Flow injection on-line preconcentration and flame atomic absorption spectrometric determination of iron, cobalt, nickel, manganese and zinc in sea-water

Abstract

A rapid and sensitive flow injection analysis–atomic absorption spectrometric procedure is described for the determination of iron, cobalt, nickel, manganese and zinc based upon on-line preconcentration on a microcolumn packed with C₁₈ material. These metals were complexed with 5,7-dichlorooxine from weakly acidic or neutral solutions in the flow system and adsorbed on the column. The preconcentrated elements were eluted with acidified methanol (pH ≥ 2) and injected directly into the nebulizer for atomization in an air–acetylene flame for measurement. The retention efficiency was better than 98%, resulting in sensitivity enhancement factors of 60, 80, 80, 80 and 60 for a 1 min preconcentration time for iron, cobalt, nickel, manganese and zinc, respectively. The respective detection limits were 4.0, 1.0, 1.0, 0.5 and 0.5 ppb, respectively. The throughput of samples was 30 h^–1, with a loading time of 1 min. The method was applied to sea-water samples.