Rh(Ⅲ)-DBC-偶氮胂络合物吸附波的研究

STUDY ON THE POLAROGRAPHIC ADSORPTIVE WAVE OF RHODIUM ( Ⅲ )-ARSENAZO-DBC COMPLEX

在pH 3.2的甲酸-甲酸钠介质中,Rh(Ⅲ)与DBC-偶氮胂生成络合物,于-1.04V(vs.SCE,下同)出现一尖锐、灵敏的极谱波,峰电流与Rh(Ⅲ)浓度在2.5×10^(-8)～9.2×10^(-7)mol·L^(-1)范围内呈良好的线性关系,检出限为6.1×10^(-9)mol·L^(-1)。用多种电化学方法研究了极谱波的性质。证明-1.04V处的极谱波为络合物吸附波,峰电流由中心离子Rh(Ⅲ)还原产生。电子转移数为3,络合物组成为Rh(Ⅲ):DBC-偶氮胂=1:2。试验了多种离子对峰电流的影响,采用离子交换法分离干扰离子,用于标样中铑的测定,得列满意结果。

In a medium of HCOOH-HCOONa (pH 3. 2),Rh( Ⅲ ) reacts with arsenazo-DBC to form a complex and a sharp and sensitive polarographic adsorptive wave appears at 1. 04V(vs. SCE ). The peak height has a linear relationship with the concentration of Rh( Ⅲ ) in the range of 2.5×10^(-5)~9. 2×10^(-7)mol ·L^(-1). Many electrochemical methods have been used to study the properties of the polarographic wave which proved that the po larographic wave at 1. 04V is an adsorptive wave of the complex. The peak current is produced by reduction of central ion Rh( Ⅲ ) of the complex, and the numbers of electrons transfered is 3. The composition of the complex is Rh( Ⅲ ) : Arsenazo-DBC = 1 : 2. Effects of interference ions have been tested. The interfering components are separated by ion exchange method. The method has been applied to the determination of Rhodium in standard sample with satisfactory results.