc缓冲溶液中，用硫脲作活化剂，铊（Ⅲ）催化亚铁氰化钾和4，7-二苯基-1，10-邻菲咯啉之间配体交换反应，从而建立测定痕量铊的新的催化动力方法。在530nm处，表观摩尔系数为9．07×10^5L-mol·cm^-1，铊（Ⅲ）的含量在0～80μg·L^-1范围内，符合比耳定律，对反应各种因素和共存离子的影响进行了研究。该方法用于多种样品中痕量铊的测定，结果满意，其回收率在95％～105％之间，相对标准偏差小于5％。

The catalytic method has been developed for the determination of traces amounts of T1 （ Ⅲ ） in nonionic micreemulsion medium. The method is based on the catalytic effect of thallium （ Ⅲ） on the rate of a ligand substitution reaction between potassium ferrocyanide and 4,7 - biphenyl - 1,10 - phenanthroline（ BPT）. The reaction was followed spectrophotometrically at 530 nm by measuring the induction period. Beer＇ s law is obeyed in the range of 0 - 80 μg· L^- 1 of Tl^3 ＋ and the apparent molar absorptivity is 9.07 × 10^5 L· mol ^- 1. cm^- 1..The range of the determination of TI（ Ⅲ ） is 0 - 80 μg· L^- 1 The coexisting ion can be separated T1 （ Ⅲ ） in samples by mercapto containing dextran gel. The method is simple, rapid and accurate.