On-line preconcentration and determination of nickel and zinc in natural water samples by flow injection–flame atomic absorption spectrometry using PTFE-turnings for column packing

Abstract

A rapid, sensitive and low cost, time-based flow injection atomic absorption spectrometric method was described for the determination of nickel and zinc upon on-line preconcentration on a micro-column packed with polytetrafluoroethylene-turnings material. The metals formed on-line complexes with ammonium pyrrolidine dithiocarbamate from acidified solutions (pH 2.0) in the flow manifold and retained in the column. The preconcentrated elements were subsequently eluted quantitatively with isobutylmethylketone and injected directly into the nebuliser for atomisation and measurement. The system offered improved flexibility, low backpressure and applicability. The enhancement factors were 170 and 65 for Ni(II) and Zn(II), respectively. The respective detection limits were 0.5 and 0.3 µg L−1, and the precision, expressed as relative standard deviation, were 2.8% (at 5.0 µg L−1) and 3.2% (at 2.0 µg L−1), respectively. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference material and spiked environmental water samples.