SIMULTANEOUS DETERMINATION OF COBALT AND NICKEL BY SINGLE-SCANNING OSCILLOPOLAROGRAPHY

Sensitive adsorptive polarographic waves were given by complexes of cobalt(Ⅱ) and nickel(Ⅱ) with nitroso R salt in the presence of tetradecyl pyridine chloride (TPC) in a Na 2CO 3 NaHCO 3 buffer medium of pH 9.7. Potentials of their second derivative peaks were found at -0.64V( vs .SCE) for nickel and -0.80V ( vs .SCE) for cobalt. Linear relationships between their peak current heights and concentrations were obtained in the ranges 3 4×10 -9 ～3.7×10 -6 mol·L -1 of nickel(Ⅱ) and 7.0×10 -11 ～6.0×10 -6 mol·L -1 of cobalt(Ⅱ). The detection limits obtained were 2.4×10 -9 mol·L -1 (for 141ng·L -1 ) and 3.2×10 -11 mol·L -1 (for 1.9ng·L -1 ) for Ni(Ⅱ) and Co(Ⅱ) respectively. The method proposed has been satisfactorily used in the determination of micro amounts of cobalt and nickel in water and biological samples.