Separation and determination of trace amounts of zinc and cadmium by on-line enrichment in flow injection flame atomic absorption spectrometry

Abstract

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 °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.