STRIPPING-VOLTAMMETRIC DETERMINATION OF TRANSITION-METALS USING ELECTRODES MODIFIED BY AZACROWN COMPOUNDS

Voltammetric properties of macrocyclic complexes of transition metals are studied by using a carbon-paste electrode modified by diaza-18-cro wn-6, Cyclam, and their derivatives. A selective stripping-voltammetri c procedure is proposed for determining Ni(II) and Co(II) with a carbo n-paste electrode modified by Cyclam and its derivatives. To improve t he sensitivity and selectivity of analysis, it is suggested that metal ions be preconcentrated at the surface of the modified electrode by u sing a 0.1 M NaCl solution as a supporting electrolyte with the follow ing recording of voltammograms in the range from -0.3 to 0.8 V in a 0. 1 M KOH solution. The detection limits for Ni(II) and Co(II) are 4 x 1 0(-8) and 1.2 x 10(-7) M, respectively.