STUDIES ON POLAROGRAPHIC ADSORPTIVE WAVE OF THE SYSTEM OF THE RARE-EARTH(III)-COPPER(II)-M-TRIFLUOMETHYL CHLOROPHOSPHONAZO

A new heteronuclear complex, rare earth (III)-copper (II)-m-trifluomet hyl chlorophosphonazo (CPA-mCF(3)) system for determining trace rare e arth ions is presented. In a medium of 0.02 mol/L NH4Cl, 1.0X10(-3) mo l/L Cu(II), 1.0X10(-5) mol/L CPA-mCF(3), a very sensitive polarographi c adsorptive wave is observed by using a single sweep oscillopolarogra ph at about -0.83V (vs. Ag/AgCl). The linear relationship between the peak current and the concentration of rare earth exists from 6.0X10(-9 ) to 1.0X10(-6) mol/L. The detection limit of rare earth is down to 2. 0X10(-9) mol/L for Tm3+. This method has been applied to determine tra ce RE in several samples of Chinese tea. The results are satisfactory. The composition of the complex is detected as RE(III) : Cu(II) : CPA- mCF(3)=1:1:2.