SEPARATION AND DETERMINATION OF TRACE AMOUNTS OF ZINC AND CADMIUM BY ONLINE ENRICHMENT IN FLOW-INJECTION FLAME ATOMIC-ABSORPTION SPECTROMETRY

Synthesis and characterization of a series of tercopolymeric chelating resins involving 8-hydroxyquinoline and resorcinol-hydroquinone are discussed. The resins were used in the determination of zinc and cadmium after preconcentration, at batch level, and by flow injection (Fl) with micro-columns of the resins. Flow rate, pH, equilibration time, microcolumn dimensions, and the type and concentration of eluents were optimized. It was observed that pH 3 for zinc and pH 3-6 for cadmium are desirable for effective preconcentration. The rate of metal exchange and the activation energy for the exchange were determined at 30, 35, 40 and 45-degrees-C. A column length of 2 cm and a flow rate of 2 ml min-1 was found to be optimum for the preconcentration of zinc and cadmium using the Fl system. The lower detection limit for the metal ions was found to be 1 ng ml-1. Column chromatographic separations of Zn + Cd; Cu + Cd; Cu + Zn; Cd + Co + Zn; and Cu + Co + Cd were carried out using an eluent switching technique.